LAUSR

Ambient air contains a number of persistent organic pollutants (POPs), to which inhalation exposure has drawn worldwide concern. However, information regarding annual changes in the concentrations and health risks of POPs in the ambient air of São Paulo, Brazil, are limited. This study provides comprehensive information on annual changes in polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), dioxin-like polychlorinated biphenyls (DL-PCBs), and 10 groups of organochlorine pesticides (OCPs) in the ambient air of São Paulo between 2010 and 2015 based on the Global Monitoring Plan. The mass concentrations of the studied POPs (PCDD/Fs, DL-PCBs, and OCPs) showed declining trends from 2010 to 2015 (from 2.65 × 10-2 to 1.33 × 10-2 pg m-3, from 9.89 × 10-2 to 3.12 × 10-2 pg m-3, and from 0.313 to 0.100 ng m-3, respectively), which might be due to the decrease of non-intentional emissions. The carcinogenic risk (CR) and non-carcinogenic risk (Non-CR) of the studied POPs were 1.48 × 10-11 to 6.08 × 10-7 and 3.44 × 10-8 to 3.34 × 10-3, respectively, which are lower than the generally accepted threshold values (10-6/10-5 and 1 for CR and Non-CR, respectively), suggesting that the health risks posed by the studied POPs were acceptable. PCDD/Fs had the highest CR (6.08 × 10-8-4.81 × 10-7), whereas the 95th percentile CR of DL-PCBs and nine of the OCPs were lower than 10-7, suggesting that among the studied POPs, PCDD/Fs in the ambient air warrant special attention. The 95th percentile CRs of dichlorodiphenyltrichloroethane (2.30 × 10-8), dieldrin (1.30 × 10-8), hexachlorocyclohexanes (1.05 × 10-8), heptachlor (8.97 × 10-9), hexachlorobenzene (6.47 × 10-9), chlordane (5.89 × 10-9), heptachlor epoxide (1.42 × 10-9), aldrin (1.33 × 10-9), and mirex (2.71 × 10-10) in ambient air were relatively low, suggesting that their threats to human health were negligible. In general, PCDD/Fs, DL-PCBs, and OCPs in the ambient air of São Paulo did not pose serious threats to human health during 2010-2015.