In-home air pollution is linked to respiratory morbidity in former smokers with chronic obstructive pulmonary disease

Rationale: The effect of indoor air pollutantsonrespiratory 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 (NO₂) 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 NO₂ concentrations were 11.4 ± 13.3 μg/m³ and 10.8 ± 10.6 ppb in the bedroom, and 12.2 ± 12.2 μg/m³ 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 NO₂ concentrations were associated with increases in nocturnal symptoms and risk of severe COPD exacerbations. Conclusions: Indoor pollutant exposure, including PM_2.5 and NO₂, 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.