Elemental carbon and respirable particulate matter in the indoor air of apartments and nursery schools and ambient air in Berlin (Germany)

This study was performed to examine exposure to typical carcinogenic traffic air pollutants in the city center of an urban area. In all, 123 apartments and 74 nursery schools were analyzed with and without tobacco smoke interference and the households in two measuring periods. Simultaneously, the air outside 61 apartment windows as well as the average daily traffic volume were measured. Elemental carbon (EC), the marker for particulate diesel exhaust and respirable particulate matter ( RPM) were determined. The thermographic EC analysis was conducted with and without prior solvent extraction of the soluble carbon fraction. Comparison of these two thermographic EC measurements clearly showed that method-related differences in the results, especially for indoor measurements, when high background loads of organic material were present (e. g. tobacco smoke), existed. Solvent extraction prior to EC determination was therefore appropriate. For the first winter measuring period, the EC concentration levels without solvent extraction in the indoor air were about 50% higher than those measured in the spring/summer period. In the second measuring period (i.e. spring/summer), the median EC concentrations after solvent extraction were 1.9 mu g/m(3) for smokers apartments and 2.1 mu g/m(3) for nonsmokers apartments, with RPM concentrations of 57 and 27 mu g/m(3), respectively. Nursery schools showed high concentrations with median values of 53 mu g/m(3) for RPM and 2.9 mu g/m(3) for EC after solvent extraction. A significant correlation between the. ne dust and EC concentrations (after solvent extraction) in the indoor and ambient air was determined. Outdoor EC values were also correlated with the average daily traffic volume. The EC ratios between indoor and ambient concentration showed a median of 0.8 (range: 0.3-4.2) in non-smoker households and 0.9 (range: 0.4-1.5) in smoker apartments. Furthermore, the EC/RPM ratio in indoor and ambient air was 0.01-0.15 (median 0.06) and 0.04-0.37 (median 0.09), respectively.