If all air pollution levels in Allegheny County were improved to resemble the least polluted levels in the county, then 100 fewer people would die of coronary heart disease every year. That’s not eliminating pollution completely — but rather as if the dirtiest quarter resembled the cleanest.

That’s according to the findings of a new study from the University of Pittsburgh Graduate School of Public Health funded by The Heinz Endowments. The team collaborated with Carnegie Mellon University, using their high-resolution spatial exposure mapping for two pollutants: nitrogen dioxide (from burning fuel) and black carbon (from any form of combustion, particularly diesel exhaust).

“I asked my students in my class, ‘How many people die of air pollution in Allegheny County?’ says Pitt professor Jim Fabisiak, lead author of the study. “Not surprisingly, nobody can come up with a good answer. I hear everything from ‘a handful’ to a number in the thousands.

“So I thought it would be good for people have at least a number that they can hang their hat on, so to speak, that might inform the conversation about air pollution in Allegheny County, and how big that burden is. So then they can ask, ‘Is that burden acceptable, or unacceptable?’”

They divided the county into fourths, from most polluted to least polluted census tracts.

“Then I ask a very simple question: where do I find census tracts that are designated as an environmental justice area. And that is essentially a working definition, of a population that is greater than 30% non-white minority, or greater than 20% in poverty …Where do they fall along the gradient of exposure? We find a disproportionate number of those environmental justice tracts are located in areas of high exposure.”

Researchers found that communities of color and poverty were 20 times more common in the most polluted quarter. While 40% of the estimated pollution-related heart disease deaths happened in those communities, they only represent 27% of the population of Allegheny County.

“We find that those two pollutants, by our estimate, would account for about 100 excess coronary heart disease deaths per year in Allegheny County,” says Fabisiak. “That’s about four percent of the total number of coronary heart disease deaths in the county.”

Specific neighborhoods aren’t singled out in the study, but by looking at the maps, you can see the most and least polluted places.

“Being in a national scientific journal, Homewood wouldn’t mean something to the rest of the world,” says Fabisiak. “But if you were to look at those maps there, those regions in red (which have the highest level of exposure) follow the river valleys to some extent, not surprisingly, because industry and traffic follow that as well.

“The industrial facilities, like the steel mills, were developed in like the ‘40s, and probably brought some economic benefit to those who lived nearby. Then, again, as that environment became more noxious, people with resources moved away.”

Nitrogen dioxide is usually associated with motor vehicle traffic, and black carbon can come from industry as well as diesel exhaust. So it’s possible that air pollution has lessened recently, due to the pandemic lockdowns.

“If we’re specifically looking at some of those traffic air pollutants — and this would be some of the work that my colleague at CMU, Albert Presto, has done — those have gone down to some extent due to the lockdown, as you might expect,” says Fabisiak.

“We’re not as sure about what’s happening with industrial facilities. It’s harder to ascertain whether or not they’ve curtailed their activities to any extent.”