D26-06 Joint Effects of Indoor Trace Elements of PM2.5 on Lung Function Among Patients With COPD

Rationale While indoor air pollution is a recognized contributor to adverse respiratory outcomes, the specific impact of chemical components within particulate matter ≤2.5 µm in diameter (PM2.5), particularly trace elements, on lung function remains poorly understood. Our aim was to assess the contribution of elemental constituents of PM2.5 on lung function in people with chronic obstructive pulmonary disease (COPD). Methods We analyzed data from two Massachusetts-based cohorts of people with COPD, comprising 777 observations from 291 participants: the Air Purification for Eosinophilic COPD Study (APECS) and the VA Boston Healthcare System COPD Study (VA COPD). Participants completed up to two pre-randomization visits over 3 months in APECS between 2021-2024, or up to four in-home assessments over 12 months in VA COPD between 2012-2017. Indoor PM2.5 samples were collected over approximately one week in each participant’s home, and concentrations of 17 trace elements, including aluminum (Al), bromine (Br), calcium (Ca), chlorine (Cl), copper (Cu), iron (Fe), potassium (K), magnesium (Mg), manganese (Mn), sodium (Na), phosphorus (P), lead (Pb), sulfur (S), silicon (Si), strontium (Sr), titanium (Ti), and zinc (Zn), were quantified via X-ray fluorescence (XRF). Quantile g-computation was used to estimate the joint association of the elemental mixture with pre-bronchodilator FEV1, FVC, and FEV1/FVC ratio. Cohort-specific associations were estimated first and subsequently pooled using random-effects meta-analysis. All models were adjusted for age, body mass index, height, and season; the APECS model was additionally adjusted for sex, which was not included in the predominantly male VA COPD cohort. Results The mean (SD) age of participants was 70.9 (8.5) years in APECS and 72.9 (8.4) years in VA COPD. We found that a simultaneous one-tertile increase across the 17-element mixture was associated with a significant reduction of -138 mL in FEV1 (95% CI: -275, -1) and a -3.9% lower FEV1/FVC ratio (95% CI: -6.9, -0.9) (Figure 1). The association with FVC was negative but not statistically significant (pooled estimate: -22 mL; 95% CI: -211, 167). The components analysis indicated that chlorine contributed most to the observed negative associations between indoor element mixtures and lung function. Conclusion Joint exposure to indoor trace element mixtures of PM2.5 was associated with lower FEV1 and FEV1/FVC ratio among people with COPD in two Massachusetts-based cohorts. These findings highlight the need to consider cumulative indoor pollutant mixtures in policies and interventions aimed at protecting respiratory health.