A review on atmospheric volatile halogenated hydrocarbons in China: ambient levels, trends and human health risks

Strict control measures on atmospheric volatile halogenated hydrocarbons (VHCs) have been taken in China over the past decades to protect the ozone layer, combat climate change, and protect human health and natural ecosystem. It is necessary to obtain overall understanding of the atmospheric dispersion characteristics and human health risks of VHCs in order to provide scientific support for further effective control in China. This paper investigated the reasons for the variations of VHCs in the urban areas in China from 2001 to 2020 based on literature review and collation, and also evaluated the human health risk of harmful VHCs to the exposed populations in the urban areas in China. The study results showed that the variation trends for six groups of VHCs corresponded well to the temporal starting point and persistence of the measures taken, and concentrations of some controlled VHCs species showed a significant decreasing trend since they were banned. While progress continues to be made in the control of VHCs, it is worth noting that some harmful VHCs imposed obvious carcinogenic risks to the exposed human in China, which means that special attention should still be paid to control the emissions of harmful VHCs in the future with China's continuous compliance with the Vienna Convention and the Montreal Protocol. The shortcomings in long-term continuity, spatial representativeness, completeness of key species, and analytical comparability of the current atmospheric VHCs measurements in China limit the acquisition of a more comprehensive and scientific understanding of VHCs pollution in China in this review. Nevertheless, the review could still provide some useful information on VHCs in China, which would improve the understanding of the overall situation and control of VHCs in China.