Air quality in Illinois is a mixed bag, according to the new State of the Air report from the American Lung Association.
Out of 23 Illinois counties with air-quality monitors, the report gives 16 failing grades for high ozone pollution.
Nationally, the Chicago area ranked 21st out of about 200 cities for its unhealthy number of high-ozone days. But there's good news as well.
Mike Kolleng, manager, Healthy Air Campaign at the American Lung Association in Illinois, says in the past three decades, the state's overall amount of ozone pollution has been slowly declining.
"Standards that are put in place to help make sure that we're controlling the amounts of ozone pollution, the amounts of tailpipe emissions, the amounts of emissions from smokestacks, from coal-fired power plants," he says. "All those changes that have been made in recent years, we're starting to see the fruits of that labor."
The report provides a snapshot of Illinois' air quality from 2011 to 2013. It also says a little more than half of all Americans are living in a county with potentially unhealthy levels of air pollution.
But this year's report for Illinois is incomplete. Particle pollution data is missing, because samples collected by the federal Environmental Protection Agency were deemed unusable and the agency didn't have the resources to run the tests again.
Kolleng says for cities like Chicago, with historic particle pollution problems, it's a challenge to measure the levels of dust, soot or smoke in the air.
"Unfortunately, this data was lost," says Kolleng. "When you start to see these resources siphoned away from things like EPA, it's really important for us to step in and do our advocacy work to make sure that doesn't happen, so that we can have accurate results and portray them to the public."
To help reverse the effects of air pollution, the American Lung Association is suggesting federal lawmakers protect the Clean Air Act, and that states could enact changes to move away from using old or dirty diesel engines.