Particulate Matter Associations with Lung Function in Pulmonary Sarcoidosis.

Rationale: Sarcoidosis is a multi-system disease with pulmonary manifestations in over 90% of patients. Environmental exposures are associated with sarcoidosis incidence, but the impact on clinical outcomes remains understudied. Objectives: To evaluate the association of ambient particulate matter ≤2.5µm (PM2.5) exposures with lung function outcomes in pulmonary sarcoidosis. Methods: PM2.5 and constituent exposures were obtained by matching monthly satellite-derived hybrid measurements to each patient's residential address obtained from time of enrollment, averaged over 5-years before registry enrollment/censoring. Linear models evaluated associations of pollutants with baseline lung function (forced expiratory volume, FEV1; forced vital capacity, FVC; FEV1/FVC; diffusing capacity for carbon monoxide, DLCO). Linear mixed effects models analyzed associations of pollutants with rate of lung function change (FEV1, FVC, DLCO change per year of follow-up). Measurements and Main Results: Two prospectively enrolled cohorts of mostly middle-aged, White and non-smoking adults with specialist-diagnosed pulmonary sarcoidosis were used. The U.S. cohort (n=400) experienced higher 5-year pre-enrollment median PM2.5 exposures (12.3µg/m3) compared to the Canadian cohort (n=112) (8.0µg/m3). Each 1µg/m3 increase in PM2.5 was associated with 0.93% predicted lower baseline FEV1 (95% CI -1.76 to -0.10, p=0.03) and 1.53% predicted lower FVC (95% CI -2.26 to -0.79, p<0.001) in the U.S. cohort, but associations were not significant in the Canadian cohort. PM2.5, sulfate, nitrate, and ammonium were associated with accelerated FEV1, FVC, and DLCO decline in the U.S. cohort. Conclusions: PM2.5 was associated with worse pulmonary disease severity and progression in a higher-exposure cohort, highlighting the importance of exposure disparities in this population.