Michelle Evoy can vouch for the foul air pollution in Chicago.
When she used to work downtown years ago, it aggravated her asthma and sometimes force her to use her inhaler.
When she moved to Florida for a time, she felt much better.
Now, even as a resident of semirural Plainfield, she notices the effects of air pollution, and uses her inhaler more often.
"It's one reason we don't live in the city," said Evoy, a mother of three. "You wouldn't think you'd have to worry about breathing there."
A recent report out suggests there is reason for worry. Downtown Chicago has the highest peak levels of nitrogen dioxide in the country, and is the only site in violation of new stricter guidelines against the irritant, which inflames asthma and other lung conditions.
That news raised the question of how bad is the Chicago area's overall air quality, 40 years after the Clean Air Act as we know it was created.
Several recent rankings may make sensitive readers choke:
Forbes magazine recently rated the Chicago metropolitan area as having the second-worst air quality of any big city in the nation, based on a federal 2007 report on the number of days with unhealthy air.
The Chicago area also ranked the third-most toxic, with more facilities releasing toxic chemicals than anywhere else.
One recent EPA analysis found Cook County was the worst in the country in terms of the relative potential health risk from industrial air pollution alone, excluding motor vehicles.
According to the American Lung Association, analyzing EPA statistics, the Chicago metro area is the ninth-most polluted city for short-term particle pollution, which causes early death, stroke, heart attacks and emergency room visits.
Though suburban air quality is generally better, the suburbs aren't immune.
The lung association gave an "F" grade last year for ozone pollution in Cook, Kane, Lake and McHenry counties.
Cook also got an F for particle pollution, while the collar counties got C's.
And anyone who lives near a busy highway, whether in the city or the suburbs, faces higher risks for heart attack, allergies, and infant death.
That's in part why the EPA is setting new tighter standards and monitoring for highway pollution.
The new report that Cook County had the worst nitrogen dioxide in the country should be tempered by the fact that only one monitor, in downtown Chicago near the Circle expressway interchange and Union Station, registered an unhealthy reading.
Six other monitors in the county, including those in Northbrook and Schiller Park, showed nowhere near that level.
Overall, the Environmental Protection Agency points out the air here is better than some other cities by several measures, and has been getting steadily better.
Chicago does much better in annual measurements of fine particles and ozone than other cities like Los Angeles, Houston, Atlanta, New York and the East Coast, said Laurel Kroack, air bureau chief at the Illinois EPA.
Annual emissions of ozone, carbon monoxide, nitrogen dioxides, particulates, sulfur dioxide, and volatile organize material have all been curtailed drastically since 1981, to roughly one-third to one-quarter of previous levels.
In 2008, the last year for which there are certified statistics, there were no days when air quality in Illinois was considered unhealthy.
And many preliminary measurements of local air pollution were down in 2009, partly because it was a cool, wet year.
Those who fight for clean air, like Brian Urbaszewski, director of environmental health programs for the Respiratory Health Association of Metropolitan Chicago, says there is no good single measure of overall air quality. But, he says, the transportation hub of the country has serious air quality issues.
"Chicago needs to do more," he said, "to clean up the air we're all breathing."
A history of pollution
A century ago, Chicago was known nationally for its foul, sooty air, thanks to coal, slaughterhouses, and manufacturing, but became a leader in regulating cleaner air, according to the Chicago Historical Society.
Still, air quality didn't improve significantly until people started burning less coal after World War II. By 1967, the federal government still ranked Chicago's air as second worst in the nation, behind only New York City.
The closing of numerous steel plants helped reduce industrial pollution, but as manufacturing left the city, it sprang up increasingly in the suburbs.
Today, the number one cause of air pollution is traffic.
Clearing the air
Cleaner burning gas and engines, most recently for new diesel engines, have improved the situation. But old diesel trucks and buses still don't face the emission controls passenger cars do, and continue to belch black smoke filled with particles that can cause heart attacks and strokes.
So clean air advocates are focusing on ways to clean up diesel.
One easy way to cut down is to stop idling. Hybrid vehicles do this by switching off their combustion engines when stopped.
Diesel trucks and buses often sit and idle for extended periods, sometimes hours at a time, out of concern they may be hard to restart in cold weather.
For most newer engines, that old wives' tale no longer applies, Urbaszewski said.
Last year, the state of Illinois passed a law to ban idling for more than 10 minutes. Chicago shortened that to three minutes.
Clean air advocates believe the laws are having a positive effect, but did not know if it's being enforced with any tickets.
At the same time, the American Lung Association is also trying to cut down on diesel emissions by working with commercial fleets to install exhaust filters and other pollution control devices on trucks and buses.
The retrofits cost $2,500 to $13,000 per vehicle, but federal stimulus funds pay for 70 to 100 percent of the cost, association CEO Harold Wimmer said.
He's worked with Pace, the suburban bus system, Black Horse Carriers in Carol Stream, ComEd, Durham School Services in Downers Grove, and Olson Transportation Inc. in Gurnee.
The Lung Association also advocates for E-85 fuel, which is 85 percent ethanol, now available for mixed-fuel vehicles at 35 gas stations in the Chicago area.
If the Chicago area continues to violate new standards for ozone and nitrogen dioxide in future years, officials may consider fixes like car pool lanes, traffic restrictions at peak travel times, and cleaner-burning fuels.
On a personal level, people can try to protect their lungs by checking the EPA's daily air quality reports at airnow.org.
If pollution levels are unhealthy, experts say, stay indoors and limit outdoor exercise. And avoid any unnecessary travel where you'll be most exposed and contributing to the bad air.
And to cut down on your local carbon footprint, of course, taking public transportation, walking, biking, conserving energy and not burning yard waste all help clear the air.
If that's not enough incentive, Green Pays on Green Days, at cleantheair.org, offers prizes to those who pledge to do something environmentally friendly. Susan Adams of Crystal Lake planted native landscape in her yard last year, reducing the need to water and mow, and won a drawing for a Toyota Prius hybrid.