Particulate Matter Fact Sheet
PM 2.5 General Information
PM2.5 Planning Efforts
PM10 and PM2.5 Attainment Fact Sheet
PM10 Redesignation Request and Limited Maintenance Plan for the City of New Haven
EPA's 2006 Proposed PM2.5 National Ambient Air Quality Standards
SIP Revisions and Other State Air Quality Plans
What is Particulate Matter?
- Particulate matter, or PM, is the term for particles found in the air, including dust, dirt, soot, smoke, and liquid droplets. Particles can be suspended in the air for long periods of time. Some particles are large or dark enough to be seen as soot or smoke. Others are so small that individually they can only be detected with an electron microscope (See Figure 1.)
- Some particles are directly emitted into the air (primary particulate matter). They come from a variety of sources such as cars, trucks, buses, factories, construction sites, tilled fields, unpaved roads, stone crushing, and burning of wood.
- Other particles may be formed in the air from the chemical change of gases (secondary particles). They are indirectly formed when gases from burning fuels react with sunlight and water vapor. These can result from fuel combustion in motor vehicles, at power plants, and in other industrial processes.
- According to the EPA (See EPA Particulate Matter), the size of particles is directly linked to their potential for causing health problems. Small particles less than 10 micrometers in diameters pose the greatest problems because they can get deep into your lungs, and some may even get into your bloodstream. Exposure to such particles can affect both your lungs and your heart.
- Small particles of concern include “fine particles” (such as those found in smoke and haze), which are 2.5 micrometers in diameter or less; and “coarse particles” (such as those found in wind-blown dust), which have diameters between 2.5 and 10 micrometers.
What are the Health Effects of Particulate Matter?(Also see EPA’s Health and Environmental Impacts of PM)
- Health studies have shown a significant association between exposure to fine particles and premature death.
- Other important effects include aggravation of respiratory and cardiovascular disease (as indicated by increased hospital admissions, emergency room visits, absences from school or work, and restricted activity days), lung disease, decreased lung function, asthma attacks, and certain cardiovascular problems such as heart attacks and irregular heartbeat.
- Individuals particularly sensitive to fine particle exposure include older adults, people with heart and lung disease, and children.
- Roughly one out of every three people in the United States is at a higher risk of experiencing fine particulate related health effects. One group at high risk is active children because they often spend a lot of time playing outdoors and their bodies are still developing. People of all ages who are active outdoors are at increased risk because, during physical activity, fine particulates penetrate deeper into the parts of the lungs that are more vulnerable to injury.
What are the Particulate Standards Promulgated by the EPA?
- The United States Environmental Protection Agency (EPA) first established National Ambient Air Quality Standards (NAAQS) for total suspended particulate matter (TSP) in 1971.
- The reference method specified for determining attainment of the original standards was the high-volume sampler, which collects TSP up to a nominal size of 25 to 45 micrometers (µm).
- EPA began to review the TSP standards for PM in October 1979. After a lengthy and elaborate process, EPA promulgated significant revisions of the original standards on July 1, 1987. In these revised standards, EPA changed the indicator for particles from TSP to PM10 , the latter referring to particles with a mean aerodynamic diameter less than or equal to 10µm.
- EPA also revised the level and form of the primary standard by defining the 24-hour PM10 standard as 150 µg/m3 with no more than one expected exceedance per year. Due to a lack of evidence linking health problems to long-term exposure to coarse particle pollution, EPA revoked the annual PM10 standard (previously set at 50 µg/m3, expected annual arithmetic mean) in 2006.
- The State of Connecticut Department of Energy and Environmental Protection (CT DEEP) has six PM10 monitoring sites operating in 2007 (See Figure 2). PM10 annual average concentrations in Connecticut since 1990 are shown in Figure 3.
- Connecticut is currently measuring attainment for both the 24-hour and the annual average NAAQS for PM10. See the PM10 and PM2.5 Attainment Fact Sheet for additional information on Connecticut’s PM10 attainment status.
- The EPA promulgated NAAQS for fine particulate matter, particles with a mean aerodynamic diameter less than or equal to 2.5 µm (PM2.5), on July 18, 1997. The annual average NAAQS for PM2.5 is 15 µg/m3 and the 24-hour average NAAQS is 35 µg/m3 (effective December 2006).
- CT DEEP designed a monitoring network and began PM2.5 monitoring in 1999.
- States were required to provide EPA with recommendations by February 15, 2004 for PM2.5 area attainment and nonattainment designations based on three years of monitored data.
- For the three-year period ending in 2004, all of the PM2.5 monitoring sites in Connecticut measured levels below the annual and 24-hour NAAQS, except for a monitoring site in New Haven. The Stiles Street site was found to be measuring very localized conditions that are not representative of population exposure in New Haven.
- The Stiles Street site is influenced by unique and highly localized factors (i.e. adjacent to an on-ramp for I-95 with high volumes of truck traffic) that result in elevated PM2.5 levels, as compared to nearby sites. EPA concurs with CT DEEP that this microscale site should not be used to determine compliance with the annual PM2.5 standard.
- CT DEEP has fourteen filter-based PM2.5 monitors operating in 2007. See Figure 4. Figure 5 shows the PM2.5 annual average concentrations since 1999, and Figure 6 shows the PM2.5 24-hour concentrations for 2003.
Air Quality Index (AQI) Forecasts for PM
- AQI is a tool that state and local agencies use to issue public alerts to actual levels of particle pollution or other common pollutants. See the EPA website for more information: Air Quality Index.
- CT DEEP issues daily air quality forecasts year-round for PM.
- Currently, CT DEEP has installed 5 “real-time” PM2.5 monitors around the State to aid in daily air quality forecasts. These are located in Bridgeport, New Haven, Waterbury, East Hartford and Cornwall.
- Whenever the average 24-hour PM2.5 concentration is expected to exceed a concentration of 35 µg/m3 (AQI=100), the air quality is forecast to be “Unhealthy for Sensitive Groups.”
- Whenever the average 24-hour PM2.5 concentration is expected to exceed a concentration of 55 µg/m3 (AQI=150), the air quality is forecast to be “Unhealthy.”
- The forecast is made available to the public on a daily basis in the following ways:
- 24-hour toll free Clean Air Hotline: 1-800-249-1234
- at the CTDEEP’s Air Quality Index webpage: CT Air Quality Web page
- Online at the US EPA’s AIRNOW website: EPA AirNow
Connecticut’s Attainment Designation for the 1997 PM2.5 NAAQS
- The CT DEEP’s technical review for the 1997 annual PM2.5 NAAQS concluded that the high annual average PM 2.5 concentrations at the Stiles Street site were the result of “microscale” effects. As outlined in EPA guidance, data from sites considered microscale should not be used to determine annual PM2.5 nonattainment status.
- In February 2004, Connecticut submitted documentation to show that the Connecticut portion of the New York City metropolitan area should not be included with the New York City nonattainment area and that the entire State of Connecticut should be designated as attainment for PM2.5. See: PM2.5 Technical Support Document.
- In June 2004, EPA informed CT DEEP that it was proposing to designate Fairfield and New Haven counties as nonattainment for PM2.5 as part of the New York City nonattainment area.
- In August 2004, CT DEEP supplied additional information to further support the recommendation that the entire State of Connecticut should be designated as in attainment for PM2.5. See: DEEP Response to Designations.
- EPA finalized designations on November 17, 2004. Both New Haven and Fairfield counties are now designated as nonattainment for PM2.5.
- The effective date of designations was February 2005.
- State implementation plans were due in April 2008. The implementation plan is required to include control measures sufficient to achieve compliance with the NAAQS by April 2010.
Connecticut’s Attainment Designation for the 2006 PM2.5 NAAQS
- Connecticut submitted recommendations for attainment designations and geographical boundaries for the revised 24-hour fine particle (PM2.5) National Ambient Air Quality Standard (NAAQS), which became effective on December 18, 2006. See: Recommended Designations for the 24-hour PM2.5 NAAQS (PDF, 2.82 MB).
- EPA responded to Connecticut's recommendations for the attainment boundaries on August 19th, 2008. EPA has concurred with Connecticut and EPA intends to designate New Haven and Fairfield Counties in Connecticut as nonattainment for the 24-hour PM2.5 NAAQS (National Ambient Air Quality Standard) as part of the New York City metropolitan nonattainment area, and the remaining counties in the state as "attainment/ unclassifiable". See: EPA Response to Connecticut's Recommendations (PDF, 2MB)
Content Last Updated on October 5, 2009