SAN FRANCISCO, Sept. 18 (Xinhua) -- A new study finds that the United States made little progress from 2000 to 2010 in reducing relative disparities between people of color and whites in exposure to harmful air pollution emitted by cars, trucks and other combustion sources.
The study builds on the work led by University of Washington (UW) researchers in both 2000 and 2010, identifying that disparities in exposure to outdoor concentrations of a transportation-related pollutant, namely nitrogen dioxide (NO2), were larger by race and ethnicity than by income, age or education.
The relative inequality persisted across the decade.
For the study, published in the recent issue of Environmental Health Perspectives, the researchers developed a first-of-its-kind model that combines satellite and regulatory measurements with land use data to predict pollution at a neighborhood level throughout the United States.
Measured in parts per billion (ppb), estimated average annual NO2 exposure decreased from 17.6 to 10.7 ppb for nonwhite populations, and from 12.6 to 7.8 ppb for white populations.
Yet people of color were, on average, consistently exposed to more air pollution than their white non-Hispanic counterparts during the decade. Considering relative differences, nonwhites experienced 40 percent higher exposures than whites in 2000; in 2010, that gap shrunk slightly, to 37 percent. Furthermore, in 2000, concentrations of NO2 in neighborhoods with the highest proportion of nonwhite residents were 2.5 times higher than in neighborhoods with the lowest proportion of nonwhite residents. In 2010, that value increased slightly, to 2.7 times higher.
The study concludes that if people of color had breathed the lower NO2 levels experienced by whites in 2010, it would have prevented an estimated 5,000 premature deaths from heart disease among the nonwhite group.
On the whole, the researchers noted, policies to reduce NO2 air pollution are working across the United States. But the finding that exposure differences are larger by race and ethnicity than by income, age or education was equally true in 2010 as in 2000.
"Everyone benefited from clean air regulations and less pollution; that's the good news," lead author and UW civil and environmental engineering doctoral student Lara Clark, was quoted as saying in a news release from UW. "But the fact that there is a pervasive gap in exposure to NO2 by race - and that the relative gap was more or less preserved over a decade - is the bad news."
NO2, which has been linked to asthma symptoms, increased susceptibility to respiratory problems and heart disease, comes from sources such as vehicle exhaust, power plants and off-road equipment and is one of six important "criteria air pollutants" monitored by the U.S. Environmental Protection Agency (EPA).