Sources and Distributions of Polycyclic Aromatic Hydrocarbons and Toxicity of Polluted Atmosphere Aerosols

Levels and sources, mass size and phase distributions of parent PAHs and the toxicity of ambient aerosols at urban and rural sites of central (Czech Republic) and south-eastern (Bosnia and Hercegovina) Europe, from 2006 to 2008, are investigated. PAH pollution levels are much higher in winter than in summer, obviously due to the seasonalities of emission strength, photochemical degradation and mixing. The levels are in the range of 10–100 ng m−3 at urban and rural sites, while strong concentration gradients exist towards background sites, in particular in summer, due to both dispersion and degradation during transport. Based on back-trajectory analysis of air masses travelling to a background site in the Czech Republic, regionally significant PAH source areas were localized in eastern and south-eastern Europe, while western European countries emit less. PAHs represent a mass fraction of ≈100–500 ppm of the inhalable particulate matter (i.e. <10 μm). Based on a size resolution of 6 fractions, unimodal PAH mass size distributions were found at urban and rural sites which peaked almost exclusively in the accumulation mode (0.1–1.0 μm). Mass median diameters were found higher for semivolatile PAHs than for non volatile PAHs, probably related to re-distribution of semivolatiles in the aerosol according to the surface size distribution. Genotoxicity and AhR-mediated (i.e. dioxin-like) activity were found in all size classes at urban and rural sites in similar magnitudes. Activities were found in general highest in the fine particulate matter (i.e. <1 μm). All biological effects tested were also found in extracts of the gas-phase. PAH TEQ and antiandrogenicity were even mostly associated with gaseous pollutants. The calculated TEQ mediated by parent PAHs corresponded by average to 7.5 and 95% of the dioxin-like activity in the particulate and gaseous fractions, respectively.