Emission factors of environmentally persistent free radicals in PM2.5 from rural residential solid fuels combusted in a traditional stove

Emission factors (EFs) are crucial for establishing emission inventory and subsequent health risk assessment of pollutants. However, the EFs of environmentally persistent free radicals (EPFRs) in PM2.5 have not been well investigated. Wemeasured EPFRs in PM2.5 fromburning of different solid fuels in a traditional stovewidely used in rural China and calculated the EFs of EPFRs (EFEPFRs). The characteristics of EPFRs varied greatly with PM2.5 depending on the feedstock, and the EFEPFRs of crop residue, firewood and bitumite was 2.13 +/- 1.04, 1.40 +/- 0.76 and 1.08 +/- 0.39 (10(20) spins.kg(-1)), respectively. The estimated results of EPFRs emission associated with PM2.5 showed that the crop residue was the main contributor to the top four provinces with high EPFRs emissions in China in 2010. Awide range (0.03-4.89 cig.person(-1).day(-1)) of equivalent cigarette number converted by inhaling EPFRs in PM2.5 was observed. Provinces with higher equivalent cigarette number were mainly agricultural provinces, because the rural residents tend to use readily available fuels. Additionally, EPFRs in collected PM2.5 during 2 - month photoaging were more stable in particles with higher organic carbon contents. Our findings provided a new insight into the risk assessment of PM2.5 from different sources by taking EPFRs into consideration. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

Emission factors (EFs) for environmentally persistent free radicals (EPFRs) in PM2.5 from burning of different solid fuels vary significantly, with crop residue identified as the main contributor to EPFRs emissions in China. Provinces with higher equivalent cigarette numbers of EPFRs in PM2.5 are mainly agricultural areas, where rural residents tend to use readily available fuels. Additionally, EPFRs in PM2.5 collected during a 2-month photoaging were found to be more stable in particles with higher organic carbon contents.