Estimated Contributions of Emissions Controls, Meteorological Factors, Population Growth, and Changes in Baseline Mortality to Reductions in Ambient PM2.5 and PM2.5-Related Mortality in China, 2013-2017

BACKGROUND: In 2013, China released the Air Pollution Prevention and Control Action Plan (Action Plan), which set the roadmap for national air pollution control actions for the period of 2013 to 2017. A decrease in the fine particulate matter with aerodynamic diameter <= 2.5 mu m (PM2.5) concentration may lead to a substantial benefit for human health. OBJECTIVE: We aimed to quantify the relative contributions four factors: emission reductions, changed meteorology, population growth, and a change in baseline mortality rates to the reduced PM2.5-related mortality (PM2.5-mortality) during the 2013-2017 period and evaluate the importance of emission controls for human health protection in China. METHODS: The integrated exposure-response function was adopted to estimate the chronic health effects of PM2.5. The annual PM2.5 concentrations were estimated from chemical transport model simulations combined with surface observations for 2013 and 2017. Relative contributions to PM2.5-mortality from emission reductions and the three factors were individually quantified through scenario analysis. RESULTS: The estimated total PM2.5-mortality in China was 1.389 million [95% confidence interval (CI): 1.005 million, 1.631 million) in 2013 but was substantially reduced to 1.102 million (95% CI: 0.755 million, 1.337 million) in 2017. Emission controls contributed 88.7% to this reduction in PM2.5-mortality, while changed meteorology, the change in baseline mortality rates, and population growth during 2013-2017 contributed 9.6, 3.8, and -2.2%, respectively. CONCLUSIONS: The implementation of the Action Plan has significantly reduced the PM2.5 concentration in regions of China where population density is high, dominating the decline in PM2.5-mortality during 2013-2017. However, the health burden of PM2.5 pollution in China is still extremely high compared with that in other developed countries. An aggressive air pollution control strategy should be implemented in densely populated areas to further reduce the health burden.