Changes in Transportation-Related Air Pollution Exposures by Race-Ethnicity and Socioeconomic Status: Outdoor Nitrogen Dioxide in the United States in 2000 and 2010.

Abstract

Background:Disparities in exposure to air pollution by race-ethnicity and by socioeconomic status have been documented in the United States, but the impacts of declining transportation-related air pollutant emissions on disparities in exposure have not been studied in detail.Objective:This study was designed to estimate changes over time (2000 to 2010) in disparities in exposure to outdoor concentrations of a transportation-related air pollutant, nitrogen dioxide (), in the United States.Methods:We combined annual average concentration estimates from a temporal land use regression model with Census demographic data to estimate outdoor exposures by race-ethnicity, socioeconomic characteristics (income, age, education), and by location (region, state, county, urban area) for the contiguous United States in 2000 and 2010.Results:Estimated annual average concentrations decreased from 2000 to 2010 for all of the race-ethnicity and socioeconomic status groups, including a decrease from to () in nonwhite [non-(white alone, non-Hispanic)] populations, and to () in white (white alone, non-Hispanic) populations. In 2000 and 2010, disparities in concentrations were larger by race-ethnicity than by income. Although the national nonwhite–white mean concentration disparity decreased from a difference of in 2000 to in 2010, estimated mean concentrations remained 37% higher for nonwhites than whites in 2010 (40% higher in 2000), and nonwhites were 2.5 times more likely than whites to live in a block group with an average concentration above the WHO annual guideline in 2010 (3.0 times more likely in 2000).Conclusions:Findings suggest that absolute exposure disparities by race-ethnicity decreased from 2000 to 2010, but relative exposure disparities persisted, with higher concentrations for nonwhites than whites in 2010. https://doi.org/10.1289/EHP959