Disparities in Fine Particulate Matter Air Pollution Exposures at the US–Mexico Border: The Intersection of Race/Ethnicity and Older Age

Environmental justice research in the United States (US) documents greater air pollution exposures for Hispanic/Latino vs. non-Hispanic White groups. EJ research has not focused on the intersection of race/ethnicity and older age nor short-term fine particulate matter (PM2.5) exposures. We address these knowledge gaps by studying US metropolitan area census tracts within 100 km of the US–Mexico border, a region with serious air quality issues. We use US Census American Community Survey data to construct sociodemographic variables and Environmental Protection Agency Downscaler data to construct long-term and short-term measures of PM2.5 exposure. Using multivariable generalized estimating equations, we test for differences in PM2.5 exposures between census tracts with higher vs. lower proportions of older Hispanic/Latino residents and older non-Hispanic White residents. The results indicate that as the proportion of the Hispanic/Latino population ≥ 65 years of age increases, long-term and short-term PM2.5 exposures significantly increase. In contrast, as the proportion of the non-Hispanic White population ≥ 65 years of age increases, changes in long-term and short-term PM2.5 exposures are statistically non-significant. These findings illuminate how race/ethnicity and older age intersect in shaping PM2.5 exposure disparities and may inform efforts to mitigate air pollution exposures for overburdened people along the US–Mexico border.