Long-term exposure to ambient PM₁ accelerates biological aging in middle-aged and older adults in China

Population aging poses significant public health challenges in China. Emerging studies have linked air pollution to physiological aging, yet evidence regarding particulate matter with an aerodynamic diameter ≤ 1 μm (PM₁) remains sparse. This two-wave panel study included 5391 Chinese adults aged 45-80 to explore the effects of long-term exposure to PM₁ on biological aging acceleration. The Klemera-Doubal method (KDM) was employed to estimate biological aging acceleration (KDM-BAA) using 11 clinical biomarkers at both the 2011 baseline and the 2015 follow-up survey. Multivariate linear models with natural cubic splines were performed to estimate the association between PM₁ exposure and KDM-BAA changes from baseline to follow-up. Sensitivity analyses and stratified analyses were also performed. The exposure-response curve indicated that exposure to ambient PM₁ was significantly positively associated with changes in KDM-BAA, with the association becoming substantially stronger when PM₁ exposure exceeded the median exposure level of 32.5 μg/m³. Per 10 μg/m³ increment in PM₁ exposure was associated with an acceleration of 1.55 (95% CI: 0.79, 2.31) years in KDM-BAA. Elderly adults over 60 years and smokers demonstrated greater susceptibility to the aging effects of ambient PM₁ exposure, whereas leisure engagement was observed to have a beneficial effect in mitigating the aging response of PM₁ exposure. Long-term exposure to ambient PM₁ may accelerate biological aging among middle-aged and older adults in China, especially in the elderly. These findings highlight the urgency for policies aimed at mitigating PM₁ pollution to promote healthy aging within an increasingly aging population.