Long-term exposure to fine particulate matter and incidence of disability in activities of daily living

Abstract

PDS 72: Environmental health issues in LMIC, Exhibition Hall (PDS), Ground floor, August 28, 2019, 10:30 AM - 12:00 PM Background/Aim: Currently the Chinese government has adopted WHO guideline air quality interim target values as the national ambient air quality standards values for fine particulate matter (PM2.5), while population-based evidence was insufficient. The study was to evaluate the association of individual-level PM2.5 exposure and incidence of disability in activities of daily living (ADL) among the oldest old. Methods: A total of 15,453 participants aged 80+ (mean age, 92.3 ± 7.3 years) with independent ADL at baseline were included. Annual average residential PM2.5 exposure with 1 km*1 km spatial resolution was estimated from satellite observations. Katz index of independence in ADL was used to assess disability from 2002 to 2014. Penalized splines were constructed to fit Cox proportional hazards models to survival data. Competing risk models were constructed to estimate risk of disability in ADL for each 10 μg/m3 increase in PM2.5 adjusted for confounders. Results: Over a follow-up of 71,396 person-years, 3,373 (21.8%) cases of incident disability in ADL occurred. After adjusting for potential confounders, a J-shaped association existed between PM2.5 exposure with a threshold concentration of 33 μg/m3, and incident disability in ADL. Above this threshold, the risk magnitude significantly increased along with PM2.5 concentrations; compared to 33 μg/m3, the hazard ratio ranged from 1.02 (1.00-1.05) at 40 μg/m3 to 2.26 (1.55-3.29) at 110 μg/m3. The risk magnitude was not significantly changed blow this threshold. Each 10 μg/m3 increase in PM2.5 exposure corresponded to a 7.6% increase in the risk of disability in ADL (hazard ratio 1.076, 95% CI 1.050-1.103). Conclusions: The study provided limited population-based evidence for the oldest old and detected a threshold of 33 μg/m3, which was basically consistent with current WHO air quality guidelines and values of Chinese national ambient air quality standards. Keywords: PM2.5, incidence, disability, activities of daily living, oldest old, cohort study.