People of color tend to live in neighborhoods that expose them to higher levels of air pollution when compared to Caucasians, a new nationwide study indicates.

This study, published in the journal PLOS ONE, is the first of its kind to show a racial divide when it comes to air quality.

Researchers at the University of Minnesota studied nitrogen dioxide (NO2) air levels in urban areas across the country and differentiated between specific areas in terms of their "nonwhite" or "white" populations. Those in the former group are subjected to NO2 levels 38 percent higher than their white counterparts, research showed.

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

NO2 is a dangerous air impurity released into our atmosphere mostly by power plants and vehicle exhaust. The chemical is linked to asthma symptoms and heart disease and has been named one of the seven key air pollutants closely monitored by the Environmental Protection Agency.

In all, around 7,000 deaths due to heart disease could be prevented every year if nonwhites breathed the lower NO2 levels experienced by whites, the researchers found.

While the team was able to confirm that income played a role in the circumstances leading to higher exposure of nonwhites to air pollution, race was the more deciding factor. New York, Pennsylvania and Illinois had the largest exposure gaps between the two ethnic groups, irrespective of income. Specifically, the places with the largest imbalances were New York/Newark, Philadelphia and Bridgeport/Stamford, Conn.