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

Concentrations of polycyclic aromatic hydrocarbons (PAH) and oxidised PAH (oxy-PAH) 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 μm. 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 μm 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.