Air Pollution and the Progression of Physical Function Limitations and Disability in Aging Adults

Abstract

Importance Physical disability reflects the cumulative burden of chronic conditions. Although generally progressive, episodes of disability can be followed by periods of recovery; therefore, there is a need to identify modifiable risk factors that contribute to the dynamic development of disability. Objective To investigate air pollution as a modifiable risk factor of transitions between states of no physical function limitation, physical function limitations, and activities of daily living (ADL) disability. Design, Setting, and Participants This cohort study included respondents older than 50 years from the nationally representative Health and Retirement Study (HRS) who participated in at least 2 interviews between 2000 and 2016. Data analysis was conducted from July 2023 to August 2025. Exposures Ten-year average ambient concentrations of particulate matter with a diameter of 2.5 µm or less (PM2.5), PM with a diameter between 10 and 2.5 µm (PM10-2.5), nitrogen dioxide (NO2), and ozone (O3) were estimated at respondent residential addresses preceding each survey using spatiotemporal models. Main Outcomes and Measures Physical disability states were assessed using self-reported mobility and Activities of Daily Living (ADL). To examine associations of exposure to air pollution with transitioning between states of physical disability, multistate models, adjusted for individual- and area-level covariates, were used. Results The sample included 29 790 respondents (mean [SD] age, 63 [11] years; 16 878 [57%] women; 3371 [11%] Hispanic, 5240 [18%] non-Hispanic Black, and 20 314 [68%[ non-Hispanic White), who were followed up for a mean (SD) of 8 (6) years. IQR-increments in PM2.5, PM10-2.5, and NO2 concentrations were mostly associated with greater hazards of transitioning from a state of no physical function limitation toward disability; a 1-IQR increment for PM2.5 was associated with lower odds of a reverse transition. For example, in the single-pollutant model, a 1-IQR higher PM2.5 concentration was associated with a hazard ratio (HR) of 1.06 (95% CI, 1.03-1.09) for transitioning from no physical function limitations to physical function limitations and an HR of 0.96 (95% CI, 0.93-0.99) for reverting back to healthy physical function from physical function limitations. By contrast, a 1-IQR higher O3 concentration was associated with lower hazards of transitioning from no physical function limitations to physical function limitations (HR, 0.92; 95% CI, 0.86-0.98) and ADL disability (HR, 0.89; 95% CI, 0.81-0.97). Conclusions and Relevance These findings suggest that air pollution may affect the progression of physical disability and hinder recovery in later life.