Each month, from March through October, EWG prepares the daily (9 am – 9 pm) maximum one-hour and eight-hour ozone concentration, in parts per billion (ppb), for each of the air quality monitors located in the St. Louis (MO-IL) region and generates the Air Quality Index (AQI) calendar. The tables use the 2015 ozone standard of 70 ppb. The AQI calendar depicts a color-coded graphic presentation of the maximum daily eight-hour ozone values for the same period. Missouri and Illinois provide this information.
Data 2018 Environment