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

## TL;DR

Long-term exposure to certain air pollutants like PM2.5 and NO2 increases the risk of physical disability progression in older adults, while ozone may have a protective effect.

## Contribution

This study is the first to examine how air pollution affects transitions between physical function states in aging adults using a multistate model.

## Key findings

- Higher PM2.5 and NO2 concentrations are linked to increased disability progression.
- Ozone exposure is associated with reduced disability risk and progression.
- PM2.5 exposure reduces the likelihood of recovery from physical function limitations.

## Abstract

Is long-term exposure to air pollution associated with the dynamic physical disability process?

In this cohort study of 29 790 adults older than 50 years who were followed up for nearly 20 years, higher concentrations of particulate matter with a diameter of 2.5 µm or less (PM2.5), PM with a diameter between 2.5 and 10 µm (PM10-2.5), and nitrogen dioxide (NO2) were associated with a higher risk of transitioning to more severe states of physical disability, and a higher concentration of PM2.5 was associated with a lower likelihood of reverting from physical function limitation to healthy physical function. Unexpectedly, higher concentrations of ozone (O3) were associated with a lower risk of disability development and progression.

These findings suggest that reducing air pollution levels may help to delay and mitigate physical disability in aging adults.

This cohort study evaluates whether exposure to common air pollutants, including particulate matter, nitrogen dioxide, and ozone, is associated with the dynamic development of disability among US adults older than 50 years.

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.

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.

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.

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.

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.

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).

These findings suggest that air pollution may affect the progression of physical disability and hinder recovery in later life.