Occurrence of particle-associated polycyclic aromatic compounds in ambient air of the city Munich.

Concentrations of polycyclic aromatic hydrocarbons (PAH) and oxidised PAH (oxy-FAH) from outdoor air were determined. Size-fractionated aerosol samples were collected in the city of Munich (Germany). Twenty-four hour samples with six- and nine-stage Berner-type low-pressure impactors were collected between 1996 and 1998. Fluoranthene, pyrene, chrysene, benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[a]pyrene and benzo[ghi]perylene were quantified by HPLC with fluorescence detection. The averaged sum of these PAH reached 1.24 ng m(-3) (range: 0.68-1.85 ng m (-3)) at the inner city site which was not directly influenced by any road nearby, whereas samples from two sites close to busy roads exhibited average PAH concentrations equal to 5.61 ng m(-3) (range: 3.65-6.65 ng m(-3)) and 5.74 ng m(-3) (range: 1.67-15.13 ng m(-3)). The PAH concentration observed at the northern outskirts of Munich ranged from 0.15 to 9.45 ng m(-3) (average, 2.4 ng m(-3)). Different distributions of the PAH in the investigated particle size fractions were observed. Close to the road (at about 1 m off), about 40% of the PAH were found in the particle fraction with diameters of 0.06-0.13 mum Similar distributions were observed at the second sampling site located close to a road when winds blew directly from this road. When winds blew from other directions, higher percents of PAH were present on larger particles. A bigger accumulation of PAH on particles ranging from 0.26 to 0.9 mum was also observed at the outskirts. Since the lung dose of particle-associated compounds is influenced by the distribution of the compounds within the particle size range, the observed differences in the distribution of PAH have implications on human exposure