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Tabline-AQAir Quality Resource Center

Air Quality History

Significant Actions by US Environmental Protection Agency

Air Quality in the St. Louis Area
Gateway's Role in Air Pollution Control
Improvement in Air Quality
Ozone Formation

Ozone Health Effects
PM Formation
PM Health Effects
National Ambient Air Quality Standard

SIGNIFICANT ACTIONS BY U.S. ENVIRONMENTAL PROTECTION AGENCY

  • 1991 - St. Louis eight county region (MO-IL) designated as a moderate non-attainment 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 in attainment for the one-hour ozone standard (120 ppb)
     
  • 2004 - St. Louis eight county region (MO-IL) and Jersey County, IL, designated as a moderate non-attainment or 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 non-attainment or the 1997 annual fine particulate (PM 2.5) standard
     
  • 2008 - eight-hour ozone standard revised (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 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 standard
     
  • October 1, 2015 - eight-hour ozone standard revised (70 ppb)
     

AIR QUALITY IN THE ST. LOUIS AREA

In the eight county St. Louis area (Missouri-Illinois) overall air quality is better today than what it was at the beginning of the 20th century.  However, work still needs to be done to reduce man-made ozone. Over the past ten years, air quality in the St. Louis area has steadily improved due in large part to the implementation of the following control programs: improvement in motor vehicle technology; additional controls on industry and coal-fired power plants; centralized inspection of car emissions; the use of cleaner fuels throughout the region; and a range of transportation control measures (I .e., traffic flow improvement projects, intelligent transportation system and regional ridesharing program and implementation of a regional light-rail system).

In 2002, the St. Louis metropolitan area reached a significant air quality milestone. Based on 2000 -2002 air quality monitoring data, the region attained the one-hour ozone standard, as established by the U.S. Environmental Protection Agency (USEPA ). On May 12, 2003, USEPA redesignated the Missouri-Illinois area as in attainment of the one-hour ozone standard. This is a meaningful accomplishment that the Missouri Department of Natural Resources (MoDNR), the Illinois Environmental Protection Agency (IEPA),  local governments, the business community and environmental groups in the area have made. However, this is only one step on the road to cleaner air in the St. Louis area.

In June 2004, the USEPA Administrator designated those areas in the U.S. which are not in attainment of the eight-hour ozone standard set in 1997. The eight-hour ozone standard (80 parts per billion or ppb) was implemented nationally because it is a more protective health-based standard.  The St. Louis area was designated as a moderate non-attainment area. The non-attainment area include: in Missouri, Franklin, Jefferson, St. Charles and St. Louis Counties and the City of St. Louis; and in Illinois, Jersey, Madison, Monroe and St. Clair Counties. Under the one-hour ozone standard, Jersey County was a stand alone maintenance area.

Based on 2008-2010 monitoring data, the area met the 1997 eight-hour ozone standard demonstrating ongoing progress due to the continuing implementation of Missouri and Illinois control programs. Both Missouri and Illinois are have developed Maintenance Plans to show that the area has attained  this standard.  The Illinois Maintenance Plan lays out how the state will maintain the 1997 ozone standard for at least ten years.  On June 12, 2012, USEPA approved the request from Illinois to redesignate the Illinois portion of the St. Louis (MO-IL) area as in attainment of the 1997 eight-hour ozone standard and approved their maintenance plan.  On February 20, 2015, USEPA approved the request from Missouri to redesignate the Missouri counties as being in attainment of the 1997 standard and approved their maintenance plan .  the 1997 standard was revoked by USEPA on April 6, 2015.

In March 2008, after a lengthy review USEPA reset the primary and secondary standards for ozone at 75 ppb with an averaging time of eight hours.  To attain this standard, the three-year average of the annual fourth highest reading at particular monitor is less than or equal to 75 ppb.  Soon after in May 2008, a petition was filed in U.S. District Court stating that the 2008 ozone standard was not protective of public health and the environment.  In March 2009, the Court granted USEPA a stay of this litigation to allow USEPA time to review its options. During 2009-2011, USEPA re -examined the 2008 standard.  In September 2011, USEPA decided to retain the 2008 eight-hour ozone standard as is.  However, USEPA is continuing to review of this standard, as required by the Clean Air Act.  A new standard proposal is expected in early 2015.

In July 2012, USEPA designated the eight-county St. Louis area (MO-IL) as a marginal non-attainment area for the 2008 eight-hour ozone standard.  Jersey County was classified as attainment of this standard.  Being marginal (closest to attaining the standard), St. Louis has until December 31, 2015, to attain the 2008 eight-hour ozone standard.  USEPA has released a rule on State Implementation Plan requirements.

Based on 2013-2015 monitoring data, the St. Louis area has met the 2008 ozone standard.  In September 2016, Missouri submitted to EPA Region 7 both a request for the redesignation of the Missouri portion of the St. Louis ozone non-attainment area to attainment and a Maintenance Plan delineating steps for this area to continue to attain this standard.  These items are under review by EPA.  The Illinois Environmental Protection Agency (Illinois EPA) is also working on a redesignation to attainment request and a Maintenance Plan for the Illinois portion of the St. Louis non-attainment area for the 2008 ozone standard.

On October 1, 2015, EPA strengthened the eight-hour ozone standard, setting it at 70 ppb.  States are to submit recommendations on designations (attainment of standard, non-attainment or unclassifiable) and associated boundaries to EPA by October 1, 2016.  For the Metro-East, Illinois EPA expects to propose that Madison, Monroe and St. Clair Counties be in the ozone non-attainment area boundary.  It will be recommended that all other counties in Illinois be designated as attainment/ unclassifiable.  Illinois is expecting that EPA will designate the Metro-East as marginal non-attainment with a 2020 attainment date.  Missouri is recommending that Franklin, Jefferson, St. Charles and St. Louis Counties and the City of St. Louis be designated as non-attainment for the 2015 ozone standard.  For each of the remaining Missouri counties, unclassifiable/attainment is the recommendation. 

The boundary recommendations for each state are to then be submitted to EPA by October 1, 2016.  EPA will review the recommendations and propose their designations no later than June 2017 and finalize the designations by October 1, 2017. EPA will be looking at 2014-2016 ozone season data and design values for each monitor. 

In 2005 the USEPA Administrator designated the St. Louis area as not meeting the annual fine particle (less than 2.5 microns in diameter) standard set in 1997. The St. Louis fine particle matter (PM 2.5) non-attainment area consists of: Franklin, Jefferson, St. Charles and St. Louis Counties and the City of St. Louis in Missouri; and Madison, Monroe and St. Clair Counties and Baldwin Township in Randolph County, Illinois. USEPA published a final rule in May 2011 stating that the St. Louis PM2.5 non-attainment area had attained the 1997 annual standard based on 2007-2009 quality assured monitor data.  Missouri submitted its maintenance plan to USEPA in August 2011 which is now under review.  Illinois continues to work on its maintenance plan.  In 2009 USEPA found the St. Louis area was in attainment of the 2006 24-hour (daily) PM2.5 standard.

In December 2012, the annual PM2.5 standard was revised by USEPA.  Effective April 15, 2015, USEPA found that it could not determine, based on available data, whether the eight-county St. Louis region (MO-IL) and Baldwin Township in Randolph County, IL, met the 2012 annual PM2.5 standard or was contributing to a nearby violation.  USEPA has designated this area as "unclassifiable."  When the states have three full years of monitoring data (2015-2017), they can make a recommendation to USEPA for attainment or or on-attainment.
 

GATEWAY'S ROLE IN AIR POLLUTION CONTROL

Since the 1977 amendments to the Clean Air Act, the East-West Gateway Council of Governments has been the lead air quality and transportation planning agency for the St. Louis metropolitan region. Gateway's air quality planning efforts have focused on:

Working with the states of Missouri and Illinois on the St. Louis Air Quality Management Plan Pilot Project; Working with Missouri and Illinois on the development and implementation of Transportation Control Measures (TCMs). TCMs are physical improvements and management strategies designed to increase the use of mass transit, expand ridesharing and improve regional traffic flow which reduce hydrocarbons and carbon monoxide emissions from motor vehicles); Insuring that transportation programs and projects do not have a negative impact on air quality; and serving as a regional clearinghouse of daily measured ozone data during the April-October ozone season and helping to maintain quality control over monitored data.

OZONE FORMATION

Ozone exists in both the upper and lower atmosphere.  The ozone layer of the upper atmosphere (10-30 miles up) occurs naturally and shields the earth from harmful ultraviolet radiation.  However, the ozone layer of the lower atmosphere (ground-level ozone) is manmade and creates a variety of health problems.  This ozone is formed when hydrocarbons, also known as volatile organic compounds (VOC), and oxides of nitrogen (NOx) from car exhaust and certain emissions from industrial processes chemically react ,or "cook", with oxygen in the lower atmosphere in the presence of strong sunlight and high temperatures.  Weather plays an important role in ozone formation.  Days when ozone may form are indicated by high pressure weather systems with high temperatures (above 85o F) and low wind speeds.  Temperature inversions during the warm summer months can trap pollutants close to the ground, stopping them from dispersing during the night.  These weather systems are common in the St. Louis area during the months of May through early September.  Changing weather patterns (especially the number of hot, sunny days) and periods of air stagnation contribute to yearly differences in ozone concentrations. 

SOURCES OF VOC

Point - Large stationary sources (manufacturing sites, power plants
Area - Sources when viewed separately do not have large enough emissions to warrant individual tracking, but in the aggregate may contribute to emissions (dry cleaners, gas stations, printers, painting)
Mobile On-Road - Vehicles traveling on public roads
Mobile Off-Road - Aircraft, rail, marine vessels, farm and construction equipment, lawn and garden equipment and other such machinery

VOCs are emitted from a variety of sources including cars and trucks, chemical plants, oil refineries, factories, other industrial activities and consumer and commercial products such as paints and solvents.  These emissions occur as the result of incomplete combustion of fossil fuels and vapors escaping from volatile organic compounds.

NOx is primarily produced by the combustion of fossil fuels by motor vehicles and coal-fired power plants and other industrial utility operations.

OZONE HEALTH EFFECTS

In large doses, ozone can cause headaches, fatigue, shortness of breath, coughing, wheezing and eye, nose and respiratory tract irritation.  It impairs lung function and limits the ability to exercise, especially in the very young and the very old.  Prolonged exposure to ozone can aggravate chronic heart disease, chronic respiratory ailments, decrease resistance to infection and trigger asthma attacks.

PEOPLE SENSITIVE TO OZONE

    Children at Play Outdoors
    Adults Who Work Outdoors during the Summer Months
    People with Respiratory Disease
    Healthy People Who Exercise Outdoors
    The Elderly

When the air quality is poor, people should exercise indoors.  If they must exercise outdoors, the early morning and evening hours are best.  Those suffering from asthma or other respiratory ailments should stay indoors.   At the end of this section is a list of things individuals can do to improve air quality.
 

PM FORMATION

Particle matter (PM) is a mix of solid particles and liquid droplets suspended in the air.  Fine PM is considered to be less than or equal to 2.5 microns in diameter (about 1/30 the width of a human hair).  Fine PM is made up of a variety of components including acids, organic chemicals, metals, dirt, or dust particles.  Many manmade and natural sources emit PM directly or emit other pollutants which have a chemical reaction in the atmosphere to form PM.  Click to view 2009AnnualPMProjectionsFine PM can be emitted directly from the  combustion of fuel (power plants, motor vehicles, wood burning), fires and certain industrial activities.  Other fine particle pollution may be formed indirectly from the chemical change of gases, such as sulfur dioxide, nitrogen oxides and volatile organic compounds, in the air.  Fine PM can be formed when these gases react with sunlight and water vapor.  PM can affect human health and is a source of haze which reduces visibility.

PM HEALTH EFFECTS

Fine PM is able to penetrate and lodge in deep areas of the lungs.  Health effects include: irritation of the eyes; sore throat; coughing; chest tightness; and shortness of breath.  PM may also trigger asthma attacks.  People most at risk from exposure include those with asthma, heart or lung disease, children and the elderly.  Children and adults who are active outdoors may be at increased risk because during physical activity, people breathe faster and more heavily, taking more particles deeper into their lungs.

When air quality is poor, if your outdoors activity involves prolonged or heavy exertion, reduce your activity time or substitute another activity that involves less exertion.  Furthermore, attempt to plan outdoor activities for days when PM levels are low.

NATIONAL AMBIENT AIR QUALITY STANDARD

AQ Resource Center Table

One-Hour Ozone Standard

The one-hour National Ambient Air Quality Standard (NAAQS) for ozone was 120 ppb.  Based on 2000-2002 air quality monitoring data, the St. Louis metropolitan region attained the one-hour ozone standard. On May 12, 2003, the U.S. Environmental Protection Agency (USEPA) designated the area as in attainment of this standard and approved each State's Maintenance State Implementation Plans (SIP). Emissions reductions committed to in the Maintenance SIPs are to remain (no backsliding policy) so that the area can continue to attain the one-hour ozone standard through 2014 or until eight-hour ozone SIPs are approved by USEPA.  With the advent of the newer, more protective eight-hour standard, the one-hour standard was rescinded on June 15, 2005.

Air Quality Index Calendar - July 2012

Air Quality Index Calendar for July 2016

Eight-Hour Ozone Standard

In 1997 after a lengthy evaluation and review process, USEPA revised the NAAQS for ozone. The change was made to protect the public from adverse health effects resulting from longer periods of exposure to ozone. With the eight-hour ozone standard , a concentration-based measurement approach has replaced the current exceedance approach. An area will be considered to attain the eight-hour ozone standard when the three year average of the annual fourth highest daily maximum eight-hour ozone concentration as measured at each monitor is less than or equal to 80 ppb. It took until 2004 for all legal challenges to this standard to be resolved and to have the standard officially set in place.

In 2004 the USEPA Administrator classified the St. Louis area as not being in attainment of the 1997 eight-hour ozone standard and designated it as a "moderate" non-attainment area. The non-attainment area included: in Missouri, Franklin, Jefferson , St. Charles and St. Louis Counties and the City of St. Louis; and in Illinois, Jersey, Madison, Monroe and St. Clair Counties. Both Missouri and Illinois have prepared new eight-hour ozone SIPs. In  June 2011, USEPA found that the St. Louis non-attainment area had three years (2008-2010) of monitor data showing attainment of the 1997 standard.  USEPA reclassified the Illinois counties to maintenance in June 2012 (attaining the 1997 standard).  Missouri submitted a redesignation demonstration and maintenance plan to USEPA in April 2014, and the agency is awaiting EPA action on its plan.

To attain the eight-hour ozone standard, the three year average of the annual fourth highest daily maximum eight-hour ozone concentration as measured at each monitor has to be less than or equal to 80 ppb. Missouri and Illinois calculate eight-hour averages based on monitored data, track the four highest eight-hour averages per monitor during the ozone season and identify exceedances of the eight-hour standard. An exceedance is considered to occur whenever an eight-hour average of values from a monitor is calculated to be 85 ppb or greater on any day. Therefore, the number of exceedances is not a good indicator of whether a monitor will be in attainment.

In March 2008, after a lengthy review USEPA reset the primary and secondary standards for ozone at 75 ppb with an averaging time of eight hours.  To attain this standard, the three-year average of the annual fourth highest reading at particular monitor is less than or equal to 75 ppb.

Shortly after the 2008 revision was finalized, a consortium of environmental groups filed a petition in U.S. District Court stating that the ozone standard was not protective of public health and the environment.  In March 2009, the Court granted USEPA a stay of this litigation allowing USEPA to review its options.  During 2009-2011, USEPA reconsidered the 2008 standard.  In September 2011, the USEPA decided to retain the 2008 eight-hour ozone standard as is.  St. Louis was designated a "marginal"  non-attainment area under the 2008 standard.  The USEPA continued their review, as required by the Clean Air Act and strengthened the eight-hour ozone standard to 70 ppb on October 1, 2015.

PM 2.5 Standard

USEPA has a standard for large size or coarse particulate matter (PM10). In 1997, after a lengthy evaluation and review process, USEPA added a fine particulate (PM2.5) national standards. The change was made to protect the public from adverse health effects of particles less than 2.5 microns in diameter. The PM 2.5 standard is based on averaging air quality measurements both annually and on a 24-hour basis. The annual standard is 15 micrograms per cubic meter (ug/m3) and is met when the three-year average of the annual arithmetic mean is less than 15.05 (ug/m3). In 2005 the USEPA Administrator announced that the St. Louis area was not meeting the annual fine particle (less than 2.5 microns in diameter) standard. The St. Louis fine particle matter (PM2.5) non-attainment area consists of: Franklin, Jefferson, St. Charles and St. Louis Counties and the City of St. Louis in Missouri; and Madison, Monroe and St. Clair Counties and Baldwin Township in Randolph County, Illinois. USEPA published a final rule in May 2011 stating that the St. Louis PM2.5 non-attainment area had attained the 1997 annual standard based on 2007-2009 quality assured monitor data.  Missouri developed a redesignation/demonstration request and maintenance plan and submitted it to USEPA in August 2011.  Missouri has prepared a technical supplement for this plan which was approved by the Missouri Air Conservation Commission in March 2014.  This supplement is awaiting approval by USEPA.  Illinois continues to work on their maintenance plan for future submission.

In 2006 the 24-hour (daily) standard was set at 35 (ug/m3).  It is met whenever the three-year average of the annual 98th percentile of values at designated monitoring sites is less than or equal to 35 (ug/m3). In 2009 USEPA found the St. Louis area was in attainment of this standard.

On December 14, 2012, the USEPA Administrator finalized the federal rule revising the annual PM 2.5 standard from 15 ug/m3 to 12 ug/m3. Missouri and Illinois submitted their recommendations for non-attainment, unclassifiable or attainment of standard counties/areas in December 2013.  Effective April 15, 2015, USEPA found that it could not determine, based on available data, whether the eight county St. Louis region (MO-IL) near Baldwin Township, Randolph County, IL, met the 2012 annual standard or was contributing to a nearby violation.  USEPA has identified this area s "unclassifiable."  When Missouri and Illinois have three calendar years of monitor data (2015-2017), they each can make recommendation to USEPA about attainment or nonattainment.

 

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East-West Gateway Council of Governments
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last update:  Wednesday, April 12, 2017