Long-term air pollution exposure and gait speed decline among older Adults: A longitudinal analysis

Long-term exposure to air pollution may contribute to gait speed decline through mechanisms involving systemic inflammation, oxidative stress, and cardiopulmonary or autonomic dysfunction. This study investigated the association of long-term exposure to fine particulate matter (PM_2.5) and nitrogen dioxide (NO₂) across different time windows with changes in gait speed.

We leveraged data from the Ginkgo Evaluation of Memory Study (GEMS), followed participants for up to six years (mean follow-up: 4.1 years, N = 2850). Gait speed was assessed annually at usual and maximum paces using a 15-foot timed walk test (2002-2008). Spatiotemporal prediction models estimated average PM_2.5 (pre-study entry: 1980-1999; concurrent with follow-up: 2001-2007) and NO₂ (pre-study entry: 1990-1999; concurrent: 2001-2007). Linear mixed-effect models were fitted, adjusting for sociodemographic and contextual covariates.

Participants' mean age was 78.6 years (SD = 3.3); 54.3 % were male. An interquartile range (IQR, 2.19 μg/m³) increase in 20-year PM_2.5 before study entry was associated with cumulative 6-year gait speed declines of 0.038 m/s (95 % CI: 0.050, -0.027) at usual pace and 0.032 m/s (95 % CI: 0.047, -0.016) at maximum pace. A 10-year NO₂ IQR (6.52 ppb) increase prior to study entry was associated with 6-year gait speed declines of 0.077 m/s (95 % CI: 0.093, -0.062) at usual pace and 0.079 m/s (95 % CI: 0.101, -0.058) at maximum pace. Patterns for concurrent exposure were similar.

These findings underscore the importance of addressing environmental risk factors to preserve mobility and reduce the risk of adverse health outcomes associated with slower gait speed.