The highest level during those days was 132 ppb., recorded on July 6. The three high ozone days were linked to weekends and holidays, periods when more people are likely to be driving, barbecuing, mowing lawns or doing other outdoor chores using pollution-generating equipment.
Ozone is a respiratory irritant found in smog.
It is formed when emissions from sources like industry, cars and household products combine with heat and sunlight on days with little wind and no precipitation. Ozone can cause health problems for some people, particularly children, the elderly and those with heart and respiratory conditions. When air pollution levels are likely to be high, the Illinois EPA provides advance warnings to local weather forecasters, utilizing a new, color-coded air quality forecasting system. On code red days, the Partners for Clean Air coalition declares an Ozone Action Day. On these days, the 250 Illinois partners among Chicago area businesses, industries and government agencies, voluntarily take action to reduce ozone by limiting employee travel, educating employees about ozone, or revising production schedules to reduce emissions.