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

Background: 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. Methods: 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. Results: 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. Conclusion: 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.