Ambient Air Quality Standards

PURPOSE: This rule is a compilation of standards for ambient air quality throughout Missouri in order to protect the public health and welfare. The U.S. Environmental Protection Agency has set National Ambient Air Quality Standards (NAAQS) for six (6) criteria pollutants (carbon monoxide, lead, nitrogen dioxide, ozone, particle pollution, and sulfur dioxide). Primary NAAQS provide public health protection and secondary NAAQS provide public welfare protection. In addition, Missouri has set standards for hydrogen sulfide and sulfuric acid. Pollutant Primary/Secondary Standard Averaging Time Level Form Reference Method Carbon monoxide Primary 8-hour 9 parts per million Not to be exceeded more than once per year As specified in 10 CSR 10-6.040(4)(C) 1-hour 35 parts per million Lead (2008) Primary and secondary Rolling 3month average 0.15 micrograms per cubic meter Not to be exceeded (see 10 CSR 106.040(4)(O)) As specified in 10 CSR 10-6.040(4)(G) Lead (1978)* Primary Calendar quarter mean 1.5 micrograms per cubic meter Not to be exceeded As specified in 10 CSR 10-6.040(4)(G) Nitrogen dioxide Primary 1-hour 100 parts per billion 98th percentile, averaged over 3 years As specified in 10 CSR 10-6.040(4)(F) Primary and secondary Annual 0.053 parts per million, equal to 53 parts per billion Annual mean Ozone (2008) Primary and secondary 8-hour 0.075 parts per million Annual fourthhighest daily maximum 8-hour, averaged over 3 years (see 10 CSR 10-6.040(4)(N)) As specified in 10 CSR 10-6.040(4)(D) Ozone (1997)** Primary 8-hour 0.08 parts per million Annual fourthhighest daily maximum 8-hour, averaged over 3 years (see 10 CSR 10-6.040(4)(I)) As specified in 10 CSR 10-6.040(4)(D) Particle pollution (2012) Particulate matter 2.5 micron (PM2.5) Primary Annual 12 micrograms per cubic meter Annual mean, averaged over 3 years As specified in 10 CSR 10-6.040(4)(L) Secondary Annual 15 micrograms per cubic meter Annual mean, averaged over 3 years Primary and secondary 24-hour 35 micrograms per cubic meter 98th percentile, averaged over 3 years (see 10 CSR 10-6.040(4)(M)) Particulate matter 10 micron (PM10) Primary and secondary 24-hour 150 micrograms per cubic meter Not to be exceeded more than once per year on average over 3 years (see 10 CSR 10-6.040(4)(K)) As specified in 10 CSR 10-6.040(4)(J) RESOURCES Particulate matter 2.5 micron (PM2.5) (1997)*** Primary Annual 15 micrograms per cubic meter Annual mean, averaged over 3 years As specified in 10 CSR 10-6.040(4)(L) Sulfur dioxide (2010) Primary 1-hour 75 parts per billion 99th percentile of 1-hour daily maximum, averaged over 3 years As specified in 10 CSR 10-6.040(A) Secondary 3-hour 0.5 parts per million, equal to 500 parts per billion Not to be exceeded more than once per year Sulfur dioxide (1971)**** Primary Annual 0.03 parts per million Annual mean As specified in 10 CSR 10-6.040(A) Primary 24-hour 0.14 parts per million Not to be exceeded more than once per year Hydrogen sulfide State only 1/2-hour 0.03 parts per million (42 micrograms per cubic meter) Not to be exceeded over 2 times in any 5 consecutive days As specified in 10 CSR 10-6.040(5) 1/2-hour 0.05 parts per million (70 micrograms per cubic meter) Not to be exceeded over 2 times per year As specified in 10 CSR 10-6.040(5) Sulfuric acid State only 1-hour 30 micrograms per cubic meter Not to be exceeded more than once in any 2 consecutive days As specified in 10 CSR 10-6.040(6) 24-hour 10 micrograms per cubic meter Not to be exceeded more than once in any 90 consecutive days As specified in 10 CSR 10-6.040(6) *The 1978 lead standard remains in effect until one (1) year after an area is designated for the 2008 standard, except that in areas designated nonattainment for the 1978 standard, the 1978 standard remains in effect until implementation plans to attain or maintain the 2008 standard are approved. **The 1997 ozone standard remains in effect. ***The 1997 particulate matter 2.5 micron (PM2.5) standard remains in effect. ****The 1971 annual and 24-hour sulfur dioxide standards remain in effect in areas until one (1) year after the area is designated for the 2010 standard, except that for areas designated nonattainment for the 1971 standards as of August 23, 2010, and for areas not meeting the requirements of a SIP call under the 1971 standards, the 1971 standards remain in effect until the area submits and the EPA approves a SIP providing for attainment of the 2010 standard. AUTHORITY: section 643.050, RSMo Supp. 2013.* Original rule filed Aug. 16, 1977, effective Feb. 11, 1978. Amended: Filed Dec. 10, 1979, effective April 11, 1980. Amended: Filed Jan. 5, 1988, effective April 28, 1988. Amended: Filed July 6, 2005, effective Feb. 28, 2006. Amended: Filed Sept. 24, 2009, effective May 30, 2010. Amended: Filed Nov. 15, 2013, effective July 30, 2014. *Original authority: 643.050, RSMo 1965, amended 1972, 1992, 1993, 1995, 2011.