Occurrence of neonicotinoid pesticides in outdoor air particulate matters from 2019 to 2021 in China

Neonicotinoid insecticides (NNIs), as a new type of insecticide, are now widely used in agriculture and daily life. Because of the problematic volatility of NNIs, few studies have evaluated them in atmospheric particulate matter. In this study, a total of 101 outdoor PM2.5 samples were collected from the Wuhan urban area from 2019 to 2021, and seven NNIs and three metabolites of NNIs were detected. The frequency of detection for all 10 substances was more than 60%, with DIN and IMI reaching 100%. DIN (53.3 pg/m 3 ) and IMI (42.8 pg/m 3 ) had higher median concentrations than did the other substances. The distributions of four neonicotinoids and one metabolite were significantly different ( p <0.05) across the four seasons: spring, summer, fall and winter. The median concentration of imidacloprid-equivalent total neonicotinoids (IMIeq: generated by the relative potency factor method) was 256.1 pg/m 3 . Finally, the estimated daily intake (EDI) of NNIs via respiration was greater in infants and young children than in the rest of the population, suggesting that infants and young children are more likely to be exposed to the health effects of airborne residual PM2.5.