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EPA Administrator Carol Browner to Sign Ozone (Smog) and Particulate (Soot) Air Quality Standards

Release Date: 07/16/97
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Attached is a fact sheet on the ozone (smog) and particulate (soot) air quality standards to be signed today by EPA Administrator Carol M. Browner.

R-103 ###

July 1997

Fact Sheet


Introduction

The Clean Air Act directs EPA to identify and set national ambient air quality standards for pollutants that cause adverse effects to public health and the environment. EPA has set national air quality standards for six common air pollutants---ground-level ozone (smog), carbon monoxide, lead, nitrogen dioxide, sulfur dioxide, and particulate matter (measured as PM₁₀ and PM_2.5.)

For each of these six pollutants, EPA has set health-based or "primary" standards to protect public health, and welfare-based or "secondary" standards to protect the environment (crops, vegetation, wildlife, buildings and national monuments, visibility, etc).

EPA is required by the Clean Air Act to review the health and welfare-based standards at least once every five years to determine whether revisions to the standards are necessary to continue to protect public health and the environment.

How Does the National Ambient Air Quality Standard Review Process Work?

EPA undertakes an extensive scientific and technical assessment process during the standard review for any pollutant. The first step in the process is the preporation of the Agency's "criteria document," an extensive assessment of scientific data pertaining to the health and environmental effects associated with the pollutant under review.

EPA then prepares a document (known as a "staff paper") that interprets the most relevant information in the "criteria document" and identifies 1) factors EPA staff believes should be considered in the standard review; 2) uncertainties in the scientific data; and 3) ranges of alternative standards the staff believes should be considered. The "staff paper" is compiled by technical staff to assess the policy implications of the science. It represents the views of the staff and, in final form, is ultimately used as the basis for staff recommendations to the EPA Administrator.

Drafts of both the "criteria document" and the "staff paper," which are based on thousands of peer-reviewed scientific studies, receive extensive review by representatives of the scientific community, industry, public interest groups and the public, as well as the Clean Air Scientific Advisory Committee (CASAC)---a Congressionally mandated group of independent scientific and technical experts.

As part of its mandate, CASAC also makes recommendations to EPA on the adequacy of the standards. Based on the scientific assessments and taking into account the recommendations of CASAC, the EPA Administrator must judge whether or not proposing revisions to the standards is appropriate.

Before making a decision, the EPA Administrator goes through an extensive public review and comment process. EPA reviews and extensively analyzes issues raised in public comments before announcing a final decision. As with every proposed and final rule, all other relevant federal agencies are given the opportunity to participate in the process.

Since 1980, EPA has completed reviews of six national ambient air quality standards. Only one of those reviews resulted in a revised standard.

What are the Current National Ambient Air Quality Standards?

EPA has completed its reviews of the national air quality standards for ozone and particulate matter. The Administrator signed both the new particulate and ozone standards in July 1997.

As a result of this review, EPA is phasing out and replacing the previous 1-hour primary ozone standard (health-based) with a new 8-hour standard to protect against longer exposure periods. In establishing the 8-hour standard, EPA is setting the standard at 0.08 parts per million (ppm) and defines the new standard as a "concentration-based" form, specifically the 3-year average of the annual 4th-highest daily maximum 8-hour ozone concentration. The standards were last revised in 1979.

EPA is also revising the primary (health-based) PM standards by adding a new annual PM_2.5 standard set at 15 micrograms per cubic meter (µg/m³⁾ and a new 24-hour PM_2.5 standard set at 65 µg/m³. EPA is retaining the annual PM₁₀ standard of 50 µg/m³ and adjusting the PM₁₀ 24-hour standard of 150 µg/m³ by changing the form of the standard.

The health-based standard for lead was last revised in 1978 and is set at 1.5 micrograms per cubic meter (µg/m³), averaged over a calendar quarter (once every three months). The secondary standard for lead is the same as the primary standard.

There are two health-based standards for carbon monoxide---an 8-hour standard set at 9 ppm and a 1-hour standard set at 35 ppm. Both standards are not to be exceeded more than once per year. EPA announced its decision to retain the current standards for carbon monoxide in 1994. There is no secondary standard for carbon monoxide.

EPA proposed to retain the current national standards for nitrogen dioxide in 1995. The primary and secondary standards for nitrogen dioxide are both set a 0.053 ppm, measured as an annual average. EPA issued its final decision on the nitrogen dioxide standards in October 1996.

EPA announced its final decision to retain the current health-based standards for sulfur dioxide in May 1996. The two primary standards are set at 0.14 ppm, 24-hour average and 0.030 ppm, averaged annually. The 24-hour standard may not be exceeded more than once per year and the annual standard is never to be exceeded. In January 1997, EPA proposed a new program to address the potential health risks posed to asthmatics by short-term peak levels of sulfur dioxide in localized situations. EPA retained the secondary standard for sulfur dioxide in 1993, which is set at 0.50 ppm, averaged over a three-hour period. The secondary standard may not be exceeded more than once per year.

July 17, 1997


Today's Action

Today the EPA announces new national ambient air quality standards (NAAQS) for ground-level ozone, the primary constituent of smog. After a lengthy scientific review process, including extensive external scientific review, EPA has determined that these changes are necessary to protect public health and the environment.

EPA is phasing out and replacing the previous 1-hour primary ozone standard (health-based) with a new 8-hour standard to protect against longer exposure periods.

In establishing the 8-hour standard, EPA is setting the standard at 0.08 parts per million (ppm) and defines the new standard as a "concentration-based" form, specifically the 3-year average of the annual 4th-highest daily maximum 8-hour ozone concentrations.

EPA also replaces the previous secondary standard (to protect the environment, including agricultural crops, national parks, and forests) with a standard identical to the new primary standard.

The 0.12 ppm 1-hour standard will not be revoked in a given area until that area has achieved 3 consecutive years of air quality data meeting the 1-hour standard. The purpose of retaining the current 1-hour standard is to ensure a smooth, legal, and practical transition to the new standard.

Background

Scientific Assessment Process for National Ambient Air Quality Standards

When EPA reviews a national ambient air quality standard, such as ozone, it develops a "criteria document" that represents a compilation and scientific assessment of all the health and welfare information available for that pollutant.

EPA also develops a "staff paper" compiled by technical staff to help translate the science into terms that can be used in making policy decisions. It represents staff interpretations of the information in the "criteria document" and it makes recommendations to the EPA Administrator on any revisions needed to the standards to protect public health and welfare.

Both the "criteria document" and "staff paper" are part of an extensive scientific assessment process that includes an extremely rigorous scientific peer review and public comment process. Before these documents become the basis for any policy decisions, they undergo repeated, detailed reviews by the scientific community, industry, public interest groups, the general public, and the Clean Air Scientific Advisory Committee -- a Congressionally mandated group of independent scientific and technical experts. As part of its mandate, the Clean Air Scientific Advisory Committee also makes recommendations to EPA on the adequacy of the standards.

Based on the scientific assessments and taking into account the recommendations of the Clean Air Scientific Advisory Committee, the EPA Administrator must judge whether it is appropriate to propose revisions to standards.

Scientific Review of the Ozone Standard

The ozone standard, when it was last revised in 1979, was set at 0.12 ppm for 1 hour and was expressed as a "1-expected-exceedance" form. Critics have charged that this form of standard could cause areas to "flip-flop" in and out of attainment based on relatively minor ozone exceedances due to variability in meteorological conditions.

Since the late 1980's, more than 3,000 new studies have been published on the health and ecological effects of ozone, as well as on ozone monitoring and ambient air quality levels. Many new health studies show that health effects occur at levels lower than the previous standard and that exposure times longer than one hour (reflected in the previous standard) are of concern.

EPA completed its last extensive assessment of the scientific information for ozone in May 1989, and reaffirmed the existing standard in March 1993.

On February 3, 1994, EPA published in the Federal Register an accelerated schedule outlining the steps it intended to take (issue draft "criteria document,” hold meetings of the Clean Air Scientific Advisory Committee, etc.) to ensure a comprehensive assessment of these new studies. The schedule called for EPA to make a final decision on whether to revise the ozone standards by mid-1997.

The Clean Air Scientific Advisory Committee reviewed the "criteria document" at meetings in July 1994 and March 1995, and reviewed a final draft in September 1995. Based on comments from the public and the Clean Air Scientific Advisory Committee, EPA revised the "criteria document." In July 1996, EPA completed and made public its final "criteria document."

EPA submitted drafts of the "staff paper" at public meetings of the Clean Air Act Scientific Advisory Committee held in March 1995, September 1995, and March 1996. Based on comments from the public and the Clean Air Scientific Advisory Committee, EPA revised the "staff paper." In June 1996, EPA completed and made public its final "staff paper."

The Clean Air Scientific Advisory Committee sent closure letters to EPA on both the "criteria document" and "staff paper" concluding that these documents provided an adequate basis for the Administrator to make a decision about revisions to the primary and secondary ozone standards.

On June 12, 1996, EPA issued an advanced notice of proposed rulemaking on ozone and particulate matter standards. The Agency announced that the schedule for both reviews was the same, explained the linkages between the two air pollutants, and gave advance notice of key issues. In addition, EPA held public meetings in St. Louis and Philadelphia on the health and environmental effects associated with ozone and particulate matter and on the implementation of possible revised standards.

On December 13, 1996, EPA published a proposal to revise the ozone standard. EPA asked for public comment on a proposed standard set at 0.08 ppm, based on the 3-year average of the annual 3rd-highest daily maximum 8-hour ozone concentrations. The Agency also solicited comments on alternative standards at the 0.07 and 0.09 ppm levels and on alternative concentration-based forms.

In January 1997, EPA held public hearings on the proposed standards in Salt Lake City, Chicago, Boston and Durham, NC.

In addition to traditional methods of soliciting public comment, EPA set up email addresses and toll-free phone number to encourage extensive public participation and input into the process. EPA received more than 50,000 comments on the ozone standards.

The Agency carefully reviewed and analyzed these comments before reaching its final decision on the standards.

What are the Ozone Effects of Concern?

Based on recent studies, the scientific review highlighted several health effects for which the previous ozone standard did not provide adequate protection.

Exposure to ambient ozone concentrations has been linked to increased hospital admissions for respiratory aliments, such as asthma. Studies conducted in the northeastern United States and Canada show that ozone air pollution is associated with 10-20 percent of all of the summertime respiratory-related hospital admissions. Repeated exposure to ozone can make people more susceptible to respiratory infection and lung inflammation, and can aggravate preexisting respiratory diseases, such as asthma.

Children are most at risk from exposure to ozone because they are active outside, playing and exercising, during the summertime when ozone levels are at their highest. For example, summer camp studies in the eastern U.S. and southeastern Canada have reported significant reductions in lung function in children active outdoors. Adults who are outdoors and moderately active during the summer months, such as construction workers and other outdoor workers, are also among those most at risk. These individuals, as well as those with respiratory illnesses, such as asthma, can experience a reduction in lung function and increased respiratory symptoms, such as chest pain and cough, when exposed to relatively low ozone levels during periods of moderate exertion.

Long-term exposures to ozone can cause repeated inflammation of the lung, impairment of lung defense mechanisms, and irreversible changes in lung structure, which could lead to premature aging of the lungs and/or chronic respiratory illnesses such as emphysema and chronic bronchitis.

The scientific review also highlighted concerns associated with ozone effects on vegetation for which the previous ozone standard did not provide adequate protection. These include reduction in agricultural and commercial forest yields, reduced growth and decreased survivability of tree seedlings, increased tree and plant susceptibility to disease, pests, and other environmental stresses, and potential long-term effects on forests and ecosystems.

Summary of the Final Rule

Primary Standard

EPA concluded that the 1-hour primary standard did not adequately protect the public from adverse health effects. Therefore, EPA replaces the previous standard with an 8-hour standard set at 0.08 ppm; an area will attain the standard when the 3-year average of the annual 4th-highest daily maximum 8-hour concentrations is below 0.08 ppm.

As the Clean Air Scientific Advisory Committee unanimously recommended, EPA is changing the ozone standard averaging time to 8-hours. Although 1- to 3-hour and 6- to 8-hour ozone exposures can be addressed through 1-hour or 8-hour standards, the 8-hour standard is more directly associated with the health effects of most concern cited in recent 6- to 8-hour exposure studies. These studies were conducted at more typical exercise levels and at lower exposure levels (0.08 ppm) than the 1-hour studies.

EPA is changing the form of the standard from an expected-exceedance form to a concentration-based form because it more directly relates to ozone concentrations associated with health effects; it avoids exceedances, regardless of size, from being counted equally in the attainment tests.

In November 1996, EPA proposed that the annual 3rd-highest daily maximum 8-hour concentrations, averaged over 3 years, be the basis to determine whether or not an area was in attainment with the standards. After carefully examining public comment on the issue, EPA changed the form of the standard from the annual 3rd- to 4th- highest daily maximum concentration. This form will provide greater stability in the designation of areas, consistent with providing strong public health protections.

In setting the 8-hour standard at 0.08 ppm, the EPA recognizes that since there is no discernible threshold below which no adverse health effects occur, no level would eliminate all risk. Thus, a zero-risk standard is not possible, nor is it required by the Clean Air Act. The selected 0.08 ppm level is based on the judgment that at this level public health will be protected with an adequate margin of safety.

The new 8-hour standard will become effective 60 days after promulgation, while the existing 1-hour standard, for most purposes, will remain in effect until EPA determines that an area has air quality meeting the 1-hour standard.

EPA will continue to use conventional rounding when assessing monitoring data.

Secondary Standard

EPA believes attainment of the new primary standard will substantially protect vegetation. Therefore, EPA is setting the secondary standard identical to the primary standard. Although the Agency is not setting a separate seasonal secondary standard at this time, the Agency is committed to enhancing rural ozone monitoring, working in conjunction with other federal agencies, and considering long-term cumulative effects of ozone on plants as additional information becomes available.

For more information

Anyone with a computer and a modem can download the new standard and this fact sheet from the Clean Air Act Amendments bulletin board of EPA's electronic Technology Transfer Network (TTN) by calling (919) 541-5742 (look under "Recently Signed Rules"). For further information about how to access the board, call (919) 541-5384. The TTN can also be accessed through EPA's homepage on the Internet. The address is: http://ttnwww.rtpnc.epa.gov

For technical questions about this rule, contact Dr. David McKee at EPA's Office of Air Quality Planning and Standards at (919) 541-5288.

July 1997

FACT SHEET



Why are We Concerned about Ground-Level Ozone?

_Ozone is the prime ingredient of smog in our cities and other areas of the country. Though it occurs naturally in the stratosphere to provide a protective layer high above the earth, at ground-level it is the prime ingredient of smog.

_When inhaled, even at very low levels, ozone can:

_cause acute respiratory problems;
_aggravate asthma;
_cause significant temporary decreases in lung capacity of 15 to over 20 percent in some healthy adults;
_cause inflammation of lung tissue;
_lead to hospital admissions and emergency room visits [10 to 20 percent of all summertime respiratory-related hospital visits in the northeastern U.S. are associated with ozone pollution]; and
_impair the body's immune system defenses, making people more susceptible to respiratory illnesses, including bronchitis and pneumonia.

Who is Most at Risk from Exposure to Ground-Level Ozone?

_Children are most at risk from exposure to ozone:

_The average adult breathes 13,000 liters of air per day. Children breathe even more air per pound of body weight than adults.

_Because children's respiratory systems are still developing, they are more susceptible than adults to environmental threats.

_Ground-level ozone is a summertime problem. Children are outside playing and exercising during the summer months at summer camps, playgrounds, neighborhood parks and in backyards.

_Asthmatics and Asthmatic Children:

_Asthma is a growing threat to children and adults. Children make up 25 percent of the population and comprise 40 percent of the asthma cases.

_Fourteen Americans die every day from asthma, a rate three times greater than just 20 years ago. African-Americans die at a rate six times that of Caucasians.

_For asthmatics having an attack, the pathways of the lungs become so narrow that breathing becomes akin to sucking a thick milk shake through a straw.

_Ozone can aggravate asthma, causing more asthma attacks, increased use of medication, more medical treatment and more visits to hospital emergency clinics.

_Healthy Adults:

_Even moderately exercising healthy adults can experience 15 to over 20 percent reductions in lung function from exposure to low levels of ozone over several hours.

_Damage to lung tissue may be caused by repeated exposures to ozone --something like repeated sunburns of the lungs -- and this could result in a reduced quality of life as people age. Results of animal studies indicate that repeated exposure to high levels of ozone for several months or more can produce permanent structural damage in the lungs.

_Among those most at risk to ozone are people who are outdoors and moderately exercising during the summer months. This includes construction workers and other outdoor workers.

How does Ground-Level Ozone Harm the Environment?

_Ground-level ozone interferes with the ability of plants to produce and store food, so that growth, reproduction and overall plant health are compromised.

_By weakening sensitive vegetation, ozone makes plants more susceptible to disease, pests, and environmental stresses.

_Ground-level ozone has been shown to reduce agricultural yields for many economically important crops (e.g., soybeans, kidney beans, wheat, cotton).

_The effects of ground-level ozone on long-lived species such as trees are believed to add up over many years so that whole forests or ecosystems can be affected. For example, ozone can adversely impact ecological functions such as water movement, mineral nutrient cycling, and habitats for various animal and plant species.

_Ground-level ozone can kill or damage leaves so that they fall off the plants too soon or become spotted or brown. These effects can significantly decrease the natural beauty of an area, such as in national parks and recreation areas.

_One of the key components of ozone, nitrogen oxides, contributes to fish kills and algae blooms in sensitive waterways, such as the Chesapeake Bay.

What Improvement Would Result from EPA's New Standards?

EPA's new ozone standards will provide increased protection beyond that provided by the previous standard from the following effects:

_Reduced risk of significant decreases (15% to over 20%) in children's lung functions (such as difficulty in breathing or shortness of breath), approximately 1 million fewer incidences each year, which can limit a healthy child's activities or result in increased medication use, or medical treatment, for children with asthma

_Reduced risk of moderate to severe respiratory symptoms in children, hundreds of thousands of fewer incidences each year of symptoms such as aggravated coughing and difficult or painful breathing

_Reduced risk of hospital admissions and emergency room visits for respiratory causes, thousands fewer admissions and visits for individuals with asthma

_Reduced risks of more frequent childhood illnesses and more subtle effects such as repeated inflammation of the lung, impairment of the lung's natural defense mechanisms, increased susceptibility to respiratory infection, and irreversible changes in lung structure. Such risks can lead to chronic respiratory illnesses such as emphysema and chronic bronchitis later in life and/or premature aging of the lungs

_Reduce the yield loss of major agricultural crops, such as soybeans and wheat, and commercial forests by almost $500,000,000.

Background: What is Ground-level Ozone?

_Ozone is not emitted directly into the air, but is formed by gases called nitrogen oxides (NOx) and volatile organic compounds (VOCs) that in the presence of heat and sunlight react to form ozone. Ground-level ozone forms readily in the atmosphere, usually during hot weather.

_NOx is emitted from motor vehicles, power plants and other sources of combustion. VOCs are emitted from a variety of sources, including motor vehicles, chemical plants, refineries, factories, consumer and commercial products, and other industrial sources.

_Changing weather patterns contribute to yearly differences in ozone concentrations from city to city. Also, ozone and the pollutants that cause ozone can be carried to an area from pollution sources located hundreds of miles upwind.

July 1997 FACT SHEET




Today’s Action:

_Today the Environmental Protection Agency announces new standards for particulate matter (PM) under the national ambient air quality standards (NAAQS). After reviewing hundreds of peer-reviewed scientific studies, the EPA has determined that these changes are necessary to protect public health and the environment.

_EPA is revising the primary (health-based) PM standards by adding a new annual PM_2.5 standard set at 15 micrograms per cubic meter (µg/m³⁾ and a new 24-hour PM_2.5 standard set at 65 µg/m³.

_EPA is retaining the current annual PM₁₀ standard of 50 µg/m³ and adjusting the PM₁₀ 24-hour standard of 150 µg/m³ by changing the form of the standard.

_EPA is revising the secondary (welfare-based) standards by making them identical to the primary standards. EPA believes that the PM_2.5 and PM₁₀ standards, combined with the Clean Air Act-required regional haze program, will provide protection against the major PM-related welfare effects, including visibility impairment, soiling and materials damage.

_EPA is issuing new rules related to PM monitoring requirements under the new standards. One rule addresses the monitoring network design needed for the new PM_2.5 standards. Other rules establish a new federal reference and equivalent methods for monitoring PM_2.5.

_Also, in a separate action, EPA is proposing rules to improve visibility by requiring states to develop programs to help reduce regional haze.

Background

Scientific Assessment Process for National Ambient Air Quality Standards

_When EPA reviews national ambient air quality standards for a pollutant such as PM, it develops a "criteria document" that represents a compilation and scientific assessment of all the health and environmental effects information available.

_EPA also develops a "staff paper" which is compiled by technical staff that interprets the most relevant information in the "criteria document" to be used in making policy decisions. It contains staff recommendations to the EPA Administrator regarding any revisions needed to the standards to protect public health and welfare.

_Both the "criteria document" and "staff paper" are based on thousands of peer-reviewed scientific studies and are part of an extensive scientific assessment process that includes an extremely rigorous scientific peer review and public comment process. Before these documents become the basis for policy decisions, they undergo repeated, detailed reviews by the scientific community, industry, public interest groups, the general public, and the Clean Air Scientific Advisory Committee -- a Congressionally mandated group of independent scientific and technical experts. As part of its mandate, the Clean Air Scientific Advisory Committee also makes recommendations to EPA on the adequacy of the standards.

_Based on the scientific assessments and taking into account the recommendations of the Clean Air Scientific Advisory Committee, the EPA Administrator must judge whether or not it is appropriate to revise the standards.

Scientific Review of the PM Standards

_The health- and welfare-based standards for particulate matter (measured as PM₁₀, particles 10 micrometers in diameter or smaller) were last revised in 1987. They were:
(1) a 24-hour standard set at 150 µg/m³, and
(2) an annual 24-hour standard set at 50 µg/m³.

_The 24-hour PM₁₀ standard was expressed in a "1-expected-exceedance" form. This standard was attained when the expected number of days per year (averaged over 3 years) that the standard was exceeded was less than or equal to 1.

_Since these PM₁₀ standards were established, a large number of important new studies have been published on the health effects of particulate matter. Many of these studies suggest that significant effects, such as premature mortality, hospital admissions, and respiratory illnesses, occur at concentrations below the previous standards.

_Drafts of the EPA "criteria document" were reviewed at public meetings of the Clean Air Scientific Advisory Committee (CASAC) in August and December of 1995 and February 1996. Based on comments from the public and the CASAC, EPA revised the “criteria document.” In April 1996, EPA completed and made public its final “criteria document.”

_Members of CASAC and the public reviewed drafts of the EPA “staff paper” at public meetings of the Clean Air Scientific Advisory Committee in December 1995 and May 1996. In July 1996, EPA completed and made public its final “staff paper.” A public meeting of the Technical Subcommittee on PM monitoring issues was held in March 1996.

_The CASAC sent closure letters to EPA on both the “criteria document” and “staff paper” concluding that these documents provided an adequate basis for the EPA Administrator to make a decision on whether revisions to the primary and secondary particulate matter standards were appropriate.

_On June 12, 1996, EPA issued an advanced notice of proposed rulemaking on the ozone and particulate matter standards. The Agency announced that the schedule for both reviews was the same, explained the linkages between these two air pollutants, and gave advance notice of key issues for which public comment was sought. In addition, EPA held public meetings in St. Louis and Philadelphia on the health and environmental effects associated with ozone and particulate matter and on the implementation of possible revised standards.

_On December 13, 1996, EPA published a proposal to revise the particulate matter standards. EPA solicited comments for a proposed PM_2.5 annual standard set at 15µg/m³ and a 24-hour standard of 50µg/m³. The Agency also asked for public comment alternative levels for PM_2.5 standards and alternative forms based on concentration percentiles. The Agency proposed to retain the annual PM₁₀ standard and to revise the form of the 24-hour PM₁₀ standard.

_In January 1997, EPA held public hearings on the proposed standards in Salt Lake City, Chicago, Boston and Durham, NC.

_March 12, 1997 was the close of the public comment period. In addition to traditional methods of soliciting public comment, EPA set up email addresses and toll-free phone number to encourage public participation in the process. EPA received more than 50,000 comments on the particulate matter standards.

_The Agency carefully reviewed and analyzed these comments and weighed this information before reaching its final decision on the revised standards.

What are the PM Effects of Concern?

_The characteristics, sources, and potential health effects of larger or "coarse" fraction particles (from 2.5 to 10 micrometers in diameter) and smaller or "fine" particles (smaller than 2.5 micrometers in diameter) are very different.

•Coarse particles come from sources such as windblown dust from the desert or agricultural fields and dust kicked up on unpaved roads by vehicle traffic.

•Fine particles are generally emitted from activities such as industrial and residential combustion and from vehicle exhaust. Fine particles are also formed in the atmosphere when gases such as sulfur dioxide, nitrogen oxides, and volatile organic compounds, emitted by combustion activities, are transformed by chemical reactions in the air.

_Coarse particles can accumulate in the respiratory system and aggravate health problems such as asthma. EPA's scientific review concluded that fine particles, which penetrate deeply into the lungs, are more likely than coarse particles to contribute to the health effects (e.g., premature mortality and hospital admissions) found in a number of recently published community epidemiological studies at concentrations that extend well below those allowed by the current PM₁₀ standards.

_These recent community studies find that adverse public health effects are associated with exposure to particles at levels well below the previous PM standards for both short-term (from less than 1 day to up to 5 days) and long-term (from generally a year to several years) periods.

• These health effects include premature death and increased hospital admissions and emergency room visits (primarily the elderly and individuals with cardiopulmonary disease); increased respiratory symptoms and disease (children and individuals with cardiopulmonary disease such as asthma); decreased lung function (particularly in children and individuals with asthma); and alterations in lung tissue and structure and in respiratory tract defense mechanisms.

_EPA believes that the new standards will protect and improve the lives of millions of Americans.

_EPA's final rules, in addition to regional haze rules, address the so-called "welfare" effects from particles for which the previous PM₁₀ secondary standards did not provide adequate protection. Chief among those is visibility impairment. Fine particulate matter adversely impacts visibility because it scatters and absorbs light.

Summary of the Final Rule

Primary Standards

PM_2.5 Standards

_EPA changes the suite of PM₁₀ standards by adding two new primary PM_2.5 standards set at 15 µg/m³, annual arithmetic mean, and 65 µg/m³, 24-hour average, to provide increased protection against the PM-related health effects found in the community studies.

_EPA's scientific review concluded that fine particles are a better surrogate for those components of PM most likely linked to mortality and morbidity effects at levels below the previous standards, while high concentrations of coarse fraction particles are linked to effects such as aggravation of asthma. The Clean Air Scientific Advisory Committee made a near unanimous (19 of 21 members) recommendation that new standards for PM_2.5 be added while retaining PM₁₀ standards as an indicator for coarse fraction particles.

Averaging Times

_EPA has set PM_2.5 standards with 24-hour and annual averaging times to protect against effects from short- and long-term exposure identified in the community studies.

_In developing a suite of PM_2.5 standards designed to protect public health, EPA considered the combined effect of the standards rather than an approach that weighed short- and long-term exposure evidence, analyses, and standards independently.

_EPA concluded that much of the total annual risk associated with short-term exposures is likely to result from days when the PM levels are in the low- to mid-range, below the 24-hour peaks. As a result, lowering a wide range of PM_2.5 concentrations through an annual standard, as opposed to focusing on controlling peak 24-hour concentrations, is the best way to reduce total PM_2.5 risk. EPA also believes that the 24-hour standard will provide additional protection for days with high PM_2.5 concentrations, localized "hot spots," and risks arising from seasonal emissions, such as woodsmoke in the winter.

Form of the Standards

_The final rule establishes a new form for the annual PM_2.5 standard. Areas will be in compliance with the new annual PM_2.5 standard when the 3-year average of the annual arithmetic mean PM_2.5 concentrations, from single or multiple community-oriented monitors, is less than or equal to 15 µg/m³. The use of averages from single or multiple community-oriented sites is more closely linked to the underlying health effects information, which relates area wide health statistics to averaged measurements of area wide air quality. EPA believes this more protective annual standard, with the supplemental protection afforded by the 24-hour standard, which is directed at peak concentrations and localized hot spots, will provide a protective target that will reduce area-wide population exposure to fine particles.

_For the new 24-hour PM_2.5 standard, the form is based on the 98th percentile of 24-hour PM_2.5 concentrations in a year (averaged over 3 years), at the population-oriented monitoring site with the highest measured values in an area. The 24-hour standard will limit peak concentration in areas with high seasonal concentrations and in areas with localized hot spots due to particular sources.

• This form will reduce the impact of a single high exposure event that may be due to unusual meteorological conditions, and thus would provide a more stable basis for effective control programs.

• The percentile form compensates for missing data and less-than-every-day monitoring, thereby reducing or eliminating the need for complex procedures previously required for the PM₁₀ attainment test.

• The forms of both the 24-hour and annual standard were adjusted to provide additional protection for community settings with higher than average concentrations within an area.


Standard Level

_EPA establishes an annual PM_2.5 standard level of 15 µg/m³, in order to protect public health with an adequate margin of safety. Although health effects at lower annual concentrations are possible, the evidence for effects at such levels is highly uncertain and the likelihood of significant health risk becomes smaller at concentrations well below the 15 µg/m³ level and approaching background levels.

_After carefully reviewing public comments on the proposed standards, EPA changed the level of the 24-hour PM_2.5 standard from 50 µg/m³ in the proposal to 65 µg/m³. In conjunction with greater protection afforded by the changes to the forms and associated monitoring requirements, EPA believes that a 24-hour PM_2.5 standard set at 65 µg/m³ will provide an appropriate supplement to the annual standard and provides an adequate margin of safety in communities that meet the annual standard, but have infrequent or isolated 24-hour peaks. The resulting suite of PM standards will give greater flexibility to individual sources of pollution while still ensuring that public health is protected.

PM₁₀ Standards

Annual Standard

_Based on its assessment of the health and other available information, EPA retains the annual PM₁₀ standard of 50 µg/m³ to protect against effects from both long- and short-term exposure to coarse fraction particles.

24-hour Standard

_EPA revises the PM₁₀ 24-hour standard of 150 µg/m³ by replacing the 1-expected-exceedance form with a 99th percentile form, averaged over 3 years, to protect against short-term exposure to coarse fraction particles. The concentration-based percentile form is a more stable target for control programs and eliminates the need for complex data handling for missing values.

• With the addition of fine particle standards, EPA has found that the original quantitative basis for the level of the previous 24-hour PM₁₀ standard is no longer appropriate. However, the new health studies and information on coarse particles do not provide a basis for a lower standard level.

•Based on careful review of public comments, many of which expressed concern that a 98th percentile might not provide adequate protection against larger particles, EPA changed the form of the PM₁₀ 24-hour standard from the 98th percentile to the 99th percentile concentration-based form.

Secondary Standard

_EPA sets the secondary standards identical to the final primary standards, in conjunction with establishment of a regional haze program. This approach will provide appropriate protection against the welfare effects associated with particulate pollution including visibility impairment, soiling and material damage.

For More Information...

_Anyone with a computer and a modem can download the final standards and this fact sheet from the Clean Air Act Amendments bulletin board of EPA's electronic Technology Transfer Network (TTN) by calling (919) 541-5742 (look under "Recently Signed Rules"). For further information about how to access the board, call (919) 541-5384. The TTN can also be accessed through EPA's homepage on the Internet. The address is: http://ttnwww.rtpnc.epa.gov

_For technical questions about this standard, contact John H. Haines at EPA's Office of Air Quality Planning and Standards at (919) 541-5533.

July 1997 FACT SHEET
OF PARTICULATE MATTER



Why are We Concerned About Particulate Matter?

_Particulate matter is the term used for a mixture of solid particles and liquid droplets found in the air. Coarse particles (larger than 2.5 micrometers) come from a variety of sources including windblown dust and grinding operations. Fine particles (less than 2.5 micrometers) often come from fuel combustion, power plants, and diesel buses and trucks.

_These fine particles are so small that several thousand of them could fit on the period at the end of this sentence.

_They are of health concern because they easily reach the deepest recesses of the lungs.

_Batteries of scientific studies have linked particulate matter, especially fine particles (alone or in combination with other air pollutants), with a series of significant health problems, including:

_Premature death;
_Respiratory related hospital admissions and emergency room visits;
_Aggravated asthma;
_Acute respiratory symptoms, including aggravated coughing and difficult or painful breathing;
_Chronic bronchitis;
_Decreased lung function that can be experienced as shortness of breath; and
_Work and school absences.

Who is Most at Risk from Exposure to Fine Particles?

_The Elderly:

_Studies estimate that tens of thousands of elderly people die prematurely each year from exposure to ambient levels of fine particles.

_Studies also indicate that exposure to fine particles is associated with thousands of hospital admissions each year. Many of these hospital admissions are elderly people suffering from lung or heart disease.

_Individuals with Preexisting Heart or Lung Disease:

_Breathing fine particles can also adversely affect individuals with heart disease, emphysema, and chronic bronchitis by causing additional medical treatment. Inhaling fine particulate matter has been attributed to increased hospital admissions, emergency room visits and premature death among sensitive populations.

_Children:

_The average adult breathes 13,000 liters of air per day; children breathe 50 percent more air per pound of body weight than adults.

_Because children's respiratory systems are still developing, they are more susceptible to environmental threats than healthy adults.
_Exposure to fine particles is associated with increased frequency of childhood illnesses, which are of concern both in the short run, and for the future development of healthy lungs in the affected children.

_Fine particles are also associated with increased respiratory symptoms and reduced lung function in children, including symptoms such as aggravated coughing and difficulty or pain in breathing. These can result in school absences and limitations in normal childhood activities.

_Asthmatics and Asthmatic Children:

_More and more people are being diagnosed with asthma every year. Fourteen Americans die every day from asthma, a rate three times greater than just 20 years ago. Children make up 25 percent of the population, but comprise 40 percent of all asthma cases.

_Breathing fine particles, alone or in combination with other pollutants, can aggravate asthma, causing greater use of medication and resulting in more medical treatment and hospital visits.

How do Particulate Matter and Fine Particles Effect the Environment?

_The same fine particles linked to serious health effects are also a major cause of visibility impairment in many parts of the U.S.

_In many parts of the U.S. the visual range has been reduced 70% from natural conditions. In the east, the current range is only 14-24 miles vs. a natural visibility of 90 miles. In the west, the current range is 33-90 miles vs. a natural visibility of 140 miles.

_Fine particles can remain suspended in the air and travel long distances. For example, a puff of exhaust from a diesel truck in Los Angeles can end up over the Grand Canyon, where one-third of the haze comes from Southern California. Emissions from a Los Angeles oil refinery can form particles that in a few days will effect visibility in the Rocky Mountain National Park. Twenty percent of the problem on dirtiest days in that Park is attributed to Los Angeles-generated smog.

_Airborne particles can also cause soiling and damage to materials.

What Improvements Would Result from EPA's New Standards?

_EPA's new standards will provide increased health protection from the following effects:

_About 15,000 lives each year will be saved, especially among the elderly and those with existing heart and lung diseases.

_Reduced risk of hospital admissions by thousands each year, and fewer emergency room visits, especially in the elderly and those with existing heart and lung diseases.

_Reduced risk of symptoms associated with chronic bronchitis, tens of thousands fewer cases each year.

_Reduced risk of respiratory symptoms in children, hundreds of thousands fewer incidences each year of symptoms such as aggravated coughing and difficult or painful breathing.

_Reduced risk of aggravation of asthma, hundreds of thousands fewer incidences each year, in children and adults with asthma.

_Reduced risks of susceptibility to childhood illnesses.

_Improved visibility over broad regions in the east and urban areas:

_The Clean Air Act placed special emphasis on preserving visibility in certain national parks and wilderness areas. In response, EPA is developing a "regional haze" program intended to ensure all parts of the country make continued progress toward the national visibility goal of "no manmade impairment."

_New standards that EPA has promulgated, together with the "regional haze" program under development, will protect against visibility impairment, soiling and material damage effects, and will further reduce acid rain.

Background: What is Particulate Matter and What are "Fine" Particles?

_Particulate matter originates from a variety of sources, including diesel trucks, power plants, wood stoves and industrial processes. The chemical and physical composition of these various particles vary widely. While individual particles cannot be seen with the naked eye, collectively they can appear as black soot, dust clouds, or grey hazes.

_Those particles that are less than 2.5 micrometers in diameter are known as "fine" particles; those larger than 2.5 micrometers are known as "coarse" particles. Fine particles result from fuel combustion (from motor vehicles, power generation, industrial facilities), residential fireplaces and wood stoves. Fine particles can be formed in the atmosphere from gases such as sulfur dioxide, nitrogen oxides, and volatile organic compounds. Coarse particles are generally emitted from sources such as vehicles traveling on unpaved roads, materials handling, and crushing and grinding operations, and windblown dust.

_EPA is also maintaining a national air quality standard focused on small particles less than 10 micrometers in diameter (known as "PM₁₀") to protect against coarse particle effects. Ten micrometers are about one-seventh the diameter of a human hair.

_Before 1987, EPA's standards regulated larger particles (so called "total suspended particulates"), including those larger than 10 micrometers. By 1987, research had shown that the particles of greatest health concern were those equal to or less than 10 micrometers that can penetrate into sensitive regions of the respiratory tract. At that time EPA and states took action to monitor and regulate particulate matter 10 micrometers and smaller.

_In the years since the previous standard was enacted, hundreds of significant new scientific studies have been published on the health effects of particulate matter. Recent health effects studies suggest those adverse public health effects, such as premature deaths and increased morbidity in children and other sensitive populations, have been associated with exposure to particle levels well below those allowed by the current standard.

July 17, 1997


Today’s Action...

_Today, EPA is revising the monitoring requirements for particulate matter (PM) to support revisions to the National Ambient Air Quality Standards (NAAQS) for particulate matter.

_In a separate action, EPA is issuing the final rules establishing new NAAQS for fine particles. An extensive ambient air quality monitoring network for PM_2.5 (fine particles) does not exist. These monitoring data will be critical in determining which areas meet or do not meet the revised PM-fine standards. This rulemaking provides the basis for establishing a PM_2.5 monitoring network.

_EPA is seeking resources to fund the purchase of all the new PM_2.5 monitors and fund a major portion of the other costs associated with establishing the PM_2.5 monitoring network.

_Among other things, the final rule establishes a new federal reference method for measuring fine particles, new criteria for placement of monitors, new schedules for data collection, and new procedures for ensuring the quality of particulate matter data.

_Procedures for establishing equivalent monitoring methods for PM_2.5 are also described. This will ensure that new, improved and easy to use monitoring methods can be incorporated into the monitoring program.

_EPA’s rule will retain much of the previous monitoring approach for PM₁₀. The principle modifications involve a change in the sampling frequency and a reduction in the number of data collection locations.

_EPA is exploring opportunities to coordinate and integrate the existing visibility monitoring requirements with the new ambient air quality monitoring requirements for particulate matter. This will serve to accommodate a better regional haze program, reduce burdens, and achieve multiple monitoring objectives.

_The effective date of these monitoring regulations will be 60 days after the actual promulgation date.

Background

_EPA requires different areas to establish and maintain air quality monitoring networks for a variety of air pollutants, including ozone, particulate matter, nitrogen dioxide, lead, carbon monoxide, and sulfur dioxide.

_Since the 1980s, EPA has required areas to monitor for PM₁₀, particles with a nominal size less than 10 micrometers in diameter. New health studies have indicated that particles smaller than PM₁₀ can pose serious health threats. This rule establishes monitoring protocols for PM_2.5. One-hundred fifty areas currently monitor for PM_2.5.

_To ensure national consistency in air pollution monitoring, a federal reference method is used for making comparisons to the standards. For particulate matter, the federal reference method is the ambient sampling device that defines the measurement of particulate matter.

_On December 13, 1996, EPA proposed new monitoring requirements for PM_2.5 in conjunction with the proposed NAAQS for fine particles.

_In developing the proposal, EPA consulted with the Clean Air Scientific Advisory Committee.

_In addition, EPA staff has discussed monitoring issues at meetings with State and local agencies over the past 2 years.

_In January 1997, EPA held a public meeting on its proposed PM_2.5 monitoring regulations. EPA received extensive public comment on the proposals. The Agency carefully reviewed and analyzed these public comments in developing its final rules.

Summary of the Final Rules

PM_2.5 Monitoring

Reference and Equivalent Samplers

_EPA has established a new federal reference method for PM_2.5. Specifications for the reference method sampler allow various sampler manufacturers to design and fabricate samplers that will meet the specifications.

_Three classes of equivalent method are established. Class I equivalent methods provide capability for collection of several sequential samples automatically without intermediate operator service. This will permit easier and more cost efficient sampling on a daily basis. Class II equivalent methods include all other filter based methods that produce a 24-hour measurement. Finally, Class III equivalent methods include both continuous or semi-continuous methods.

Network Design

_The new PM_2.5 network will consist of core community-oriented monitors; many will be required to sample every day (or continuously), and supplementary monitors that will be allowed to sample less frequently. The core monitors are required in all of the largest metropolitan areas. The supplementary monitors will provide coverage in small cities and rural areas, some of which are intended to study the long-range transport of fine particles.

_Frequent measurements will be focused in the most heavily polluted or densely populated areas and are important to understand episodic behavior of PM_2.5 . These monitors will also establish peak concentrations. This information will allow EPA to establish effective emission control strategies to assure protection of public health.

_The network of required monitors will be phased in over a 3-4-year period beginning in 1997. In 1998, all metropolitan areas with at least 500,000 people are required to have at least one core monitor and each State is required to have at least two additional monitors. Additional monitoring sites will also be established. Areas will be selected for monitoring by the State; States will select monitoring sites according to the likelihood of observing high PM_2.5 concentrations and based on the size of the affected population. In addition, one PM_2.5 site would be collocated at one site in each of the "serious,” "severe," or "extreme" ozone nonattainment areas in order to study the relationship between ozone and fine particles. During the subsequent years, all other required core and other required monitors will be added, including those needed to study regional transport.

_In addition, special purpose monitors will be used to identify potential PM_2.5 problem areas and help define the boundaries, clarify diurnal patterns, determine the spatial scale of high concentration areas, and help characterize the chemical composition of PM (using alternative samplers and supplemental analyzers), especially on high concentration days or during special studies. Special purpose monitors are an important part of the overall PM monitoring program, and EPA is working to financially support their operation.

_The new network design and siting requirements mandate the placement of PM_2.5 monitors outside population centers in more rural areas for two reasons: 1) to provide the air quality data necessary to facilitate implementation of the NAAQS, and 2) to augment the existing visibility fine particle monitoring network. The coordination of these two monitoring objectives will facilitate implementation of a regional haze program and lead to an integrated monitoring program for fine particles.

_The network will also assist in reporting of data to the public, especially during air pollution episodes. To these ends, additional monitoring requirements include the use of continuous particulate matter measuring devices (such as nephelometers) at some core monitoring sites.

_Selected monitors will be set up to track long-term trends of PM and its chemical constituents. This is necessary to understand the emission sources contributing to fine particles, study the effectiveness of emission control programs, and better understand trends in population exposure to fine particles.

Comparison to the Standards with Monitoring Data

_Comparisons to the PM_2.5 annual standard will be based on data from community-oriented (core) monitoring locations in order to provide increased protection against the PM-related health effects found in the community-based health studies. This may involve the maximum individual core monitor or a community-wide spatial average based on eligible core sites within a community monitoring zone. Additional population-oriented monitoring stations will be located in areas reflective of the highest measured values within each metropolitan area and elsewhere throughout the State for comparison to the 24-hour standards.

_States will be divided into monitoring planning areas that in turn may contain community monitoring averaging zones. These zones are intended to contain reasonably homogenous air quality, influenced by similar sources of PM, and provide the basis for the selection of monitoring sites for community-wide air quality averaging. The designation of monitoring planning areas, community monitoring zones and core sites eligible for comparison to the annual standard, will be proposed by the State, and subject to EPA review and approval.

_Finally, in order to encourage the deployment of special purpose monitors (SPMs), today's action states that nonattainment designations will not be based on data produced at a SPM site, with any monitoring method, for the first two complete calendar years of its operation.

_The rationale for this concept is based on the need for the nation to begin building a monitoring infrastructure from "ground zero.” EPA needs to build this infrastructure because PM is a complex problem that cannot be addressed without data that will identify the sources of PM and the location of problem areas.

Data Collection and Reporting

_The ambient concentration of PM_2.5 (total mass) will be directly compared with the standards.

_Compositional analysis is essential to understanding PM_2.5. In addition, chemical analysis, required at approximately 50 sites nationwide, is encouraged in monitoring areas. The EPA is also seeking funding to financially support this important monitoring activity. Following data collection, archiving collected PM_2.5 filters will be required for 1 year. These filters will be stored for possible subsequent compositional analysis that will help identify PM emission sources and develop effective control programs.

_The concentration of the total mass of PM_2.5 derived from the network of PM_2.5 samplers will be reported to EPA. Although not required, the results from chemical analysis should also be reported to EPA.

_Because of the costs associated with conducting filter analysis on a routine basis, this rule only requires filters to be archived so they are available for analysis on an “as needed” basis. EPA will archive collected PM_2.5 filters because we will need them for subsequent compositional analysis that will help identify PM emission sources and develop effective control programs. This includes: 1) whether specific monitoring sites should be designated for such analyses; 2) the criteria to be used to select sites for speciated sampling and analysis; 3) the extent and frequency to which speciation should be required by EPA for at least some monitoring stations; and 4) the need for monitoring methodologies not described in this proposal that may be needed to facilitate compositional analysis.

Quality Assurance

_EPA's standards for PM_2.5 require great attention to achieving data of high quality with minimal imprecision and relative error. This will reduce the chance that PM_2.5 measurements could lead to unwarranted health risk to the population when measurements underestimate true concentrations, or unnecessary control requirements when the true concentrations are over estimated.

_Enhanced quality assurance will be required in all areas relating to sampler performance, including sampler manufacturing and sampler operation. A new operational requirement involves auditing each monitoring location using a Federal Reference Method sampler. This will ensure consistent data collection nationwide. The user agency will be required to obtain 4 collocated measurements per year with a reference method "audit" sampler for 25 percent of all routinely operating PM_2.5 monitors. In addition, 25 percent of all PM_2.5 samplers will be permanently collocated with a reference of equivalent PM_2.5 sampler. Data from these audits and collocated samplers will be used to assess operating performance nationally. These data will also be used to identify reporting organizations or individual sites that have abnormal bias or precision and instruments that are not operating properly.

PM₁₀ Monitoring

_The allowed monitoring methods for PM₁₀ remain the same. The frequency of sampling will be changed to once in 3 days and the number of sampling locations are expected to be fewer because the PM_2.5 standards will likely be the controlling standards in most situations.

_The network design and siting requirements for the annual and 24-hour PM₁₀ NAAQS will continue to emphasize identification of locations with maximum concentrations.

_The revised network will ensure continuation of the analysis of national trends in PM₁₀, maintenance of air surveillance in areas with established PM emission control programs, and protection of public health from additional growth in PM₁₀ emissions.

_PM₁₀ sites should be collocated with new PM_2.5 sites at key population-oriented monitoring stations, so that better definition of fine and coarse contributions to PM₁₀ can be determined to provide a better understanding of exposure, emission controls, and atmospheric processes.

For More Information...

_Anyone with a computer and a modem can download the proposal and this fact sheet from the Clean Air Act Amendments bulletin board of EPA's electronic Technology Transfer Network (TTN) by calling (919) 541-5742 (look under "Recently Signed Rules"). For further information about how to access the board, call (919) 541-5384. The TTN can also be accessed through EPA's homepage on the Internet. The address is: http://ttnwww.rtpnc.epa.gov

_For technical questions about this proposal, contact Neil Frank at EPA's Office of Air Quality Planning and Standards at (919) 541-5560.