Airborne particles impact weather, climate, and air quality. Ultrafine particles (UFP; diameter <100nm) account for the majority, by number, of these particles. Whether or not UFPs pose a risk to human and/or environmental health strongly depends on their size and chemical composition. A precise chemical investigation of UFPs can help to understand underlying atmospheric processes and their impact.
Impactors are useful tools to separate and collect environmental particles from the air. After physical characterization of different cascade impactors regarding their cut-off characteristic, pressure drop and sampling volume, we report on size dependent UFP sampling during the winter season in urban and rural areas in Bavaria, Germany. The impactors were operated simultaneously for different time-periods, partly after their optimization for the separation and collection of the ultrafine fraction. The chemical composition of the collected UFPs was examined off-line with various chromatographic analytical methods.
For testing our methods, we focused on specific marker components of anthropogenic and biogenic sources. Our aims are first, to draw comparisons between the performance of the impactors, second, to investigate different analytical methods for chemical UFP analysis and third, to provide data on the spatial distribution.
The initial results of the physical characterization of various impactors indicate that not all devices are suitable for separating and collecting UFPs. Additionally we found variations in the chemical composition of the size class of ultrafine particles for the tested marker components depending on the deployed impactor. Another cause of uncertainty were the different analytical methods used. Our findings highlight, that it is crucial for the quality of airborne UFP analysis to compare and evaluate the currently applied methodology. This project is financed by the Bavarian Ministry of the Environment and Consumer Protection.