News Releases

Chicago Area Attainment Designation Delayed By Recent Ozone Levels Linked to Weather Conditions

Chicago, Ill. -- Redesignation of the Chicago metro area for meeting the federal one-hour health standard for ground-level ozone will be delayed as a result of unusual weather conditions in late June, Illinois Environmental Protection Agency Director Renee Cipriano announced today.

"Our analysis indicates weather conditions were extremely conducive in the June 22-24 period for ozone formation and for the first time in four years, ozone levels in the Illinois portion of the metro area violated the health standard," Director Cipriano added.

After last year's ozone season, the Chicago area was the largest metropolitan area in the nation to meet the requirements to comply with the standard and the first in the nation that achieved this milestone after having been designated "severe nonattainment" in 1990.

Air monitors in Zion and at the Jardine water plant in Chicago, as well as the Chiwaukee monitoring station just across the Wisconsin border recorded exceedances -- or one-hour levels above the standard -- in the June 22-24 period.

In order to be deemed attainment for the ozone standard, the Chicago area cannot have more than three exceedances at any one monitoring station in the area over a three-year period. The Chiwaukee station in Wisconsin had three exceedances during the June 22-24 weekend and one in 2000.

"This delay is unfortunate but we must not forget the achievements we have made in air quality, and more importantly, we must work harder to regain that status," Director Cipriano said.

She said preliminary Illinois EPA analysis indicates that not since July 4, 1988 have weather conditions been so conducive to formation of ozone, as they were on the 22nd - 24th. Ozone is created when sunlight reacts with volatile organic materials and nitrogen oxides.

"Although there isn't much we can do about the weather, there are actions we can take as individuals to reduce the potential for high ozone levels," said Director Cipriano.

She urged citizens and organizations to redouble their efforts on Ozone Action Days by taking public transit, car-pooling, delaying fueling and postponing barbecues that contribute to ozone.

Vehicles and other individual and consumer activities account for 58 percent of the volatile organic materials and 59 percent of nitrogen oxides in the Chicago area.

In other words, over half of the pollution in the Chicago area is caused by our everyday activities, like driving our children to soccer practice, fueling our cars during the heat of the day, mowing our lawns and firing up our barbecues.

Director Cipriano noted there is an added incentive this summer for taking "clean air actions" because of the Green Pays on Green Days drawings for environmentally-friendly prizes, including a grand prize of a Honda electric hybrid car at the end of this summer. More information is available at www.nbc5.com or www.cleantheair.org.

(Attached are charts showing the contributions of various sources to ozone formation and trends in pollutant reductions, as well as the Top 10 tips for individual clean air actions).