Air quality in the Pittsburgh metro area is getting worse, according to a new report from the American Lung Association. The report looks at data from 2015 to 2017 and compares it to last year's report, which included data from 2014 to 2016.

The 12-county region, which spans from Butler County to Ohio County, W. Va. and from Jefferson County, Ohio to Westmoreland County, saw increased levels of ozone pollution, as well as more daily and long-term fine particle pollution. Fine particle pollution includes the chemicals in exhaust and the byproducts from burning wood and trash, and can irritate the lungs.

From 2014 to 2016, there were some improvements. The Pittsburgh metro area had fewer days with unhealthy levels of ozone. The latest data show a reversal of that trend, which the report said is likely due to higher temperatures from climate change.

Kevin Stewart, the Lung Association's director of environmental health, said this is bad news for residents already at risk.

"That can be the young and the elderly," Stewart said. "It can also be people with chronic lung disease, chronic bronchitis, emphysema, also people with heart disease and diabetes."

For the second year in a row, Allegheny County is the only county outside of California to receive failing grades for ozone, daily and long-term fine particle pollution from the American Lung Association.

"This is multiple years in a row that we're showing up on a list that we don't want to be on," said Matt Mehalik, executive director of the Breathe Project. "It means we need to start looking to serious solutions so this trend can come to an end."

Mehalik said the Breathe Project supports regulations for industrial pollutors. Because the report looked at data from 2014 to 2017, pollution data from last year, including from the Clairton Coke Works fire, are not included.