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It is well known from medical studies that fine particulate matter has adverse effects to human health. However, exceeding of limit values for fine particulate matter PM10 and PM2.5 is still a problem in major German cities. Therefore, fine particulate matter is monitored in Germany by environmental state agencies at fixed stations with certified instruments. These certified instruments are able to deliver reliable and high quality results. However, because of the costs of these certified instruments and the maintenance efforts, only few measurements stations are placed in the cities at places, which are regarded as representative for the air pollution. On the other hand, it is of interest to know the concentration of fine particulate matter in areas and at places, which are not covered by the fixed measurement stations of the environmental state agencies.
In this situation citizen science projects started in Germany using low cost sensors for fine particulate matter. In principle, with these low cost sensors citizens could measure fine particulate matter at places and in situations of their interests.
However, at that point the question of reliability of the low cost sensor data arises. Therefore the Duesseldorf University of Applied Sciences (HSD) in Germany started a project for the testing and evaluation of low-cost sensors. For this reason 20 low-cost sensor units have been built up based on the SDS 011 sensor of Nova Fitness Inc. within the Laboratory for Environmental Measurement Techniques at HSD. The sensor measurement data can be transferred into a network and can be visualized on a digital map.
This testing and evaluation at HSD of the low-cost sensors comprised:
• Short term and long term comparison studies within the laboratory and at different urban sites with a certifiedwide range aerosol measurement system (Grimm WRAS).
• Short term and long term comparison studies within the laboratory and at different urban sites with mid-cost sensors (Alphasense AN2).
• Intercomparison testing and evaluation of sensors of the same production charge.
• Intercomparison testing and evaluation of sensors of different production charges.
• Testing and evaluation of the sensors at different meteorological conditions.
The results of this testing and evaluation will be presented at the conference. Moreover, the potential of additional applications for low-cost sensors, e.g. for mobile measurements (multicopter UAS, bicycles, pedestrians) or for the validation of air pollution models, will be discussed
For this study an octocopter UAV was used for carrying an ultrafine (UFP) particle monitor, an optical particle counter (OPC) and a micro aethalometer. The UFP-monitor, based on electrical charging of UFPs, was able to count the number of UFPs and give an estimated mean diameter of the measured particles. The OPC, based on the particle induced light scattering of a laser beam, was able to detect aerosols in a size range of about 250 nm to 32 μm in 31 bins. The micro aethalometer measured the soot by optical attenuation of a light beam which is caused by carbon particulate matter. The octocopter with a lift off weight by 10.5 kg was especially designed and constructed at the University of Applied Sciences, Duesseldorf, for the measurement of air pollutants. It was equipped with eight 900 W electric engines and a pixhawk flight control. Technically this octocopter was able to climb up to altitudes of up to 2 km AGL. However, during this study an altitude range of several 10 meters was used. During this study about 60 octocopter flights were performed. The flights clearly revealed a plume of UFPs coming from the traffic on the bridge. This result was confirmed by various upwind and downwind measurements with the octocopter in the region of the bridge.
Emissions of air pollutants from the road traffic are still a major problem in Germany. It is well known that traffic induced fine particulate matter (PM10, PM2.5, PM1), ultrafine particles (UFPs) and gaseous air pollutants, like e.g. NOx, are adverse to human health. Therefore it is important to monitor these air pollutants in the cities. In this study an octocopter UAV is used as a carrier for measurement systems for UFPs, fine particulate matter and soot. This instrumented octocopter was used for studying the vertical and horizontal variation of the air pollution plume, which originated from the traffic on a river bridge, connecting two parts of Duesseldorf in Germany. This octocopter UAV had been especially designed and built at the Duesseldorf University of Applied Sciences for measurements of air pollutants. It was featuring eight 900 W electric propeller drives and was equipped with a pixhawk flight control. Its lift off weight was about 10.5 kg. About 60 measurement flights were performed by the instrumented octocopter throughout this study. These measurement flights could clearly determine the traffic induced air pollution plume originating from the bridge. Moreover, the dispersion of UFPs within the pollution plume could be monitored with the octocopter flights.
In this study we investigated the performance of two portable hand-held measurement devices (Testo DiSCMini, Grimm NanoCheck) under real environmental conditions at an area on the new campus of the University of Applied Sciences Duesseldorf, which was influenced by construction activities and traffic. The values were compared to the data from a freshly calibrated SMPS (Grimm SMPS+C) as a reference system. The SMPS measured the particle number concentration as well as the particle number size distribution in a range from 5 nm to 350 nm. This was done as a quality assurance for the use of these portable devices for other measurement campaigns for detecting the particle number concentration in mobile applications by e.g. unmanned aerial systems, bicycles, or small aircraft. The results show a good correlation between all the systems. The agreement between the reference system and the NanoCheck was really good, but lower between the DiSCMini and the reference system. Due to the good correlation the data could be post processed with a correction function to reduce the deviation. Finally, it can be stated, that both systems work well under environmental conditions and are well suited for the mobile use for the investigation of ultrafine particle concentration.