Aromatic hydrocarbons in the atmospheric environment: Part I. Indoor versus outdoor sources, the influence of traffic

Six aromatic hydrocarbons (benzene, toluene, ethylbenzene and the three iso meric xylenes) were monitored in the indoor and outdoor air of 115 private non-smoker homes ( similar to 380 rooms), about half of which were located in two city streets in Hannover (Northern Germany) with high traffic densit y, the other half in rural areas with hardly any traffic at all. This envir onmental monitoring was complemented by human biomonitoring (i.e. the deter mination of aromatic hydrocarbons in blood and exhaled air). Particular att ention was paid to benzene as a result of its carcinogenicity. In the city streets with high traffic density, an average benzene concentration of 3.1 mug m(-3) and in the rural areas of 1.8 mug m(-3) was found in these non-sm oker homes tall data = geometric means), which reflects the influence of th e traffic (automobile exhaust) on the benzene level found indoors. Source i dentification is also possible by determining the indoor/outdoor (I/O) conc entration ratio. For the rooms facing the city street, this I/O ratio is cl ose to 1 for all aromatic hydrocarbons studied with the exception of toluen e (I/O = 3.5), while in the rural areas I/O ratios for the individual compo unds ranging in 6-9 were determined, with the exception of benzene where th e I/O ratio is only 1.5. These I/O ratios in the city street with high traf fic density indicate that an equilibrium between indoor and outdoor air is almost reached. Indoor sources prevail only in the case of toluene. In cont rast, in the rural area, indoor sources dominate for all aromatic hydrocarb ons except benzene, the indoor level of which is mainly influenced by the o utdoor air even in areas of very low traffic density. However, weak indoor sources must exist also for this compound even in non-smoker homes. The int ernal exposure of the non-smoking inhabitants of these homes to benzene is very low. Depending on the living area, mean values of 61-67 ngl(-1) benzen e in blood and 0.9-1.2 mug m(-3) in the exhaled air were found. (C) 2001 El sevier Science Ltd. All rights reserved.