Associations of PM2.5 mass, its constituents and extreme temperature events with physical function in a Chinese nationwide cohort

The combined effects of air pollution and extreme temperature events (ETEs) on physical function remain understudied. This study evaluated the individual and interactive associations of PM2.5 mass, its constituents and ETEs with physical function in mid-to-older-aged Chinese adults. Utilizing 2011–2015 CHARLS data, this longitudinal analysis included 8834 observations from 4110 participants across 125 cities. Physical function (0 − 16 points) was assessed through physical tests of grip strength, balance, chair-rise capability, and walking speed. Linear mixed-effects models were used to investigate the associations of PM2.5 constituents and ETEs with physical function, and bidirectionally stratified analyses were performed to testify the potential interaction between ETEs and PM2.5 exposure. PM2.5 mass and its components were consistently associated with poorer physical function. For each interquartile range rise, the greatest decline in physical function was − 0.481 (95% confidence interval: -0.552, -0.410) points for BC, followed by SO42−, OM, NH4+, and NO3-. For per 10-day increase in ETEs duration per year under multiple definitions, physical function score was declined by 0.216 − 0.290 points for heat waves and 0.205 − 0.251 points for cold spells, respectively. Regional heterogeneity was observed in associations of physical function with PM2.5 constituents and cold spells. We observed markedly intensified PM2.5-related effects in the group of high-frequency cold spells only and intensified ETEs-related effects in high-pollution groups. These results suggested that prolonged PM2.5 pollution and ETEs days were individually and interactively associated with impaired physical function in middle-aged and older adults, highlighting the importance for collaborative interventions amid climate change and aging.