[Pollution Level and Health Risk Assessment of Heavy Metals in Atmospheric PM₂.₅ in Nanjing Before and After the Youth Olympic Games].

The influence of human activities on the atmospheric environment has attracted people's attention. This study reported the dynamic changes in PM₂.₅ concentration, its heavy metal compositions and health risk assessment from April to September, 2014 in Nanjing when the Youth Olympic Games ( YOG) was held. The results showed that the mass levels of PM₂.₅ ranged from 26.39 to 80.31 µg · m⁻³ from April to September. The mass levels of PM₂.₅ met the level II standard of ambient air quality in China (24 h average concentration, 75 µg · m⁻³) in months of April, May and July while met the level I standard (24 h average concentration, 35 µg · m⁻³) in August during the YOG. The average mass concentration of PM₂.₅ reached 76.14 µg · m⁻¹ after the YOG, showing resilience of air pollution. The variations of heavy metals were not consistent with each other throughout the observation period. Principal component analysis indicated that emission sources significantly affected the variations of PM₂.₅ and its heavy metals. PM₂.₅ and all of the heavy metals decreased to their minimum values during the YOG, indicating the effectiveness of those temporary measures for reducing atmospheric pollutant before and during the YOG. The health risks of Cd, Cu, Ni and Pb in PM₂.₅ via breathing and dermal contact exposure were all within the acceptable ranges, but potential carcinogenic risk existed for Cr in PM₂.₅. There was potential non-carcinogenic health risk for adult males via breathing of Mn and greater non-carcinogenic health risk for children via dermal contact exposures to all these 6 heavy metals.