SPRINGFIELD, Ill. (CBS) — You might be inclined to hold your breath upon hearing this news – air quality in Illinois is getting a little worse.

A report issued Monday by the Illinois Environmental Protection Agency indicated that measuring sites showed good or moderate air quality 91 percent of the time in 2010.

In 2009, it was 96 percent of the time.


In total, there were 32 days in 2010 when air quality was considered “unhealthy for sensitive groups” in certain areas. In 2009, there were 13 such days.

Still, the EPA considers measurements in the 90 percent range to be “good.”

The EPA monitors air quality from 80 sites, using more than 200 instruments through statewide. The monitoring network is set up to identify pollution trends.

The monitors track a variety of pollutants – including particulate matter of larger (PM10 and smaller PM2.5 sizes, ozone, sulfur dioxide, nitrogen dioxide, carbon monoxide and lead. The monitors also pick up some other heavy metals, nitrates, sulfates, and volatile organic and toxic compounds.

The data from 2001 to 2010 show decreases across the board. Most dramatically, the carbon monoxide level has dropped 52 percent, the sulfur dioxide level 43 percent, and the lead level 33 percent.