Source apportionment and health risk assessment of PM2.5-bound elements on winter pollution days in industrial cities on the northern slope of Tianshan Mountain, China

Frequent haze pollution during winter crucially affects public health in the urban agglomerations on the northern slopes of the Tianshan Mountains. However, research examining the relationship between local environmental emissions and the associated health hazards is scarce. In this study, PM2.5 filter membrane samples were collected from the residential and industrial areas of Shihezi during December 2020-January 2021. Seventeen elements were measured to evaluate the health risks associated with PM2.5. Total element concentrations on severe pollution days were 2.6 and 2.8 times higher than those on low-pollution days in residential and industrial areas, respectively. The sources of elements in residential and industrial areas were resolved into vehicle-related emissions, coal combustion, industrial pollution, dust emissions, and oil combustion using positive matrix factorisation (PMF). In residential areas, a complex mixture of vehicular emissions, coal combustion, and dust pollution is prevalent, whereas industrial parks are more susceptible to industrial pollution. Notably, a significant increase in coal combustion sources was observed during days of severe pollution in the residential areas. Simultaneously, industrial pollution in industrial parks rapidly escalated during days characterised by moderate and severe pollution levels. Combining the methods of source apportionment and health risk assessment, we observed that vehicles, coal combustion, and industrial pollution dominated the non-carcinogenic risk (NCR) of residential and industrial area elements, whereas coal combustion was the most important contributor to induced carcinogenic risk (CR).