Pittsburgh ranks fourth out of all large U.S. metropolitan areas in the number of days where the air posed moderate-to-serious health risks, according to new analysis from a statewide environmental organization.

The report by the PennEnvironment Research and Policy Center, titled “Trouble in the Air,” looks at 2016 data from the Environmental Protection Agency. It found Pittsburghers breathe hazardous air during one out of every three days.

Ashleigh Deemer, PennEnvironment’s western Pennsylvania director, hosted the city hall announcement. She said poor air quality risks include smog and particles of toxic chemicals.

“These particles are so small that they can be inhaled deep into the lungs and enter the blood stream. They cause respiratory and cardiovascular problems like heart attacks and strokes,” she said. “Smog…produces [an] inflammatory response, similar to sunburn in the lungs."

Deemer said smog can cause a range of respiratory problems from throat irritation to permanent lung damage. Warming temperatures caused by climate change means that air pollution will become greater and more concentrated, she said, resulting in even more severe health hazards. She called on the Allegheny County Health Department to do a better job regulating industrial polluters.

In an emailed statement, health department director Karen Hacker said, "The Health Department has been extremely active in recent years when it comes to enforcing air quality regulations, both unilaterally, and in partnership with the EPA."

She pointed to recent updates in the department's process for assessing civil penalties, which she said will help deter future violations. She also said U.S. Steel’s Clairton Coke Works facility is now subject to additional inspections.

Matt Dean, the environmental exchange coordinator for New Voices Pittsburgh, which promotes the health and well being of black women, femmes and girls, was also at the event. He said pollution is tied to systemic racism.

“Historical forces of housing discrimination, segregation, redlining and economic injustice have created an environment where communities of color are much more likely to be exposed to air pollution than white communities,” said Dean. “Couple that with limited access to health care in many of these communities, and we see that the health impacts of poor air quality...are disproportionately hurting people of color.”

Data the bears this out. A 2017 study found that black children are six times more likely to die from asthma than Hispanic or white children. And in 2013, the hospitalization rate for black residents was more than fives higher than white.

Both Dean and Deemer said they want to protect the Clear Air Act and more robust policies that promote clean energy, like wind and solar, over fossil fuels.