Temporal responses of PM2.5-bound trace elements and health risks to air control policy in a typical northern city in China during 2016-2020

A package of macro-control policies at the national level was an effective way to control air pollution. It was of great practical significance to study the trends of pollution sources and source-specific health risks of PM2.5- bound trace elements under long-term policies implementation, which in turn can not only gain insight into the substantive impact of policies, but also provide accurate guidance for future environmental management. In this study, winter PM2.5 samples were collected in Baoding City in northern China from 2016 to 2020, and variations in pollution sources and source-specific health risks of trace elements in PM2.5 were comprehensively analyzed. The results demonstrated that the concentrations of 10 elements displayed a declining trend, especially those of As, Sn, Zn, Sb, and Cd. By contrast, the concentration of Cr increased (except in 2020). Although the non-carcinogenic risk (NCR, including dust source) and carcinogenic risk (CR) from coal combustion and indus-trial emissions had decreased in the past five years, the NCR and CR still exceed the widely accept level for both adults and children in the winter of 2020. Coal combustion source was no longer the major contributor to the health risks caused by PM2.5-bound trace elements in winter, but vehicle related non-exhaust emissions have gradually become the main source of pollution.