The Association Between Air Pollution and Lung Function in Sarcoidosis and Implications for Health Disparities.

Abstract

Sarcoidosis is a granulomatous disease with varying courses of disease progression. Environmental exposures are thought to be contributors to disease onset. Exposure to air pollutants such as fine particulate matter of 2.5 μm diameter or smaller (PM_2.5) and nitrogen dioxide (NO₂) have been identified as contributors to health disparities in lung diseases; little is known about these environmental exposures' associations with disease outcomes in sarcoidosis. Is higher exposure to PM_2.5 and NO₂ associated with worse lung function in sarcoidosis? We conducted a retrospective, cross-sectional study of individuals with pulmonary sarcoidosis seen from 2005 to 2015. Home addresses at the year of enrollment were geocoded, and exposure to PM_2.5 and NO₂ was modeled using high-resolution 1 km × 1 km annual surface exposure data during the year of enrollment. Racial and sex differences in exposure were determined. Multivariable linear regression models were used to examine the associations between PM_2.5 and NO₂ and the pulmonary function test measures FVC, FEV₁, and diffusing capacity of the lungs for carbon monoxide (Dlco). Among the 415 individuals in the analysis, Black individuals had significantly higher exposure to PM_2.5 and NO₂ compared with non-Hispanic White individuals, 12.2 μg/m³ (SD 2.4) vs 11 μg/m³ (SD 2.2) and 6.3 parts per billion (ppb) (SD 1.9) vs 5.0 ppb (SD 2.0), respectively. Every 1 μg/m³ higher exposure to PM_2.5 was associated with 1.12% lower Dlco% predicted (95% CI, -1.83 to -0.41; P < .05). Every 1 ppb higher exposure to NO₂ was associated with 1.04% lower Dlco% predicted (95% CI, -1.91 to -0.18; P < .05) in fully adjusted models. There were no significant associations between these pollutants and either FVC or FEV₁% predicted. Higher exposure to PM_2.5 and NO₂ was associated with worse Dlco% predicted. Black individuals with sarcoidosis were exposed to higher PM_2.5 and NO₂ than non-Hispanic White individuals. Air pollution exposure may be a contributor to reported health disparities in sarcoidosis.