By examining individual episodes of high mass and number concentrations, we show that the seasonality in the physicochemical properties of aerosol particles was caused by the sources' diversity and was related to the different air masses and meteorology. We also confirmed the relation between particle size and age that is reflected in oxidation state and shape (difference in densities; effective vs. material). The results have general validity and thus transcend the study regional character.

Measurements of stable carbon and nitrogen isotopic compositions in the PM₁ atmospheric aerosol provide partial insight into the possible sources of aerosol at a Central European rural background station but mainly offers a deeper insight into the physical and chemical processes taking place between the gas phase and particulate matter. These processes are probably valid in general (not only at this site), especially for nitrogen compounds.

This work assessed the performance of 4 cascade impactors, by means of two intercomparison exercises in 2 European locations. The comparability between the different types of impactors assessed was dependent on particle size and on impactor design characteristics. Particle processes such as particle bounce, dissociation of semi volatiles in the coarser stages and/or particle shrinkage were identified as the main causes for the differences observed in particle mass across size fractions.