Established in 1975, the air monitor at Watkins Mill State Park is one of the state's longest-running stations. The park lies about 40 miles northwest of the Kanas City line, and the monitor helps determine ozone exposure of a population segment in the Kansas City metropolitan statistical area. The state park is adjacent to the Watkins Woolen Mill State Historic Site. The park and historic site bear the name of entrepreneur Waltus Watkins.
The primary National Ambient Air Quality Standard for ozone is 0.070 parts per million averaged over eight hours (annual fourth-highest daily maximum 8-hour concentration, averaged over three years). The federal ozone season for monitoring runs from March 1 to Oct. 31.