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Micro-(nano-)encapsulation technology involves building of a barrier between the core and the environment and offers a number of benefits to preserve the functional and physicochemical properties of core material. Tremendous progress has been made in synthesizing well-defined capsules to achieve desired properties such as particle size, chemical composition, and controlled release of the payload.
Encapsulation of volatile organic compounds (VOCs) that could evaporate with a defined rate is of immense interest for application in emission reference materials (ERM). These are urgently needed for quality assurance and quality control purposes (QA/QC) required by test standards for the determination of chemical emissions of construction and other materials for interior use. As such ERMs are hardly available on the market, the EU-funded EMPIR project MetrIAQ [1] was started to fill this gap by developing a material with temporally constant emission of VOCs typically found in indoor air.
Different capsules in a size range between 5 and 50 μm were synthesized through an interfacial polyaddition/polycondensation reaction in direct (water-in-oil) system. As VOC several types of hydrophobic liquid materials were used. After synthesis, the morphology and physicochemical properties of capsules were characterized by electron microscopy, FTIR and DSC/TGA. An encapsulation efficiency up to 90% could be reached. The emission kinetic of volatile agents was studied in emission test chambers at 23 °C and 50% RH for 14 days. First results indicate that variation of the cross-linking grade of the shell material is one important parameter to adjust the desired emission rate. The overall aim is to achieve a consistent emission profile that decreases by less than 10 % over a target period of at least 14 days.
Micro-(nano-)encapsulation technology involves building a barrier between the core and the environment and offers several benefits to preserve the functional and physicochemical properties of core material. Tremendous progress has been made in synthesizing well-defined capsules to achieve desired properties such as particle size, chemical composition, and controlled release of loaded compounds.
Encapsulation of volatile organic compounds (VOCs) that could evaporate with a defined rate is of immense interest for application in emission reference materials (ERM). These are urgently needed for quality assurance and quality control purposes (QA/QC) required by test standards for the determination of chemical emissions of construction and other materials for interior use. As such ERMs are hardly available on the market, the EU-funded EMPIR project MetrIAQ was started to fill this gap by developing a material with temporally constant emission of VOCs typically found in indoor air.
Reliable measurement of the size of polydisperse, complex-shaped commercial nanopowders is a difficult but necessary task, e.g., for regulatory requirements and toxicity risk assessment. Suitable methods exist for the accurate characterization of the size of non-aggregated, stabilized, spherical and monodisperse nanoparticles. In contrast, industrial nanoscale powders usually require dedicated sample preparation procedures developed for the analysis method of choice. These nano-powders tend to agglomerate and/or aggregate, a behavior which in combination with an innate broad particle size distribution and irregular shape often significantly alters the achievable accuracy of the measured size parameters. The present study systematically tests two commercially available nanoscale powders using different sample preparation methods for correlative analysis by scanning electron microscopy, dynamic light scattering, Brunauer–Emmet–Teller method and differential mobility analysis. One focus was set on the sample preparation by embedding nanoparticles in carbon-based hot-mounting resin. Literature on this topic is scarce and the accuracy of the data extracted from cross sections of these particles is unclearly stated. In this paper systematic simulations on the deviation of the size parameters of well-defined series of nanoparticles with different shapes from the nominal value were carried out and the contributing factors are discussed.
BAM is currently building up a platform of novel nanoRMs relying on iron oxide nanoparticles of different shape, size and surface chemistry. Iron oxide was chosen as a core material because of its relevance to the material and life sciences.
As a first candidate of this series, we present cubic iron oxide nanoparticles with a nominal edge length of 8 nm. These particles were synthesized by thermal decomposition of iron oleate in high boiling organic solvents adapting well-known literature procedures. After dilution to a concentration suitable for electron microscopy (TEM and SEM) as well as for small-angle X-ray scattering (SAXS) measurements, the candidate nanoRM was bottled and assessed for homogeneity and stability by both methods following the guidelines of ISO 17034 and ISO Guide 35.
The particle sizes obtained by both STEM-in-SEM and TEM are in excellent agreement with a minimum Feret of 8.3 nm ± 0.7 nm. The aspect ratio (AR) of the iron oxide cubes were extracted from the images as the ratio of minimum Feret to Feret resulting in an AR of 1.18 for TEM to 1.25 for SEM. Alternatively, a rectangular bounding box was fitted originating from the minimum Feret and the longest distance through the particle in perpendicular direction. This led to AR values of 1.05 for TEM and 1.12 for SEM, respectively. The results confirm the almost ideal cubic shape.
Laser Powder Bed Fusion (L-PBF) is a promising additive manufacturing (AM) technology for metal part production especially for complex and lightweight structures or functional designs. In L PBF processes several by-products including welding plume and its condensates, spatter and ejected powder are generated during laser exposure. Investigations of micro- and nano-sized by-products have received little attention in literature. This study focuses on the analysis of particle emissions in L PBF of 316L stainless steel using a scattered light aerosol spectrometer and a fast mobility particle sizer spectrometer during the process which allows for in-situ analysis of particle sizes in the range of 6 nm to 100 µm. A distinct correlation of emission signals to part position can be revealed. In addition, a significant influence of laser scanning vector directions on emission signals is presented. Furthermore, differing powder layer thicknesses can be recognised by deviations in emission signals.
Laser Powder Bed Fusion (L-PBF) is a promising additive manufacturing (AM) technology for metal part production especially for complex and lightweight structures or functional designs. In L PBF processes several by-products including welding plume and its condensates, spatter and ejected powder are generated during laser exposure. Investigations of micro- and nano-sized by-products have received little attention in literature. This study focuses on the analysis of particle emissions in L PBF of 316L stainless steel using a scattered light aerosol spectrometer and a fast mobility particle sizer spectrometer during the process which allows for in-situ analysis of particle sizes in the range of 6 nm to 100 µm. A distinct correlation of emission signals to part position can be revealed. In addition, a significant influence of laser scanning vector directions on emission signals is presented. Furthermore, differing powder layer thicknesses can be recognised by deviations in emission signals.
Growing awareness of the impact of monoterpenes on climate, atmospheric chemistry, and indoor air quality has necessitated the development of measurement standards to globally monitor and control their emissions. For National Metrology Institutes to develop such standards, it is essential that they demonstrate measurement equivalence for assigned values at the highest levels of accuracy. This report describes the results of a pilot comparison for 4 key monoterpene species: α-pinene, 3-carene, R-limonene and 1,8-cineole, at a nominal amount-of-substance fraction of 2.5 nmol mol-1. The objective of this comparison is to evaluate participant capabilities to measure trace-level monoterpenes using their own calibration techniques.
The new OECD test guideline will address the following four main steps in the determination of the length and width distributions of fibers: sample preparation, image acquisition, data evaluation and uncertainty analysis. As the sample preparation has to be optimized for each material, general quality criteria will be given in the protocol. For full visibility of a fiber the appropriate resolution has to be chosen. In the data evaluation the length and diameter of each fiber will be determined concurrently to allow for application of different regulatory definitions. The quality of the results critically depends on the sample preparation as well as the data evaluation. In this step the classification rules have to be formulated and followed accurately in order to optimize reproducibility of the method. The SOP will be validated in an international round robin test, which is planned for 2018/2019.
The new OECD test guideline will address the following four main steps in the determination of the length and width distributions of fibers: sample preparation, image acquisition, data evaluation and uncertainty analysis. As the sample preparation has to be optimized for each material, general quality criteria will be given in the protocol. For full visibility of a fiber the appropriate resolution has to be chosen. In the data evaluation the length and diameter of each fiber will be determined concurrently to allow for application of different regulatory definitions. The quality of the results critically depends on the sample preparation as well as the data evaluation. In this step the classification rules have to be formulated and followed accurately in order to optimize reproducibility of the method. The SOP will be validated in an international round robin test, which is planned for 2018/2019.
The particle size distribution is considered the most relevant information for nanoscale property identification and material characterization. The current OECD test guideline on particle size and size distribution (TG 110) is not applicable to ‘nano-sized’ objects. In this project we thus develop a new OECD test guideline for the measurement of the size and size distribution of particles and fibers with at least one dimension in the nanoscale. A fiber is defined as an object having an aspect ratio of length/diameter l/d >3. The width and length of each fiber should be measured concurrently.
In order to measure the particle size distributions, many techniques are available. 9 methods for particles and 2 methods for fibres have been tested in a prevalidation study and appropriate methods will be compared in an interlaboratory round robin test starting in February 2019.
Vorstellung der Ergebnisse bei der Entwicklung einer neuen OECD Prüfrichtlinie zur Bestimmung der Partikelgröße und Anzahlgrößenverteilung von Nanomaterialien. (Projektteil Fasern.)
Ergebnisse:
Abweichungen zwischen SEM and TEM insbesondere bei langen Fasern
Die Anwendung von TEM auf kurze Fasern < 5 µm beschränkt
Für SEM wurde keine signifikante Abhängigkeit der Bestimmung der Faserdurchmesser von der Pixelgröße der Aufnahmen festgestellt
Für TEM wurde eine Abhängigkeit der Bestimmung der Faserdurchmesser von der Pixelgröße festgestellt
Der Einfluss der Bildauswertenden auf die Varianz der Ergebnisse ist klein im Vergleich zu der gesamten Varianz.
Nanofasern können mit TEM und SEM bestimmt werden!
The particle size distribution is considered the most relevant information for nanoscale property identification and material characterization. The current OECD test guideline on particle size and size distribution (TG 110) is not applicable to ‘nano-sized’ objects. In this project we thus develop a new OECD test guideline for the measurement of the size and size distribution of particles and fibers with at least one dimension in the range of 1 - 1000 nm. A fiber is defined as an object having an aspect ratio of length/diameter l/d >3. The width and length of each fiber should be measured concurrently.
In order to measure the particle size distributions, many techniques are available. 9 methods for particles and 2 methods for fibres have been tested in a prevalidation study and appropriate methods will be compared in an interlaboratory round robin test starting in February 2019.
The particle size distribution is considered the most relevant information for nanoscale property identification and material characterization. The current OECD test guideline on particle size and size distribution (TG 110) is not applicable to ‘nano-sized’ objects. In this project we thus develop a new OECD test guideline for the measurement of the size and size distribution of particles and fibers with at least one dimension in the range of 1 - 1000 nm. A fiber is defined as an object having an aspect ratio of length/diameter l/d >3. The width and length of each fiber should be measured concurrently.
In order to measure the particle size distributions, many techniques are available. 9 methods for particles and 2 methods for fibres have been tested in a prevalidation study and appropriate methods will be compared in an interlaboratory round robin test starting in February 2019.
AbstractThe correlation between altered extracellular pH and various pathological conditions, including cancer, inflammation and metabolic disorders, is well known. Bulk pH measurements cannot report the extracellular pH value at the cell surface. However, there is a limited number of suitable tools for measuring the extracellular pH of cells with high spatial resolution, and none of them are commonly used in laboratories around the world. In this study, a versatile ratiometric nanosensor for the measurement of extracellular pH was developed. The nanosensor consists of biocompatible polystyrene nanoparticles loaded with the pH-inert reference dye Nile red and is surface functionalized with a pH-responsive fluorescein dye. Equipped with a targeting moiety, the nanosensor can adhere to cell membranes, allowing direct measurement of extracellular pH at the cell surface. The nanosensor exhibits a sensitive ratiometric pH response within the range of 5.5–9.0, with a calculated pKa of 7.47. This range optimally covers the extracellular pH (pHe) of most healthy cells and cells in which the pHe is abnormal, such as cancer cells. In combination with the nanosensors ability to target cell membranes, its high robustness, reversibility and its biocompatibility, the pHe nanosensor proves to be well suited for in-situ measurement of extracellular pH, even over extended time periods. This pH nanosensor has the potential to advance biomedical research by improving our understanding of cellular microenvironments, where extracellular pH plays an important role.
The European building sector is moving towards more complex and high-tech building approaches. While focusing on energy efficiency, aspects e.g. occupant health, sustainability and life cycle costing are often neglected. This study highlights the potential of earthen plasters in combination with natural ventilation for low-tech solutions.
The EU funded project [H]house established the outstanding performance of earthen materials in light of hygrothermal and air purifying properties, which were further supported by experimental data from monitoring of naturally ventilated pilot buildings in Berlin. Additionally, [H]house demonstrated through LCC an increased cost efficiency of earth based low-tech solutions in comparison to conventional constructions relying on mechanical ventilation.
The physical and chemical analysis of aerosols using reliable and physically traceable methods is important for the thorough investigation of airborne particles to support a better understanding of their origin as well as their health and climate impacts. Within the European Metrology Research AeroMet project,the aim of hysikalisch–Technische Bundesanstalt’s (PTB) X-ray spectrometry group is to develop and establish traceable and reliable X-ray methods to measure the elemental mass deposition per unit area, the elemental composition,and the chemical binding state of particulate matter supported by a flat substrate. This approach can substantially contribute to support quantitative analytical methods during on-site measurement campaigns where portable Instrumentation is employed by qualifying suitable calibration samples for commercial analytical X-ray instruments and by investigating samples collected during the field campaign.
Industrial and agricultural waste streams (waste water, sludges, tailings, etc.) which contain high concentrations of NH4+, PO43–, and transition metals are environmentally harmful and toxic pollutants. At the same time, phosphorous and transition metals constitute highly valuable resources. Typically, separate pathways have been considered to extract hazardous transition metals or phosphate independently from each other. Investigations on the simultaneous removal of multiple components have been carried out only to a limited extent. Here, we report the synthesis routes for Ni- and Co-struvites (NH4MPO4·6H2O, M = Ni2+ and Co2+), which allow for P, ammonia, and metal co-precipitation. By evaluating different reaction parameters, the phase and stability of transition metal struvites as well as their crystal morphologies and sizes could be optimized. Ni-struvite is stable in a wide reactant concentration range and at different metal/phosphorus (M/P) ratios, whereas Co-struvite only forms at low M/P ratios. Detailed investigations of the precipitation process using ex situ and in situ techniques provided insights into the crystallization mechanisms/crystal engineering of these materials. M-struvites crystallize via intermediate colloidal amorphous nanophases, which subsequently aggregate and condense to final crystals after extended reaction times. However, the exact reaction kinetics of the formation of a final crystalline product varies significantly depending on the involved metal cation in the precipitation process: several seconds (Mg) to minutes (Ni) to hours (Co). The achieved level of control over the morphology and size makes precipitation of transition metal struvites a promising method for direct metal recovery and binding them in the form of valuable phosphate raw materials. Under this paradigm, the crystals can be potentially up-cycled as precursor powders for electrochemical or (electro)catalytic applications, which require transition metal phosphates.
We present how mesoporosity can be engineered in transition metal phosphate (TMPs) materials in a template-free manner. The method involves the transformation of a precursor metal phosphate phase, called M-struvite (NH4MPO4·6H2O, M = Mg2+, Ni2+, Co2+, NixCo1−x2+). It relies on the thermal decomposition of crystalline M-struvite precursors to an amorphous and simultaneously mesoporous phase, which forms during degassing of NH3 and H2O. The temporal evolution of mesoporous frameworks and the response of the metal coordination environment were followed by in situ and ex situ scattering and diffraction, as well as X-ray spectroscopy. Despite sharing the same precursor struvite structure, different amorphous and mesoporous structures were obtained depending on the involved transition metal. We highlight the systematic differences in absolute surface area, pore shape, pore size, and phase transitions depending on the metal cation present in the analogous M-struvites. The amorphous structures of thermally decomposed Mg-, Ni- and NixCo1−x-struvites exhibit high surface areas and pore volumes (240 m2 g−1 and 0.32 cm−3 g−1 for Mg and 90 m2 g−1 and 0.13 cm−3 g−1 for Ni). We propose that the low-cost, environmentally friendly M-struvites could be obtained as recycling products from industrial and agricultural wastewaters. These waste products could be then upcycled into mesoporous TMPs through a simple thermal treatment for further application, for instance in (electro)catalysis.
Der Mensch verbringt die überwiegende Zeit des Tages in Innenräumen von Gebäuden. Der Aufenthalt in Innenräumen umfasst das Wohnen, Bürotätigkeiten oder auch Nutzung öffentlicher Gebäude wie Kindertagesstätten, Schulen, Sporthallen und Bibliotheken. Um Innenräume von Gebäuden ohne Gefährdung für die menschliche Gesundheit nutzen zu können, müssen diese bei ihrer Errichtung und Verwendung dauerhaft die an sie gestellten hohen Anforderungen zu Gesundheit und Hygiene erfüllen. Die Innenraumluftqualität und ihre Wahrnehmung durch die Raumnutzer spielt für das individuelle Wohlbefinden und die Gesundheit eine entscheidende Rolle.
Dieses Buch richtet sich bevorzugt an Bauplaner, Architekten, Bauingenieure und Bauherren aber auch an Bauproduktehersteller. Ihnen allen fällt die wichtige Aufgabe zu, Aufenthaltsräume von Gebäuden durch eine gezielte Bauproduktverwendung zu gestalten und dauerhaft nutzbar zu machen. Die Frage, ob der Aufenthalt in Gebäuden den Menschen gesundheitlich beeinträchtigen oder sogar krank machen kann, hängt wesentlich von der qualitativen und quantitativen Zusammensetzung der Raumluft ab.
„Innenraumluftqualität und Bauprodukte“ enthält Angaben über wichtige Inhaltsstoffe der Raumluft und damit verbundene Einflussfaktoren, und geht im Besonderen auf Emissionen aus Bauprodukten ein. So vermögen Bauprodukte oftmals als großflächige Emissionsquellen die Innenraumluft mit verschiedenartigen Stoffen und Stoffgemischen anzureichern, mit der Folge, dass Raumnutzer diesen dauerhaft und teilweise intensiv ausgesetzt sind.
Das Buch vermittelt wichtige Erkenntnisse über flüchtige organische Verbindungen (VOC) aus Bauprodukten sowie deren Verhalten in der Raumluft etwa in Bezug auf Emissionsdauer, Hausstaubdeposition und Sekundärquellenbildung. Auf spezifische VOC-Einzelstoffemissionen – sehr flüchtige (VVOC) bis hin zu schwerflüchtigen (SVOC) – und einzelne chemische Stoffgruppen in Zusammenhang mit ihrem Vorkommen in Bauprodukten wird eingegangen.
Die wesentlichen Voraussetzungen und die Bedeutung einzelner VOC und VOC-Stoffgemische für die Expositionssituation und die Gesundheit von Raumnutzern werden in einem eigenen Kapitel beschrieben. Wichtige Kenntnisse über gesundheitliche Stoffwirkungen werden transparent erläutert. Angesprochen werden der inhalative Aufnahmepfad, Effekte durch Reizstoffe an den Atemwegen, andere toxische Wirkungen und die Auswirkungen von geruchsintensiven und -belästigenden Stoffen.Das Kapitel „Bewertung der Innenraumluftqualität“ vermittelt die allgemein anerkannte Vorgehensweise zur Beurteilung der Luftqualität und erstreckt sich auf chemische Stoffe, Geruchseinwirkungen sowie auf das Edelgas Radon. Bauplaner, Architekten, Bauingenieure und Bauherren werden in die Lage versetzt, die Bedeutung und Anwendung verschiedener Beurteilungsparameter und ihre Beurteilungswerte anschaulich nachzuvollziehen und deren Verwendung in Beurteilungen und Prüfberichten gezielt einzuordnen. Im Detail wird die notwendige Abgrenzung der Verwendung der Begrifflichkeiten „Grenzwerte“ und „toxikologisch begründete Innenraumluftrichtwerte des Ausschusses für Innenraumrichtwerte (AIR)“ mit den dazugehörigen aktuellen Richtwerten (RW II bzw. RW I) erklärt. Auch die Bedeutung und der Anwendungsbereich internationaler Beurteilungen der WHO und der europäischen Chemikalienbewertung (REACH) werden erläutert. Das Buch liefert Informationen über die Ermittlung und Verwendung statistisch abgeleiteter Beurteilungswerte, die als Referenzwerte definiert sind.
Die Ergebnisse aktueller Referenzwertstudien zum Vorkommen einzelner VOC und von VOC-Stoffgemischen als Summe aller nachgewiesenen VOC (TVOC-Wert) in Wohnräumen, Büros und auch öffentlichen Gebäuden wie Schulen – einschließlich ihrer Methodik und Analytik – werden erläutert und diskutiert. Der Verwendungszweck eines Bauproduktes in Gebäuden zwingt dazu, bereits vor dessen Einbau mittels konkretisierten Produktanforderungen eine Beurteilung des Gesundheitsschutzniveaus für die späteren Raumnutzer zu gewährleisten. Daher sind alle am Bau beteiligten Personen wie Bauplaner, Architekten, Bauingenieure und Bauproduktehersteller gefordert. Zwar treten in den Bauproduktemissionen viele VOC in eher geringeren Konzentrationen auf, jedoch zeigen einige nachweisbare Einzelstoffe sowohl Reizeffekte oder andere toxische Wirkungen als auch erhebliche Geruchsintensitäten auf.
„Innenraumluftqualität und Bauprodukte“ geht aus diesem Grund zwei bedeutsamen Fragen nach: Wie lässt sich das Gefährdungspotenzial der emittierten VOC aus Bauprodukten bevorzugt bewerten und wie lassen sich die Anforderungen an den Aufenthaltsraum zum Gesundheitsschutzniveau in Bezug auf Bauproduktemissionen prüfen, beurteilen und letztlich gewährleisten?
Hierzu gibt das Buch aktuelle Informationen zum anerkannten Prüf- und Bewertungsverfahren vom Ausschuss zur gesundheitlichen Bewertung von Bauprodukten (AgBB). Über das breit etablierte AgBB-Schema zur gesundheitlichen Beurteilung von Emissionen flüchtiger organischer Verbindungen (VVOC, VOC, SVOC) aus innenraumrelevanten Bauprodukten wird im Detail nachvollziehbar berichtet. Im Fokus steht die Anwendung des AgBB-Schemas in der Praxis. In einem umfangreichen Kapitel wird auf die Durchführung von Materialemissionsmessungen sowie Bewertungen der Geruchsemissionen und die dafür notwendigen Voraussetzungen eingegangen. Abbildungen und Messberichte geben einen weitreichenden Einblick zum Verständnis einer Prüfkammeruntersuchung auf flüchtige organische Verbindungen (VVOC, VOC, SVOC). Zur Verdeutlichung werden beispielhaft Messdaten angeführt zu unterschiedlichen Bauprodukten, wie Bodenbelägen, Bodenbelagsklebstoffen, Holz und Holzwerkstoffen, Lacken und Farben,
Kunstharzfertigputzen und Dichtstoffen. Das Buch bietet tabellarische Übersichten über das Vorkommen und die Konzentration ermittelter VOC-Emissionen aus Bauprodukten verschiedener Produktgruppen und zeigt Möglichkeiten auf, wie in der Praxis bestimmte SVOC-Emissionen, etwa Flammschutzmittel und Biozide, sowie Sekundäremissionen aus Bauprodukten analysiert und quantifiziert werden können. Darüber hinaus gibt es einen Überblick über die geltenden baurechtlichen Anforderungen in Bezug auf Hygiene und Gesundheit. Öffentlich-rechtliche Mindestforderungen zur Sicherstellung des Gesundheitsschutzniveaus für in Innenräume von Gebäuden eingebrachte Bauprodukte werden mit den zugrunde zu legenden Bestimmungen der Musterbauordnung (MBO) und ihrer neuen Muster-Verwaltungsvorschrift Technische Baubestimmungen (MVV TB) beschrieben.
Eigens wird ein Einblick in rechtliche Regelungen – in Bezug auf die gesundheitsbezogenen Anforderungen an bauliche Anlagen, die über die „Anforderungen an bauliche Anlagen bezüglich des Gesundheitsschutzes (ABG)“ konkretisiert sind – gegeben. Es wird ersichtlich, dass die Anforderungen für Emissionen flüchtiger organischer Verbindungen (VVOC, VOC, SVOC) aus Bauprodukten mindestens denen des AgBB entsprechen. Die in Europa noch lückenhafte und unvollständige Harmonisierung der Normen zum Gesundheitsschutz wird dargelegt. Das Buch leistet so Hilfestellung, um trotzdem gemäß den MBO- bzw. MVV TB-Anforderungen gesundheitsbezogene Angaben zu Produktleistungen zu ermöglichen.
Mit dem Fokus auf eine saubere Innenraumluft wird darauf eingegangen, welche Emissionen aus Materialien und Produkten es gibt und wie sie nach Art und Flüchtigkeit definiert sind und wie sie gemessen werden. Im weiteren wird dargestellt, was und wie viel aus Materialien und Produkten emittieren kann und wie die Emissionen zu bewerten sind. Hierbei wird auch auf besonders emissionsarme Materialien und Produkte eingegangen.
Der mitteleuropäische Mensch hält sich 80 – 90 % der Zeit in Innenräumen auf. Je nach Aktivität atmet er 10 – 20 m³ bzw. 12 - 24 kg Luft täglich, das ist weit mehr als das Doppelte der Summe an Essen und Trinken. Die technischen Voraussetzungen für die Bestimmung von Emissionen aus Bauprodukten in die Luft liegen vor – harmonisierte horizontale Prüfnorm EN 16516. Es dürften mittlerweile zig-tausende Emissionsdatensätze vorliegen. Defizite gibt es bei der Kennzeichnung zur Unterscheidung emissionsarmer und emissionsreicher Produkte, die bestehende CE-Kennzeichnung ist unvollständig, ersatzweise gibt es nationale Regelungen.
Gerade bei modernen, dichten Bauten mit geringem natürlichen Luftwechsel sind hohe Schadstoffkonzentrationen zu erwarten, wenn nicht emissionsarme Materialien und Produkte zum Einsatz kommen.
Es lässt sich feststellen, dass eine Vielzahl unterschiedlicher flüchtiger organischer Verbindungen aus Bauprodukten freigesetzt werden kann. Hierbei gibt es in den meisten Bauproduktgruppen sowohl emissionsarme als auch emissionsreiche Produkte. Manche Verbindungen sind produktgruppenspezifisch; so werden beispielsweise Siloxane aus Silikondichtmassen freigesetzt, andere Verbindungen sind eher unspezifisch wie Formaldehyd und Essigsäure, die aber in unterschiedlichen Konzentrationen aus einer Vielzahl von Produkten abgegeben werden und zu den am häufigsten emittierten Verbindungen zählen. Es ist darauf hinzuweisen, dass VOC-Analytik und Gerüche im Allgemeinen keinen Zusammenhang zeigen. Gerade bei modernen, dichten Bauten mit geringem natürlichem Luftwechsel sind hohe Schadstoffkonzentrationen zu erwarten, wenn nicht emissionsarme Materialien und Produkte zum Einsatz kommen.
Es lässt sich feststellen, dass eine Vielzahl unterschiedlicher flüchtiger organischer Verbindungen aus Bauprodukten freigesetzt werden kann. Hierbei gibt es in den meisten Bauproduktgruppen sowohl emissionsarme als auch emissionsreiche Produkte.
Manche Verbindungen sind produktgruppenspezifisch; so werden beispielsweise Siloxane aus Silikondichtmassen freigesetzt, andere Verbindungen sind eher unspezifisch wie Formaldehyd und Essigsäure, die aber in unterschiedlichen Konzentrationen aus einer Vielzahl von Produkten abgegeben werden und zu den am häufigsten emittierten Verbindungen zählen.
Es ist darauf hinzuweisen, dass VOC-Analytik und Gerüche im Allgemeinen keinen Zusammenhang zeigen.
Gerade bei modernen, dichten Bauten mit geringem natürlichem Luftwechsel sind hohe Schadstoffkonzentrationen zu erwarten, wenn nicht emissionsarme Materialien und Produkte zum Einsatz kommen.
Metagenomic datasets of air samples collected during episodes of severe smoke-haze in Malaysia
(2021)
Transboundary emissions of smoke-haze from land and forest fires have recurred annually during the dry period (June to October, over the past few decades) in South East Asia. Hazardous air quality has been recorded in Malaysia during these episodes. Agricultural practices such as slash-and-burn of biomass and peat fires particularly in Sumatera and Kalimantan, Indonesia, have been implicated as the major causes of the haze. Past findings have shown that a diversity of microbes can thrive in air including in smoke-haze polluted air. In this study, metagenomic data were generated to reveal the diversity of microorganisms in air during days with and without haze. Air samples were collected during non-haze (2013A01) and two haze (2013A04 and 2013A05) periods in the month of June 2013. DNA was extracted from the samples, subjected to Multiple Displacement Amplification and whole genome sequencing (Next Generation Sequencing) using the HiSeq 2000 Platform. Extensive bio-informatic analyses of the raw sequence data then followed. Raw reads from these six air samples were deposited in the NCBI SRA databases under Bioproject PRJNA662021 with accession numbers SRX9087478, SRX9087479 and SRX9087480.
Menschen, die in der gemäßigten Klimazone leben, verbringen bis zu 90% ihres Lebens in Innenräumen. Deshalb hat das Innenraumklima eine sehr große Bedeutung für deren Wohlergehen, Gesundheit und Leistungsfähigkeit. In Deutschland wird ca. 40% der eingesetzten Primärenergie für das Heizen, Kühlen und Klimatisieren der Innenräume verwendet.
Das Forschungsvorhaben hat eine Laufzeit vom Oktober 2013 bis März 2017. Es wird in Kooperation mit der Bundesanstalt für Materialforschung und –prüfung (BAM) und der Hochschule für Technik und Wirtschaft Berlin (HTW Berlin) durchgeführt. Die HTW Berlin koordiniert das Projekt. Die Rheinisch-Westfälische Technische Hochschule Aachen (RWTH) wird teilweise über einen Auftrag in das Projekt integriert.
Ziel des Projektes ist es Baustoffe auf ihre Geruchsemissionen zu untersuchen, um Bauprodukte mit niedrigen Emissionen und Gerüchen identifizieren zu können. Den Verbraucherinnen und Verbrauchern wird somit die Möglichkeit gegeben emissions- und geruchsarme Baustoffe zu wählen.
Die Aufgabenstellung des Projektes ist nachfolgend aufgeführt:
Arbeitspaket 1: Geruchsmessung bei Produkten mit dem Blauen Engel (siehe Kapitel 4 und 5);
Arbeitspaket 2: Untersuchung von Vergleichsmaßstäben (siehe Kapitel 6);
Arbeitspaket 3: Untersuchung der Linearität der Acetonskala (siehe Kapitel 7);
Arbeitspaket 4: Erstellung einer Produktdatenbank (siehe Kapitel 8).
Die Geruchsuntersuchung ist in den Vergabekriterien für den „Blauen Engel“ für textile Bodenbeläge (RAL UZ-128) eingebunden worden. Aus den weiteren Untersuchungen sind für die Normung wichtige Erkenntnisse erarbeitet worden.
Moderne Vitrinen sollen gleichzeitig eine hohe Dichtigkeit und die Abwesenheit jeglicher Fremdstoffe in den Vitrinen gewährleisten. Diese Anforderungen sind zeitgleich kaum erfüllbar, da es emissionsfreie Materialien (vor allem Kleb- und Beschichtungsstoffe) nicht gibt. Um die potentiellen Emissionen zu minimieren wurde ein Messverfahren entwickelt, welches inzwischen als BEMMA-Schema (Bewertung von Emissionen aus Materialien für Museumsausstattungen) in die Museumswelt Einzug genommen hat.
Die erfolgreiche Bewertung der für den Bau verwendeten Materialien gemäß BEMMA-Schema resultiert nicht in einer emissionsfreien Vitrine, sondern soll bei der Auswahl geeigneter Materialien zur Herstellung möglichst emissionsarmer Vitrinen helfen. Konkrete handwerkliche Durchführungen beim Bau, Dichtheits¬anforderungen, wie auch die Aufstellbedingungen (Umgebung der Vitrine) beeinflussen die Emissionscharakteristik der fertigen Vitrine in der Praxis. Eine saubere Vitrine hilft nichts in einer belasteten Umgebung oder auch bei emittierenden Exponaten. Inzwischen liegen Erfahrungen mit dem Schema seit 2012 vor.
Der Messablauf sieht vor, dass von den Materialien kleine Muster mit der Mikrokammer (Markes) innerhalb von 2 Tagen untersucht werden. Dabei wird mit Silikagelkartuschen auf Ameisen- und Essigsäure, mit DNPH auf Aldehyde und Ketone und mit Tenax® sowohl auf VOC als auch für die spezifische Oxim-Analytik die Abluft der Mikrokammern untersucht. Die Bewertungskriterien basieren auf den Ergebnissen einer Vorstudie mit ca. 150 verschiedenen Produkten im Zeitraum 2010 bis 2012.
Museumsvitrinen sollen Kunst- und Kulturgut „ins rechte Licht“ setzen und vor Diebstahl oder Vandalismus schützen. Vergleicht man historische Schauvitrinen, die zumeist aus einfachen Glasscheiben in Holzrahmungen bestehen, mit heutigen Konstruktionen, lässt sich eine Entwicklung zu hochtechnisierten Gebilden ablesen, die deutlich mehr Ansprüchen genügen müssen als in der Vergangenheit.
Zahlreiche Beispiele verdeutlichen, dass Kunstwerke nicht nur außerhalb, sondern auch innerhalb von Museen oder Archiven ungünstigen Umwelteinflüssen ausgesetzt sind. So können Einbauten bzw. Dekorationen in Ausstellungsräumen, Aufbewahrungsbehältnisse in Depoträumen oder Ausstellungsvitrinen flüchtige Substanzen, sogenannte VOCs (Volatile Organic Compounds) freisetzen, die zu irreversiblen Veränderungen an den Objekten führen und diese schädigen. Hierzu zählen organische Säuren, wie Ameisen- oder Essigsäure, aber auch Verbindungen, die Sulfide enthalten. Hier wird die an der BAM entwickelte BEMMA-Bewertungsmethode vorgestellt, die von Museen verwendet werden kann Materialien mit einem geringeren Emissionspotential auszusuchen.
Museums worldwide are equipped with different display cases. Exhibit display cases should protect cultural objects from dust as well as from mechanical and physical damage. To ensure a stable climate inside the display cases, a low air exchange rate is maintained. Typically air exchange rates are often smaller than 0.1 d 1, which can result in rising concentrations of potential harmful immissions inside of the display cases due to emissions from materials. Especially high concentrations of organic acids, which can emit from e.g. sealing materials, can produce damage of cultural objects. In 2012 BAM introduced a procedure witch is called: BEMMA-Scheme (Bewertung von Emissionen aus Materialien für Museumsausstattungen) which stands for: “Assessment of Emissions from Materials for Museum Equipment”. Micro chambers are used for VOC emission tests of display case construction materials, e.g. textiles, plastics, sealing material, coatings and others. Each sampling procedure is carried out in duplicate. Emissions like formic acid, acetic acid, formaldehyde and oximes are excluded and the sum of emissions of VVOCs, VOCs and SVOCs is limited. For a positive assessment all listed criteria must be fulfilled; otherwise the display construction material fails the BEMMA scheme. The BEMMA scheme is not a guarantee for an emission free display case, but a necessary requirement for the choice of suitable materials for emission and immission reduced display cases.
BEMMA steht für Bewertung von Emissionen aus Materialien für Museumsausstattungen. Es ist die Kurzbezeichnung für ein Schema/Verfahren zur Untersuchung und Bewertung flüchtiger organischer Verbindungen aus Werkstoffen, die im mittelbaren Kontakt mit historischen Materialien des Kunst- und Kulturgutes stehen. Ergebnisse der Untersuchungen seit ca. 2010 bis 2017 werden präsentiert und diskutiert.
Anregungen aus dem N.i.Ke.-Workshop 2017 und künftige Anforderungen. BEMMA steht für Bewertung von Emissionen aus Materialien für Museumsausstattungen. Es ist die Kurzbezeichnung für ein Schema/Verfahren zur Untersuchung und Bewertung flüchtiger organischer Verbindungen aus Werkstoffen, die im mittelbaren Kontakt mit historischen Materialien des Kunst- und Kulturgutes stehen. Hier wird der Status-Quo des Erreichten dargestellt. Wie wird das Schema in der Museumsöffentlichkeit wahrgenommen und seine Akzeptanz.
Museums worldwide are equipped with different display cases. Exhibit display cases should protect cultural objects from dust as well as from mechanical and physical damage. To ensure a stable climate inside the display cases, a low air exchange rate is maintained. Typically, air exchange rates are often smaller than 0.1 d-1, which can result in rising concentrations of potential harmful VOC inside of the display cases due to emissions from materials. Especially organic acids, e. g. formic or acetic acid which can emit from e.g. sealing materials or wood-based materials, can produce damage of cultural objects.
In 2012 BAM introduced a procedure which is called: BEMMA-Scheme (Bewertung von Emissionen aus Materialien für Museums¬ausstattungen) which stands for: “Assessment of Emissions from Materials for Museum Equipment”. Regarding the testing procedure only construction materials were evaluated, not the display cases their self. Micro chambers are used for VOC emission tests of display case construction materials, e.g. plastics, sealing materials, coatings, textiles and others. Each sampling procedure is carried out in duplicate. Emissions like formic acid, acetic acid, formaldehyde, piperidine-derivates and oximes are excluded and the sum of emissions of VVOCs, VOCs and SVOCs is limited. For a positive assessment all listed criteria must be fulfilled; otherwise the display construction material fails the BEMMA scheme.
Quality Improvement of VOC chamber emission tests observed for 10 years with round robin tests
(2018)
In Europe, the Construction Products Regulation (CPR, 2011/305/EU) sets basic requirements (BR) on how construction works must be designed and built. BR 3 “hygiene, health and the environment” states low emissions of toxic gases, Volatile Organic Compounds (VOCVOCs), particles, etc. from building materials. Meanwhile, a worldwide network of professional Commercial and non-commercial laboratories performing emission tests for the evaluation of products for interior use has been established.
Therefore, comparability of test results must be ensured. The participation in Round Robin Tests (RRTRRTs) is a means to prove a laboratory’s proficiency. Since 2006 BAM offers such proficiency test for emission chamber test every two years.
Any commercially available product on the market can be used as reference material, provided it is thoroughly characterised. However, these materials often emit only a few and material specific VOCs and appropriate homogeneity is not given. Therefore, alternative materials should be found. BAM used different materials over the years. Currently, the best suited reference material is a cured lacquer surface which contained several VOCs added to the liquid lacquer system. The round robin tests 2014, 2016 and 2018 were conducted with such a system.
Compounds like Styrene or n-Alkanes like Decane or Tridecane were tested in many of the proficiency test operated by BAM. Up to now the relative standard deviation of these compounds decrease continuously. Starting with values about 30 % in 2008 we reached values for the mentioned compounds 15 to 20 % now. But even for more polar compounds improved results were received.
Over the years the results of a large group of laboratories detected many compounds with much higher accuracy than at the beginning. So, the comparability between results of different laboratories becomes much better.
Moderne Vitrinen sollen gleichzeitig eine hohe Dichtigkeit und die Abwesenheit jeglicher Fremdstoffe in den Vitrinen gewährleisten. Diese Anforderungen sind zeitgleich kaum erfüllbar, da es emissionsfreie Materialien (vor allem Kleb- und Beschichtungsstoffe) nicht gibt. Um die potentiellen Emissionen zu minimieren wurde ein Messverfahren entwickelt, welches inzwischen als BEMMA-Schema (Bewertung von Emissionen aus Materialien für Museumsausstattungen) in die Museumswelt Einzug genommen hat.
Die erfolgreiche Bewertung der für den Bau verwendeten Materialien gemäß BEMMA-Schema resultiert nicht in einer emissionsfreien Vitrine, sondern soll bei der Auswahl geeigneter Materialien zur Herstellung möglichst emissionsarmer Vitrinen helfen. Konkrete handwerkliche Durchführungen beim Bau, Dichtheits-anforderungen, wie auch die Aufstellbedingungen (Umgebung der Vitrine) beeinflussen die Emissionscharakteristik der fertigen Vitrine in der Praxis. Eine saubere Vitrine hilft nichts in einer belasteten Umgebung oder auch bei emittierenden Exponaten. Inzwischen liegen Erfahrungen mit dem Schema seit 2012 vor.
Der Messablauf sieht vor, dass von den Materialien kleine Muster mit der Mikrokammer (Markes) innerhalb von 2 Tagen untersucht werden. Dabei wird mit Silikagelkartuschen auf Ameisen- und Essigsäure, mit DNPH auf Aldehyde und Ketone und mit Tenax® sowohl auf VOC als auch für die spezifische Oxim-Analytik die Abluft der Mikrokammern untersucht. Die Bewertungskriterien basieren auf den Ergebnissen einer Vorstudie mit ca. 150 verschiedenen Produkten im Zeitraum 2010 bis 2012.
Ein Ringversuch ist eine Methode der externen Qualitätssicherung für sowohl Messverfahren als auch die Eignung von Mess- und Prüflaboratorien. Dabei werden möglichst identische Proben mit identischen Verfahren oder mit unterschiedlichen Verfahren untersucht. Die Teilnahme an Ringversuchen ist für alle akkreditierten Laboratorien ein wesentlicher Baustein der institutsinternen und -externen Qualitätssicherung. Je mehr Faktoren Einfluss auf das Endergebnis haben können, desto wichtiger ist es diese Faktoren zu kennen und deren Einflüsse durch weitestgehende Vergleichbarkeit der Messverfahren zu minimieren.
Für die Bewertung von Emissionen aus Bauprodukten haben sich Emissionsmess-kammer-Untersuchungen als Messverfahren etabliert. Um den Geruch auch für Innenraumanwendungen bewertbar zu machen sind in den letzten Jahren erste Normen entstanden (z. B. DIN ISO 16000-28 und VDI 4302-1). Um die Eignung dieser Normen und deren Anwendung zu untersuchen sind seit 2012 nunmehr 3 Ringversuche der BAM auch zum Thema Geruch durchgeführt worden.
Die bislang durchgeführten Ringversuche mit dem Ziel der Geruchsbewertung wiesen Standardabweichungen von ca. 24 bis 30 % um den jeweiligen Mittelwert auf und wiesen somit ähnliche Werte auf, die auch bei den VOC-Vergleichen ermittelt wurden. Diese Entwicklungen werden hier aufgezeigt.
A new facility has been developed which allows for a stable and reproducible production of ambient-like model aerosols (PALMA) in the laboratory. The set-up consists of multiple aerosol generators, a custom-made flow tube homogeniser, isokinetic sampling probes, and a system to control aerosol temperature and humidity. Model aerosols containing elemental carbon, secondary organic matter from the ozonolysis of α-pinene, inorganic salts such as ammonium sulfate and ammonium nitrate, mineral dust particles,and water were generated under different environmental conditions and at different number and mass concentrations. The aerosol physical and chemical properties were characterised with an array of experimental methods, including scanning mobility particle sizing, ion chromatography, total reflection X-ray fluorescence spectroscopy and thermo-optical analysis. The facility is very versatile and can find applications in the calibration and performance characterisation of aerosol instruments monitoring ambient air. In this study, we performed, as proof of concept, an intercomparison of three different commercial PM (particulate matter) monitors (TEOM1405, DustTrak DRX 8533 and Fidas Frog) with the gravimetric reference method under three simulated environmental scenarios. The results are presented and compared to previous field studies. We believe that the laboratory-based method for simulating ambient aerosols presented here could provide in the future a useful alternative to time-consuming and expensive field campaigns, which are often required for instrument certification and calibration.
This study investigated the adaptation of the state-of-the-art test procedure for the determination of emissions of volatile organic compounds (VOC) from materials into indoor air to test for the radon exhalation from stony construction products. A complete robustness validation including all relevant parameters showed that the procedure can be well applied by testing institutes already holding available the required VOC testing infrastructure that solely needs to be complemented by calibrated commercial radon measurement instrumentation. When measurements of the radon exhalation from construction materials become mandatory by law, test capacity can easily be applied. This work can serve as a recommendation for the European standardisation that still is on hold in this point.
Regional standardisation activities and how VAMAS can help in any way to promote activities are reported.
Activities related to organisational updates, government initiatives/priorities (especially related to Materials), details of any strategy documents publicly available, networks within Germany and how we engage are presented.
Das Prozessmonitoring stellt einen wichtigen Baustein für eine Qualitätssicherung additiv gefertigter Bauteile dar, insbesondere bei kleinen Losgrößen. Der Vortrag zeigt einen Überblick aktueller Entwicklungen der BAM im Bereich des Prozessmonitorings für das Laserstrahlschmelzen (laser powder bed fusion) metallischer Werkstoffe. Durch Vergleich mit der Referenzmethode Computertomografie wird am Beispiel der thermografischen Verfahren gezeigt, wie relevante Defekte in Bauteilen detektiert werden können und Einsatzpotenziale sowie Limitierungen aufgezeigt.
In many late-breaking research fields as in photovoltaics, microelectronics, nuclear waste glasses or at least mirror glasses silver diffusion in glasses is relevant to the issues of high-level functionality and recycling. The present study is focused on silver diffusion in innovative, low-melting alkali zinc borate glasses (X2O-ZnO-B2O3, X = Li, Na, K, Rb) potentially usable for silver metallization-pastes in solar cells. The glasses were coated with a thin metallic silver layer and heat treatments in air and nitrogen close to Tg at 470 °C for 2 h were performed. After heat treatment under air and nitrogen atmospheres the coating thickness, measured by a white light interferometer, was about 1.8 µm thick. Silver depth profiles determined by means of secondary neutral mass spectrometry (SNMS) indicate the fastest silver diffusion to a depth of 3.5 µm for Li2O-ZnO-B2O3 (LZB) glass. Nevertheless, the influence of the different alkali ions on the silver diffusion is small. The oxygen availability determines the silver diffusion into the glasses. The oxygen promotes the oxidation of the silver layer enabling Ag+ to diffuse into the glass and to precipitate as Ag0. Both species were detected by x-ray absorption spectroscopy (XAS). The precipitated metallic silver particles in Na2O-ZnO-B2O3 (NZB) glass have a mean size of 5.9 nm ± 1.2 nm diameter, which was determined using transmission electron microscopy (TEM). Phase separation in zinc-rich and zinc-poor phases with a mean diameter of 75 nm ± 20 nm occurred in NZB glass after heat treatment. Ion diffusion of the glasses into the silver layer was suggested by EDX-line scans.
The possible impact of ultrafine particles from laser printers on human health is controversially discussed although there are persons reporting substantial symptoms in relation to these emissions. A randomized, single-blinded, cross-over experimental design with two exposure conditions (high-level and low-level exposure) was conducted with 23 healthy subjects, 14 subjects with mild asthma, and 15 persons reporting symptoms associated with laser printer emissions. To separate physiological and psychological effects, a secondary physiologically based categorization of susceptibility to particle effects was used. In line with results from physiological and biochemical assessments, we found no coherent, differential, or clinically relevant effects of different exposure conditions on subjective complaints and cognitive performance in terms of attention, short-term memory, and psychomotor performance. However, results regarding the psychological characteristics of participants and their situational perception confirm differences between the participants groups: Subjects reporting symptoms associated with laser printer emissions showed a higher psychological susceptibility for adverse reactions in line with previous results on persons with multiple chemical sensitivity or idiopathic environmental intolerance. In conclusion, acute psychological and cognitive effects of laser printer emissions were small and could be attributed only to different participant groups but not to differences in exposure conditions in terms of particle number concentrations.
Herein we report the synthesis of a zeolitic imidazolate framework (ZIF-8) by an easy “mix and wait” procedure. In a closed vial, without any interference, the mixture of 2-methylimidazole and basic zinc carbonate assembles into the crystalline product with approx. 90% conversion after 70 h. The reaction exhibits sigmoidal kinetics due to the self-generated water which accelerates the reaction.
In industrialised countries more than 80% of the time is spent indoors. Products, such as building materials and furniture, emit volatile organic compounds (VOCs), which are therefore ubiquitous in indoor air. VOC in combination may, under certain environmental and occupational conditions, result in reported sensory irritation and health complaints. Emission concentrations can become further elevated in new or refurbished buildings where the rate of air exchange with fresh ambient air may be limited due to improved energy saving aspects. A healthy indoor environment can be achieved by controlling the sources and by eliminating or limiting the release of harmful substances into the air. One way is to use (building) materials proved to be low emitting. Meanwhile, a worldwide network of professional commercial and non-commercial laboratories performing emission tests for the evaluation of products for interior use has been established. Therefore, comparability of test results must be ensured. A laboratory’s proficiency can be proven by internal and external validation measures that both include the application of suitable emission reference materials (ERM). For the emission test chamber procedure according to EN 16516, no artificial ERM is commercially available. The EU-funded EMPIR project MetrIAQ aims to fill this gap by developing new and improved ERMs. The goal is to obtain a material with a reproducible and temporally constant compound release (less than 10% variability over 14 days). Different approaches, such as the impregnation of porous materials, are being tested. The generation as well as results of the most promising materials will be presented.
How the rock-inhabiting fungus K. petricola A95 enhances olivine dissolution through attachment
(2020)
Free-living and mycorrhizal fungi are able to enhance the weathering of rock and other solid substrates. Deciphering the exact mechanisms of these natural processes requires their experimental simulation. Moreover, by performing these simulations with genetically amenable rock-weathering fungi, one can knock-out certain fungal traits and consequently identify their weathering-relevant function. Here, the effect of the rock-inhabiting fungus, Knufia petricola A95, on the dissolution kinetics of an Fe-bearing olivine (Mg1.86Fe0.19SiO4) is investigated at 25 °C and pH 6 using reproducible batch and mixed flow experiments. The availability of a melanin-deficient mutant (ΔKppks) of K. petricola A95, which produces more extracellular polymeric substances (EPS) than the wild type (WT), enables the comparative study of the role of melanin and EPS in olivine dissolution. In abiotic dissolution experiments, the olivine dissolution rate decreased considerably over time at pH 6 but not at pH 3.5. This inhibition of abiotic olivine dissolution at pH 6 was most likely caused by the in-situ oxidation of ferrous Fe and/or the precipitation of ferric hydroxides at the olivine surface. In corresponding biotic experiments at pH 6, both the wild type K. petricola and its melanin-deficient mutant ΔKppks solubilised and bound significant amounts of Fe released by olivine dissolution. Fe oxidation and precipitation were thus prevented and olivine dissolution proceeded faster than in the abiotic experiments. By sequestering Fe directly at the olivine surface, the attached wild type K. petricola cells were particularly efficient at preventing the oxidation of Fe at the mineral surface: the slowdown of olivine dissolution almost completely disappeared. The attachment capacity of these wild type cells is most likely mediated by wild type-specific EPS. Our presented experimental systems allow the oxidation of mineral-released Fe and include a rock-inhabiting fungus, thus simulating chemical, physical and biological conditions that set dissolution rates in a way that is relevant to natural ecosystems.
In arid sun-exposed environments, rock-inhabiting fungi dominate microbial communities on rock surfaces. Fungi are known to enhance rock weathering, although the exact mechanisms are not completely understood. These natural processes can be simulated by reproducible experimental systems. Particularly attractive are genetically amenable rock-weathering fungi, where certain traits can be knocked-out to identify weathering-relevant functions. Here, we studied the effect of the rock-inhabiting fungus Knufia petricola A95 and its melanin-deficient mutant (ΔKppks) on the weathering of a Fe-bearing olivine. We examined the olivine dissolution kinetics and looked at the olivine-fungus interface. For the former we inoculated olivine powder with the fungus in batch and mixed flow reactors and analysed the medium solution by ICP-OES, for the latter biofilm-covered olivine sections from flow-through reactors were analysed by FIB-TEM.
In general olivine dissolution was lower when olivine was incubated without fungi: the abiotic olivine dissolution rates were lowest and the surface of the abiotically reacted olivine sections showed no etching. Various chemical analyses show Fe (oxyhydr)oxide precipitation on top of the abiotically reacted olivine, indicating its role in inhibiting olivine dissolution. Both the wild type (WT) and ΔKppks solubilised and bound significant amounts of Fe released by olivine dissolution. Fe (oxyhydr)oxide precipitation was thus reduced, explaining the enhanced olivine dissolution in their presence. Particularly efficient at preventing Fe precipitation were attached WT cells: the inhibition of olivine dissolution almost completely disappeared. The attachment capacity of the WT is most likely caused by the production of WT-specific extracellular polymeric substances. Our presented experimental systems allowed the precipitation of Fe (oxyhydr)oxides and included a rock-inhabiting fungus and thus simulated weathering processes relevant to natural ecosystems.
Formaldehyde is considered as carcinogenic and is emitted from particleboards and plywood used in toy manufacturing. Currently, the flask method is frequently used in Europe for market surveillance purposes to assess formaldehyde release from toys, but its concordance to Levels measured in emission test chambers is poor. Surveillance laboratories are unable to afford laborious and expensive emission chamber testing to comply with a new amendment of the European Toy Directive; they need an alternative method that can provide reliable results. Therefore, the application of miniaturised emission test chambers was tested. Comparisons between a 1 m3 emission test chamber and 44 mL microchambers with two particleboards over 28 days and between a 24 L desiccator chamber and the microchambers with three puzzle samples over 10 days resulted in a correlation coefficient r2 of 0.834 for formaldehyde at steady state. The correlation between the results obtained in microchambers vs. flask showed a high variability over 10 samples (r2: 0.145),
thereby demonstrating the error-proneness of the flask method in comparison to methods carried out under ambient parameters. An exposure assessment was also performed for three toy puzzles: indoor formaldehyde concentrations caused by puzzles were not negligible (up to 8 µg/m3), especially when more conservative exposure scenarios were considered.
The ISO 16000-6 standard describes a method for the determination of volatile organic compounds (VOCs) in indoor and test chamber air by sorbent-based active sampling, thermal desorption and gas chromatography coupled with mass spectrometry (GC/MS). It also gives directions to adapt this methodology to very volatile organic compounds (VVOCs). Indeed, toxicologically based guideline values are being implemented for these compounds and it becomes necessary to measure them. But a comprehensive and robust measurement method is lacking. This work highlights the points that still need to be explored towards the standardisation of a suitable procedure: investigations on sorbent combinations, the suitability of chromatography columns and the use of gaseous standards are required. The biggest challenge remains in the fact that strong sorbents adsorb water together with VVOCs. Water may impair the analysis and the optimal approach to eliminate it is still to be found and integrated into the sampling strategy.
The ISO 16000-6 standard gives directions to adapt the analysis of volatile organic compounds (VOCs) in indoor and test chamber air to very volatile organic compounds (VVOCs). The same techniques with sorbent-based active sampling, thermal desorption and gas chromatography coupled with mass spectrometry (TD-GC/MS) should be used. However, VVOCs require gaseous standards, an adapted GC column and a reliable sampling adsorbent. This work presents experimental results to tackle those three experimental gaps. A stable standard gas mixture containing 47 VVOCs, 13 VOCs and an internal standard was successfully generated. It was employed to study the suitability of seven types of chromatography columns. The use of PLOT (Porous Layer Open Tubular) columns such as PoraBOND Q is well suitable for VVOC analysis. The recoveries of the 60 analytes on a total of 16 adsorbents and their combinations were determined: A combination of the graphitized carbon black Carbograph 5TD 40/60 and the carbon molecular sieve CarbosieveTM SII showed great recoveries for all analytes. Carbon molecular sieves adsorb water which can impair the analysis. A dry purge of the multi-sorbent in the sampling direction led to a complete water removal and promising recoveries of the analytes.
The ISO 16000 standard series provide guidelines for emission measurements of volatile organic compounds (VOCs) from building materials. However, polymer-based consumer products such as toys may also release harmful substances into indoor air. In such cases, the existing standard procedures are unsuitable for official control laboratories due to high costs for large emission testing chambers. This paper aims at developing and comparing alternative and more competitive methods for the emission testing of consumer products. The influence of the emission chamber size was investigated as smaller chambers are more suited to the common size of consumer products and may help to reduce the costs of testing. Comparison of the performance of a 203 l emission test chamber with two smaller chambers with the capacity of 24 l and 44 ml, respectively, was carried out by using a polyurethane reference material spiked with 14 VOCs during the course of 28 days. The area-specific emission rates obtained in the small chambers were always similar to those of the 203 l reference chamber after a few hours. This implies that smaller chambers can provide at least useful numbers on the extent of polymer-based consumer product emissions into indoor air, thereby supporting meaningful exposure assessments.
There is a need for an assessment of the emission properties of volatile organic compounds (VOCs) from consumer products. A method comparison was carried out to evaluate adapted and cost-effective procedures for such items. Smaller and automated emission chambers depicted similar kinetics compared to a 203 L standard chamber. Toy samples made of PVC (Polyvinyl chloride) emitted more VOCs compared to other tested polymeric products. The emissions from 2 selected samples were studied to allow an evaluation of the resulting room concentration and external exposure of a child. Obtained concentrations were not of concern.
The ISO 16000-6 standard describes a method for the determination of volatile organic compounds (VOCs) in indoor and test chamber air by sorbent-based active sampling, thermal desorption and gas chromatography coupled with mass spectrometry (GC/MS). It also gives directions to adapt this methodology to very volatile organic compounds (VVOCs). Indeed, toxicologically based guideline values are being implemented for these compounds and it becomes necessary to measure them. But a comprehensive and robust measurement method is lacking. Investigations on the use of gaseous standards, the suitability of chromatography columns, the suitable sorbent combinations and the water removal are required. The talk will highlight the points that need to be explored towards the standardisation of a suitable procedure and provide appropriate preliminary results.
There is a need for an assessment of the emission properties of volatile organic compounds (VOCs) from consumer products. A method comparison was carried out to evaluate adapted and cost-effective procedures for such items. Smaller and automated emission chambers de-picted similar kinetics compared to a 203 L standard chamber. Toy samples made of PVC (Polyvinyl chloride) emitted more VOCs compared to other tested polymeric products. The emissions from 2 selected samples were studied to allow an evaluation of the resulting room concentration and external exposure of a child. Obtained concentrations were not of concern.
Since 1997, the Committee for Health-related Evaluation of Building Products (AgBB) has been developing the basis for building regulations for protection against indoor health risks that may arise when building products are used. In 2009, the AgBB decided to include relevant VVOCs in the assessment procedure. The ISO 16000-6 (2021) states that the use of the thermal desorption gas chromatography technique is appropriate for VVOCs, if adaptations are considered. However, a suitable method for the trustworthy quantification of VVOC emissions from building products and in the indoor air is still missing.
This webinar will present the results of a research project on the development of a procedure for VVOC analysis:
• identification of the gaps towards standardization
• investigations on gas standards and the suitability of chromatography columns
• investigations on sorbent combinations and water management
• validation of the method and screening of VVOC emissions from building products.
Formaldehyd gilt als krebserregend und wird von Spanplatten und Sperrholz emittiert, die bei der Spielzeugherstellung verwendet werden. Die Untersuchungsänter benötigen eine wirtschaftliche und zuverlässige Methode. Die Anwendung miniaturisierter Emissionsprüfkammern wurde getestet und mit größeren Emissionsprüfkammern und die Flaschenmethode verglichen. Eine Expositionsabschätzung wird auch vorgestellt.
Formaldehyde is considered as carcinogenic and is emitted from particleboards and plywood used in toy manufacturing. Currently, the flask method is frequently used in Europe for market surveillance purposes to assess formaldehyde release from toys, but its concordance to levels measured in emission test chambers is poor. Surveillance laboratories are unable to afford laborious and expensive emission chamber testing to comply with a new amendment of the European Toy Directive; they need an alternative method that can provide reliable results. Therefore, the application of miniaturised emission test chambers was tested. Comparisons between a 1 m3 emission test chamber and 44 mL microchambers with two particleboards over 28 days and between a 24 L desiccator chamber and the microchambers with three puzzle samples over 10 days resulted in a correlation coefficient r2 of 0.834 for formaldehyde at steady state. The correlation between the results obtained in microchambers vs. flask showed a high variability over 10 samples (r2: 0.145), thereby demonstrating the error-proneness of the flask method in comparison to methods carried out under ambient parameters. An exposure assessment was also performed for three toy puzzles: indoor formaldehyde concentrations caused by puzzles were not negligible (up to 8 μg/m3), especially when more conservative exposure scenarios were considered.
Mehrere Aspekte wurden im Hinblick auf die Standardisierung eines geeigneten Verfahrens für die Analyse sehr flüchtiger organischer Verbindungen (VVOCs) untersucht. Die Verwendung gasförmiger Standards ist notwendig und es wurde ein stabiles Standardgasgemisch aus 60 Substanzen erfolgreich erzeugt und auf Stabilität und Reaktivität überprüft. Die Eignungsuntersuchung verschiedener Chromatographiesäulen ergab, dass PLOT-Säulen (Porous Layer Open Tubular) für die VVOC-Analytik gut geeignet sind. Für die 60 Analyten wurden Wiederfindungsraten auf mehreren Adsorbenzien und deren Kombinationen bestimmt. Dabei zeigte eine Kombination aus einem graphitierten Ruß und einem Kohlenstoff-Molekularsieb hervorragende Ergebnisse für alle Zielkomponenten. Nachteilig an Kohlenstoff-Molekularsieben ist, dass sie Wasser adsorbieren, was die Analyse beeinträchtigen kann. Zur Wasserentfernung wurden verschiedene Optionen wie das Trockenspülen oder der Einsatz eines Trocknungssystems untersucht.
Several aspects were explored towards the standardization of a suitable procedure. The use of gaseous standards is necessary and a standard gas mixture containing 60 substances was successfully generated and employed for further investigations. The suitability of different chromatography columns was addressed: The use of PLOT (Porous Layer Open Tubular) columns is well suitable for VVOC analysis. The recoveries of the 60 analytes on several adsorbents and their combinations were determined: A combination of a graphitized carbon black and a carbon molecular sieve showed great results for all analytes. Carbon molecular sieves adsorb water which can impair the analysis. Different options such as purging, the use of a drying system or splitting were investigated for water removal. This contribution will present experimental results supporting the standardization of a method for VVOC analysis.
This poster summarizes the points that need to be addressed towards the standardization of an efficient procedure for the analysis of VVOC emissions: Standard mixture generation and investigations on mutual reactivity, selection of an appropriate sorbent combination, water management and choice of a suited GC column.
This study shows that formaldehyde Emission results in micro-scale emission chambers are comparable with results in bigger chambers both for particle boards and wooden toys. On the contrary, the WKI flask method was leading to more variable results depending on sample geometry. Thus, microchambers could be used for reliable routine market surveillance. An exposure assessment led to noticeable formaldehyde indoor air concentration values, pointing out the need for an effective Surveillance of such samples.
The BAM Data Store
(2023)
As a partner in several NFDI consortia, the Bundesanstalt für Materialforschung und -prüfung (BAM, German federal institute for materials science and testing) contributes to research data standardization efforts in various domains of materials science and engineering (MSE). To implement a central research data management (RDM) infrastructure that meets the requirements of MSE groups at BAM, we initiated the Data Store pilot project in 2021. The resulting infrastructure should enable researchers to digitally document research processes and store related data in a standardized and interoperable manner. As a software solution, we chose openBIS, an open-source framework that is increasingly being used for RDM in MSE communities.
The pilot project was conducted for one year with five research groups across different organizational units and MSE disciplines. The main results are presented for the use case “nanoPlattform”. The group registered experimental steps and linked associated instruments and chemicals in the Data Store to ensure full traceability of data related to the synthesis of ~400 nanomaterials. The system also supported researchers in implementing RDM practices in their workflows, e.g., by automating data import and documentation and by integrating infrastructure for data analysis.
Based on the promising results of the pilot phase, we will roll out the Data Store as the central RDM infrastructure of BAM starting in 2023. We further aim to develop openBIS plugins, metadata standards, and RDM workflows to contribute to the openBIS community and to foster RDM in MSE.
Angesichts der zunehmenden Digitalisierung und dem Einsatz datenintensiver Methodiken in der Wissenschaft stehen Forschende vor der Herausforderung, stetig wachsende Datenmengen nachvollziehbar zu dokumentieren, langfristig zu speichern und für Dritte nachnutzbar zu machen. Um diesen Anforderungen gerecht zu werden, bietet sich die Nutzung von Software-Lösungen an, welche Forschungsdatenmanagement mit der digitalen Dokumentation von Laborinventar und Experimenten in elektronischen Laborbüchern (engl. electronic lab notebooks (ELN)) verknüpfen.
Textile floor coverings are often used in offices and residential buildings. Large areas like meeting rooms, cinemas, theaters and hotels are often equipped with such coverings. They contribute to the comfort of the users as they provide high pedaling comfort and sound absorption. The weakness of these building materials is due to the odor emission that is released from the floor covering, which affects the comfort of the users. A bad air quality and the resulting dissatisfaction can lead to lower employee productivity. The research project of the Hochschule für Technik und Wirtschaft Berlin (HTW-Berlin) is promoted by the German Environment Agency (UBA). The project has the following title: Low-emission and low-odor building products for energy-efficient buildings - Development of requirements and concepts for the Blue Angel from a climate protection perspective; investigates the emission and odor behavior of textile floor coverings (Emissions- und geruchsarme Bauprodukte für energieeffiziente Gebäude - Entwicklung von Anforderungen und Konzepten für den Blauen Engel aus Klimaschutzsicht; untersucht das Emissions- und Geruchsverhalten textiler Bodenbeläge).
EN 16516 sets the test method and requirements for the determination of emissions of Volatile Organic Compounds (VOCs) from building materials into indoor air. To address the quality control requirements for the class of semi-VOCs (SVOCs), VSL developed gaseous reference materials. A novel home-made dynamic gas mixture preparation system, operating according to ISO 6145-4 (continuous injection method), has recently been developed and validated. Thanks to the stable temperature control up to 100 oC, the system can prevent condensation of the SVOCs in air at indoor air concentration levels. The in-situ obtained SVOC gas standards can be sampled in sorbent tubes to obtain SVOC transfer standards. A study was performed to determine the optimal sorbent material and storage conditions. This study will be presented together with the results of the 2018 Round Robin test for emission test chamber measurements organised by BAM. Using the novel system, VSL prepared transfer standards with known amounts of VOCs and SVOCs for participants to evaluate their analytical performance.
In this work, we characterise the performance of a Sharp optical aerosol sensor model GP2Y1010AU0F. The sensor was exposed to different environments: to a clean room, to a controlled atmosphere with known aerosol size distribution and to the ambient atmosphere on a busy city street. During the exposure, the output waveforms of the sensor pulses were digitised, saved and a following offline analysis enabled us to study the behaviour of the sensor pulse-by-pulse. A linear response of the sensor on number concentration of the monosized dispersed PSL particles was shown together with an almost linear dependence on particle diameters in the 0.4 to 4 micrometer range.
The gathered data about the sensor were used to predict its response to an ambient atmosphere, which was observed simultaneously with a calibrated optical particle counter.
The OECD Working Party on Manufactured Nanomaterials (WPMN) has actively worked towards understanding possible safety issues for manufactured nanomaterials and has contributed significantly to resolving these by developing Test Guidelines, Guidance Documents, Test Reports and other publications with the aim of a safe use of manufactured nanomaterials. To address the specific needs of manufactured nanomaterials, the OECD Test Guideline No. 110 “Particle Size Distribution/Fibre Length and Diameter Distributions” was identified as one of the test guidelines (TGs) to require an update. The current TG 110 (adopted in 1981) is only valid for particles and fibres with sizes above 250 nm. The WPMN prioritised to either update TG 110 to be applicable also to particles at the nanoscale or draft a new nanomaterial specific (TG).
Eventually, it was decided to develop a new TG that covers the size range from 1 nm to 1000 nm, intended for particle size and particle size distribution measurements of nanomaterials. Paragraph 11 provides further justification on the need for such measurements for nanomaterials. This TG overlaps with TG 110 in the size range from 250 nm to 1000 nm. When measuring particulate or fibrous materials, the appropriate TG should be selected depending on the size range of particles tested. In line with TG 110, the new TG for nanomaterials includes separate parts for particles and fibres.
For the part of this TG which addresses particles, several methods applicable to nanomaterials were reviewed and included to take into account developments since 1981 when the TG 110 was adopted. This TG includes the following methods: Atomic Force Microscopy (AFM), Centrifugal Liquid Sedimentation (CLS)/Analytical Ultracentrifugation (AUC), Dynamic Light Scattering (DLS), Differential Mobility Analysis System (DMAS), (Nano)Particle Tracking Analysis (PTA/NTA), Small Angle X-Ray Scattering (SAXS), Scanning Electron Microscopy (SEM), and Transmission Electron Microscopy (TEM). The method Single Particle Inductively Coupled Plasma Mass Spectrometry (sp-ICP-MS) could not be sufficiently validated within the interlaboratory comparison (ILC) carried out for the different methods in this TG (see also paragraph 6 for further details on the ILC). Applicability of sp-ICP-MS is strongly limited to nanomaterials with high mass values in combination with a sufficiently high particle size. However, the general method ICP-MS is widely used and the sp-mode for the size measurement of specific nanomaterials was successfully performed in ILCs elsewhere. The method is therefore included in the Appendix Part C of this TG, which further details the limitations of sp-ICP-MS.
For measuring the diameter and length of fibres, analysing images captured with electron microscopy is currently the only method available. This TG includes Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM).
To test the validity of this TG, an ILC was performed. Test materials were chosen to reflect a broad range of nanomaterial classes, e.g. metals, metal oxides, polymers and carbon materials. Where possible, well-characterised test materials were used.
Additionally, the test materials were chosen to reflect a broad range of sizes representing the size range 1 nm to 1000 nm. Specifically for fibres, a broad range of aspect ratios was included (length/diameter of 3 to > 50). Some of the test materials used are commercially available and further references are given in the validation report of the ILC. Sample preparation for physical chemical characterisation is critical for all listed methods. Due to the differences between individual nanomaterials and due to the wide range of individual material properties it is impossible to have a generic protocol to obtain the best possible sample preparation for every nanomaterial. Therefore, a generic protocol on sample preparation is not part of this TG. Information on sample preparation is given in the paragraphs 25-29, 33, 34 and 39 for particles and in paragraphs 159) for fibres. Further information on sample preparation of nanomaterials for physical chemical characterisation can be found in the OECD Guidance on Sample Preparation and Dosimetry for the Safety Testing of Manufactured Nanomaterials and elsewhere.
Final Draft of the OECD Test Guideline for Particle Size and Particle Size Distribution of Nanomaterials.
The OECD Working Party on Manufactured Nanomaterials (WPMN) has actively worked towards understanding possible safety issues for manufactured nanomaterials and has contributed significantly to resolving these by developing Test Guidelines, Guidance Documents, Test Reports and other publications with the aim of a safe use of manufactured nanomaterials. The OECD website (www.oecd.org/science/nanosafety) and the referenced publications contain more background information.
Among others, the OECD Test Guideline “Particle Size Distribution/Fibre Length and Diameter Distributions” (TG 110, adopted in 1981) was identified to require an update to address the specific needs of manufactured nanomaterials as the TG 110 is currently only valid for particles and fibres with sizes above 250 nm. The WPMN prioritised to either update TG 110 to be applicable also to particles at the nanoscale or draft a new nanomaterial specific Test Guideline (TG). Eventually, it was decided to develop a new TG for particle size and particle size distribution measurements of nanomaterials covering the size range from 1 nm to 1000 nm for further justification. This TG overlaps with TG 110 in the size range from 250 nm to 1000 nm. When measuring particulate or fibrous materials, the appropriate TG should be selected depending on the size range of particles tested. In line with TG 110, the new TG for nanomaterials includes separate parts for particles and fibres. For the part of this TG which addresses particles, several methods applicable to nanomaterials were reviewed and included to take into account developments since 1981 when the TG110 was adopted. This TG includes the following methods: Atomic Force Microscopy (AFM), Centrifugal Liquid Sedimentation (CLS)/Analytical Ultracentrifugation (AUC), Dynamic Light Scattering (DLS), Differential Mobility Analysis System (DMAS), (Nano)Particle Tracking Analysis (PTA/NTA), Small Angle X-Ray Scattering (SAXS), Scanning Electron Microscopy (SEM), and Transmission Electron Microscopy (TEM).
For measuring the diameter and length of fibres, analysing images captured with electron microscopy is currently the only method available. This TG includes Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM).
To test the validity of this TG, an ILC was performed. Test materials were chosen to reflect a broad 68 range of nanomaterial classes, e.g. metals, metal oxides, polymers and carbon materials. Where possible, well-characterised test materials were used. Additionally, the test materials were chosen, so that they reflect a broad range of sizes representing the size range 1 nm to 1000 nm and finally,
for fibres only, aspect ratios from length/diameter of 3 to > 50.
The properties of nanomaterials are influenced not only by their chemical composition but also by physical properties (such as size, geometry and crystal structure). For the reliable determination and assessment of behaviour and effects of nanomaterials as well as for the determination of the exposure of humans and environment a comprehensive physical-chemical characterization of nanomaterials is essential. This is an important prerequisite to identify them as nanomaterials and to interpret and compare test results and - in future – to forecast interaction and effects of nanomaterials.
In 2006, the OECD launched a sponsorship program for the testing of nanomaterials in which 11 nanomaterials were thoroughly investigated using a variety of methods. The aim of the project was, among other things, to find out where problems occur and where there are gaps in the measurement and test procedures and where are changes required. An important outcome of the sponsorship program was the finding that the OECD Test Guidelines should in several cases be extended to the specific needs in testing of nanomaterials. The existing standardized test methods of the OECD for physical-chemical characterization have not been developed for nanomaterials in particular. A high demand for an extension of the test guidelines was identified. Germany complied with the OECD's request in 2017 and has agreed to extend the “Test Guideline on Particle Size Distribution / Fiber Length and Diameter Distributions Test Guideline” for Manufactured Nanomaterials (MN). UBA commissioned BAM and BAuA with the preparation of the Test Guideline. The aim of the project is the development of a harmonized test protocol for a valid and reproducible determination of particle size and size distribution which is one of the most relevant physical-chemical properties for MNs.
Different measuring methods provide different results for the size distribution of the particles. This is caused by the different measuring principles of the methods. Each method measures a specific parameter that ultimately determines particle size. First, the measured quantity differs for each method (Scattered light intensity, 2D image / projection, electric mobility, etc.). Second, the calculated diameters of the MN may differ (Feret Diameter, Area Projection, Mobility Diameter, Aerodynamic Diameter, Hydrodynamic Diameter). Third, a measuring method provides a size distribution which is measured either mass-based, surface-based or number-based. A conversion between the results requires additional parameters and thus possibly increases the measurement error.
In addition to the technical differences, the individual parameters are strongly influenced by the structure and material of the nanoparticles. For example, a surface functionalization can lead to very different results in the size distribution. The suitability of measurement methods differs with the material of the MN. As a result, two very different results can be measured for the particle size distribution using two different methods, which are nevertheless both correct. Several large projects in recent years therefore concluded that nanomaterials should be characterized by at least two complementary method. Imaging techniques are regarded as one of these methods for the characterization, the complementary methods are supposed to be statistical methods.
The different results for the size distribution of nanomaterials become problematic for the registration of new MN. A comparable and reproducible size distribution is a prerequisite for a standardized registration. In the future, the particle size distribution in the EU will also decide on the classification of a substance as a nanomaterial or as a non-nanomaterial. Especially in borderline cases, a standardized and comparable measurement methodology is therefore essential.
Die gemeinsame Forschungsstrategie der Bundesoberbehörden zur Nanotechnologie wurde 2016 veröffentlicht. Die darin enthaltenen Aufgaben wurden von den Bundesoberbehörden vielfältig bearbeitet. Diese Präsentation gibt einen Überblick über die Projekte, die von der BAM bis 2019 bearbeitet wurden/werden und sich in den Rahmen der Forschungsstrategie einordnen.
Electron microscopy (EM) is the gold standard for the characterisation of the morphology (size and shape) of nanoparticles. Visual observation of objects under examination is always a necessary first step in the characterisation process. Several questions arise when undertaking to identify and count particles to measure their size and shape distribution. In addition to challenges with the dispersion and identification of the particles, more than one protocol for counting particles is in use. This paper focuses on precise rules for the counting of particles in EM micrographs, as this influences the measurement accuracy of the number of particles, thus implicitly affecting the size values of the counted particles. We review and compare four different, commonly used methods for counting, which we then apply in case studies. The impact of the selected counting rule on the obtained final particle size distribution is highlighted. One main aim of this analysis is to support the application of a specific, well-defined counting approach in accordance with regulatory
requirements to contribute to achieving more reliable and reproducible results. It is also useful for the new harmonised measurement procedures for determining the particle size and particle size distribution of nanomaterials.
The properties of nanomaterials are influenced not only by their chemical composition but also by physical properties (such as size, geometry and crystal structure). For the reliable determination and assessment of behaviour and effects of nanomaterials as well as for the determination of the exposure of humans and environment a comprehensive physical-chemical characterization of nanomaterials is essential. This is an important prerequisite to identify them as nanomaterials and to interpret and compare test results and - in future – to forecast interaction and effects of nanomaterials.
In 2006, the OECD launched a sponsorship program for the testing of nanomaterials in which 11 nanomaterials were thoroughly investigated using a variety of methods. The aim of the project was, among other things, to find out where problems occur and where there are gaps in the measurement and test procedures and where are changes required. An important outcome of the sponsorship program was the finding that the OECD Test Guidelines should in several cases be extended to the specific needs in testing of nanomaterials. The existing standardized test methods of the OECD for physical-chemical characterization have not been developed for nanomaterials in particular. A high demand for an extension of the test guidelines was identified. Germany complied with the OECD's request in 2017 and has agreed to extend the “Test Guideline on Particle Size Distribution / Fiber Length and Diameter Distributions Test Guideline” for Manufactured Nanomaterials (MN). UBA commissioned BAM and BAuA with the preparation of the Test Guideline. The aim of the project is the development of a harmonized test protocol for a valid and reproducible determination of particle size and size distribution which is one of the most relevant physical-chemical properties for MNs.
Different measuring methods provide different results for the size distribution of the particles. This is caused by the different measuring principles of the methods. Each method measures a specific parameter that ultimately determines particle size. First, the measured quantity differs for each method (Scattered light intensity, 2D image / projection, electric mobility, etc.). Second, the calculated diameters of the MN may differ (Feret Diameter, Area Projection, Mobility Diameter, Aerodynamic Diameter, Hydrodynamic Diameter). Third, a measuring method provides a size distribution which is measured either mass-based, surface-based or number-based. A conversion between the results requires additional parameters and thus possibly increases the measurement error.
In addition to the technical differences, the individual parameters are strongly influenced by the structure and material of the nanoparticles. For example, a surface functionalization can lead to very different results in the size distribution. The suitability of measurement methods differs with the material of the MN. As a result, two very different results can be measured for the particle size distribution using two different methods, which are nevertheless both correct. Several large projects in recent years therefore concluded that nanomaterials should be characterized by at least two complementary method. Imaging techniques are regarded as one of these methods for the characterization, the complementary methods are supposed to be statistical methods.
The different results for the size distribution of nanomaterials become problematic for the registration of new MN. A comparable and reproducible size distribution is a prerequisite for a standardized registration. In the future, the particle size distribution in the EU will also decide on the classification of a substance as a nanomaterial or as a non-nanomaterial. Especially in borderline cases, a standardized and comparable measurement methodology is therefore essential.
This presentation was held in an OECD Webinar introducing the newly developed and published OECD TG 125 on particle size and size distribution. The presentation is explaining the structure if the TG 125 and addresses all included methods and methodologies in a short and understandable way for the broader public. The presentation includes sections about nano-particles and nano-fibres.
OECD Prüfrichtlinie 125
(2023)
Diese Präsentation ist eine Einführung in die OECD TG 125 zur Bestimmung der Partikelgrößen von Nanomaterialien. Es wird auf die verchiedenen Probleme der Partikelgrößenbestimmung eingegangen wie z.B. verschiedene Oberflächenschichten, Äquivalenzdurchmesser und Verteilungsfunktionen. Gleichzeitig werden die neuen Begrifflichkeiten eingeführt, die in der TG 125 definiert neu werden.
Die Bestimmung der Nanopartikelgrößen- und -formverteilung nach OECD TG 125 mit einem Differentiellen Mobilitäts Analyse System (DMAS), auch bekannt als SMPS, wird vorgestellt:
- Generelles Messprinzip
- Welchen Durchmesser misst die Methode?
- Welche Partikel kann diese Methode messen?
- Welche Informationen kann diese Methode liefern?
- Wo stößt die Methode an ihre Grenzen?
- Implementierung und Datenauswertung,
- Reporting.
Anschließend wurde eine Q&A-Session für DMAS/SMPS organisiert.
The intention of the presentation is to inspire a discussion on the needs and challenges for the digitalisation of SOPs. SOPs are available for the disciplines of physical-chemical characterisation, for toxicology, for environmental applications and for exposure applications. Furthermore the SOPs need to be integrated in the regulatory framework and need to be detailed enough for the digital processing. This is highlighted in this presentation.
In 1981 the OECD published the Test Guideline on Particle size and size distribution. This TG is still a valid document for the measurement of particles all over the world.
When nanomaterials gained importance, ISO set up a technical commitee for Nanotechnologies in 2005 and the OECD followed this step in 2006 with the Working Party on Manufactured Nanomaterials.
In the following years ISO and OECD published several documents about nanomaterials and the systematisation developed.
In 2017 it was finally clear that nanomaterials need to be adressed in another way than chemicals and in 2020 ECHA revised the REACH-Annexes accordingly and included nanomaterials.
Unfortunately there is a little problem with this: Only a few applicable test guidelines exit for the measurement of the nanomaterials. Several test guidelines date from 1981 and do not address nanomaterials.
The logical next step for the OECD would be to publish a series of test guidelines which are indeed currently prepared and will be shown in this talk.
Finally there is an additional need for the future of NM standardisation: Digitalisation.
Vorstellung der Ergebnisse bei der Entwicklung einer neuen OECD Prüfrichtlinie zur Bestimmung der Partikelgröße und Anzahlgrößenverteilung von Nanomaterialien.
Ergebnisse:
Ideal sphärische Partikel sind gut und verlässlich mit vielen Methoden charakterisierbar.
Reale (Nicht ideale) Materialien sind gut charakterisierbar, wenn eine gewisse Homogenität und Stabilität vorliegt.
Stark inhomogene und stark agglomerierende Partikel liefern deutlich unterschiedliche Ergebnisse für verschiedene Methoden.
Partikel mit geringen Größenunterschieden lassen sich mit allen Methoden gut charakterisieren.
Partikel mit sehr deutlichen Größenunterschieden führen häufig zu einer Unterbewertung der kleineren Partikel.
Vollautomatische Partikeldetektion bei elektronenmikroskopischen Aufnahmen ist z.Zt. noch stark fehleranfällig und kann daher nicht empfohlen werden.
Es hat sich gezeigt, dass alle Methoden zur Bestimmung der Partikelgrößenverteilung Vor- und Nachteile haben. Es ist dringend zu empfehlen Größenverteilungen immer mit mindestens zwei unterschiedlichen Methoden zu bestimmen: Bildgebend und mit gute Anzahlstatistik.
Verschiedene Durchmesser wurden in der TG-PSD mit einem Indexsystem versehen, welches zukünftig Verwechslungen zwischen unterschiedlichen Durchmessern vermeiden soll.
Wird ein bestimmter Durchmesser benötigt (z.B. hydrodynamisch, aerodynamisch), muss die Methode passend gewählt werden. Eine Umrechnung von einem Durchmesser in einen anderen ist in der Regel fehlerbehaftet.
Es wurde ein einheitliches Reporting-System in der TG-PSD eingeführt.
OECD Prüfrichtlinie zur Bestimmung der Partikelgröße und Anzahlgrößenverteilung von Nanomaterialien
(2021)
Abschlusspräsentation des Projektes "OECD Prüfrichtlinie zur Bestimmung der Partikelgröße und Anzahlgrößenverteilung von Nanomaterialien" - Projektteil Nanopartikel.
Es hat sich gezeigt, dass alle Methoden zur Bestimmung der Partikelgrößenverteilung Vor- und Nachteile haben. Es wird dringend empfohlen Größenverteilungen immer mit mindestens zwei unterschiedlichen Methoden zu bestimmen: Bildgebend und mit gute Anzahlstatistik.
Verschiedene Durchmesser wurden in der TG-PSD mit einem Indexsystem versehen, welches zukünftig Verwechslungen zwischen unterschiedlichen Durchmessern vermeiden soll.
Wird ein bestimmter Durchmesser benötigt (z.B. hydrodynamisch, aerodynamisch), muss die Methode passend gewählt werden. Eine Umrechnung von einem Durchmesser in einen anderen ist in der Regel fehlerbehaftet.
Es wurde ein einheitliches Reporting-System in der TG-PSD eingeführt.
Tour de table - BAM
(2021)
Data for the publication "The role of extracellular polymeric substances of fungal biofilms in mineral attachment and weathering" (https://doi.org/10.1038/s41529-022-00253-1). It includes:
- The Summary of the EPS concentration, EPS sugar components and EPS linkages.
- The Summary of the XPS analysis of freeze-dried biofilm samples of all strains.
- The Summary of the pH, Mg, SI and Fe concentration, biomass and olivine dissolution rate for each time point of all dissolution experiments.
The roles extracellular polymeric substances (EPS) play in mineral attachment and weathering were studied using genetically modified biofilms of the rock-inhabiting fungus Knufia petricola strain A95. Mutants deficient in melanin and/or carotenoid synthesis were grown as air-exposed biofilms. Extracted EPS were quantified and characterised using a combination of analytical techniques. The absence of melanin affected the quantity and composition of the produced EPS: mutants no longer able to form melanin synthesised more EPS containing fewer pullulan-related glycosidic linkages. Moreover, the melanin-producing strains attached more strongly to the mineral olivine and dissolved it at a higher rate. We hypothesise that the pullulan-related linkages, with their known adhesion functionality, enable fungal attachment and weathering. The released phenolic intermediates of melanin synthesis in the Δsdh1 mutant might play a role similar to Fe-chelating siderophores, driving olivine dissolution even further. These data demonstrate the need for careful compositional and quantitative analyses of biofilm-created microenvironments.
Bauprodukte, die in Innenräumen verwendet werden, sollten die Gesundheit und das Wohlbefinden der Personen die sich darin aufhalten nicht durch das Ausdünsten von Geruchsstoffen stören. Die DIN ISO 16000-28 „Bestimmung der Geruchsstoffemissionen aus Bauprodukten mit einer Emissionsprüfkammer“ (DIN ISO 16000-28) beschreibt umfassend die Möglichkeiten der Geruchsprüfung. In Verbindung mit der Anwendung der VDI-Richtlinie 4302 Blatt 1 „Geruchsprüfung von Innenraumluft und Emissionen aus Innenraummaterialien“ (VDI 4302 Blatt 1) ist sie zur Bewertung der empfundenen Intensität von Bauprodukten mit Vergleichsmaßstab geeignet (Umweltbundesamt 2015). In einem vom Umweltbundesamt (UBA) geförderten Forschungsprojekt der Hochschule für Technik und Wirtschaft Berlin (HTW Berlin) und der Bundesanstalt für Materialforschung und –prüfung (BAM) wurden erstmals verschiedene Vergleichsmaßstäbe miteinander verglichen. Ziel des derzeitigen Folgeprojektes ist nun, Mindestanforderungen an Vergleichsmaßstäbe zu erarbeiten, welche die Reproduzierbarkeit der Ergebnisse erhöhen und mit denen die Norm konkretisiert werden kann. Dieser Beitrag stellt die Untersuchungen und Ergebnisse des ersten Projektes und die Schlussfolgerungen für die Durchführung des zweiten Projektes dar.
Bauprodukte und Einrichtungsgegenstände für Innenräume, wie Bodenbeläge und Wandpaneele, sollen das Wohlbefinden und die Gesundheit der Raumnutzerinnen und -nutzer nicht durch das Ausdünsten von Geruchsstoffen stören. Mit der Geruchsprüfung nach ISO 16000-28 „Innenraumluft - Bestimmung der Geruchsstoffemissionen aus Bauprodukten mit einer Emissionsprüfkammer“ wird der Produktgeruch zu einer messbaren Größe. So kann z. B. die empfundene Intensität, also die Stärke eines Geruchseindruckes, mit Hilfe eines Vergleichsmaßstabes von Probandinnen und Probanden ermittelt werden. Im hier vorgestellten Projekt werden Vorschläge zur Weiterentwicklung der Methode vorgestellt, um im Ergebnis die Reproduzierbarkeit der Messergebnisse weiter zu verbessern. Dabei werden vor allem das Probenpräsentationssystem und die Bewertungsmethodik für die empfundene Intensität bei der Bewertung von Bauprodukten gemäß AgBB-Schema betrachtet, da diese einen wesentlichen Einfluss haben.
Zur Weiterentwicklung der Probenpräsentation wurde ein Adapter entwickelt, der Emissionsprüfkammer und Bewertungstrichter miteinander verbindet und dadurch eine der direkten Messung vergleichbare Geruchsbewertung ermöglicht. Die analytischen Messungen zeigen, dass es kaum Unterschiede in der Zusammensetzung der Probenluft in der Kammer im Vergleich zum Probenbehälter gibt. Bei den olfaktorischen Messungen kam es jedoch bei der Bewertung der Probenluft mit Hilfe des Adapters zu Minderbefunden. Anschließende Untersuchungen zeigten, dass beim Ausschalten des Geräts Umgebungsluft über den Trichter in den Adapter strömt und zu einer Verdünnung der Probenluft führt. Um dies zu vermeiden, werden derzeit weitere Messungen durchgeführt.
Eine weitere Versuchsreihe wurde durchgeführt, um den Messaufwand bei der Bewertung der empfundenen Intensität zu reduzieren. Die entwickelte „größer-oder-kleiner/gleich“ Abfrage kann hier hilfreich sein. Die Untersuchungen im Luftqualitätslabor und im Rahmen eines Ringversuches mit verschiedenen Laboren, zeigen, dass die Abfrage in fast allen Fällen zu den gleichen Ergebnissen führt, wie die normgerechte aber aufwendigere Ermittlung der empfundenen Intensität mithilfe des Vergleichsmaßstabes.
Indoor air quality is affected by the emission of volatile organic compounds (VOC) or the odour from building products. Odours can be measured by applying the standard ISO 16000-28:2020.
In the study presented here proposals for further technical development of the ISO method are presented. The sampling procedure and evaluation
method of the perceived intensity are investigated in particular because they have a major influence on reproducibility of measurement results.
Healthy and energy efficient buildings must be free from disturbing odours. Odour emissions from building materials can be measured with the well-known and accepted standard ISO 16000-28 “Indoor air – Part 28: Determination of odour emissions from building products using test chambers”. For commonly used emission test chambers the sample air is collected in containers (bags) and presented to a group of panel members for the purpose of evaluating the odour. A standard sets requirements for the on-demand presentation in detail. These include the validation procedure for container materials, pre-treatment of bags, details on storage of filled bags and how to carry out the measurements. However, although these measures are proven in practice, incorrect measurements are still possible. Also errors can occur due to a very complex measurement procedure. So, there is a great need for research into how the odour samples are presented.
The proposal planned to be presented will introduce a new development in sample provision by using an adapter which enables collection and provision of sample air without storage or transport of bags. The adapter is a sample container which is permanently positioned on the emission test chamber´s outlet and continuously filled with sample air flowing through it. The flow is briefly interrupted at the time when a sample is taken by a panel member for the test.
The size of the container is sufficient to provide enough sample air for evaluation by at least one panel member via a funnel. Since sampling and presentation are technically connected, it means you can almost do away with storage or transportation and thus it can be presented almost unchanged to the panelmembers. The aim is to reduce measurement errors in the odour samples provision process and the improvement of measurement reproducibility. The paper presents the construction of the adapter as well as the results of emission and odour tests carried out so far.
One criterion to evaluate the odour of a sample is perceived
intensity П which is evaluated with the aid of a comparative scale. The procedure is well accepted but also time consuming and extensive. The study should help simplify the testing procedure by asking the panel members to only indicate whether a sample is perceived as less to equally intense or of greater intensity in comparison to a given acetone concentration of 7 pi on the comparative scale. In Germany a value of 7 pi is required for products to be suitable for the indoor use. The results show that the simplified test is basically suitable.
Sintered bioactive glass scaffolds of defined shape and porosity, e.g. made via additive manufacturing, must provide sufficient bioactivity and sinterability. As higher bioactivity is often linked to high corrosion and crystallization tendency, a certain compromise between sintering ability and bioactivity is therefore required. Groh et al. developed a fluoride-containing bioactive glass (F3), which allows fiber drawing and shows a bioactivity well comparable to that of Bioglass®45S5.
To study whether and to what extent the sinterability of F3 glass powder is controlled by particle size, coarse and fine F3 glass powders (300-310µm and 0-32µm) were prepared by crushing, sieving and milling. Sintering, degassing and phase transformation during heating were studied with heating microscopy, vacuum hot extraction (VHE), DTA, XRD, and SEM.
For the coarse glass powder, sintering proceeds slowly and is limited by surface crystallization of primary Na2CaSi2O6 crystals. Although the crystallization onset of Na2CaSi2O6 is shifted to lower temperature, full densification is attained for the fine powder. This finding indicate that certain porosity might be tuned via particle size variation. Above 900°C, intensive foaming is evident for the fine powder. VHE studies revealed that carbon species are the main foaming source.
Equipping ZIF particles with a polyelectrolyte membrane provides functional groups at their interface, enabling further conjugations necessary for applications such as targeted drug delivery. Previous approaches to coat ZIF particles with polyelectrolytes led to surface corrosion of the template material. This work overcomes previous limitations by performing a Layer-by-Layer (LbL) polyelectrolyte coating onto ZIF-8 and ZIF-67 particles in nonaqueous environment. Using the 2-methylimidazolium salt of polystyrensulfonic acid instead of the acid itself and polyethyleneimine in methanol led to intact ZIF particles after polyelectrolyte coating. This was verified by electron microscopy. Further, zetapotential and atomic force microscopy measurements confirmed a continuous polyelectrolyte multilayer built up. The here reported adaption to the well-studied (LbL) polyelectrolyte selfassembly process provides a facile method to equip ZIF particles with a nanometer thin polyelectrolyte multilayer membrane.
In this work, we use a gas sensor system consisting of a commercially available gas sensor in temperature cycled operation. It is trained with an extensive gas profile for detection and quantification of hazardous volatile organic compounds (VOC) in the ppb range independent of a varying background of other, less harmful VOCs and inorganic interfering gases like humidity or hydrogen. This training was then validated using a different gas mixture generation apparatus at an independent lab providing analytical methods as reference. While the varying background impedes selective detection of benzene and naphthalene at the low concentrations supplied, both formaldehyde and total VOC can well be quantified, after calibration transfer, by models trained with data from one system and evaluated with data from the other system. The lowest achievable root mean squared errors of prediction were 49 ppb for formaldehyde (in a concentration range of 20–200 ppb) and 150 μg/m³ (in a concentration range of 25–450 μg/m³) for total VOC. The latter uncertainty improves to 13 μg/m³ with a more confined model range of 220–320 μg/m³. The data from the second lab indicate an interfering gas which cannot be detected analytically but strongly influences the sensor signal. This demonstrates the need to take into account all sensor relevant gases, like, e.g., hydrogen and carbon monoxide, in analytical reference measurements.
Fluorometric sensing is a versatile approach for trace analysis outside of the laboratory, requiring suitable sensor materials and their integration into sensing devices. The versatility of fluorophores as probes, especially in terms of the possibility to tailor their optical as well as their recognition properties by synthetic modifications in a wide range, renders them as superior active component for the preparation of optical sensing devices. Recent works at BAM in this field include, for example, the detection of nerve gas agents, illustrating impressively the aforementioned benefits of fluorophores in optical sensing applications.
In the interdisciplinary project presented here, we target hazardous gases such as ammonia, benzene, and hydrogen sulfide, next to others, which pose a major threat to human health and environmental safety and for which the availability of a sensitive and reliable detection method is highly desirable. The dyes presented follow a “turn-on” fluorescence schematic, which allows for the selective and sensitive detection of the respective gaseous analyte. The immobilization of the probe in polymeric matrices is then the next step toward the fabrication of a prototype device for molecular sensing. Further steps in the project include the assembly of instruments for test-atmosphere generation, the referencing of the sensor system, development and implementation of an optical setup, and the testing of the prototype device under laboratory conditions and in the field.
In this presentation, we give an overview over the recent developments on this topic in our groups. Highlights are hydrogen sulfide sensitive, BODIPY based transition metal complexes, which allow for a sensitive as well as selective detection of the toxic gas. In addition, we present a novel class of highly substituted BODIPY derivatives – pocket-BODIPYs – which are of a synthetically high versatility and can readily be modified to create pockets in the periphery of the molecule of defined geometries. This is illustrated on the successful encapsulation of benzene by a pocket-BODIPY derivative, confirmed by X-ray crystallographic analysis as well as by further spectroscopic and analytical methods.
Dass Viren sich über Aerosolpartikel ausbreiten können, wurde bereits in vielen Studien gezeigt. Als Aerosol bezeichnet man ein Gemisch aus Luft mit darin verteilten festen oder flüssigen Partikeln. Ein Aerosol ist dabei immer dynamisch, da Partikel neugebildet, in oder mit der Luft transportiert und aus der Luft entfernt werden oder sich im luftgetragenen Zustand verändern. Zum Verständnis der Rolle von Aerosolpartikeln als Übertragungsweg von SARS-CoV-2 ist daher die Kenntnis der verschiedenen Prozesse in einem Aerosol von besonderer Bedeutung. Mit diesem Papier möchte die GAeF einen Beitrag dazu leisten, den momentan so häufig anzutreffenden Begriff „Aerosol“ sowie die relevanten Aerosolprozesse anschaulich darzustellen und zu erläutern. Dabei wird im Rahmen dieses Papiers nur auf die wesentlichen Grundlagen eingegangen.
Für ein tiefergehendes Verständnis der teilweise komplexen Prozesse sei auf die angeführte Sekundärliteratur verwiesen. Das Papier fasst eine Vielzahl von Studien zur Entstehung von virenbeladenen Aerosolpartikeln sowie deren Ausbreitung zusammen. Darauf basierend kann festgestellt werden, dass ausgeatmete Aerosolpartikel auch bei der Corona-Pandemie eine prominente Rolle bei der Verbreitung der Viren spielen. Abschließend geht dieses Papier auf mögliche Maßnahmen zur Verringerung der Ausbreitung von Aerosolpartikeln ein. Die diskutierten Maßnahmen orientieren sich an der derzeitigen öffentlichen Diskussion und beinhalten entsprechend die folgenden Punkte: Lüften, Luftreiniger, Lüftungsanlagen und Masken. Es werden Hinweise zum richtigen und sinnvollen Einsatz dieser Maßnahmen gegeben. Aerosolpartikel haben Größen zwischen ca. 0,001 und mehreren 100 Mikrometern (und nicht wie in vielen Publikationen derzeit definiert < 5μm) und verteilen sich mit Luftströmungen relativ schnell, auch über größere Distanzen. Größere Aerosolpartikel sinken – abhängig von ihrer Größe und Dichte – zu Boden; kleine Aerosolpartikel können hingegen sehr lange in der Luft verbleiben (s. Kapitel 3). Jeder Mensch stößt durch die Atmung sowie beim Sprechen, Husten und Niesen flüssige Aerosolpartikel unterschiedlicher Größen aus (s. Kapitel 4). Ist eine Person mit einem Virus, wie z. B. SARS-CoV-2, infiziert, so können diese Aerosolpartikel Viren enthalten, die in die Luft gelangen und von anderen Personen eingeatmet werden können. SARS-CoV-2 hat eine Größe von 0,06 bis 0,14 Mikrometer, die exhalierten flüssigen Aerosolpartikel sind hingegen größer. Die flüssigen Aerosolpartikel können aber je nach Umgebungsbedingungen durch Verdunstung schrumpfen (s. Kapitel 3.3). Für den Partikeltransport und die Partikelabscheidung ist dabei jeweils die aktuelle Partikelgröße relevant. Das höchste Infektionsrisiko besteht in geschlossenen Innenräumen, da sich hierin Aerosolpartikel anreichern können. Insbesondere hier sind entsprechend Maßnahmen zu treffen, die eine Reduktion der Aerosolpartikelkonzentration ermöglichen.
Vor dem Hintergrund der Aerosolwissenschaften ordnet die GAeF die aktuellen Maßnahmen zur Eindämmung der Pandemie wie folgt ein:
• Prinzipiell gilt: Keine Maßnahme kann für sich alleine funktionieren! Das Zusammenspiel der verschiedensten Maßnahmen ist nach derzeitigem Wissensstand der beste Weg zur Minimierung des Infektionsrisikos.
• Abstand halten ist wichtig, denn mit zunehmendem Abstand werden direkt ausgeatmete Viren verdünnt, und die Wahrscheinlichkeit sich anzustecken sinkt. Der vielfach vorgeschriebene Mindestabstand kann als Anhaltspunkt dienen, sollte aber insbesondere bei längeren Zusammenkünften und auch in Innenräumen mit verringerter Luftbewegung vergrößert und durch weitere Maßnahmen (s.u.) ergänzt werden.
• Masken helfen, einen Teil der exhalierten Partikel (und Viren) zu filtern. Dadurch sinkt die Konzentration der exhalierten Partikel (und Viren) in einem Raum und damit das Infektionsrisiko. Hierbei ist zu beachten, dass die ausgeatmeten Aerosolpartikel durch anhaftende Feuchtigkeit relativ groß sind und somit auch von einfachen Masken effizient zurückgehalten werden können. Da diese Partikel aber mit längerer Verweilzeit in der Raumluft schrumpfen, sind einfache Mund-Nasen-Bedeckungen für den Selbstschutz weniger effizient. Hierfür sind Atemschutzmasken erforderlich, die auch für feine Partikel eine hohe Abscheidung zeigen, z. B. der Klassen FFP2, N95 oder KN95. Diese sind sowohl für den Selbst- als auch den Fremdschutz effizient, sofern sie über kein Ausatemventil verfügen. Masken mit Ausatemventil dienen hingegen nur dem Selbstschutz und widersprechen daher dem Solidaritätskonzept, dass Mitmenschen durch kollektives Maskentragen geschützt werden.
• Gesichtsvisiere, die ohne zusätzliche Verwendung von Masken eingesetzt werden, sind hinsichtlich Aerosolpartikeln weitgehend nutzlos, da die Luft mit Partikeln (und Viren) ungefiltert um die Visiere herumströmt. Gesichtsvisiere werden im klinischen Alltag zusätzlich zu Masken getragen, um Tröpfcheninfektion über die Schleimhäute der Augen zu verhindern. Ebenfalls weitgehend unwirksam gegen die Aerosolverbreitung in Innenräumen sind mobile oder fest installierte Plexiglasbarrieren. Diese können nur kurzfristig die kleinräumige Ausbreitung eines Aerosols, z. B. im Kassenbereich eines Supermarkts, verhindern, bieten aber längerfristig keinen Schutz. Gesichtsvisiere und Plexiglasscheiben dienen im Wesentlichen als Spuck- und Spritzschutz gegenüber großen Tröpfchen.
• Im Freien finden so gut wie keine Infektionen durch Aerosolpartikel statt. Allerdings können Tröpfcheninfektionen auftreten, insbesondere in Menschenansammlungen, wenn Mindestabstände nicht eingehalten und/oder keine Masken getragen werden. In geschlossenen Räumen ist Lüften unerlässlich, um die ausgeatmete Luft in einem Raum durch frische Luft von draußen zu ersetzen. Häufiges Stoß- und Querlüften sind dabei vergleichbar effektiv wie dauernd das Fenster vollständig geöffnet zu lassen. Aus energetischer Sicht ist Stoß- oder Querlüften insbesondere im Winter allerdings effizienter. CO2-Monitore können bei der Überwachung der Luftqualität in Innenräumen helfen. Sie zeigen an, wann gelüftet werden sollte und wann die Luft in einem Raum während des Lüftens ausreichend gewechselt ist. Sie können jedoch nur als Indikator verwendet werden und verhindern selbst bei Einhaltung der vorgeschlagenen CO2-Grenzkonzentrationen keine direkte Infektion durch unmittelbar benachbarte Personen.
• Luftreiniger können einen sinnvollen Beitrag leisten, um die Partikel- und Virenkonzentration in einem Raum zu reduzieren. Bei der Beschaffung von Luftreinigern muss darauf geachtet werden, dass diese für den betrachteten Raum und die betrachtete Anwendung ausreichend dimensioniert sind, um die Partikel- und Virenlast signifikant zu verringern. Dem Luftdurchsatz des Gerätes kommt dabei eine größere Bedeutung zu, als der reinen Effizienz des Filters. Aus energetischen und Kostenerwägungen kann die Verwendung hocheffizienter Filter sogar kontraproduktiv sein. Fest verbaute Lüftungsanlagen können ebenso sinnvoll sein, sofern sie die Luft filtern, um die Partikel- und Virenlast in einem Raum zu verringern. Hierbei ist es zur Vermeidung von Infektionen sinnvoll, diese möglichst mit 100 % Frischluft zu betreiben.
Aus Sicht der Gesellschaft für Aerosolforschung besteht erheblicher Forschungsbedarf insbesondere an den interdisziplinären Grenzen zu Forschungsfeldern der Epidemiologie, Infektiologie, Virologie, Lüftungstechnik und Strömungsmechanik. Die Durchführung gezielter Studien sollte kurzfristig mit speziellen Förder- und Forschungsprogrammen ermöglicht werden. Dieses Papier wurde von Mitgliedern der Gesellschaft für Aerosolforschung verfasst und wird von einer Vielzahl internationaler Aerosolexperten unterstützt (s. Kapitel 8). Neben der vorliegenden Version existiert auch eine englischsprachige Übersetzung (siehe www.info.gaef.de). Sämtliche Abbildungen in diesem Papier stehen unter folgendem Link zum kostenlosen Download bereit: https://www.info.gaef.de/positionspapier. Bei jeder Verwendung ist „Gesellschaft für Aerosolforschung e. V.“ als Quelle zu nennen.
Many studies have already shown that viruses can spread via aerosol particles. An aerosol is a mixture of air with solid or liquid particles dispersed in it. To understand the role of aerosol particles as a transmission path of SARS-CoV-2, knowledge of the different processes in an Aerosol is therefore of particular importance. With this paper, GAeF would like to contribute to a better understanding of the term “aerosol” and the relevant aerosol processes. In the context of this paper only the essential basics will be discussed. For a deeper understanding of the partly complex processes, please refer to the literature mentioned at the end of the paper.
The paper summarises a large number of studies on the formation of virus-laden aerosol particles and their spread. Based on this, it can be concluded that exhaled aerosol particles may play a prominent role in the spread of viruses in the corona pandemic. Finally, this paper discusses possible measures to reduce the spread of aerosol particles. The measures discussed are based on the current public debate including ventilation, air purifiers, HVAC systems and masks. Advice is given on the correct and sensible use of these measures.
An aerosol is always dynamic, as particles are newly formed, transported in or with the air, removed from the air or change in the airborne state. Aerosol particles have sizes between approx. 0.001 and several 100 micrometres (and not < 5 μm as currently defined in many publications) and spread relatively quickly with air currents, even over longer distances. Larger aerosol particles sink to the ground, depending on their size and density, while small aerosol particles can remain in the air for a very long time (see Section 3). Every person emits liquid aerosol particles of various sizes through breathing and when speaking, coughing and sneezing (see Section 4). If a person is infected with a virus, such as SARS-CoV-2, these aerosol particles can contain viruses that can be released into the air and inhaled by other people. SARS-CoV-2 has a size of 0.06 to 0.14 micrometres, but the exhaled liquid aerosol particles are larger. The liquid aerosol particles can shrink by evaporation, depending on the ambient conditions (see Section 3.3). Particle size is relevant for particle transport and particle separation. The highest risk of infection exists in closed indoor spaces, as aerosol particles can accumulate there.
Here in particular, appropriate measures must be taken to reduce the concentration of aerosol particles (see Section 5).
Against the background of aerosol science, the GAeF classifies the current measures to contain the pandemic as follows:
• In principle, no measure can work on its own! According to the current state of knowledge, the interaction of the most varied measures is the best way to minimise the risk of infection.
• Keeping distance is important, because with increasing distance, directly exhaled viruses are diluted and the probability of infection decreases. The often prescribed minimum distance can be used as a guide, but it should be increased and supplemented by other measures (see below), especially for longer meetings and also indoors with reduced air movement.
• Masks help to filter some of the exhaled particles (and viruses). This reduces the concentration of exhaled particles (and viruses) in a room and thus the risk of infection. It should be noted here that the exhaled aerosol particles are relatively large due to adhering moisture and can therefore also be efficiently retained by simple masks. However, since these particles shrink with longer dwell time in the room air, simple mouth-nose masks are less efficient for self-protection. Respiratory masks are required for this purpose, which show a high degree of separation even for fine particles, e.g. of classes FFP2, N95 or KN95. These are efficient for both self-protection and protection of others unless they have an exhalation valve. Masks with an exhalation valve, on the other hand, are only for self-protection and therefore contradict the solidarity concept that fellow human beings are protected by collective mask wearing. Face shields which are used without additional masks are largely useless with regard t• aerosol particles, as the air with particles (and viruses) flows unfiltered around the shields. In everyday clinical practice, facial shields are worn in addition to masks to prevent droplet infection via the mucous membranes of the eyes. Mobile or permanently installed Plexiglas barriers are also largely ineffective against the spread of aerosols indoors. These can only prevent the smallscale spread of an aerosol in the short term, e.g. in the checkout area of a supermarket, but offer no protection in the longer term. Face shields and Plexiglas panels essentially serve as spit and splash protection against large droplets.
• Outdoors, there are practically no infections caused by aerosol transmission. However, droplet infections can still occur, especially in crowds, if minimum distances are not observed and/or masks are not worn. In closed rooms, ventilation is essential to replace the exhaled air in a room with fresh air from outside. Frequent airing and cross-ventilation is just as effective as leaving the window open all the time. From an energy point of view, however, it is more efficient to ventilate the room, especially in winter. CO2 monitors can help to monitor indoor air quality. They indicate when it is necessary to ventilate and when the air in a room has been sufficiently changed during ventilation. However, they can only be used as an indicator and even if the proposed CO2 limit concentrations are met, they do not prevent direct infection by people in the immediate vicinity.
• Air purifiers can make a useful contribution to reducing the concentration of particles and viruses in a room. When procuring air purifiers, care must be taken to ensure that they are adequately dimensioned for the room and application in question in order to significantly reduce the particle and virus load. The air throughput of the unit is more important than the pure efficiency of the filter. For energy and cost reasons, the use of highly efficient filters can even be counterproductive. Permanently installed ventilation systems can also be useful, provided they filter the air to reduce the particle and virus load in a room. To avoid infections, it is advisable to operate them with 100 % fresh air if possible.
From the point of view of the Gesellschaft für Aerosolforschung, there is a considerable need for research, especially at the interdisciplinary borders to research fields of epidemiology, infectiology, virology, ventilation technology and fluid mechanics. The implementation of targeted studies should be made possible at short notice with special funding and research programmes.
This paper was written originally in German by members of the Gesellschaft für Aerosolforschung and is supported by a large number of international aerosol experts. Both the English and German version as well as all images in the paper are available for free download at the following link: https://www.info.gaef.de/positionspapier. The “Gesellschaft für Aerosolforschung e. V.” must be named as the source, whenever an image is used.