Pollution Characteristics and Health Risk Assessment of Heavy Metals in PM<sub>2.5</sub> during Winter in the Suburb of Cangzhou, China

The heavy metals in atmospheric fine particles are of great concern to human health. To understand the pollution characteristics and health risks of heavy metals in particulate matter with an aerodynamic equivalent diameter ≤2.5 μm (PM2.5) during winter in the suburb of Cangzhou, PM2.5 samples were collected with an intelligent medium-flow atmospheric particulate matter sampler from January to February 2019. The Fe, Cu, Mn, Pb and Zn contents in PM2.5 were determined via inductively coupled plasma optical emission spectrometry (ICP-OES). The sources and health risks of heavy metals in PM2.5 were analysed via the enrichment factor (EF) method and the United States Environmental Protection Agency (US EPA) health risk assessment model. The results showed that the average PM2.5 concentration in the suburb of Cangzhou reached 71.6 μg/m3, ranging from 23.7 to 169.5 μg/m3. The exceeding standard rate was 29.4% during the sampling period. The PM2.5 concentration during the nighttime was higher than that during the daytime. The heavy metal concentrations in PM2.5 decreased in the order of Fe > Mn > Zn > Cu > Pb, and the Fe, Mn, Pb and Zn concentrations decreased in the order of clean days the daytime. EF analysis revealed that Zn, Pb and Cu were significantly enriched, and Pb was highly enriched on heavy pollution days with increasing pollution degree. The enrichment level of heavy metals during the nighttime was higher than that during the daytime. Health risk assessment demonstrated that Mn posed non-carcinogenic risks to both adults and children, following the sequence of clean days . The study revealed that the pollution levels of heavy metals in PM2.5 in the suburb of Cangzhou were low, and Pb and Mn in PM2.5 posed certain health risks to the population.