An appraisal of relative airborne sub-urban concentrations of polycyclic aromatic hydrocarbons monitored indoors and outdoors.

Particle-size distribution studies of polycyclic aromatic hydrocarbons in city and sub-urban atmospheres indicate that these compounds are associated with particles having MMD values of about 0.5 micrometer. Ambient airborne concentrations of pyrene, chrysene, benzo[a]pyrene, benzo[e]pyrene and coronene at suburban sites between 11 and 17 km from a city centre are shown to be approximately similar inside and outside detached residential houses. At all sites, monitored chrysene appears in highest concentration in the range 4-7 ng m-3, followed by benzo[a]pyrene and benzo[e]pyrene between 2-4 ng m-3, with coronene generally less than 1 ng m-3. By taking benzo[a]pyrene as a typical example of this class of compounds, these results indicate that the lungs of sub-urban populations will be exposed to about 34 ng of benzo[a]pyrene per day. This background amount is roughly equivalent to the exposure to this chemical experienced by the lung when one cigarette is smoked per day.