Air pollution and respiratory outcomes in COPD above and below current environmental protection agency standards.

Abstract

Background: Rigorous studies are needed to defend the current National Ambient Air Quality Standards and prompt policymakers to acknowledge a dose-response relationship between air pollution and respiratory outcomes. In the most recent Environmental Protection Agency comprehensive review, scientists determined there was insufficient evidence to claim a causal relationship between chronic particulate matter air pollution (PM_2.5) and respiratory outcomes, despite acknowledging one for cardiovascular outcomes (Integrated Science Assessment, Table 5-27).

Methods: This study examined the associations between chronic PM_2.5 levels and respiratory outcomes in 169,713 patients within Kaiser Permanente Northern California who had chronic obstructive pulmonary disease (COPD) between 2007 and 2016.

Results: For every 10 μg/m³ rise in average yearly PM_2.5, there was a statistically significant increase in relative risk of death (hazard ratio [HR] = 1.15; 95% confidence interval [CI] = 1.10, 1.20), respiratory-related death (HR = 1.22; 95% CI = 1.15, 1.30), COPD exacerbation (HR = 1.35; 95% CI = 1.29, 1.41), and the combined endpoint of COPD exacerbation or respiratory-related hospitalization with any-cause death as competing risk (HR = 1.30; 95% CI = 1.25, 1.35). We demonstrate a dose-response relationship between 1-year average PM_2.5 exposure and respiratory outcomes for key regulatory categories of PM_2.5.

Conclusions: These findings add rigorous evidence to support the continuation of the current annual PM_2.5 standard, which was lowered to 9 μg/m³ in 2024. Our novel contribution is documenting the dose-response relationship between chronic PM_2.5 and multiple respiratory outcomes in a longitudinal cohort with patients followed for up to 10 years.