PM_2.5-bound elements in Hebei Province, China: Pollution levels, source apportionment and health risks

Particle-bound elements have attracted increasing attentions due to their health effects and atmospheric catalytic reactivity. However, elements in atmospheric fine particulate matter (PM_2.5) have not been well investigated even in some highly polluted area. In this study, 22 elements in PM_2.5 were measured by a multi-metal monitor in ten prefecture-level and county-level cities in Hebei province, one of the most polluted provinces in China, during the heating and non-heating seasons. Source apportionment of PM_2.5-bound elements were conducted, and health risks of individual elements and different sources were assessed. The results showed that, total elements (TEs) measured contributed to 2%-7% of the PM_2.5 mass, with potassium (K), calcium (Ca), iron (Fe), and zinc (Zn) as the most abundant elements, accounting for about 71%- 87% of TEs mass. Concentrations of chromium (Cr), arsenic (As), and cadmium (Cd) were more likely to exceed the World Health Organization (WHO) limits. Source apportionment results indicated that PM_2.5-bound elements were primarily from coal combustion, dust, traffic, ferrous metal smelting and oil combustion, and other industrial related sources. Therein, ferrous metal smelting and oil combustion, coal combustion and industry were the predominant source of Cr, As and Cd, respectively. Health risk assessment indicated that the carcinogenic and non-carcinogenic risks of As for children could exceed the precautionary criteria, and coal combustion source had the highest carcinogenic and non-carcinogenic risks. This study suggested that attentions should be paid not only on PM_2.5 mass but also PM_2.5-bound compounds especially heavy metals and metalloids to reduce health risks in the future.