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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.
The reliable measurement of very volatile organic compounds (VVOC) in indoor air by use of thermal desorption gas chromatography (TD-GC) in order to include them into evaluation schemes for building products even nowadays is a great challenge. For capturing these small molecules with carbon numbers ranging from C 1 –C 6 , strong adsorbents are needed. In the present study, recovery rates of nine suitable adsorbents of the groups of porous polymers, graphitised carbon blacks (GCB) and carbon molecular sieves (CMS) are tested against a complex test gas standard containing 29 VVOC. By consideration of the recovery and the relative humidity (50% RH), combinations of the GCB Carbograph 5TD, the two CMS Carboxen 1003 and Carbosieve SII as well as the porous polymer Tenax® GR were identified to be potentially suitable for sampling the majority of the VVOC out of the gas mix. The results reveal a better performance of the adsorbents in combination than being used alone, particularly under humid sampling conditions. The recovery rates of the chosen compounds on each adsorbent should be in the range of 80–120%.
Comparison of Formaldehyde Concentrations in Emission Test Chambers Using EN 717-1 and EN 16516
(2018)
For more than 25 years EN 717-1 (Wood-based panels - Determination of formaldehyde re-lease - Part 1: Formaldehyde emission by the chamber method) is the standard for formalde-hyde emission testing of wooden boards. In 2017 EN 16516 (Construction products - Assess-ment of release of dangerous substances - Determination of emissions into indoor air) was published as a new harmonised standard for the emission testing of construction products. Because test chamber conditions are different, both standards give different concentrations for formaldehyde. To determine a conversion factor four test series were set up with different wooden boards. For a loading of 1 m²/m³ the conversion factor is 1.6. This means that the formaldehyde concentration measured under the conditions of EN 16516 is a factor of 1.6 higher compared to EN 717-1.
Compared to the intended EU reference level of 300 Bq m−3 for indoor radon concentrations, the contribution of building materials appears to be low. Considering the recommended limit of 100 Bq m−3 by WHO, their contribution is supposed to be relevant, especially at low air exchange rates. This study as part of a two-part research project investigated the suitability of direct low level 222Rn measurement under simulated indoor conditions with commercial radon monitors and dynamically operated emission test chambers. Active measuring devices based on ionisation or scintillation chambers with 1-σ uncertainties below 8.6% at 20 Bq m−3 were found to be best suitable for a practical test procedure for the determination of radon exhalation rates of building materials. For the measurement of such low concentrations, the knowledge of the accurate device background level is essential.
Wood-based materials are well-known sources for formaldehyde emission in the indoor environment. Different testing standards lead to different emission values for the materials. Such standards are compared in this study. Besides scenarios with varying loading factors, air exchange rates and climatic conditions were investigated to evaluate the formaldehyde emission potential of different building products.
Under realistic indoor conditions used for the emission chamber tests, exceeding of formaldehyde indoor guide values were obtained. Results showed the need for improvement of wood-based materials with lower formaldehyde emissions and the adaption of testing parameters closer to realistic conditions.
Acoustics is an important aspect for large rooms especially in schools, kindergartens and offices. Foam tiles made from melamine resins are often used for acoustic insulation because they show good fire resistance and good thermal insulation properties. But they can emit formaldehyde. In Germany there are cases with a resulting indoor air concentration of higher than 100 µg/m³. In this study samples from two schools and one office were investigated. Additionally, new tiles were purchased and tested to evaluate the general potential as formaldehyde source.
Most VVOC were rarely considered in the evaluation of construction products. (Salthammer, 2014) In Germany this will change because the latest version of the German AgBB scheme for health evaluation (2015) now include VVOC, e.g. ethyl acetate and ethanol. In this study selected compounds were tested with the procedure described in ISO 16017 and a method for measuring VVOC with thermal desorption was developed.
Three different adsorbents Tenax TA, Carbograph 5TD and Carbopack X were tested to analyse VVOC according to ISO 16017. For the tested VVOC, Carbograph 5TD showed the best results under the chosen analytical conditions.
Besides measurement of VOC emissions also the evaluation of odour emissions and the perceived intensity of odours gains in importance. Due to difficulties detected in the measurement method of the perceived intensity described in (ISO 16000-28, 2012) the introduction of “reference” odours will be recommended for the training of panellists and as basis for interlaboratory comparisons.
In order to generate the “reference” odours standard liquid substances were directly injected into the main gas flow provided to the panellists. One of the substances tested was ethyl acetate. A pre-evaluation was conducted with six untrained panellists and has shown that ethyl acetate is potentially suitable as reference odour. For further validation of those “reference” odours they additionally will be provided to and evaluated by trained panellists of well established-measurement institutes.
The latest version of the German AgBB evaluation scheme (2015) for construction products includes some VVOC, e.g. formaldehyde, acetaldehyde and acetone. For these VVOC so-called LCI values (lowest concentration of interest) were derived which are used for the calculation of the so-called R-value (risk index, see reference 1 for the calculation). Test chamber measurements of particle boards show that the emissions of VVOC might have significant impact on the R-value and therefore for the health evaluation.
The inhalation of radon (222Rn) decay products is the leading cause of lung cancer apart from tobacco smoking. Besides the permeation of radon from the subsoil through the basement as main source of radon in indoor air, also building materials have to be taken into consideration, especially at low air change rates in buildings. The Construction Products Regulation (EC, 2010) gives essential requirements for construction works regarding the release of dangerous substances such as toxic gases and radiation to which radon can be assigned. The recently adopted Basic Safety Standards Directive (EC, 2013), which has to be ratified by each European member state in between the next three years sets reference levels for indoor radon concentrations for the first time. In research project financed by the German Ministry for the Environment, Nature Conservation, Building and Nuclear Safety a practical, reliable and easily applicable test procedure for the determination of radon exhalation from building materials – based on ISO 16000-9 (ISO, 2006) and CEN/TS 16516 (CEN, 2013) – should be developed. In contrast to the static test procedure published by Richter et al. (2013), dynamically operated test chambers shall be foregrounded. First results of this study are presented, focused on the reliable measurement of radon background concentration and the selection of suitable radon test devices, representing the basic elements of the subsequent work.