Impact of Multiple Air Pollutants on Probable Sarcopenia in the UK Population: The Mediating Role of Physical Activity and Biological Aging

Background Emerging evidence links air pollution to probable sarcopenia, yet combined effects of multiple pollutants and their mediating pathways remain unclear. We aimed to evaluate both individual and combined associations of air pollutants with probable sarcopenia, and to explore mediating roles of physical activity and biological aging. Methods Data from 211,808 UK Biobank participants were analyzed. Probable sarcopenia was defined by the EWGSOP criteria. Concentrations of NO _x , NO ₂ , PM _2.5 , PM ₁₀ , and PM _2.5−10 were estimated using land use regression models. Multivariate logistic regression, weighted quantile sum (WQS) analysis, and Cox regression were employed to investigate cross-sectional, combined and longitudinal associations, respectively. Parallel mediation analyses quantified contributions of physical inactivity and accelerated biological aging. Results In cross-sectional analyses, each 10 µg/m³ increase in NO ₁₀ (OR = 1.11, 95% CI:1.08–1.15), NO ₂ (1.03, 1.02–1.04), PM _2.5 (1.41, 1.15–1.72), and PM ₁₀ (1.34, 1.21–1.49) was associated with elevated probable sarcopenia risk. The combined effects, indicated by WQS index, yielded an OR of 1.14 (95% CI: 1.11–1.17), primarily driven by NO _x and PM ₁₀ . Physical inactivity mediated 7.0–10.2% of total effects, while accelerated biological aging mediated 9.7% to 30.7%. Longitudinal analyses over 2.9 years further confirmed an increased incident risk. Conclusion Individual and combined exposures to air pollutants elevate probable sarcopenia risk, partially mediated by physical inactivity and accelerated biological aging, underscoring the need for improved air quality, active lifestyles and healthy aging to mitigate sarcopenia burden.