EXPOSURE OF THE POPULATION AGAINST VOLATI LE ORGANIC-COMPOUNDS INSIDEA CAR AND A SUBWAY-TRAIN

Air quality, in particular in urban regions, is affected by the emissi ons of the traffic and meanwhile for some substances motor vehicles be came the dominating source. For valid quantitative risk assessment of the general population it is necessary to have informations about the main routes of exposure. Therefore in a pilot study 1994 and two times in summer 1995 and winter 1996 aromatic hydrocarbons, carbon monoxide (CO) and carbon dioxide (CO2) were determined under different meteoro logic conditions inside of a car (a two year old VW-Golf with a three- way catalyst) and in a subway-train. The car route followed the subway (31 km underground) and crossed the central parts of Berlin in street s with high traffic density. The mean values for benzene obtained duri ng the three measurement periods inside the car were 21.1/21.5 and 21. 6 mu g/m(3) (daily maximum: 31.9/26.3 and 35.0 mu g/m(3)) and inside t he subway 8.4/5.4 and 7.4 mu g/m(3) (daily maximum: 16.0/7.4 and 10.3 mu g/m(3)). The mean levels of CO in the car were 6 ppm (summer) and 5 ppm (winter) respectively, with peak concentrations of 33 and 70 ppm (10-minutes maximum). In the subway the values were 2 ppm (summer and winter); (10-minutes maximum: 5 and 12 ppm). A comparison between the two types of traffic shows three times higher concentrations of benzen e inside the car. Our results demonstrate that the exposure of car occ upants to benzene has to be taken into account for risk assessment. Th e concentration of CO inside the car is three to four times higher tha n in the subway train. Compared with other studies we found only low c oncentrations of CO inside the car.