Indoor Pollution and Lung Function Decline in Current and Former Smokers: SPIROMICS AIR.

Overview

abstract

RATIONALE: Indoor pollutants have been associated with COPD morbidity, but it is unclear whether they contribute to disease progression. OBJECTIVES: We aim to determine whether indoor particulate matter (PM) and nitrogen dioxide (NO2) are associated with lung function decline among current and former smokers. METHODS: Of the 2,382 subjects with a history of smoking in SPIROMICS AIR, 1,208 participants had complete information to estimate indoor PM and NO2, using individual-based prediction models, in relation to measured spirometry at two or more clinic visits. We used a 3-way interaction model between time, pollutant, and smoking status; and assessed the indoor pollutant-associated difference in FEV1 decline separately using generalized linear mixed model. MEASUREMENTS AND MAIN RESULTS: Participants had an average rate of FEV1 decline of 60.3 mL/year for those currently smoking compared to 35.2 mL/year for those who quit. The association of indoor PM with FEV1 decline differed by smoking status. Among former smokers, every 10 µg/m3 increase in estimated indoor PM was associated with an additional 10 mL/year decline in FEV1 (p=0.044). Among current smokers, FEV1 decline did not differ by indoor PM. The results of indoor NO2 suggest similar trends to PM2.5. CONCLUSIONS: Former smokers with COPD, who lived in homes with high estimated PM have accelerated lung function loss and those in homes with low PM had lung function loss similar to normal aging. In-home PM exposure may contribute to variability in lung function decline in people who quit smoking and may be a modifiable exposure.