Geospatial-based neighborhood hazards and asthma in adults: Interaction with social vulnerability

Few studies have examined the joint association of multiple residential hazards with asthma across social vulnerability levels. We investigated co-exposure patterns among neighborhood environmental hazards and estimated their mixture associations with adult asthma, stratified by the social vulnerability index (SVI). This cross-sectional study included 7092 adults from a North Carolina-based cohort (2013-2022). Adult asthma was defined as physician-diagnosed asthma with active symptoms in adulthood. We assessed 29 residential hazards using validated spatiotemporal models and hazard maps, including air pollutants, industrial volatile organic compound (VOC) emissions, highway density, and proximity to 13 pollution sources. Census tract-level SVI was linked to residential addresses. We conducted an exposome-wide association study (ExWAS) for individual hazard-asthma associations. Network analysis characterized co-exposure patterns, and quantile g-computation estimated mixture-asthma associations. All analyses were stratified by median SVI. In the ExWAS, proximity to dry-cleaning solvent-contaminated sites was associated with increased asthma odds in the overall population. In high-SVI neighborhoods, eight hazards-predominantly particulate matter (PM) constituents and VOCs-were positively associated with asthma (FDR < 0.05). Hazard correlations were stronger in high-SVI areas. Each one-quintile increase in hazard mixture was linked to 35% (95% CI: 6%, 73%) higher asthma odds in the high-SVI group. Toluene, dry-cleaning site proximity, PM organic matter, and carbon monoxide each contributed over 10% to the joint association. Socioeconomic and housing/transportation vulnerability domains interacted with key hazards on asthma. These findings suggest that prioritizing air pollutant and VOC emission controls and contaminated site remediation in socioeconomically and infrastructurally vulnerable communities may help reduce asthma disparities.