The air monitoring station at Mark Twain State Park is not close to urban areas or large air pollution sources. Therefore, it provides important information on regional background levels of air pollutant concentrations.


Ozone Pollutant

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.

Departmental information about ozone (O3)

  • Description
  • Health effects
  • Tips to reduce ozone
  • 2008 and 2015 standards plus related documents

Sulfur Dioxide

EPA not only established a new one-hour standard in 2010, but it also introduced a new form for determining compliance. The new form requires three years of data — the average SO2 concentration from each hour of the year. The department and EPA calculate the design value, using the 99th percentile of one-hour daily maximum concentrations, averaged over three years.

Departmental information about sulfur dioxide (SO2)

  • Description
  • 2010 standard and related documents

Nitrogen Dioxide

Nitrogen dioxide is a foul-smelling gas. It comes primarily from the burning of fossil fuels — coal, oil and gas. NO2combines with volatile organic compounds (VOCs) in the presence of sunlight and heat to create ozone. (VOCs are compounds with carbon that easily become vapors or gases.)

In 2010, EPA revised the one-hour NO2 standard to 100 parts per billion. An area is in compliance if the design value is at or below the standard. The one-hour standard is based on a three-year design value, which is calculated by taking the 98th percentile of the daily high one-hour average concentrations recorded each year, for three years, and averaging the three years together. The annual standard of 0.053 parts per million is based on the annual arithmetic mean and is not to be exceeded.

Departmental information about nitrogen dioxide (NO2)

  • 2010 standard and related documents

Particulate Matter (PM 10)

Departmental information about particulate matter (PM)

  • Description of two groups of particulate matter: PM2.5 and PM10
  • 1997, 2006 and 2012 standards for PM2.5 plus related documents
  • 2006 PM10 standard and pertinent documents
Mark Twain State Park Air Monitoring Site

20057 State Park Office Road
Stoutsville, MO 65283
United States

Date Established
Pollutants Monitored
Nitrogen Dioxide
Particulate Matter
Sulfur Dioxide
39.4571, -91.78899