Exposure to residential traffic and trajectories of unhealthy ageing in older adults

Abstract

Background/Objectives: Exposure to traffic has been associated with biomarkers of increased biological aging, incidence of chronic morbidities and increased cause-specific and all-cause mortality. However, no previous study has evaluated whether traffic pollution is associated with trajectories of unhealthy ageing. The present study aims to fill some of the gaps in existing research by evaluating the association between residential traffic and unhealthy ageing, as assessed through the accumulation of overall and domain-specific health deficits over a 10-year follow-up of a nationally representative cohort of community-dwelling older adults in Spain. Methods: Population-based prospective study with individuals aged ≥ 60 years who contributed 8,291 biannual visits. Unhealthy ageing was estimated with a deficit accumulation index (DAI, range 0 to 100%), calculated with the number and severity of health deficits including 22 objectively-measured impairments in physical and cognitive functioning. Differences in DAI at each follow-up across categories of residential traffic density (RTD) at 500 and 1,000 meters, as well as of quintiles of nearest distance to a petrol station, were estimated using marginal structural models with inverse probability of censoring weights. Models were adjusted for sociodemographic and time-varying lifestyle factors, social deprivation index at the census tract and residential exposure to natural spaces. Results: The average increase in DAI (95% confidence interval) for participants in quintiles 2 to 5 vs. 1 (Q2-Q5 vs. Q1) of RTD at 500 meters was of 0.08 (-0.43, 0.59), 0.25 (-0.28, 0.78), 0.43 (-0.09, 0.95) and 0.80 (0.30, 1.30), respectively. Similar findings were observed across quintiles of RTD at 1000 meters. Distance to the nearest petrol station showed a linear inverse dose-response with prospective changes in DAI: results in quintiles Q2-Q5 vs. Q1 were -0.57 (-1.14, -0.01), -0.66 (-1.21, -0.11), -0.43 (-0.99, 0.13), and -0.91 (-1.44, -0.39), respectively. Conclusions/Recommendations: Exposure to traffic is associated with accelerated trajectories of unhealthy ageing. Diminishing traffic pollution should become a priority intervention for adding healthy years to life in the old age.