Fine Particulate Matter (PM2.5) Information

Industrial and residential combustion and vehicle exhaust emit fine particles into the air.  These activities include burning oil, coal, wood, or residential waste.  Fine particles also form in the atmosphere when chemical reactions in the air transform gases such as sulfur dioxide, nitrogen oxides, and volatile organic compounds into microscopic solid or liquid particles.  Fine particles can affect the health of everyone but primarily affect children, elderly and individuals with asthma and cardiopulmonary disease.  Additional information regarding PM2.5 is available on the EPA's Particulate Matter webpage.

On Dec. 14, 2012, EPA revised the National Ambient Air Quality Standard (NAAQS) for PM2.5.  The previous standards for PM2.5 were promulgated in 1997 and 2006 and included an annual standard and a 24-hour standard.  The annual standard, which was set in 1997, was 15 micrograms per cubic meter (µg/m3), and the 24-hour standard, which was set in 2006, is 35 µg/m3.  The revised NAAQS finalized in December 2012 retained the 24-hour standard, but lowered the annual standard from 15 µg/m3 to 12 µg/m3.

Boundary Designation Recommendations for the 2012 PM2.5 Standard

With the revised standard, the first step in the implementation process is for EPA to designate all areas of the country either attainment/unclassifiable or nonattainment.  As part of this process, states are allowed to submit boundary designation recommendations to EPA to be considered when EPA establishes the final boundary designations.  The state's recommendations for area boundary designations under the 2012 annual PM2.5 NAAQS are available below:

2012 PM2.5 Boundary Recommendations

These boundary recommendations were submitted to EPA in December 2013.  If EPA intends to modify the state's recommendations when making the final designations, they must submit a letter to the state indicating the modifications they intend to make and give the state a chance to respond to the letter prior to the finalization of designations.  This is commonly referred to as the 120-day letter, and for the 2012 PM2.5 NAAQS, this letter is expected to be delivered to the state by Aug. 14, 2014.  EPA is anticipated to finalize designations by Dec. 12, 2014.

Information about past and present boundary designation processes for recently revised NAAQS are available on the NAAQS Boundary Designations webpage.

State Implementation Plan Development Process

After a new NAAQS is finalized, states have three years to develop an infrastructure State Implementation Plan that demonstrates the state’s ability to implement, maintain, and enforce the NAAQS.  Therefore, the infrastructure State Implementation Plan for the newly revised PM2.5 NAAQS will be due to EPA in December 2015.

If any area of the state is ultimately designated nonattainment under the 2012 PM2.5 NAAQS, then several nonattainment State Implementation Plan elements will be required to be developed for such areas to demonstrate the state’s plan to improve air quality and come into compliance with the NAAQS.

As new State Implementation Plan elements are released for public notice, they will be available for public review and comment online on the State Plans on Public Notice webpage. 

For information regarding past State Implementation Plan submittals addressing particulate matter, including State Implementation Plans submitted to address the 1997 and 2006 PM2.5 NAAQS, click the link below.

Particulate Matter State Implementation Plan

PM2.5 Special Monitoring Plans

PM2.5 includes all airborne particles with aerodynamic diameters less than or equal to 2.5 micrometers (about 1/50th the width of a human hair).  Therefore, the range of particles that make up PM2.5 concentrations in the ambient air is vast.   PM2.5 can include several different categories of pollutants to make up the full PM2.5 concentration, including but not limited to, sulfates, nitrates, organic carbon, elemental carbon, and crustal material.  Additionally, PM2.5 concentrations are impacted both at the regional and local level.  Some pollutants act as precursors to PM2.5 and can either chemically react or condense to form PM2.5 miles from the original source of the pollution, while other pollutants are considered direct PM2.5 emissions and immediately contribute to PM2.5 concentrations as soon as they are emitted.  In the past the Air Program and other groups have used special purpose monitors to determine the various species that comprise PM2.5 concentrations in the St. Louis area in an effort to better understand the composition of PM2.5 in the area and the impact of regional vs. local sources that contribute to PM2.5 concentrations in the area.  Two of these past special purpose monitoring plans are listed below.  For information regarding daily PM2.5 concentration levels at our currently operating monitors visit the Environmental Services Program webpage.

Air Quality Forecast Links

St. Louis and Kansas City have systems in place to inform the public about the level of air pollution in those areas each day.  EPA also maintains a website to give air quality forecasts for every area in the country.  The information is given to encourage the public to take steps to reduce air pollution on days when air pollution concentrations are forecasted to be above acceptable levels, and to alert the public and offer suggestions for limiting exposure time outdoors during periods of high air pollution potential.  The websites below provide the air quality forecasts for St. Louis and Kansas City, respectively.  For information about air quality forecasts for all areas of the county visit the federal AIRNow webpage.

PM Health Effects

Particle exposure can lead to a variety of health effects. For example, numerous studies link particle levels to increased hospital admissions and emergency room visits, and even to death from heart or lung diseases. Both long- and short-term particle exposures have been linked to health problems.

Long-term PM Exposures

Exposure experienced by people living for many years in areas with high particle levels is considered long-term. This length of exposure has been associated with problems such as reduced lung functioning and the development of chronic bronchitis and even premature death.

Short-term PM Exposures

Exposure to particles for several hours or several days can aggravate lung disease, causing asthma attacks and acute bronchitis, and may also increase susceptibility to respiratory infections. To those with heart disease, short-term exposures have been linked to heart attacks and arrhythmias.

Other Helpful Links