A study recently put together by a group of environmental scientists at the University of Minnesota finds that people of color living in American cities are exposed to a lot more air pollution than urban whites.
The research, which overlays census and air-quality data, finds that the correlation between race and the amount of nitrogen dioxide a person is exposed to is stronger than the correlation between between exposure and income. (Read the study here.)
The findings hold true for Minneapolis, which is in the highest quintile of cities with regard to the difference in air quality between neighborhoods primarily inhabited by people of color and those primarily inhabited by whites.
Nitrogen dioxide is mainly emitted from combustion in vehicles and power plants. It's "a marker for traffic emissions and has high within-urban variability," the paper notes, meaning that while one neighborhood might have relatively clean air, an adjacent one might be polluted thanks in part to a busy highway running through it, for example.
Nationally, the study finds that population-weighted nitrogen dioxide concentrations are 38 percent higher for nonwhites than for whites.
"The environmental health implications of that concentration disparity are compelling," the paper says. "For example, we estimate that reducing nonwhites' NO2 concentrations to levels experienced by whites would reduce Ischemic Heart Disease (IHD) mortality by ~7,000 deaths per year, which is equivalent to 16 million people increasing their physical activity level from inactive (0 hours/week of physical activity) to sufficiently active (>2.5 hours/week of physical activity)."
Minnesota ranks 15th among states with regard to the difference between average nitrogen dioxide concentrations for nonwhites and whites. New York is the worst offender, with Wisconsin ranking ninth.
As far as implications go, the researchers write, "Results given here can aid policy-makers in identifying locations with high environmental injustice and inequality."
We reached out to one of the study's co-authors, environmental engineering professor Julian Marshall, but he hasn't yet gotten back to us yet as this is published (We've since talked to him -- read our follow-up here).