Ambient Air Pollution and Chronic Bronchitis in a Cohort of U.S. Women

BACKGROUND: Limited evidence links air pollution exposure to chronic cough and sputum production. Few reports have investigated the association between long-term exposure to air pollution and classically defined chronic bronchitis. OBJECTIVES: Our objective was to estimate the association between long-term exposure to particulate matter (diameter [Formula: see text] , [Formula: see text]; [Formula: see text] , [Formula: see text]), nitrogen dioxide [Formula: see text] , and both incident and prevalent chronic bronchitis. METHODS: We estimated annual average [Formula: see text] , [Formula: see text] , and [Formula: see text] concentrations using a national land-use regression model with spatial smoothing at home addresses of participants in a prospective nationwide U.S. cohort study of sisters of women with breast cancer. Incident chronic bronchitis and prevalent chronic bronchitis, cough and phlegm, were assessed by questionnaires. RESULTS: Among 47,357 individuals with complete data, 1,383 had prevalent chronic bronchitis at baseline, and 647 incident cases occurred over 5.7-y average follow-up. No associations with incident chronic bronchitis were observed. Prevalent chronic bronchitis was associated with [Formula: see text] [adjusted odds ratio (aOR) per interquartile range (IQR) difference [Formula: see text]; 95% confidence interval (CI): 1.01, 1.13]. In never-smokers, [Formula: see text] was associated with prevalent chronic bronchitis ([Formula: see text] per IQR difference; 95% CI: 1.04, 1.34), and [Formula: see text] was associated with prevalent chronic bronchitis ([Formula: see text]; [Formula: see text]), cough ([Formula: see text]; 95% CI: 1.05, 1.16), and phlegm ([Formula: see text]; 95% CI: 1.01, 1.14); interaction p-values (nonsmokers vs. smokers) [Formula: see text]. CONCLUSIONS: [Formula: see text] exposure was related to chronic bronchitis prevalence. Among never-smokers, [Formula: see text] and [Formula: see text] exposure was associated with chronic bronchitis and component symptoms. Results may have policy ramifications for [Formula: see text] regulation by providing evidence for respiratory health effects related to long-term [Formula: see text] exposure. https://doi.org/10.1289/EHP2199