Changes in transportation-related air pollution exposures by race-ethnicity and socioeconomic status: Outdoor nitrogen dioxide in the United States in 2000 and 2010

Lara P. Clark, Dylan B. Millet, Julian D. Marshall

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74 Scopus citations


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 (NO2), in the United States. METHODS: We combined annual average NO2 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 NO2 concentrations decreased from 2000 to 2010 for all of the race-ethnicity and socioeconomic status groups, including a decrease from 17:6 ppb to 10:7 ppb (−6:9 ppb) in nonwhite [non-(white alone, non-Hispanic)] populations, and 12:6 ppb to 7:8 ppb (−4:7 ppb) in white (white alone, non-Hispanic) populations. In 2000 and 2010, disparities in NO2 concentrations were larger by race-ethnicity than by income. Although the national nonwhite–white mean NO2 concentration disparity decreased from a difference of 5:0 ppb in 2000 to 2:9 ppb in 2010, estimated mean NO2 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 NO2 concentration above the WHO annual guideline in 2010 (3.0 times more likely in 2000). CONCLUSIONS: Findings suggest that absolute NO2 exposure disparities by race-ethnicity decreased from 2000 to 2010, but relative NO2 exposure disparities persisted, with higher NO2 concentrations for nonwhites than whites in 2010.

Original languageEnglish (US)
Article number097012
JournalEnvironmental health perspectives
Issue number9
StatePublished - Sep 2017

Bibliographical note

Funding Information:
The authors are grateful for support from the National Science Foundation (NSF; Sustainability Research Network award 1444745 and grant 0853467) and the U.S. Environmental Protection Agency (EPA; Assistance Agreement RD83587301). This article has not been formally reviewed by the NSF or the U.S. EPA; views expressed herein are solely those of authors and do not necessarily reflect those of either agency.

Publisher Copyright:
© 2017, Public Health Services, US Dept of Health and Human Services. All rights reserved.


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