The effect of long-term exposure to a mixture of air pollutants on chronic obstructive pulmonary disease.

Chronic obstructive pulmonary disease (COPD) is a major global cause of morbidity and mortality; however, evidence on the effects of air pollutant mixtures on COPD remains limited. This study assessed the impact of long-term exposure to multiple pollutants on COPD prevalence and identified vulnerable subgroups. We analyzed Korea National Health and Nutrition Examination Survey (2010-2017) data linked to 5-year moving average concentrations of CO, NO₂, SO₂, O₃, PM₂.₅, and PM₁₀. Bayesian kernel machine regression (BKMR) estimated the combined effects of pollutants on COPD prevalence, with subgroup analyses performed according to sex, smoking status, and airflow limitation. Adjustments included age, sex, BMI, smoking status, and household income. Among 21,804 participants, 3515 had COPD. BKMR analysis showed that long-term exposure to a pollutant mixture was associated with increased COPD prevalence. O₃ and NO₂ were identified as the most influential pollutants (posterior inclusion probabilities > 0.50). Further analysis showed a significant increase in COPD risk with higher NO₂ and O₃ concentrations, particularly when other pollutants were at lower or median levels. Significant interactions were observed, particularly between SO₂ and CO, CO and O₃, and NO₂ and O₃. Subgroup analyses identified vulnerable populations, indicating stronger associations among females and never smokers and more pronounced effects in individuals with GOLD 2-4. These findings suggest that long-term exposure to multiple air pollutants could increase COPD risk, particularly for females, never smokers, and individuals with more severe COPD. Targeted interventions and policy measures are needed to reduce exposure, especially for these at-risk populations.