For Release 11-01-01

For More Information Contact     Brian Button 515-281-7832

DES MOINES-Halloween and the end of October marks the close of the "smog season," the time of year when sunlight, heat and emissions can create unhealthy air and this year was nearly a clean sweep, say state officials.

Ozone, the main ingredient in smog and a powerful oxidant that can burn lungs and trigger asthmatic attacks, hit unhealthy levels only one day this season. Several days approached but did not reach unhealthy levels later in the summer.

Officials say this season was good news from a regulatory and health perspective. "Lower ozone smog helps maintain Iowa's clean air designation status," said Brian Button, DNR air quality information specialist. "Areas with numerous unhealthy days are prone to face tougher emission reduction plans."

He said the fourth highest value measured is averaged over three years to determine if the area meets the standards. Some areas of the state are pushing, but still meeting the standards. "Who knows what next year will bring, that's why it is nice to have lower levels this year to help improve the average."

The warm-weather ozone smog season begins in April and runs through October. Seasons' end means monitoring equipment is shut down until the spring, although other air pollutants are monitored all year.

The only unhealthy level occurred during June in several northeastern counties. Weather conditions, sunlight, wind conditions and emissions all affect how pollution can react, form and travel. The number of unhealthy days can fluctuate from year to year given the nature of the summer season. Hot, sunny and calm days are most likely to produce ozone smog.

While ozone smog levels were down this year, particulate pollution levels have increased. So far, four days of unhealthy particulate pollution have been detected, sometimes over large regions of the state. Past years have had one or two days. There are also concerns about long-term exposure to roughly a dozen toxic chemicals as well.

"We will continue to monitor and manage our air resources," said Button. He said Iowans can obtain air quality information at www.iowacleanair.com.