A new study suggested people of color are exposed to about 38 percent more air pollution than white people.

The pollutant nitrogen dioxide (NO2) can come from sources such as "vehicle exhaust and power plants"; breathing in the pollutant has been linked with health problems such as asthma and heart disease, a University of Minnesota news release reported.

The researchers looked at NO2 levels (one of the seven Environmental Protection Agency-monitored pollutants) in urban areas across the country.  They compared urban areas within the cities that were "nonwhite" or "white" based on population data from the U.S. census.

The determined if nonwhites breathed in the same NO2 levels as whites, it would prevent about 7,000 deaths from heart disease in nonwhites annually.

"We were quite shocked to find such a large disparity between whites and nonwhites related to air pollution," Julian Marshall, a civil engineering associate professor in the University of Minnesota's College of Science and Engineering and co-author of the study, said in the news release.. "Our study provides a great baseline to track over time on important issues of environmental injustice and inequality in our country."

The 15 states with the largest exposure gaps included "New York, Pennsylvania, Illinois, Michigan, New Jersey, Rhode Island, Massachusetts, California, Wisconsin, Connecticut, Missouri, Ohio, Kentucky, Indiana, [and] Minnesota."

The team found that almost everywhere lower income nonwhites were more exposed to the pollutant than higher income whites.  New York, Pennsylvania and Illinois had the largest data gaps between races when income was not taken into account.

"Our findings are of broad interest to researchers, policy makers and city planners," Lara Clark, co-author of the study and civil engineering Ph.D. student in the University of Minnesota's College of Science and Engineering, said in the news release. "The next step in the research would be to look at why this disparity occurs and what we can do to solve it."