With only 10 days left in ozone season, ground-level ozone readings have remained consistently below allowable standard limits. So far this year, only one reading at Farrar, in Perry County has exceeded the allowable limit on June 9. Hot, humid weather can raise monitor readings. A Perryville air-quality committee tracks daily readings taken by the Missouri Department of Natural Resources. The department collects data from air monitors to see whether the state’s air quality meets the Environmental Protection Agency’s National Ambient Air Quality Standards, according to dnr.mo.gov. If the ozone standard for an area is violated, the county is designated a non-attainment area, and actions must be taken to reduce emissions contributing to the formation of ground-level ozone, or smog. Ozone season runs from April 1 to Oct. 31.