大气细颗粒物(PM2.5)环境持久性自由基(EPFRs)是一种高活性组分。我国特有大气污染状况导致灰霾发生时氮氧化物等高反应性组分与细颗粒物污染共存，其能通过与EPFRs或其前体分子反应而改变PM2.5体系生物活性与毒性效应。本项目拟采用计算模拟与实验测试相结合的方法，选取多环芳烃、氯代苯酚、氯代苯等作为煤烟型污染、汽车尾气等一次气溶胶有机组分的模型分子，以我国PM2.5中含量较多的Fe(III)2O3、Zn(II)O和Cu(II)O等为典型细颗粒物固相组成，重点开展效应导向的典型大气共存组分对PM2.5中EPFRs毒性影响的化学机制研究工作，以期揭示一次细颗粒物EPFRs毒性变化的分子机制，阐明二次细颗粒物生成过程EPFRs体系毒性组分演化的化学本质，为科学认识灰霾有害成分的环境演化并从源头上有效减少和控制能使组分活化的污染排放提供理论依据与方法储备。

Environmentally persistent free radicals (EPFRs) in airborne fine particulate matters (PM2.5) possess relatively high bioactivity. Owing to the unique pollution situation in China, coexistent air pollutants of high reactivity, like NOx, may present at high concentration during regional haze episode. Therefore, a working hypothesis has been proposed that such coexistent air pollutants may directly interact with EPFRs or their precursors in PM2.5 to transform the original speciations into possibly more/less toxic components. In this project, typical PM2.5 organic components such as polycyclic aromatic hydrocarbon and chlorophenols will be chosen as model compounds for precursors from different sources like coal-combustion or vehicle exhaust, while representative solid phase such as Fe(III)2O3, Zn(II)O and Cu(II)O will be used for modeling the surface of airborne fine particulate matters. Major efforts will be made to reveal the influencing mechanism of PM2.5-EPFRs toxicity by classical coexistent air pollutants which prevail in the haze events. By using the integrated approach based on computational simulation methods and effect-directed toxic component identification techniques, the applicant believes that both theoretical prediction and experimental results would provide valuable information for elucidating the molecular mechanism of the change in toxicity for PM2.5-EPFRs in the primary particulate matters and revealing the chemical nature of toxic component transformation for PM2.5-EPFRs in the secondary particulate matters. The progress made in the project not only may help understanding the environmental transformation of toxic components in PM2.5, but also can provide theoretical support to the emission control of air pollutants capable of component activation.