Exposure-response relationship between long-term PM_2.5 exposure and COPD mortality in China

Objective To synthesize the domestic epidemiological evidence from China and fit an exposure-response relationship curve between long-term inhalation exposure to ambient fine particulate matter (PM_2.5) and mortality from chronic obstructive pulmonary disease (COPD) in the Chinese population, thereby providing localized parameters for precise environmental health risk assessment. Methods On the basis of a refined global exposure mortality model (GEMM) framework, epidemiological studies conducted in China on the association between long-term PM_2.5 exposure and COPD mortality were systematically integrated to derive an exposure-response relationship curve. The attributable disease burden was further assessed and spatially analyzed with the data from 2015 to 2024.

Results A nonlinear association was observed between ambient PM_2.5 exposure and COPD mortality risk. The fitted curve revealed a risk coefficient (θ) of 0.028 5 and an inflection point concentration (μ) of 17.34 μg/m³, indicating a significant increase in risk even at low exposure levels. From 2015 to 2024, the annual mean PM_2.5 concentration at the city level in China decreased from (49.45±18.47) μg/m³ to (30.24±10.42) μg/m³, a reduction of 38.8%, with the concentration range narrowing from 10.88–116.68 μg/m³ to 6.24–87.21 μg/m³. During the same period, the annual average PM_2.5-attributable COPD excess mortality was approximately 56 000 cases, with the total attributable deaths decreasing from approximately 69 800 cases in 2015 to approximately 48 300 cases in 2024. The standardized excess mortality per 100 000 decreased from 1 802 cases to 1 193 cases, a reduction of 33.8%, showing a steady downward trend year by year. In terms of spatial distribution, the attributable risk presented significant heterogeneity, with the highest risks observed in eastern regions such as the Beijing-Tianjin-Hebei area, the Yangtze River Delta, and the Pearl River Delta, higher risks observed in western Xinjiang, and lower risks observed in central and most western regions of China.

Conclusions The exposure-response relationship curve developed in this study provides key localized parameters for conducting environmental health risk assessments related to COPD in China. The findings support the formulation of differentiated air pollution prevention and disease control strategies tailored to the pollution characteristics and risk levels of different regions.