The state of particulate matter contamination, particulate matter-bound heavy metals, and persistent organic pollutants (POPs) in megacities, China

The megacities in China have experienced severe particulate matter (PM) pollution along with rapid industrialization and urbanization. The PM mass exhibited distinct spatial and temporal trends with particle-size distributions in different megacities, especially in the Pearl River Delta region, Jing-Jin-Ji region and the Yangtze River Delta region. The concentrations of both PM2.5 and PM10 in megacities lowered generally with the significant decrease of hazy episodes. Obvious spatial and temporal distributions were observed for PM-bound heavy metals and semivolatile organic contaminants such as polycyclic aromatic hydrocarbons, polybrominated diphenyl ethers, polychlorinated biphenyls, and polychlorinated dibenzo-p-dioxin and dibenzofuran listed in the Stockholm Convention on persistent organic pollutants. This review highlights the recent progress associated with PM contamination, PM-bound contaminants and their effects on human health. Advanced analysis technology such as energy dispersive spectrometer and metagenomics for understanding PM-bound contaminants and pathogenic microorganism (or antibiotic resistance genes) were discussed respectively. Finally, PM perspectives in megacities are highlighted.