Environmental exposure to fine particles in Gothenburg - personal exposure and its variability, indoor and outdoor levels, and effects on biomarkers

Abstract

Urban particulate air pollution has been associated with adverse health effects in epidemiological as well as experimental studies. The overall aim of this thesis was to characterize environmental exposure to fine particles (PM2.5), black smoke (BS) and particulate trace elements among the general adult population in Gothenburg. Exposure was assessed during 24 hours by personal sampling on 30 subjects, along with parallel residential indoor and outdoor measurements and fixed-site urban background monitoring. Repeated samplings were performed for 20 individuals. In a subsequent study, short-term effects of exposure to urban air pollution on blood biomarkers were examined in healthy volunteers. The mean personal exposure to PM2.5 was 12 µg/m3 (95% CI 9.6-14 µg/m3). There was a strong correlation (rs=0.71) between personal exposure and indoor levels of PM2.5, and a moderate correlation between personal exposure and urban background levels (rs=0.61). Personal exposure exceeded residential outdoor levels for PM2.5 and for several of the trace elements also the urban background levels. Air mass origin affected urban background levels of PM2.5, BS and several trace elements, and also personal exposure to some elements derived from combustion processes. Determinants of personal exposure to PM2.5 were season, smoking and the urban background levels. The within-person variance component dominated the variability of personal exposure to PM2.5, BS and trace elements for non-smokers. Large within-person variance components point to the importance of performing repeated sampling when assessing environmental exposures. Levels of biomarkers were not found to be increased after days with elevated levels of ambient air pollution compared with low levels in healthy adults. Since there is no evidence of a threshold level below which no health effects of PM occur, further reduction of exposure to particulate air pollution would result in significant health benefits within the population of Gothenburg.