Environmental black carbon exposure in Singapore school children

Abstract

Background: Air pollution has many adverse effects on health. In addition to the common sources of urban air pollution, Singapore is periodically affected by smoke haze due to biomass burning in South East Asia. Black carbon (BC) represents one of the most harmful components of air borne Particulate Matter (PM). Aim: of this study was to do continuous ambulatory monitoring of BC exposure levels in Singapore school children and to identify activities that are associated with higher levels of BC exposure. Methods: School children aged 10-12 years, were recruited. The subjects carried a portable aethalometer (microAeth® model AE51) for 24 hours on a typical school day. The aethalometer was set up to record the BC levels at every 5 minute interval at flow rate of 100ml/min. The children filled in a concurrent activity diary. The data was downloaded and analysed. Results: 46 children (mean [SD] age = 11.3 [0.9] years, 22 [47.8%] males) completed the study. The mean (± SE) BC exposure on a typical school day was 3343 (± 174.4) ng/m3/min. Analyses of activity related BC exposure levels showed a significantly higher BC exposure during commuting to and from school (median [IQR] BC = 5082 [3026–6304] ng/m3/min), compared to that when at home (median [IQR] BC = 2936 [1745–3911] ng/m3/min, p<0.001), school (median [IQR] BC = 3336 [2360–4569] ng/m3/min, p<0.05) and during other activities (median [IQR] BC = 2757 [2084–3940] ng/m3/min, p<0.001). Conclusions: Our findings suggest that commuting to and from school is associated with higher BC exposure in Singapore school children. Comparative BC exposure levels in other global megacities and the potential adverse respiratory health effects of BC exposure warrant further studies.