http://www.epa.gov/oar/particlepollution/naaqsrev2006.html
Background
Particle pollution, also called particulate matter or PM, is a complex mixture of extremely small particles and liquid droplets in the air. When breathed in, these particles can reach the deepest regions of the lungs. Exposure to particle pollution is linked to a variety of significant health problems, ranging from aggravated asthma to premature death in people with heart and lung disease. Particle pollution also is the main cause of visibility impairment in the nation’s cities and national parks.
To protect public health and welfare, EPA issues National Ambient Air Quality Standards (NAAQS) for six criteria pollutants, particulate matter is one of these. EPA first issued standards for particulate matter in 1971; and revised the standards in 1987 and 1997. In September 2006, the Agency revised the 1997 standards.
The revised 2006 standards address two categories of particle pollution: fine particles(PM2.5), which are 2.5 micrometers in diameter and smaller; and inhalable coarse particles (PM10) which are smaller than 10 micrometers and larger than 2.5 micrometers.
The 2006 standards tighten the 24-hour fine particle standard from 65 micrograms per cubic meter (µg/m3) to 35 µg/m3, and retain the current annual fine particle standard at 15 µg/m3.
EPA has decided to retain the existing 24-hour PM10 standard of 150 µg/m3. Due to a lack of evidence linking health problems to long-term exposure to coarse particle pollution, the Agency has revoked the annual PM10 standard.
The Agency selected the levels for the final standards after reviewing thousands of peer-reviewed scientific studies about the effects of particle pollution on public health and welfare. External scientific advisors and the public examined EPA’s science and policy review documents. The Agency also carefully considered public comments on the proposed standards. EPA held three public hearings and received over 120,000 written comments.
While EPA provisionally assessed new, peer-reviewed studies about particulate matter and health (including some studies received during the comment period), these studies were not the basis for the final decision. EPA will consider those studies during the next review of the PM standards. Learn more about the process of reviewing air quality standards.
What do the New Standards Mean for Your Area?
In 2004, several areas in the United States were designated as not meeting the 1997 air quality standards for fine particulate matter (PM2.5). See if your area was designated as not meeting the 1997 standards.
In 2006, EPA strengthened the air quality standards for particle pollution. The Agency expects designations based on 2007-2009 air quality data to take effect in 2010.
Maps
- Graph and Maps (10/25/06) (PDF, 10 pp, 1.2 MB)
Timeline
| Milestone | 1997 PM2.5 Primary NAAQS | 2006 PM2.5 Primary NAAQS |
| Promulgation of Standard | July 1997 | Sep. 2006 |
| Effective Date of Standard | Sep. 1997 | Dec. 18, 2006 |
| State Recommendations to EPA | Feb. 2004 (based on 2001-2003 monitoring data) |
Dec. 18, 2007 (based on 2004-2006 monitoring data) |
| Final Designations Signature | Dec. 2004 | October 8, 2009 |
| Effective Date of Designations | April 2005 | 30 days after publication in the Federal Register |
| SIPs Due | April 2008 | 3 years after effective date of designations |
| Attainment Date | April 2010 (based on 2007-2009 monitoring data) |
No later than 5 years after effective date of designations |
| Attainment Date with Extension | Up to April 2015 | No later than 10 years from effective date of designations |
PM Implementation – Programs and Requirements for Reducing Particle Pollution
Announcements
April 21, 2011 – Draft Energy Efficiency / Renewable Energy manual available for comment
The Clean Air Act requires EPA to set National Ambient Air Quality Standards (NAAQS) for six criteria pollutants; particle pollution (also known as particulate matter) is one of these. EPA works with partners at state, local, and tribal air quality agencies to meet these standards.
Under the Clean Air Act (CAA), as amended in 1990, each state must develop a plan describing how it will attain and maintain the NAAQS. In other words, how it plans to clean up polluted areas and keep them clean. This plan is called the State Implementation Plan (SIP) and is required under Section 110 of the CAA (40 CFR Part 51, Subparts F & G). In general, the SIP is a collection of programs, including:
- a monitoring program, which is a collection of monitoring devices throughout the country which provide actual measurements of the concentrations in the air, to identify whether an area is meeting the air quality standards, and if not, how much reductions are needed to meet those standards;
- air quality calculations and computer modeling, which are used to predict future trends and the effects of emissions reduction strategies;
- emissions inventories, which describe the sources and categories of emissions to the air for a given pollutant, and how much is emitted by each source or source category;
- control strategy studies whose goal is finding the best way to reduce emissions in order to meet air quality standards;
- formal adoption of measures (enforceable by EPA, States and citizens) which ensure that we will achieve the reductions deemed necessary in the planning process;
- periodic review to evaluate whether those needed reductions were achieved in reality, and whether they had the predicted result.
The air quality agency responsible for the State Implementation Plan, (usually a state agency) must provide the public an opportunity to review the plan before sending it to EPA for approval.
In cases where the EPA fails to approve a state implementation plan, the Agency can issue and enforce a Federal Implementation Plan (FIP) to ensure attainment and maintenance of the NAAQS. In addition, the Clean Air Act contains penalties, referred to as “sanctions” which EPA can impose in areas not satisfying the State Implementation Plan requirements.
More information
PM Air Quality Standards (NAAQS) – find out what air quality levels are used to define “clean air” for particles under the Federal Clean Air Act
Particulate Matter Designations – find out if a geographic area you are interested in meets clean air standards for particle pollution
Regulatory Actions – find EPA regulations detailing the requirements for State Implementation plans for particle pollution, and fact sheets and summaries of those regulations
Controlling Particle Pollution – find information, and links to information, on work that is underway to reduce particles in the air, both by reducing directly emitted particles, and by reducing emissions of pollutants that are gases when emitted, but which form particles in the atmosphere.
Links to State Web Sites – State web sites with helpful information to meet the 1997 PM 2.National Ambient Air Quality Standards (NAAQS)
The Clean Air Act, which was last amended in 1990, requires EPA to set National Ambient Air Quality Standards (40 CFR part 50) for pollutants considered harmful to public health and the environment. The Clean Air Act established two types of national air quality standards. Primary standards set limits to protect public health, including the health of “sensitive” populations such as asthmatics, children, and the elderly. Secondary standardsset limits to protect public welfare, including protection against decreased visibility, damage to animals, crops, vegetation, and buildings.
The EPA Office of Air Quality Planning and Standards (OAQPS) has set National Ambient Air Quality Standards for six principal pollutants, which are called “criteria” pollutants. They are listed below. Units of measure for the standards are parts per million (ppm) by volume, parts per billion (ppb – 1 part in 1,000,000,000) by volume, milligrams per cubic meter of air (mg/m3), and micrograms per cubic meter of air (µg/m3).
National Ambient Air Quality Standards
| Primary Standards | Secondary Standards | |||
| Pollutant | Level | Averaging Time | Level | Averaging Time |
| Carbon Monoxide |
9 ppm (10 mg/m3) |
8-hour (1) | None | |
| 35 ppm (40 mg/m3) |
1-hour (1) | |||
| Lead | 0.15 µg/m3 (2) | Rolling 3-Month Average | Same as Primary | |
| Nitrogen Dioxide |
53 ppb (3) | Annual (Arithmetic Average) |
Same as Primary | |
| 100 ppb | 1-hour (4) | None | ||
| Particulate Matter (PM10) |
150 µg/m3 | 24-hour (5) | Same as Primary | |
| Particulate Matter (PM2.5) |
15.0 µg/m3 | Annual (6) (Arithmetic Average) |
Same as Primary | |
| 35 µg/m3 | 24-hour (7) | Same as Primary | ||
| Ozone | 0.075 ppm (2008 std) |
8-hour (8) | Same as Primary | |
| 0.08 ppm (1997 std) |
8-hour (9) | Same as Primary | ||
| 0.12 ppm | 1-hour (10) | Same as Primary | ||
| Sulfur Dioxide |
0.03 ppm (11) (1971 std) |
Annual (Arithmetic Average) |
0.5 ppm | 3-hour (1) |
| 0.14 ppm (11) (1971 std) |
24-hour (1) | |||
| 75 ppb (12) | 1-hour | None | ||
(1) Not to be exceeded more than once per year.
(2)Final rule signed October 15, 2008. The 1978 lead standard (1.5 µg/m3 as a quarterly average) remains in effect until one 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.
(3) The official level of the annual NO2 standard is 0.053 ppm, equal to 53 ppb, which is shown here for the purpose of clearer comparison to the 1-hour standard
(4) To attain this standard, the 3-year average of the 98th percentile of the daily maximum 1-hour average at each monitor within an area must not exceed 100 ppb (effective January 22, 2010).
(5) Not to be exceeded more than once per year on average over 3 years.
(6) To attain this standard, the 3-year average of the weighted annual mean PM2.5 concentrations from single or multiple community-oriented monitors must not exceed 15.0 µg/m3.
(7) To attain this standard, the 3-year average of the 98th percentile of 24-hour concentrations at each population-oriented monitor within an area must not exceed 35 µg/m3 (effective December 17, 2006).
(8) To attain this standard, the 3-year average of the fourth-highest daily maximum 8-hour average ozone concentrations measured at each monitor within an area over each year must not exceed 0.075 ppm. (effective May 27, 2008)
(9) (a) To attain this standard, the 3-year average of the fourth-highest daily maximum 8-hour average ozone concentrations measured at each monitor within an area over each year must not exceed 0.08 ppm.
(b) The 1997 standard—and the implementation rules for that standard—will remain in place for implementation purposes as EPA undertakes rulemaking to address the transition from the 1997 ozone standard to the 2008 ozone standard.
(c) EPA is in the process of reconsidering these standards (set in March 2008).
(10) (a) EPA revoked the 1-hour ozone standard in all areas, although some areas have continuing obligations under that standard (“anti-backsliding”).
(b) The standard is attained when the expected number of days per calendar year with maximum hourly average concentrations above 0.12 ppm is < 1.
(11) The 1971 sulfur dioxide standards remain in effect until one year after an area is designated for the 2010 standard, except that in areas designated nonattainment for the 1971 standards, the 1971 standards remain in effect until implementation plans to attain or maintain the 2010 standards are approved.
(12) Final rule signed June 2, 2010. To attain this standard, the 3-year average of the 99th percentile of the daily maximum 1-hour average at each monitor within an area must not exceed 75 ppb.
5 NAAQS.