Unraveling health disparities across cause-specific outcomes associated with emerging air pollutants: Evidence on black carbon and ultrafine particles in Buffalo, New York

Black carbon (BC) and ultrafine particles (UFPs) are combustion-related air pollutants that remain largely unregulated despite growing evidence of adverse health effects. Few studies have evaluated their short-term health effects on wide spectrum of disease morbidity in U.S. cities or examined disparities across communities. Using a time-stratified case-crossover design, we examined associations of BC and UFPs exposures with cause-specific hospital admissions (HAs) and emergency department (ED) visits in Buffalo, New York. Higher BC and UFP exposures were associated with increased HAs across multiple disease categories, with the largest associations observed at lag 0. For BC exposure (per IQR increase of 0.7 μg/m³), relatively larger associations were observed for eye (OR: 1.08; 95% CI: 1.01, 1.17), endocrine (OR: 1.05; 95% CI: 1.04, 1.07), and circulatory diseases (OR: 1.04; 95% CI: 1.03, 1.06). UFPs exposure (per IQR increase of 11,600.5 counts/cm³) was associated with endocrine (OR: 1.03; 95% CI: 1.03, 1.04) and respiratory diseases (OR: 1.03; 95% CI: 1.02, 1.03). Associations with ED visits were generally weaker, although UFP exposure was associated with blood (OR: 1.03; 95% CI: 1.01, 1.05) and genitourinary (OR: 1.02; 95% CI: 1.01, 1.03) in ED visits. Stratified analyses suggested higher estimated ORs among predominantly African American communities, including for respiratory HAs associated with BC exposure (OR: 1.06; 95% CI: 1.02, 1.11 vs. OR: 1.01; 95% CI: 0.98, 1.03 in other communities). These findings highlight the need to incorporate BC and UFP metrics into health-based air quality standards and to prioritize pollution mitigation in environmental justice areas.