Abstract
RATIONALE: The effect of indoor air pollutants on respiratory morbidity among patients with chronic obstructive pulmonary disease (COPD) in developed countries is uncertain. OBJECTIVES: The first longitudinal study to investigate the independent effects of indoor particulate matter (PM) and nitrogen dioxide (NO(2)) concentrations on COPD morbidity in a periurban community. METHODS: Former smokers with COPD were recruited and indoor air was monitored over a 1-week period in the participant's bedroom and main living area at baseline, 3 months, and 6 months. At each visit, participants completed spirometry and questionnaires assessing respiratory symptoms. Exacerbations were assessed by questionnaires administered at clinic visits and monthly telephone calls. MEASUREMENTS AND MAIN RESULTS: Participants (n = 84) had moderate or severe COPD with a mean FEV1 of 48.6% predicted. The mean (± SD) indoor PM(2.5) and NO(2) concentrations were 11.4 ± 13.3 µg/m(3) and 10.8 ± 10.6 ppb in the bedroom, and 12.2 ± 12.2 µg/m(3) and 12.2 ± 11.8 ppb in the main living area. Increases in PM(2.5) concentrations in the main living area were associated with increases in respiratory symptoms, rescue medication use, and risk of severe COPD exacerbations. Increases in NO(2) concentrations in the main living area were independently associated with worse dyspnea. Increases in bedroom NO(2) concentrations were associated with increases in nocturnal symptoms and risk of severe COPD exacerbations. CONCLUSIONS: Indoor pollutant exposure, including PM(2.5) and NO(2), was associated with increased respiratory symptoms and risk of COPD exacerbation. Future investigations should include intervention studies that optimize indoor air quality as a novel therapeutic approach to improving COPD health outcomes.