Specific differences and responses to reductions for premature mortality attributable to ambient PM_2.5 in China

Although recent assessments have quantified the impact of ambient PM_2.5 on public health in China, air quality managers would benefit from assessing specific differences in premature mortality and its responses to air quality improvement. Using PM_2.5 data simulated by an observation-fused air quality model and an integrated exposure-response model for the full range of PM_2.5, we determined the premature mortality attributable to ambient PM_2.5 across mainland China in 2016. Overall, the total number of PM_2.5-related deaths nationwide was 1.31 million, of which lung cancer, chronic obstructive pulmonary disease, ischemic heart disease, and stroke represented 0.13, 0.13, 0.42, and 0.62 million, respectively. Per capita PM_2.5-related mortality in China was 95 per 100,000 person-years, and that of elderly people aged ≥75 years (1166 deaths per 100,000) was much higher than that of young people aged 25-44 years (11 deaths per 100,000). Additionally, there were significant spatial differences in premature deaths, which mainly occurred in regions with high PM_2.5 levels or/and population density. Halving deaths across mainland China required an average of 63% reduction of PM_2.5 nationwide and a decrease by 73% in high concentration regions exceeding 70 μg/m³ and 19% in low concentration locales below 10 μg/m³. Moreover, reducing PM_2.5 to the WHO interim target I (IT-1) of 35 μg/m³ would only result in a 12.6% reduction in premature mortality, while a more exacting standard (reducing PM_2.5 to 10 μg/m³) would avoid 73.0% of mortality. In particular, there is a large potential for reducing the high PM_2.5-related mortality in heavily polluted locales. In conclusion, to further reduce premature mortality across mainland China, targets stricter than the IT-1 and tight policies to improve air quality and protect public health are necessary, especially for vulnerable groups such as the elderly and patients with cardio-cerebrovascular diseases, particularly in areas with high premature mortality.