Residential Wood Burning and Pulmonary Function in the Agricultural Lung Health Study

BACKGROUND: In low- and middle-income countries, burning biomass indoors for cooking or heating has been associated with poorer lung function. In high-income countries, wood, a form of biomass, is commonly used for heating in rural areas with increasing prevalence. However, in these settings the potential impact of chronic indoor woodsmoke exposure on pulmonary function is little studied. OBJECTIVE: We evaluated the association of residential wood burning with pulmonary function in case–control study of asthma nested within a U.S. rural cohort. METHODS: Using sample weighted multivariable linear regression, we estimated associations between some and frequent wood burning, both relative to no exposure, in relation to forced expiratory volume in 1 s ([Formula: see text]), forced vital capacity (FVC), their ratio ([Formula: see text]), and fractional exhaled nitric oxide (FeNO). We examined effect modification by smoking or asthma status. RESULTS: Among all participants and within smoking groups, wood burning was not appreciably related to pulmonary function. However, in individuals with asthma ([Formula: see text]), frequent wood burning was significantly associated with lower [Formula: see text] [[Formula: see text]: [Formula: see text]; 95% confidence interval (CI): [Formula: see text] , [Formula: see text]], FVC ([Formula: see text]: [Formula: see text]; 95% CI: [Formula: see text] , [Formula: see text]), and [Formula: see text] ([Formula: see text]: [Formula: see text]; 95% CI: [Formula: see text] , [Formula: see text]), whereas no appreciable association was seen in individuals without asthma ([Formula: see text]). These differences in association by asthma were statistically significant for [Formula: see text] ([Formula: see text]) and [Formula: see text] ([Formula: see text]). Frequent wood burning was also associated with higher FeNO levels in all individuals ([Formula: see text]; [Formula: see text]: [Formula: see text]; 95% CI: 0.02, 0.2), but associations did not differ by asthma or smoking status. DISCUSSION: Frequent exposure to residential wood burning was associated with a measure of airway inflammation (FeNO) among all individuals and with lower pulmonary function among individuals with asthma. This group may wish to reduce wood burning or consider using air filtration devices. https://doi.org/10.1289/EHP10734