Excess deaths and loss of life expectancy attributed to long-term NO 2 exposure in the Chinese elderly.

Background: Evidence linking nitrogen dioxide (NO ₂ ) air pollution to life span of high-vulnerability older adults is extensively scarce in low- and middle-income countries. This study seeks to quantify mortality risk, excess deaths, and loss of life expectancy (LLE) associated with long-term exposure to NO ₂ among elderly individuals in China.
Methods: A nationwide dynamic cohort of 20352 respondents ≥65 years old were enrolled from the China Longitudinal Health and Longevity Survey during 2005-2018. Residential exposures to NO ₂ and co-pollutants were assessed by well-validated spatiotemporal prediction models. A Cox regression model with time-dependent covariates was utilized to quantify the association of all-cause mortality with NO ₂ exposure, controlling for confounders such as demographics, lifestyle, health status, and ambient temperature. NO ₂ -attributable deaths and LLE were evaluated for the years 2010 and 2020 based on the pooled NO ₂ -mortality relation derived from multi-national cohort investigations. Decomposition analyses were conducted to dissociate net shift in NO ₂ -related deaths between 2010 and 2020 into four primary contributing factors.
Results: A total of 14313 deaths were recorded during follow-up of approximately 100 hundred person-years (median 3.6 years). We observed an approximately linear relationship (nonlinear P = 0.882) of NO ₂ exposure with all-cause death across a broad range from 6.6 to 95.7 μg/m ³ . Every 10-μg/m ³ rise in yearly average NO ₂ concentration was linked to a hazard ratio (HR) of 1.045 (95% confidence interval [CI]: 1.031-1.059). In the updated meta-analysis of this study and 9 existing cohorts, we estimated a pooled HR of 1.043 (95% CI: 1.023-1.063) for each 10-μg/m ³ growth in NO ₂ . Reaching a 10-μg/m ³ counterfactual target of NO ₂ concentration in China could avoid 0.33 (95% empirical CI: 0.19-0.49) million premature deaths and an LLE of 0.40 (95% empirical CI: 0.23-0.59) years in 2010, which greatly dropped to 0.24 (95% empirical CI: 0.14-0.36) million deaths and 0.21 (95% empirical CI: 0.12-0.31) years of LLE in 2020. The net fall in NO ₂ -attributable deaths (-26.8%) between 2010 and 2020 was primarily driven by the declines in both NO ₂ concentration (-41.6%) and mortality rate (-27.1%) under population growth (+41.0%) and age structure transition (+0.9%).
Conclusions: Our findings provide national evidence for increased risk of premature death and loss of life expectancy attributed to later-life NO ₂ exposure among the elderly in China. In an accelerated aging society, strengthened clean air actions should be formulated to minimize the health burden and regional inequality in NO ₂ -attributable mortality.
Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
(Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)