Health impact assessment on life expectancy gains ascribed to particulate matter reduction

How the shape characterization of the concentration-response relationships between particulate matter (PM) and all-cause mortality influences life expectancy (LE) gains remains unclear. Based on the Pearl River Cohort, the 2021 World Health Organization air quality guidelines, and an integrated comparative risk assessment framework, we identified sigmodal relationships between PM_2.5, all-cause mortality, and LE reduction. A 10-unit increase in PM_2.5 was associated with an excess mortality risk of 31.2% (95% uncertainty interval: 27.6–35.0%). Reducing PM_2.5 to the guideline threshold of 5 μg/m³ could prevent 0.193 (0.175–0.212) million deaths, contributing to a 4.07–year (3.60–4.52) average LE gain. In contrast, PM_2.5 reductions by 5.6% and 10% resulted in smaller LE gains of 0.33 (0.28–0.38) and 0.58 (0.49–0.67) years, respectively. These findings highlight the importance of accounting for the nonlinear relationship in air pollution control and provide essential incentives for tailoring sustainable plans to enhance population longevity.