People of color exposed to more pollution from cars, trucks, power plants over 10 years

September 14, 2017
In columns A and B, red identifies locations where NO2 concentrations were higher for nonwhites than whites; blue indicates that NO2 concentrations were higher for whites than nonwhites; and white means they were equal. In column C, red indicates that the absolute difference in NO2 concentration between nonwhites and whites increased over time; blue indicates that difference decreased over time; and white indicates no change. Credit: University of Washington

A new nationwide study finds that the U.S. 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 groundbreaking study led by University of Washington researchers estimated to outdoor concentrations of a transportation-related pollutant—nitrogen dioxide (NO2)—in both 2000 and 2010, based on neighborhoods where people live. It found disparities in NO2 exposure were larger by race and ethnicity than by income, age or education, and that those inequities persisted across the decade.

While absolute differences in exposure to the air pollutant dropped noticeably during that time period for all populations, the relative difference—or the gap between pollution levels to which white people and people of color were exposed—narrowed only a little.

The study will be published Sept. 14 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.

The positive news is that across the U.S., average exposure to NO2 for all races and income levels dropped from 2000 to 2010. 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 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 only 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 among the nonwhite group.

"The finding that shocks us is that when it comes to how much NO2 a person breathes, it's still race that matters," said senior author Julian Marshall, UW professor of civil and environmental engineering.

"At any income level—low to medium to high—there's a persistent gap by race, which is completely indefensible. It says a lot about how segregated neighborhoods still are and how things are segregated," Marshall said.

The video will load shortly.
Credit: Abby VanMuijen/University of Washington

NO2 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 Environmental Protection Agency. It has been linked to asthma symptoms, increased susceptibility to respiratory problems and heart disease.

The research team, which began their work at the University of Minnesota, previously analyzed NO2 concentrations for the year 2006 by race, income and other demographic factors identified in the U.S. Census. The team's air pollution model, which combines existing EPA and satellite data with detailed land use information, allows them to accurately predict pollution concentrations across the country at the U.S. Census block level—information previously unavailable at that scale.

In this first longitudinal study of its kind, researchers wanted to examine how much progress was made in addressing inequities in NO2 exposure over a decade. They compared environmental injustice metrics in 2000 and 2010 on a national basis and by region, state, county and urban areas.

On the whole, researchers said, policies to reduce NO2 air pollution are working. 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," said lead author and UW civil and doctoral student Lara Clark. "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."

The UW study did not explore the underlying reasons for that gap, but its findings are consistent with previous research. Both racial minorities and low-income households are disproportionately likely to live near a major road where transportation-related is typically highest. U.S. cities, in general, also tend to be more segregated by race and ethnicity than by income.

The UW team did conclude that the narrowing of the racial gap in NO2 exposures was driven more by improving air quality than by demographic changes over the 10-year period.

"That suggests that is coming down faster than cities are becoming less segregated," Marshall said.

Next steps for the research team include looking at how changes in demographics, industry and urban form at the city level affect NO2 exposure, and developing similar models for other EPA criteria air pollutants.

Explore further: Noise pollution loudest in black neighborhoods, segregated cities

More information: Environmental Health Perspectives (2017). DOI: 10.1289/EHP959

Related Stories

Noise pollution loudest in black neighborhoods, segregated cities

July 25, 2017
As the number of white residents in a neighborhood declines, noise rises. But noise pollution is inescapable in segregated cities, where noise pollution is worse for everyone, according to the first breakdown of noise exposure ...

Groundbreaking nationwide study finds that people of color live in neighborhoods with more air pollution than whites

April 15, 2014
A first-of-its-kind study by researchers at the University of Minnesota found that on average nationally, people of color are exposed to 38 percent higher levels of nitrogen dioxide (NO2) outdoor air pollution compared to ...

Study links unhealthy segregated neighborhoods to childhood asthma

August 7, 2017
Researchers have had trouble explaining why black children are much more likely than other children to suffer from asthma. A new study by Princeton University strongly suggests that much of the answer lies in persistent residential ...

Air pollution may disrupt sleep

May 22, 2017
High levels of air pollution over time may get in the way of a good night's sleep, according to new research presented at the ATS 2017 International Conference.

Study of US seniors strengthens link between air pollution and premature death

June 28, 2017
A new study of 60 million Americans—about 97% of people age 65 and older in the United States—shows that long-term exposure to airborne fine particulate matter (PM2.5) and ozone increases the risk of premature death, ...

Study shows telomere shortening in youth with higher pollution exposure

May 24, 2017
Children and teens exposed to high levels of traffic-related air pollution have evidence of a specific type of DNA damage called telomere shortening, reports a study in the May Journal of Occupational and Environmental Medicine.

Recommended for you

New shoe makes running 4 percent easier, 2-hour marathon possible, study shows

November 17, 2017
Eleven days after Boulder-born Shalane Flanagan won the New York City Marathon in new state-of-the-art racing flats known as "4%s," University of Colorado Boulder researchers have published the study that inspired the shoes' ...

Vaping while pregnant could cause craniofacial birth defects, study shows

November 16, 2017
Using e-cigarettes during pregnancy could cause birth defects of the oral cavity and face, according to a recent Virginia Commonwealth University study.

Study: For older women, every movement matters

November 16, 2017
Folding your laundry or doing the dishes might not be the most enjoyable parts of your day. But simple activities like these may help prolong your life, according to the findings of a new study in older women led by the University ...

When vegetables are closer in price to chips, people eat healthier, study finds

November 16, 2017
When healthier food, like vegetables and dairy products, is pricier compared to unhealthy items, like salty snacks and sugary sweets, Americans are significantly less likely to have a high-quality diet, a new Drexel University ...

Children's exposure to secondhand smoke may be vastly underestimated by parents

November 15, 2017
Four out of 10 children in the US are exposed to secondhand smoke, according to the American Heart Association. A new Tel Aviv University study suggests that parents who smoke mistakenly rely on their own physical senses ...

How pomegranate extract alters breast cancer stem cell properties

November 15, 2017
A University at Albany research team has found evidence suggesting that the same antioxidant that gives pomegranate fruit their vibrant red color can alter the characteristics of breast cancer stem cells, showing the superfood's ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.