Abstract

Fine particulate matter (PM_2.5) is one of the main pollutants in the atmosphere and poses a huge threat to public health. Secondary aerosol pollutants that are formed by precursor pollutants in the atmosphere represent a large proportion of PM_2.5; furthermore, photochemical reactions play an important role in their transformation processes. This review systematically presents the chemical and toxicological transformations of secondary organic aerosol (SOA), secondary inorganic aerosol (SIA), and metal species in PM_2.5 under photochemical conditions. Specifically, major SOAs and SIAs are observed to be formed from volatile organic compounds (VOCs) and sulfur/nitrogen oxides through photochemical reactions, while metal species in PM_2.5 participate in a series of photochemical reactions. Additionally, we compare the toxicities of precursor pollutants with their secondary pollutants after photochemical reactions. In general, major SOAs are found to be more toxic than their precursors, while major SIAs are less toxic than their precursors. As different metal species have different toxicities, changes in their toxicities after photoreaction depend on the specific metal and the photochemical reaction. By demonstrating that photochemical reactions can affect the toxicities of PM_2.5 components, this review provides a promising perspective toward reducing air pollution and its health risks by investigating the related photochemical reactions.

摘要

细颗粒物（PM _2.5）是大气中的主要污染物之一，对公众健康构成巨大威胁。大气中前体污染物形成的二次气溶胶污染物占PM _2.5的很大比例；此外，光化学反应在其转化过程中发挥着重要作用。本综述系统地介绍了光化学条件下PM _2.5中二次有机气溶胶 (SOA)、二次无机气溶胶 (SIA) 和金属物质的化学和毒理学转化。具体而言，观察到主要的 SOA 和 SIAs 是由挥发性有机化合物 (VOC) 和硫/氮氧化物通过光化学反应形成的，而 PM _{2.5 中的}金属物种参与一系列的光化学反应。此外，我们比较了前体污染物与光化学反应后的二次污染物的毒性。一般而言，主要 SOA 的毒性大于其前体，而主要 SIA 的毒性小于其前体。由于不同的金属种类具有不同的毒性，光反应后其毒性的变化取决于具体的金属和光化学反应。通过证明光化学反应可以影响 PM _2.5成分的毒性，本综述通过研究相关的光化学反应，为减少空气污染及其健康风险提供了一个有前景的视角。