Impact of Heavy PM_2.5 Pollution Events on Mortality in 250 Chinese Counties

We explored the impact of heavy PM_2.5 pollution events on the health of residents in 250 counties in China. A time-series approach involving a two-stage analysis was applied to estimate the association between heavy PM_2.5 pollution events and mortality from 2013 to 2018. The associations between heavy (PM_2.5 ≥75 μg/m³ and <150 μg/m³) and extremely heavy (PM_2.5 ≥150 μg/m³) PM_2.5 pollution days with mortality were explored. The added effects of the heavy PM_2.5 pollution events were evaluated by controlling PM_2.5 concentration in the model. From 2013 to 2018, there were 57,279 county days of heavy PM_2.5 pollution and 21,248 county days of extremely heavy PM_2.5 pollution. The risks of mortality during this period of heavy PM_2.5 pollution events increased by 1.22% (95% CI: 0.82-1.63%), 1.14% (95% CI: 0.74-1.53%), 1.09% (95% CI: 0.58-1.60%), and 1.30% (95% CI: 0.40-2.20%), for all-cause, nonaccidental, circulatory, and respiratory mortality, respectively. We also observed that heavy PM_2.5 pollution events had an added effect on mortality risk associated with all-cause, nonaccidental, circulatory, and respiratory mortality, evident from an observed increase by 0.77% (95% CI: 0.29-1.24%), 0.73% (95% CI: 0.27-1.19%), 0.96% (95% CI: 0.37-1.55%), and 0.55% (95% CI: -0.52-1.63%), respectively. Heavy PM_2.5 pollution events increased mortality risks and caused an independent added effect. The findings serve as a foundation for policymakers in developing early warning systems and policy interventions.