Air pollution in American Indian vs. Non-American Indian communities

Abstract

BACKGROUND AND AIM: Fine particulate matter (PM2.5) exposure is associated with increased risk of numerous adverse health outcomes. Prior research shows that PM2.5 is disproportionately concentrated in communities of low socioeconomic status and with higher proportions of ethnic and racial minorities. Studies characterizing concentrations in primarily American Indian- (AI-) populated areas are currently lacking. Our aim was to compare fine particle (PM2.5) concentrations in American Indian (AI-) vs. non-AI-populated counties over time (2000 – 2018) in the contiguous US. METHODS: We used a multi-criteria approach to classify counties as AI- or non-AI-populated. We ran linear mixed effects models to estimate the difference in county-wide annual PM2.5 concentrations from monitoring sites and well-validated prediction models (measured and modeled PM2.5, respectively) in AI- vs. non-AI-populated counties, adjusting for population density and median household income. We estimated whether differences in AI- vs. non-AI-populated counties varied over time using interaction terms with calendar year. RESULTS:We included 3,109 counties in our final analysis, 199 of which were classified as AI-populated (6.4%). On average, adjusted measured PM2.5 concentrations in AI-populated counties were 0.79 μg/m3 (95%CI: 0.33, 1.26) lower than in non-AI-populated counties. However, this association was not constant over time; while in 2000, adjusted concentrations in AI-populated counties were 1.83 μg/m3 (95%CI: 1.53, 2.13) lower, by 2018, they were 0.84 μg/m3 (95%CI: 0.53, 1.15) higher. Over the study period, measured PM2.5 mean concentrations in AI-populated counties decreased by 2.49 vs. 5.18 μg/m3 in non-AI-populated counties. Results were similar for satellite-based, modeled PM2.5. CONCLUSIONS:This study highlights disparities in PM2.5 trends between AI- and non-AI-populated counties over time, underscoring the need to strengthen air pollution regulations in tribal territories and areas where AI populations live. KEYWORDS: air pollution, particulate matter, environmental disparities, environmental justice