Long-term exposure to PM2.5 and incidence of disability in activities of daily living among oldest old

Lv, Yuebin; Zhou, Jinhui; Kraus, Virginia Byers; Li, Tiantian; Sarnat, Jeremy A.; Wang, Jiaonan; Liu, Yang; Chen, Huashuai; Brasher, Melanie Sereny; Mao, Chen; Zeng, Yi; Zheng, Tongzhang; Shi, Xiaoming

Long-term exposure to PM2.5 and incidence of disability in activities of daily living among oldest old

2020

Currently the Chinese government has adopted World Health Organization interim target-1 values as the national ambient air quality standards values. However, the population-based evidence was insufficient, especially for the oldest old (aged 80+). We evaluated the association of fine particulate matters (PM₂.₅) exposure and incidence of disability in activities of daily living (ADL) in 15 453 oldest old in 886 counties/cities in China from 2002 to 2014 using Cox model with penalized splines and competing risk models to evaluate the linear or non-linear association. 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 with increase of PM₂.₅ concentrations; compared to 33 μg/m³, the hazard ratio ranged from 1.03 (1.00–1.06) at 40 μg/m³ to 2.25 (1.54–3.29) at 110 μg/m³. The risk magnitude was not significantly changed below this threshold. Each 10 μg/m³ increase in PM₂.₅ exposure corresponded to a 7.7% increase in the risk of disability in ADL (hazard ratio 1.077, 95% CI 1.051–1.104). Men, smokers, and participants with cognitive impairment might be more vulnerable to PM₂.₅ exposure. The study provided limited population-based evidence for the oldest old and detected a threshold of 33 μg/m³, and supported that reduction to current World Health Organization interim target-1value (35 μg/m³) and Chinese national ambient air quality standards (35 μg/m³) or lower may be associated with lower risk of disability in ADL.

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