Abstract
BACKGROUND: Radon ((222)Rn) decay products can attach to particles in the air, be inhaled, and potentially cause airway damage. RESEARCH QUESTION: Is short-term exposure to particle radioactivity (PR) attributable to radon decay products emitted from particulate matter ≤2.5 μm in diameter (PM(2.5)) associated with pulmonary function in chronic obstructive pulmonary disease (COPD) patients? STUDY DESIGN AND METHODS: In this cohort study, 142 elderly, predominantly male patients with COPD from Eastern Massachusetts each had up to 4 one-week long seasonal assessments of indoor (home) and ambient (central site) PR and PM(2.5) over the course of a year (467 assessments). Ambient and indoor PR were measured as α-activity on archived PM(2.5) filter samples. Ratios of indoor/ambient PR were calculated, with higher ratios representing PR from an indoor source of radon decay. We also considered a measure of outside air infiltration that could dilute the concentrations of indoor radon decay products, the indoor/ambient ratio of sulfur concentrations in PM(2.5) filter samples. Spirometry pre- and post-bronchodilator (BD) forced expiratory volume in 1 s (FEV(1)) and forced vital capacity (FVC) were conducted following sampling. Generalized additive mixed models were adjusted for meteorologic variables, seasonality, and individual-level determinants of pulmonary function. We additionally adjusted for indoor PM(2.5) and black carbon (BC). RESULTS: PR exposure metrics indicating radon decay product exposure from an indoor source were associated with a reduction in FEV(1) and FVC. Patients in homes with high indoor PR (≥median) and low air infiltration (