Computational and experimental assessment of health risks of fine particulate matter in Nanjing and Yangzhou, China.

Fine particulate matter (PM_2.5) is a major air pollutant in most cities of China, and poses great health risks to local residents. In this study, the health effects of PM_2.5 in Nanjing and Yangzhou were compared using computational and experimental methods. The global exposure mortality model (GEMM), including the results of a cohort study in China, was used to estimate the disease-related risks. Premature mortality attributable to PM_2.5 exposure were markedly higher in Nanjing than that in Yangzhou at comparable levels of PM_2.5 (8191 95% CI, 6975–9994 vs. 6548 95% CI, 5599–8049 in 2015). However, the baseline mortality rate was on a country-level and the age distribution was on a province-level, traditional estimation method could not accurately represent the health burdens of PM_2.5 on a city-level. We proposed a refined calculation method which based on the actual deaths of each city and the disease death rates. Conversely, similar concentrations of PM_2.5 exposure resulted in higher actual deaths per million population in Yangzhou (1466 95% CI, 1266–1746) than that in Nanjing (1271 95% CI, 1098–1514). Health risks of PM_2.5 are associated with the generation of reactive oxygen species, among which hydroxyl radial (·OH) is the most reactive one. We then collected these PM_2.5 samples and quantified the induced ·OH. Consistently, average ·OH concentration in 2015 was higher in Yangzhou than that in Nanjing, again indicating that PM_2.5 in Yangzhou was more toxic. The combination of computational and experimental methods demonstrated the complex relationship between health risks and PM_2.5 concentrations. The refined estimation method could help us better estimate and interpret the risks caused by PM_2.5 exposure on a city-level. [ABSTRACT FROM AUTHOR]