Association between ambient air pollution and county-level cardiovascular mortality in the United States by social deprivation index

Background: Air pollution and socioeconomic status have both been strongly associated with cardiovascular (CV) outcomes. We sought to determine if socioeconomic status modifies the risk association between fine particulate matter air pollution (PM_2.5) and CV mortality.

Methods: We linked county-level age-adjusted CV mortality data from Multiple Cause of Death files (2000-2016, ICD10: I00-I99) with 2015 Social Deprivation Index (SDI), a validated estimate of socioeconomic status, and modelled spatial and temporal mean annual PM_2.5 exposures (2012-2018). Higher SDI suggests greater deprivation and lower socioeconomic status. Associations between PM_2.5 and age adjusted CV mortality were estimated using linear models.

Results: A total of 5,769,315 cardiovascular deaths from 2012-2018 across 3106 United States counties were analyzed. Both PM_2.5 (β (SE) 7.584 (0.938), P < .001) and SDI scores (β (SE) 0.591 (0.140), P < .001) were independently associated with age-adjusted CV mortality (R² = 0.341). The association between PM_2.5 and CV mortality were stronger among counties with highest SDI, P value for interaction = .012.

Conclusion: Social deprivation and PM_2.5 exposures were independently associated with county level age-adjusted CV mortality. The associations between PM_2.5 and CV mortality were stronger in counties with high vs low social deprivation. SDI and PM_2.5 represent potential targets to reduce CV mortality disparities and interventions to reduce PM_2.5 exposure may be most impactful in communities of low socioeconomic status.