Personal exposures and microenvironment concentrations of PM2.5, VOC, NO2 and CO in Oxford, UK

Between 1998 and 2000 in Oxford, UK, simultaneous personal exposures and microenvironmental measurements (home indoor, home outdoor and work indoor) to fine particulate matters PM2.5, volatile organic compounds (VOC), nitrogen dioxide (NO2) and carbon monoxide (CO) were carried out once per person among 50 adults over a 48-h period. Thirty-seven elements in PM2.5 and 30 different VOCs were analysed. Questionnaires were distributed to record their time-activity patterns and exposure-related information. Results showed that participants spent more time (89.5%) in all indoors than in other microenvironments. Geometric mean (GM) of personal and home indoor levels of PM2.5, 14 elements (aluminium, arsenic, bromine, calcium, copper, iron, gallium, potassium, sodium, phosphorus, lead, selenium, silicon, titanium), total VOC (TVOC) and 8 individual compounds (nonane, decane, undecane, trimethylbenzene, toluene, benzaldehyde, alpha-pinene and d-limonene) were over 20% higher than their GM outdoor levels. Those of NO2, 5 aromatic VOCs (benzene, o-xylene, ethylbenzene, propylbenzene, m,p-xylene) and 5 other elements (chlorine, magnesium, manganese, sulphur, zinc) were close to their GM outdoor levels. For PM2.5 and TVOC, personal exposures and residential indoor levels (in GM) were about 2 times higher among the tobacco-smoke exposed group compared to the non-smoke exposed group, suggesting that smoking is an important determinant of these exposures. Determinants for CO were visualised by real-time monitoring, and we showed that the peak levels of personal exposure to CO were associated with smoking, cooking and transportation activities. Moderate to good correlations were only found between the personal exposures and residential indoor levels for both PM2.5 (r=0.60, p<0.001) and NO2 (r=0.47, p=0.003).