Environmental Progress - Summer 2001

Agency Releases Annual Air Quality Report

For first time, Illinois did not exceed federal one-hour air quality standard.

The latest annual outdoor air quality report, for the year 2000, was released in June 2001. The report notes the year 2000 was the first during which ozone levels did not exceed the federal one-hour air quality standard anywhere in the state. Cooler weather patterns are credited with playing a role, but continued emissions reductions achieved through implementation of Clean Air Act requirements and such activities as the Chicago area Ozone Action Days program are at the core of the reductions.

"We continue to work hard with our partners to develop and implement programs that will result in even cleaner and healthier air for Illinois citizens," said Illinois EPA Director Tom Skinner.

The report incorporates the new Air Quality Index (AQI) for the first time. It shows that the outdoor air in Illinois was considered healthy more than 93 percent of the time during 2000. The AQI incorporates the new eight-hour ozone standard and the small particle standard (PM2.5) proposed by U.S. EPA and affirmed by the U.S. Supreme Court last year after a court challenge. On 25 days, air quality in some parts of the state did not meet the "good" or "moderate" categories and posed a potential risk to sensitive individuals. These were attributable to either the more stringent eight-hour average ozone levels or PM2.5.

U.S. EPA has not yet provided implementation plan guidelines or a schedule for the eight-hour ozone standard and PM2.5, but the process is expected to take several years.

"While there have been great improvements in air quality over the years, there are still challenges ahead, especially in the area of ozone and fine particulate matter," said Director Skinner.

Of the 25 unhealthy days, 18 were due to PM2.5 and nine were due to eight-hour ozone. Two days had unhealthy levels of both ozone and PM2.5. Three counties were out of compliance with the eight-hour ozone standard for the time period 1998 - 2000: Cook, Jersey, and Madison.

Compliance with the PM2.5 standards will be based on data from 2000 - 2002. Data from 2000 indicated that the Chicago and East St. Louis metropolitan areas will likely not meet the annual standard.

The Illinois EPA maintains more than 200 monitors at nearly 100 locations statewide that track pollutants with federal health-based standards - called criteria pollutants - as well as other pollutants and compounds.

Over the past decade, the trends reflected in the air monitoring network data show steady improvement in air quality or levels stabilized well below the air quality standards statewide. The report is available on the Agency web site or printed copies may be requested from the Illinois EPA's Bureau of Air.