AIR QUALITY HISTORY

In the eight county St. Louis Metro area (Missouri-Illinois), overall air quality is better today than what it was at the beginning of the 20th century.

Over the past ten years, air quality in the Metro area has steadily improved as a result of improvements in motor vehicle technology, tighter controls on industry and coal-fired power plants, required emissions inspections, the use of cleaner fuels, efforts to improve traffic flow, the implementation of a regional light-rail system and efforts to encourage drivers to rideshare when possible.

*Below are some key historical Environmental Protection Agency milestones in the fight for cleaner air in our region:

1991 – St. Louis eight county region (MO-IL) designated as a moderate non-attainment area for the 1979 one-hour ozone standard (120 parts per billion or ppb)

1997 – Eight-hour ozone standard (80 ppb) established and annual fine particulate (PM 2.5) standard (15 microgams per cubic meter or ug/m3) established

2002 – St. Louis eight county region (MO-IL) designated as being in attainment for the one-hour ozone standard (120 ppb)

2004 – St. Louis eight county region (MO-IL) and Jersey County, IL, is designated as a moderate non-attainment area for the 1997 eight-hour ozone standard (80 ppb)

2005 – St. Louis eight county region (MO-IL) and Baldwin Township in Randolph County, IL, designated as being in non-attainment of the 1997 annual fine particulate (PM 2.5) standard

2008 – eight-hour ozone standard is revised to 75 ppb

2008-2011 – 2008 eight-hour ozone standard reconsidered

2009 – St. Louis eight county region (MO-IL) designated as in attainment for the 24-hour (daily) PM 2.5 standard

June 12, 2012 – Illinois portion of St. Louis region (including Jersey County) attained the 1997 eight-hour ozone standard (80 ppb)

July 2012 – St. Louis eight county region (MO-IL) designated as a marginal non-attainment area for the 2008 one-hour ozone standard (75 ppb)

December 14, 2012 – Annual fine particulate (PM 2.5) standard revised (12ug/m3)

February 20, 2015 – Missouri portion of St. louis region attained 1997 eight-hour ozone standard

April 15, 2015 – St. Louis eight county region (MO-IL) and Baldwin Township, Randolph County, IL, identified as “unclassifiable” for 2012 annual PM 2.5 standar

October 1, 2015 – eight-hour ozone standard is revised to 70 pp

*Source: East-West Gateway Council of Governments