Concentrations of heavy metals in PM2.5 and health risk assessment around Chinese New Year in Dalian, China

Twelve samples of heavy metals were analyzed by using a 1108A-1 mid-current particle sampler in Dalian, Liaoning Province, for 31 days before and after the spring festival 2019. The results showed that the concentrations of heavy metals were decreased by more than 25% during the spring festival, which was probably due to the shutdown of the factories and the decrease in people's travel. During the spring festival, the concentration of Ba was increased by 343.39% as compared to the concentration of Ba before the spring festival, which indicated that the fireworks had a great influence on the concentration of Ba. At the same time, this study also evaluated the health risk of heavy metals. For the heavy metals As, Cd, Co, Cr, and Ni, the lifetime cancer risk was found to be 2.13 x 10(-4), 2.08 x 10(-5), 8.64 x 10(-7), 4.39 x 10(-4)and 7.93 x 10(-7), respectively. The lifetime cancer risk of As, Cd, and Cr exceeds the threshold range of cancer risk (10(-6)-10(-4)), indicating that they are carcinogenic to humans. Also, during the spring festival, the non-carcinogenic risk value of V exceeded the limit value of environmental protection agency (EPA), and the lifetime carcinogenic risk value of As, Cd, and Cr exceeded the threshold range of carcinogenic risk; hence, they need to be carefully monitored and controlled.