[Federal Register Volume 63, Number 236 (Wednesday, December 9, 1998)]
[Proposed Rules]
[Pages 67818-67834]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-32571]
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ENVIRONMENTAL PROTECTION AGENCY
40 CFR Part 58
[FRL-6198-6]
RIN 2060-AH92
Air Quality Index Reporting
AGENCY: Environmental Protection Agency (EPA).
ACTION: Proposed rule.
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SUMMARY: EPA proposes to change the uniform air quality index used by
States for daily air quality reporting to the general public in
accordance with section 319 of the Clean Air Act (Act). These proposed
changes include the addition of the following elements: a new category
described as ``unhealthy for sensitive groups,'' new breakpoints for
the ozone (O3) sub-index in terms of 8-hour average
O3 concentrations, a new sub-index for fine particulate
matter (PM2.5), and conforming changes to the sub-indices
for inhalable particulate matter (PM10), carbon monoxide
(CO), and sulfur dioxide (SO2). These proposed changes
reflect the revisions to the health-based primary national ambient air
quality standards (NAAQS) for O3 and particulate matter (PM)
published in the Federal Register on July 18, 1997. This document
discusses the development of related informational materials on
pollutant-specific health effects and sensitive groups and on
precautionary actions that can be taken by individuals to reduce
exposures of concern. This document also discusses the
interrelationship between the uniform air quality index and other
programs that provide air quality information and related health
information to the general public, including State and local real-time
air quality data mapping and community action programs.
DATES: Written comments on this proposed rule must be received by
January 25, 1999.
ADDRESSES: Submit comments (in duplicate if possible) on the proposed
rule to: Air and Radiation Docket and Information Center (6102), Attn:
Docket No. A-98-20, Environmental Protection Agency, 401 M St., SW,
Washington, DC 20460.
FOR FURTHER INFORMATION CONTACT: Terence Fitz-Simons, MD-14, Office of
Air Quality Planning and Standards, EPA, Research Triangle Park, NC
27711, telephone (919) 541-0889, e-mail fitz-
[email protected]. For health effects information contact
Susan Lyon Stone, MD-15, Office of Air Quality Planning and Standards,
EPA,
[[Page 67819]]
Research Triangle Park, NC 27711, telephone (919) 541-1146, e-mail
[email protected].
SUPPLEMENTARY INFORMATION: In compliance with President Clinton's June
1, 1998 Executive Memorandum on Plain Language in government writing,
this package is written using plain language. Thus, the use of ``we''
or ``us'' in this package refers to EPA. The use of ``you'' refers to
the reader and may include industry, State and local agencies,
environmental groups and other interested individuals.
Docket
Docket No. A-98-20, containing information relating to the EPA's
revision of the uniform air quality index, is available for public
inspection in the Air and Radiation Docket and Information Center of
the Environmental Protection Agency, 401 M St. SW, room M-1500,
Washington, DC. The docket may be inspected between 8:00 a.m. and 4:00
p.m., Monday through Friday, excluding holidays. A reasonable fee may
be charged for copying.
Availability of Related Information
Certain documents are available from the U.S. Department of
Commerce, National Technical Information Service, 5285 Port Royal Road,
Springfield, VA 22161. Available documents include:
(1) The Review of the National Ambient Air Quality Standards for
Ozone: Assessment of Scientific and Technical Information (``Staff
Paper'')(EPA-452/R-96-007, June 1996, NTIS # PB-96-203435, $67.00 paper
copy and $21.50 microfiche). (Add a $3.00 handling charge per order.)
(2) Review of the National Ambient Air Quality Standards for
Particulate Matter: Policy Assessment of Scientific and Technical
Information (``Staff Paper'') (EPA-452/R-96-013, July 1996, NTIS #PB-
97-115406, $47.00 paper copy and $19.50 microfiche). (Add a $3.00
handling charge per order.)
The following document will be available in January 1999 from the
National Center for Environmental Publications and Information (NCEPI).
Requests for this publication can be mailed to: U.S. Environmental
Protection Agency, NCEPI, P.O. Box 42419, Cincinnati, OH, 45242. Your
request may also be phoned in to NCEPI at 1-800-490-9198 or faxed to
513-489-8695.
(1) Community Action Programs: Blueprint for Program Design (EPA
420-R-98-003).
Table of Contents
I. Background
A. What are the Legislative Requirements?
B. What is the History of the Air Quality Index?
C. What Programs are Related to the PSI?
1. Ozone and Particulate Matter NAAQS Revisions
2. Real-Time Data Reporting Initiative (Ozone Mapping Project)
3. Community Action Programs
II. Rationale for Proposed Revisions
A. What was the Early Input from State/local Agencies?
B. Staff Draft Revisions to PSI Sub-index for Ozone
1. Availability for Use in the 1998 Ozone Season
2. What were the Staff Draft Revisions?
3. Related Informational Materials
4. What was the Feedback on the Staff Draft?
C. What is the Basis for the Proposed Revisions?
1. What are the Proposed General Changes?
2. What are the Proposed Changes to the Sub-Indices?
3. What are the Changes to Related Informational Materials?
III. Regulatory and Environmental Impact Analyses
A. Executive Order 12866: OMB Review of ``Significant Actions''
B. Regulatory Flexibility Analysis/Small Business Regulatory
Enforcement Fairness Act
C. Unfunded Mandates Reform Act
D. Paperwork Reduction Act
E. Executive Order 13045: Children's Health
F. Executive Order 12848: Environmental Justice
G. Executive Order 12875: Enhancing Intergovernmental
Partnerships
H. Executive Order 13084: Consultation and Coordination with
Indian Tribal Governments
I. National Technology Transfer and Advancement Act
IV. References
I. Background
A. What Are the Legislative Requirements?
Section 319 of the Act governs the establishment of uniform air
quality index for reporting of air quality. This section directs the
Administrator to ``promulgate regulations establishing an air quality
monitoring system throughout the United States which utilizes uniform
air quality monitoring criteria and methodology and measures such air
quality according to a uniform air quality index'' and ``provides for
daily analysis and reporting of air quality based upon such uniform air
quality index* * *''.
B. What Is the History of the Air Quality Index?
In 1976, we established a nationally uniform air quality index
(AQI), called the Pollutant Standard Index (PSI), for use by State and
local agencies on a voluntary basis (41 FR 37660). This uniform index
was established in light of a study conducted by EPA and the
President's Council on Environmental Quality (CEQ, 1976). This study
found that the 55 urban areas in the U.S. and Canada reporting an index
of air quality used 14 different indices, in conjunction with different
cautionary messages, such that in essence 55 different indices were
being used to report air quality. This diversity of indices sent a
confusing message about air quality to the public. Based in part on
this study, we developed an index to meet the needs of State and local
agencies that has the following advantages: it sends a clear and
consistent message to the public by providing nationally uniform
information on air quality; it is keyed to the NAAQS and the
significant harm level (SHL) 1 which have a scientific basis
relating air quality and public health; it is simple and easily
understood by the public; it provides a basis for accommodating changes
to the NAAQS; and it can be forecasted to provide advance information
on air quality.
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\1\ Significant harm levels are those ambient concentrations of
air pollutants that present an imminent and substantial endangerment
to public health or welfare, or to the environment, as established
in 40 CFR part 51.151.
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The PSI, which is also commonly referred to by some State and local
agencies as the AQI, includes sub-indices for O3, PM, CO,
SO2, and nitrogen oxide (NO2), which relate
ambient pollutant concentrations to index values on a scale from 0
through 500. This represents a very broad range of air quality, from
pristine air to air pollution levels that present imminent and
substantial endangerment to the public. The index is normalized across
pollutants by defining an index value of 100 as the numerical level of
the primary NAAQS for each pollutant and an index value of 500 as the
SHL.2 Such index values serve to divide the index into
categories, with each category being
[[Page 67820]]
identified by a simple informative descriptor. The descriptors are
intended to convey to the public information about how air quality
within each category relates to public health, with increasing public
health concerns being conveyed as the categories range to the upper end
of the scale. Additional information about the general health effects
associated with each category, and precautions that sensitive groups
and the general public should take to avoid exposures of concern, has
been made available through an informational booklet, updated as
appropriate, that also presents and explains the PSI (EPA, 1994).
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\2\ Intermediate index values of 200, 300, and 400 were defined
and are the basis for the Alert, Warning, and Emergency episode
levels included in 40 CFR part 51, appendix L, as part of the
Prevention of Air Pollution Emergency Episodes program. This program
requires specified areas to have contingency plans in place and to
implement these plans during episodes when high levels of air
pollution, approaching the SHL, are in danger of being reached.
Changes to this emergency episode program will be proposed in the
near future.
Below an index value of 100, an intermediate value of 50 was
defined either as the level of the annual standard if an annual
standard has been established (for PM10 and
SO2), or as a concentration equal to one-half the value
of the short-term standard used to define an index value of 100 (for
O3 and CO). Inhalable particulate matter,
PM10, refers to particles with an aerodynamic diameter
less than or equal to a nominal 10 micrometers.
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In 1979, we made changes to the PSI, in part to reflect revisions
to the NAAQS for O3, and to establish requirements for PSI
reporting (44 FR 27598). The requirement for State and local agencies
to report the PSI appears in 40 CFR part 58.50, and the specific
requirements (e.g., what to report, how to report, reporting frequency,
calculations) are in appendix G to 40 CFR part 58.
C. What Programs Are Related to the PSI?
Historically, State and local agencies have used primarily the PSI,
or other AQIs, to provide general information to the public about air
quality and its relationship to public health. In recent years, many
States and local agencies, as well as EPA, have been developing new and
innovative programs and initiatives to provide more information to the
public, in a more timely way. These initiatives, including real-time
data reporting through the Ozone Mapping Project and community action
programs, can serve to provide useful, up-to-date, and timely
information to the public about air pollution and its effects. Such
information will help individuals take actions to avoid or reduce
exposures of concern and can encourage the public to take actions that
will reduce air pollution on days when levels are projected to be in
air quality categories of concern to local communities. Thus, these
programs are significantly broadening the ways in which State and local
agencies can meet the nationally uniform AQI reporting requirements,
and are contributing to State and local efforts to provide community
health protection and to attain or maintain compliance with the NAAQS.
We and State and local agencies recognize that these programs are
interrelated with AQI reporting and with the information on the effects
of air pollution on public health that is generated through the
periodic review, and revision when appropriate, of the NAAQS.
The most recent revisions to the O3 and PM NAAQS, the
Ozone Mapping Project, and community action programs are discussed
briefly below. In light of the interrelationships among these programs,
we have developed the revisions to the uniform AQI being proposed today
with the goal of creating a revised AQI that can effectively serve as a
nationally uniform link across these programs. In so doing, we intend
to support and encourage State and local participation in real-time
data reporting initiatives and the development and implementation of
community action programs that serve public education and health
protection goals.
1. Ozone and Particulate Matter NAAQS Revisions
On July 18, 1997, we revised the primary NAAQS for O3
and PM based on a thorough review of the scientific evidence linking
exposures to ambient concentrations of these pollutants to adverse
health effects at levels allowed by the previous NAAQS. In particular,
we replaced the 1-hour O3 NAAQS with an 8-hour O3
NAAQS and supplemented the PM NAAQS with 24-hour and annual standards
for fine particulate matter (measured as PM2.5
3). These revisions provide the basis for changes to the PSI
to maintain the relationship between an index value of 100 and the
level of the NAAQS, as well as to establish the relationships between
ambient concentrations of these pollutants and index values across the
full scale of index values from 0 to 500.
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\3\ PM2.5 refers to particles with an aerodynamic
diameter less than or equal to a nominal 2.5 micrometers.
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In addition, as a result of the reviews of the scientific
information upon which the O3 and PM NAAQS are based, an
expanded understanding emerged as to the nature of the relationships
between exposure to ambient concentrations of these pollutants and the
health effects likely to be experienced, especially near the level of
the NAAQS. We and the Clean Air Scientific Advisory Committee (CASAC)
4 recognized that for these pollutants there are no
discernible thresholds below which health effects are not likely to
occur in the most sensitive individuals, but rather there is a
continuum of effects potentially extending down to background levels.
As ambient concentrations increase, the proportion of individuals
likely to experience effects and the seriousness of the health effects
increase. Thus, the standards are not risk free. While the standards
protect public health with an adequate margin of safety, in accordance
with sections 108 and 109 of the Act, including the health of sensitive
groups, exposures to ambient concentrations just below the numerical
level of the standards may result in exposures of concern for the most
sensitive individuals. Conversely, exposures to ambient concentrations
just above the numerical level of the standards are not likely to
result in exposures of concern for most healthy people. This expanded
understanding is reflected in the new forms of the standards, which
allow for multiple days above the numerical level of the standards.
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\4\ CASAC is a scientific advisory committee established under
the Act to review the scientific criteria and standards and to
advise the Administrator on revision of the NAAQS, as appropriate.
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These understandings were reflected in CASAC's advice to the
Administrator during the O3 NAAQS review, urging expansion
of the public health advisory system (i.e., a uniform AQI) and
communication to the public of the nonthreshold nature of the health
effects. More specifically, a number of CASAC panel members recommended
``that an expanded air pollution warning system be initiated so that
sensitive individuals can take appropriate `exposure avoidance'
behavior'' (Wolff, 1995). Consistent with this advice, in the preamble
to the proposed revisions to the O3 NAAQS (61 FR 65733-4),
the Administrator requested comment on the usefulness of providing
specific health effects information when ambient concentrations are
around the numerical level of the standard, the appropriateness of
using the PSI to convey such information to the public, the possible
addition of two new PSI categories (one just above and one just below
the numerical level of the standard) and associated descriptors and
levels, as well as related health effects and cautionary statements.
Broad support for modifying the PSI was received in public comments
on this aspect of the O3 NAAQS proposal, as discussed in the
final rule establishing revisions to the O3 NAAQS (62 FR
38873-4). Commenters overwhelmingly endorsed expanding the use of the
PSI for various reasons, while many expressed concern with the possible
category descriptors suggested in the proposal (i.e., ``moderately
good'' and ``moderately unhealthful''). Many commenters felt that an
expanded PSI could help particularly sensitive people take action to
minimize their exposures, and that the PSI could be combined with
community action programs to reduce ambient concentrations when the
numerical level of the standard was forecasted to be exceeded. Some
commenters endorsed increasing the
[[Page 67821]]
specificity of health and cautionary statements related to the PSI
categories. Commenters from State and local agencies encouraged us to
develop any approaches to revising the PSI in consultation with them,
specifically in the areas of sharing real-time monitoring data, risk
communication with the public, and coordination of a national program.
2. Real-time Data Reporting Initiative (Ozone Mapping Project)
The Ozone Mapping Project is part of EPA's Environmental Monitoring
for Public Access and Community Tracking (EMPACT) initiative--a new
approach to providing timely environmental information to communities.
It is a cooperative effort of the EPA, State and local air pollution
control agencies, and regional organizations including the Mid-Atlantic
Regional Air Management Association (MARAMA), the Northeast States for
Coordinated Air Use Management (NESCAUM), the northeast Ozone Transport
Commission (OTC), and the Lake Michigan Air Directors Consortium
(LADCO). During the summer of 1998, EPA's Office of Air Quality
Planning and Standards assumed coordination of the project.
The Ozone Map provides simple and timely information about ground-
level O3. During the 1998 O3 season it was
available on EPA's AIRNOW web site (http://www.epa.gov/airnow) and on
some local television and news reports. It is an animated contour map
that shows concentrations of O3, in categories ranging from
good to moderate to varying degrees of unhealthy, based on PSI values,
as it develops across the eastern U.S. It was created from real-time,
hourly O3 data provided by a network of more than 400 air
monitoring stations from South Carolina to Wisconsin and Maine. When
accessed on a computer, cautionary statements for each category could
be displayed by running a cursor over the legend. Also available on the
AIRNOW web site were still maps of maximum values and forecasted
values, and archived animated maps.
Along with the Ozone Map, the AIRNOW web site contains information
about O3 health effects in the ``Health Facts'' section, and
emission reduction activities in the ``What You Can Do'' section. It
also provides links to real-time data, and community action program web
sites, that are maintained by State and local agencies around the
country. The goals of the web site are to: (1) Provide real-time air
pollution data in an understandable, visual format, (2) provide
information about the public health and environmental effects of air
pollution, and (3) provide the public with information about ways in
which they can protect their health and actions they can take to reduce
pollution.
3. Community Action Programs
The implementation of community action programs (also referred to
as episodic emission control programs) is becoming increasingly popular
across the country as an innovative approach used to reduce emissions
of O3 precursors, CO, and PM. Motivation for implementation
of this type of program often stems from local government and business
concerns about the NAAQS attainment status of the area and the
restrictions, additional controls, and costs associated with being
classified as a nonattainment area. Many areas are also motivated by
public health concerns and believe that increasing the amount of air
quality information available to sensitive populations raises awareness
and results in significant health benefits. Specific goals which are
usually associated with community action programs include: (1) Educate
the public and enhance protection of public health; (2) attain or
maintain NAAQS attainment status and the associated economic benefits;
(3) meet specific emission reduction targets; and (4) manage/reduce
traffic congestion.
Community action programs are usually voluntary and generally
provide multiple steps that the public, business, and industry can take
to reduce emissions when higher levels of air pollution are forecast to
occur, including in particular transportation-related measures such as
trip reduction, postponement of certain activities such as vehicle
refueling, and maintenance of cars. The programs emphasize educating
the public about the impact of individual activities on local air
quality and the basics of air pollution. The educational component of
these programs also helps to create a strong link between environmental
goals and associated public health benefits.
Most of these programs are based on the categories of the PSI and
make use of the PSI descriptors and related health effects and
cautionary statements on action days. By linking action days to the
PSI, local control programs hope to alter individual behavior to reduce
emissions and to reduce exposures to the population. In addition to
reduced pollutant exposure of the general population due to improved
air quality, there are other health benefits directly associated with
community action programs that can be enhanced by linkage to the PSI.
Different population groups are more sensitive to the harmful effects
of the different air pollutants included in the PSI, and the revisions
to the PSI proposed today, together with related informational
materials, will significantly improve the effectiveness of
communications with these groups. Public education or programs directly
targeting these groups may provide the most significant benefits of a
community action program. Forecasting days with elevated pollution
levels, and then communicating effectively about air quality and
associated health effects, may help these groups selectively limit
their outdoor activities and, therefore, limit their potential for
exposures of concern.
We are committed to providing States and local agencies with
support in their efforts to meet air quality standards, to inform the
public about air quality, and to educate the public about the impacts
of air pollution. The revisions to the PSI being proposed today have as
a goal the creation of a revised PSI that can effectively serve as a
nationally uniform link across the range of programs (e.g., real-time
data reporting initiatives, community action programs) that have these
functions.
In support of community action programs, we have developed
informational materials related to the PSI, including the health
effects and cautionary statements associated with each category and
more detailed health effects information (see section II.B.3),
available on the AIRNOW web site, that State and local agencies may use
to enhance their community action programs. Focusing on transportation
measures that are often a major component of community action programs,
EPA's Office of Mobile Sources (OMS) has developed a report entitled,
``Community Action Programs: Blueprint for Program Design.'' This
document describes the major steps needed to put together a successful
episodic control program and provides criteria that State and local
agencies can use to examine and evaluate their own programs. The report
will be available in January 1999 from NCEPI (See Availability of
Related Information).
II. Rationale for Proposed Revisions
In developing the revisions to the PSI that are being proposed
today, we sought extensive input from State, local agencies, and from
the public. As discussed below, we sponsored a workshop with State and
local agencies, participated in numerous meetings, prepared and made
available a staff draft revision to the PSI sub-index for O3
for use during the 1998 O3 season, and conducted several
focus groups to obtain public input on the effectiveness
[[Page 67822]]
of draft revisions to the PSI and related O3 maps and
informational materials.
A. What Was the Early Input From State/local Agencies?
In January 1998, we conducted a workshop for State and local air
pollution control agencies on the PSI and related programs. The
objectives of the Workshop were: (1) To give State/local agencies a
preview and opportunity for input on anticipated revisions to the PSI,
with particular focus on the O3 sub-index; (2) to provide
information and generate discussion regarding the expansion of the
Ozone Mapping Project and air quality forecasting approaches; (3) to
share information about State/local real-time data reporting and Ozone
Action Day programs (community action programs); and (4) to explore
cross-cutting issues focusing on how these tools to facilitate
communication (i.e., the PSI, Ozone Maps, forecasting) can best be
linked to State/local programs. The Workshop provided a forum for broad
discussion of these topics, among the participants, with many different
points of view expressed.
With regard to revisions to the PSI, broad consensus seemed to
exist on the key issues of maintaining simplicity in the structure of
the PSI and of providing up-to-date, consistent information relating
air quality and public health. More specifically, it was the consensus
view that the PSI should be kept as simple as possible, while being
consistent with the expanded health information that emerged from the
recently completed review of the O3 and PM NAAQS. The
creation of two possible new categories (i.e., one just above and one
just below the numerical level of the standard), as described in the
O3 NAAQS proposal (61 FR 65733-4) and final decision (62 FR
38873-4) notices, seemed to evoke negative reactions from most
participants for varying reasons (e.g., too complex, too much
information, too difficult to forecast in the narrow ranges suggested).
Most participants favored creation of a new category above the
numerical level of the standard (i.e., dividing the current
``unhealthful'' category into two categories) considering both the
expanded health information and linkages to community action programs.
Creation of a new category below the level of the standard (i.e.,
dividing the current ``moderate'' category into two categories) was
less generally supported--some felt that a new category just below the
level of the standard was important for communicating risks and
appropriate cautions, whereas many seemed to feel it was an unnecessary
complication that could be confusing to the public.
The Workshop discussion also produced consensus among the
participants that any revisions to the descriptors used for PSI
categories above the numerical level of the NAAQS should maintain the
root word ``health'' rather than more neutral air quality descriptors
(e.g., unsatisfactory). The Workshop participants generally preferred
the use of the plain English word ``unhealthy'' to the currently used
word ``unhealthful.''
The Workshop participants generally encouraged us to revise the
calculation methods for the PSI to be consistent with the conventions
used in defining the NAAQS. More specifically, the participants
supported changing the conventions for rounding numbers in calculating
the PSI to be consistent with the rounding conventions used for the
NAAQS. This revision would avoid situations where a health advisory
could be issued that describes the air as unhealthy, when in fact the
numerical level of the standard has not been exceeded.
With regard to forecasting air quality and associated PSI values,
Workshop participants generally recognized that for standards that have
an averaging period longer than 1 hour (e.g., the 8-hour O3
NAAQS), forecasting becomes increasingly important. Such forecasts can
help people plan to avoid exposures of concern and can provide a basis
for providing advance public notice of community action programs. There
was strong support for us to prepare guidance on air quality
forecasting, especially on using hourly O3 concentrations as
predictors for 8-hour averages.
The Workshop participants expressed strong support in general for
enhancements to the Ozone Mapping Project, including real-time data
reporting and forecasting. The selection of colors to be associated
with the PSI categories depicted on the maps was the subject of much
discussion. While there was broad recognition of the importance of
using colors with such air quality maps, different views were expressed
as to which colors should be associated with specific categories. For
example, some participants from areas that had already developed or
were developing community action programs expressed the view that the
use of the color red on the map should be used for the category that
triggers their programs' ``code red'' days. However, different programs
have or intend to use different PSI index values to trigger action
days, depending on the general level of air quality in the area and the
objectives of the action day program in that area.
In summary, Workshop participants encouraged us to develop
revisions to the PSI with immediate emphasis on a revised sub-index for
O3, reflecting the 8-hour O3 NAAQS. Many
participants expressed an interest in using such a revised index during
the 1998 O3 season. The participants also encouraged us to
prepare additional information, including appropriate cautionary
statements that could be used in conjunction with reporting a revised
O3 sub-index and more in-depth information on O3
health effects to help meet the educational goals of community action
programs.
Following the Workshop, we continued coordination with State and
local air agencies and associations as part of the process of
developing draft revisions to the PSI, particularly the O3
sub-index, and related informational materials. Some of the agencies
and associations that participated in meetings and discussions with us
were the State and Territorial Air Pollution Program Administrators and
the Association of Local Air Pollution Control Officials (STAPPA/
ALAPCO), the OTC, NESCAUM, MARAMA, the California Air Resources Board,
the California Air Pollution Control Officers Association (CAPCOA), and
the South Coast Air Quality Management District. While different points
of view were expressed, all of these discussions reflected the
importance of having a nationally uniform advisory system to present
consistent health effects information that is related to air quality
levels. These discussions helped shape the preparation of a staff draft
PSI sub-index for O3, related O3-specific
cautionary statements, and a draft booklet on O3 health
effects, ``SMOG--Who Does It Hurt?''.
B. Staff Draft Revisions to PSI Sub-index for Ozone
1. Availability for Use in the 1998 Ozone Season
Building on health effects information from the review of the
O3 and PM standards, comments received on the O3
NAAQS proposal, and input from State, local agencies, and associations,
EPA staff prepared draft revisions to the PSI sub-index for
O3. Recognizing that some State and local agencies wanted to
use a sub-index based on the new 8-hour O3 NAAQS for the
1998 O3 season, in early March we made the draft revised
O3 sub-index available through our AIRNOW web site and
through appropriate organizations across the nation. The availability
of this revised
[[Page 67823]]
O3 sub-index made possible uniform reporting of the PSI
during the 1998 O3 season based on the 8-hour O3
NAAQS for those agencies that chose to do so.5 The draft
sub-index categories, descriptors, and related O3
concentrations, together with related cautionary statements, were the
basis for the 1998 O3 maps produced by the Ozone Mapping
Project. The draft O3 sub-index also provided a link to the
8-hour O3 standard for use in O3 action programs
around the country.
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\5\ For the 1998 O3 season, State and local air
agencies could use either the staff draft revised O3 sub-
index based on the 8-hour O3 standard, or the PSI based
on the 1-hour O3 standard.
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2. What Were the Staff Draft Revisions?
Draft revisions to the PSI and the O3 sub-index,
together with new O3 specific cautionary statements, were
based on the expanded understanding of O3 health effects
gained during the review of the O3 NAAQS, comments received
on the O3 NAAQS proposal and subsequent input from State and
local agencies, and consideration of the implications of the draft
revisions for the pollutants other than O3 that are included
in the PSI.
The staff draft O3 sub-index reflected general changes
to the structure of the PSI as well as specific changes to reflect the
new 8-hour O3 NAAQS. In particular, the primary change to
the structure of the PSI was to divide the ``unhealthful'' category
(PSI values of 101 to 200) into two categories, ``unhealthy for
sensitive groups'' and ``generally unhealthy.'' The use of the
descriptor ``unhealthy for sensitive groups,'' for PSI values from 101
to 150, was intended to appropriately caution members of sensitive
groups 6 without unduly alarming the general public. This
revision recognized that the NAAQS are established to protect sensitive
groups, such that at air quality concentrations just above the
numerical level of NAAQS the general population is unlikely to
experience exposures of concern. Secondly, while the ``moderate''
category (PSI values of 51 to 100) was not divided into two categories,
allowance was made to create, in essence, a sub-category in the upper
half of this range (PSI values of 76 to 100) for pollutants for which a
limited health notice might be appropriate. Such a limited notice would
recognize that the NAAQS are not risk free, and that even at
concentrations below the numerical level of a NAAQS some extremely
sensitive individuals may experience exposures of concern for some
pollutants. The only other change made to the PSI was to replace the
descriptor ``very unhealthful'' (PSI values from 201 to 300) with the
descriptor ``very unhealthy.'' The other categories of ``good'' (PSI
values from 0 to 50) and ``hazardous'' (PSI values from 301 to 500)
were left unchanged.
---------------------------------------------------------------------------
\6\ The staff draft recognized that groups may be ``sensitive''
or particularly at-risk to the effects of a pollutant due to
inherent sensitivity, medical conditions and exposure conditions.
More specifically, sensitive groups at increased risk to
O3 effects, include active children and outdoor workers
who regularly engage in outdoor activities and people with
preexisting respiratory disease (e.g., asthma, chronic obstructive
lung disease). Some individuals within these groups are unusually
responsive to O3 and may experience much greater
functional and symptomatic effects from exposure to O3
than the average person in the group.
---------------------------------------------------------------------------
Consistent with these structural changes and with the new 8-hour
03 NAAQS, the staff draft identified breakpoints for the
03 sub-index in terms of 8-hour 03 concentrations
to the extent possible based on the available health effects
information. A breakpoint between the good and moderate categories
needed to be defined since there is no annual standard for
03 to use as the breakpoint. An 8-hour 03
concentration of 0.06 ppm was identified based in part on risk
estimates done in conjunction with the review of the 03
NAAQS which suggested that risk to healthy people likely becomes
negligible at this level (Whitfield et al., 1996). This consideration
was judged by staff to be a more appropriate basis for distinguishing
between good and moderate categories than the historical approach of
setting this breakpoint equal to one-half the numerical level of the
short-term standard in the absence of an annual standard. Further, a
breakpoint at this level would result in a sufficiently broad range of
concentrations for the moderate category to facilitate forecasting and
to make gradations in air quality more visually apparent in the Ozone
Map. On the other hand, the concentration of 0.07 ppm, 8-hour average,
was judged by staff as the appropriate breakpoint for starting to
convey a limited health message for extremely sensitive individuals.
Thus, this intermediate level of 0.07 ppm, associated with a PSI value
of 75, resulted in essentially creating a sub-category in the upper
half of the moderate category. Conveying such a limited health message
for extremely sensitive individuals at concentrations just below the
level of the NAAQS is consistent with the advice of CASAC during the
review of the 03 NAAQS (Wolff, 1995).
For PSI categories above the numerical level of the 03
NAAQS, staff again drew in part upon the risk assessment (Whitfield et
al., 1996) done in conjunction with the review of the NAAQS to provide
a basis for selecting the breakpoint between the generally unhealthy
and very unhealthy categories (corresponding to a PSI value of 200).
Our risk assessment estimates that above a level of 0.12 ppm, 8-hour
average, healthy individuals (adults and children) at prolonged,
moderate exertion would likely experience the following risks: (1)
Approximately 50 percent are estimated to experience temporary moderate
lung function impairment, (2) approximately 20 percent are estimated to
experience temporary large lung function impairments, and (3)
approximately 10 to 15 percent are estimated to experience temporary
moderate to severe respiratory symptoms (e.g., chest pain and
aggravated cough). Individuals with asthma or other respiratory
conditions would be more severely impacted than healthy individuals,
leading some to increase medication usage and seek medical attention,
such as increased doctor visits, increased emergency room and clinic
visits, and increased hospital admissions. Staff judged that it was
appropriate to characterize risks at these levels and above as being
very unhealthy. The draft breakpoint between the two new categories
(corresponding to a PSI value of 150) was set at 0.10 ppm, 8-hour
average. This is the level at which staff judged that exposures are
associated with an increase in the number of individuals who could
potentially experience effects, including possible respiratory effects
in the general population and a greater likelihood of respiratory
symptoms and breathing difficulty in sensitive groups. For many
locations across the country, this 8-hour average breakpoint of 0.10
ppm approximately corresponds to a 1-hour average concentration of 0.12
ppm, the level of the 1-hour 03 standard.
Since no human health effects information was available for 8-hour
average O3 concentrations at significantly higher levels,
the breakpoints at the upper end of the PSI scale (between the very
unhealthy and hazardous categories and the SHL which corresponds to the
top of the PSI scale of 500) were retained in terms of the existing 1-
hour average concentrations.
3. Related Informational Materials
In April, 1998, we put on the AIRNOW Web site a draft booklet,
called ``SMOG--Who Does It Hurt? What You Need To Know About Ozone and
Your Health,'' that provides information for the general public about
O3 health effects and is based on
[[Page 67824]]
scientific information gained in the recent review of the O3
standard. The impetus for the development of this booklet was the
recognition that many members of the public would appreciate more
detailed information about the health effects associated with different
levels of air pollution, especially since better understanding of
health effects empowers individuals to make personal decisions
regarding exposure reduction. This recognition was encouraged by
commenters on the O3 NAAQS proposal who endorsed increasing
the specificity of warnings with regard to health effects. Such
commenters noted that citizens are capable of dealing with complex
information and that individuals with respiratory disease and their
families appreciate such information. ``SMOG--Who Does It Hurt?'' was
designed to provide, in simple language, enough detail for individuals
to understand who is at most risk from O3 exposure and why,
the nature of O3 health effects, and a detailed explanation
of how individuals can reduce the likelihood of exposure using common
everyday activities as examples. This booklet was also intended to
support programs such as the Ozone Mapping Project and State/local
community action programs.
Currently, there are other materials available that provide
information about O3 and the PSI on the AIRNOW web site.
Information about ground-level as contrasted to stratospheric
O3 may be found in EPA's publication ``Ozone: Good Up High,
Bad Nearby.'' The EPA's video ``Ozone Double Trouble'' also provides
information about ground-level and stratospheric O3 and the
health effects associated with exposure to ground-level O3,
or smog. A short fact sheet, called the ``Air Quality Guide,'' provides
information about O3 health effects and the sources of
ground-level O3. The brochure ``The Pollutant Standards
Index'' (EPA 1994) will be updated to reflect final revisions to the
PSI and will include as guidance pollutant-specific health effects and
cautionary statements.
4. What Was the Feedback on the Staff Draft?
a. Focus Groups. We sponsored eight focus groups to help evaluate
how effectively the PSI descriptors and the colors used with the Ozone
Map, the related cautionary statements, and the O3 health
effects booklet communicate air quality and health effects information.
The focus groups were conducted by a contractor, including the
selection of participants, securing meeting facilities, and producing
necessary materials. The methods and materials used and the results
from the focus groups are summarized below and presented in a final
report, ``Report of the Focus Groups on the Ozone Map, the Pollutant
Standards Sub-Index for Ozone, and the Ozone Health Effects Booklet,''
(SAIC, 1998) available in the docket.
Background. From August to October, 1998, focus groups were held in
eight locations around the country that have different air quality with
respect to ozone. Five focus groups, held in Denver, CO; Atlanta, GA;
Houston, TX; San Bernardino, CA; and St. Louis, MO; were comprised of
members of the general public. A focus group held in Miami, FL was
comprised of people over 50 years of age with chronic lung disease
(asthma, chronic bronchitis, or emphysema). Another focus group, held
in Chicago, IL was comprised of urban parents of children with asthma.
Lastly, in October, a focus group was conducted in Los Angeles that was
comprised of journalists. Twelve participants and three alternates were
recruited for each of the eight focus groups. Participants in the
general public focus groups were selected to fit a profile that matched
the demographic characteristics of each city in terms of ethnicity,
age, gender, and education level. The participants in the Miami and
Chicago focus groups were selected to represent target audiences that
EPA believes may benefit most from understanding and applying the
information provided by the PSI, the Ozone Map, and the O3
health effects booklet. Journalists were selected as a target audience
because they use these informational materials to inform and educate
the public.
At the focus groups, participants were asked about various versions
of the Ozone Map, and the PSI descriptors presented in the legends of
the maps, related informational materials such as the cautionary
statements and O3 health effects booklet, and the Index
name. Four different versions of the Ozone Map were compared for
effectiveness in conveying information about air quality and associated
health effects. Each version of the map showed O3 levels in
the eastern third of the U.S. on a day with high O3
concentrations. The first three maps differed only in the descriptors
used in the legend (Maps 1 and 2) and in the addition of the definition
of sensitive groups to the bottom of the map (Map 3). The fourth map
used two shades of yellow in the moderate category to depict a
subcategory that could be associated with a limited health message. The
comparison of these maps evaluated the most basic configuration of
information, the colors and descriptors associated with different PSI
categories, which are used not only with the Ozone Map, but are also
often used in newspaper reports. With a minimal introduction, the
participants were asked questions about each map to determine if they
understood what that map says about air quality and associated health
effects. In addition, the four maps were displayed side-by-side and
participants were asked: Which map does the best job of communicating
whether air quality was good or bad for your health? Which map did you
prefer?
Lastly, because comments received earlier from many State and local
agencies indicated a preference for the name ``Air Quality Index
(AQI),'' rather than the ``PSI,'' participants in four of the seven
focus groups (Atlanta, Houston, Miami and Chicago) were asked which of
two names (Pollutant Standards Index or Air Quality Index) they
preferred and why.
Participants also were shown the cautionary statements included
with the staff draft (and used in conjunction with the Ozone Map) for
the ``moderate,'' ``unhealthy for sensitive groups,'' and ``generally
unhealthy'' categories, and were asked questions to evaluate the
effectiveness of the statements in providing cautionary information. In
addition, the O3 health effects booklet, ``SMOG--Who Does It
Hurt?'' was evaluated to assess how well it conveys information in an
easily understandable form about three basic concepts, O3
health effects, sensitive groups, and ways to minimize exposures of
concern. The booklet was designed to communicate these three basic
concepts that staff believe are important to enhance people's
understanding of the PSI. Participants read the booklet and then
answered questions to determine if they understood the three basic
concepts.
Results. The results of the focus groups held across the nation
were fairly consistent. Only the results pertaining to the maps and
descriptors are discussed below, since these results were considered in
the development of this proposal. Results pertaining to the cautionary
statements and the O3 health effects booklet have been
considered in revising these related informational materials.
The messages of the maps were generally well understood. Comments
indicated that the descriptor ``unhealthy for sensitive groups''
communicates the intended health effects information. Participants
identified that at this level only members of sensitive groups, and not
the general population, should be concerned about personal exposure.
[[Page 67825]]
Many participants in each group preferred the simpler descriptor
``unhealthy'' to ``generally unhealthy.''
Considering the first three maps, participants commented that the
definition of sensitive groups, added in Map 3, provides information
that they found useful. Whereas most participants expected the
sensitive groups to include those with respiratory diseases, such as
asthma, the inclusion of healthy active children and outdoor workers in
the definition of sensitive group was a surprise to many participants.
The majority of participants agreed that Map 3 communicated air quality
and health effects information most effectively, and it was also the
preferred Map. There were a couple of participants in each group who
preferred a simpler map.
The responses from the focus groups about Map 4 reflected confusion
on the part of many participants about the two shades of yellow used to
depict the moderate category. This confusion was due in part because
only one shade of yellow was apparent in the legend. Although many
participants understood that the lighter shade of yellow represented
better air quality, many felt this information was of questionable
value since the legend did not explain what this meant in terms of a
health message. Some noted that without an associated health message,
it was not clear why different colors or shadings would be used to
depict the ``moderate'' category. As part of further discussion on the
cautionary statement associated with the ``moderate'' category,
participants learned that there was, in essence, a subcategory at the
upper end of this range for extremely sensitive individuals. Some
participants then questioned why the lower end of the moderate range
should not just be included in the good category if there was no
associated health message.
Almost all of the participants preferred the name Air Quality Index
to Pollutant Standards Index. In general, participants felt that the
name Air Quality Index communicates what the index is about more
effectively than the name Pollutant Standards Index. Participants
noted, for example, that the name Pollutant Standards Index does not
indicate that the index is about air quality rather than pollution in
general.
b. State/local agencies. In the many meetings with State and local
agencies and national and regional associations, one key issue that
continued to be discussed in the context of the Ozone Map and community
action programs was the issue of what colors to associate with the
``unhealthy for sensitive groups'' and ``generally unhealthy''
categories in particular. These discussions typically focused on which
category should be associated with the color red. As at the January
workshop, some have maintained that red should be used for the
``unhealthy for sensitive groups'' category. Others expressed the view
that red should be used when air quality is in the ``generally
unhealthy'' category and that orange should be used for the ``unhealthy
for sensitive groups'' category. These commenters have argued that
given the form of the standard, using red at the level of the standard
could allow many days to be classified as ``code red'' days in
community action programs, even when the standard is attained in that
area and public health is being protected. One commenter from a State
agency that used the categories and health advisories from the staff
draft, together with the color orange when air quality was in the
``unhealthy for sensitive groups'' category and red when air quality
was in the ``generally unhealthy'' category, indicated that their
agency encouraged the same emissions reductions activities when air
quality was in either category. The commenter reported that people
appeared to understand the difference in the health advisories and to
take both levels of air quality advisories seriously.
C. What Is the Basis for the Proposed Revisions?
The primary consideration that shaped these proposed revisions is
the importance of providing nationally uniform health information
associated with daily ambient levels of the air pollutants included in
the index, consistent with the requirement of section 319 of the Act
for an index to achieve national uniformity in daily air quality
reporting. More specifically, the revisions to the O3 and PM
NAAQS provide the basis for the proposed specific changes to the PSI
sub-indices for O3 and PM to maintain the relationship
between an index value of 100 and the level of the NAAQS, and to
establish the relationships between ambient concentrations of these
pollutants and index values across the full scale of index values from
0 to 500. The proposed general changes to the structure of the PSI and
to related informational materials are based on the expanded
understanding that emerged during these reviews as to the nature of the
relationships between exposure to ambient concentrations of these
pollutants and the health effects likely to be experienced,
consideration of the implications of changes for the other pollutants,
and the broad input from State and local agencies and the public
discussed above. The proposed general changes to the PSI and related
informational materials will expand the use of the PSI to provide more
pollutant-specific health information, especially when ambient
concentrations are close to the level of the primary NAAQS.
1. What Are the Proposed General Changes?
a. Categories and related descriptors, index values and colors. The
PSI currently incorporates the pollutants O3, PM, CO,
SO2, and NO2. Index values range from 0 to
500,7 and the index is segmented into five categories named
by descriptor words that were chosen to characterize the relationship
between daily air quality and public health. To reflect better the
current understanding of the health effects associated with exposure to
these air pollutants, we are proposing to revise the PSI index values,
descriptors, and associated colors as shown below in Table 1.
---------------------------------------------------------------------------
\7\ For NO2, the index ranges from 200 to 500, since
there is no short-term NAAQS for this pollutant.
[[Page 67826]]
Table 1.--Proposed Category Index Values, Descriptors, and Colors
----------------------------------------------------------------------------------------------------------------
Index
Values Descriptor Color Purpose
----------------------------------------------------------------------------------------------------------------
0-50...... Good.................................... Green......................... Convey positive message
about air quality.
51-100.... Moderate................................ Yellow........................ Convey message that daily
air quality is acceptable
from public health
perspective, but every
day in this range could
result in potential for
chronic health effects;
and for O3, convey a
limited health notice for
extremely sensitive
individuals.
101-150... Unhealthy for Sensitive Groups.......... Orange........................ Health message for members
of sensitive groups.
151-200... Unhealthy............................... Red........................... Health advisory of more
serious effects for
sensitive groups and
notice of possible
effects for general
population when
appropriate.
201-300... Very Unhealthy.......................... Purple........................ Health alert of more
serious effects for
sensitive groups and the
general population.
301-500... Hazardous............................... Maroon........................ Health warnings of
emergency conditions.
----------------------------------------------------------------------------------------------------------------
These proposed changes reflect the addition of a new category above
the level of the standard (above a PSI of 100), created by dividing the
current ``unhealthful'' category into two categories. The ``unhealthy
for sensitive groups'' category would start just above the level of the
standard, and index values would range from 101 to 150. The
``unhealthy'' category would start at an index value of 151 and range
to an index value of 200.
When air quality is in the ``unhealthy for sensitive groups''
range, people that are in the sensitive group, whether the sensitivity
is due to medical conditions, exposure conditions, or inherent
sensitivity, may experience exposures of concern. However, exposure to
ambient concentrations in this range are not likely to result in
exposures of concern for most healthy people. The descriptor
``unhealthy for sensitive groups'' was chosen to convey this message
clearly. Participants in focus groups clearly understood that
``sensitive groups'' does not refer to the general public, indicating
that this descriptor effectively communicates the intended health
message. This category would include a caution that while perhaps of
interest to all citizens, would be of particular interest to
individuals and families of individuals who are members of sensitive
groups.
As air quality moves into the ``unhealthy'' range, exposures are
associated with an increase in the number of individuals who could
potentially experience effects and includes a greater proportion of
members of the general public. Based on input received on the staff
draft revisions, the descriptor ``unhealthy'' appropriately
characterizes air quality in this range and does not need to be
modified further by the word ``generally'' as in the staff draft.
In addition to an increasing number of exposures of concern, when
air quality moves into the ``unhealthy'' range and above, individuals
who were affected at lower levels, typically members of sensitive
groups, are likely to experience more serious health effects than
members of the general public. To reflect this understanding, it is
appropriate to convey two messages in the cautionary statements for
both the ``unhealthy'' and ``very unhealthy'' categories. One message
is directed to members of sensitive groups, and the other is directed
to the general public. The use of a distinct cautionary message for
members of sensitive groups is entirely consistent with an original
goal that the index be based on the relationships between pollutant
concentrations and adverse health effects within various groups, e.g.,
aggravation of disease in people with respiratory disease and incidence
of respiratory effects in healthy people. Guidance on pollutant-
specific cautionary statements related to the categories of the PSI is
discussed below in section II.C.3.
We are not proposing to add a new category or subcategory below the
numerical level of the standard to caution extremely sensitive
individuals, as was previously contemplated or included in the staff
draft. While commenters on the O3 NAAQS proposal broadly
endorsed expanding the use of the PSI to provide more specific health
information around the level of the standard, many commenters did not
support the addition of another category below the level of the
standard to convey this message. Many commenters expressed the view
that the addition of two new categories would unduly complicate the
index. Further, we recognize that while such a category may be
meaningful and appropriate for O3, based on the expanded
information from the most recent O3 NAAQS review, it would
not be an appropriate distinction for the other pollutants included in
the index. Rather, this proposal addresses these issues by setting the
breakpoint between good and moderate categories for O3 at
the concentration where a limited health message for extremely
sensitive individuals could appropriately be conveyed and by providing
guidance on pollutant-specific cautionary statements for use in
conjunction with PSI reporting (discussed in section II.C.3 below and
in a related guidance document). This approach is intended to retain
simplicity in the index while allowing for more detailed cautionary
information to be made available to the public when appropriate.
Consistent with the overarching goal of national uniformity in the
reporting of air quality, we are proposing that the specific colors
listed in Table 1 be associated with each category. While the PSI can
be reported without the use of colors (through text and numbers alone),
when the index is reported using colors, we propose to require that
only these specified colors be used. Three examples of PSI reports that
use color are the color bars that appear in many newspapers, the color
scales on State and local agency web sites, and the color contours of
the Ozone Map. We have participated in many discussions with State and
local agencies and associations regarding which specific colors should
be associated with the PSI categories, particularly above the level of
the standard. These discussions typically have been in the context of
either the Ozone Mapping Project or community action programs. It is
clear that the color associated with a category can be part of the
health effects and cautionary message being conveyed, and that
different colors convey different messages to different people. Were
various State and local agencies to use different colors to represent
the same category, and thus the same level of air quality, it could
well send a confusing message about air quality and associated health
effects to the public. Because it is a fundamental goal of the PSI to
[[Page 67827]]
provide nationally uniform information about daily air quality and the
public health messages that are appropriately associated with various
daily air quality levels, in a format that is timely and easily
understood, we believe that requiring specified colors when the PSI
categories are reported in color format is both necessary and
appropriate.
Further, we believe that the specific colors being proposed are
appropriate for the health messages being conveyed in each category. As
discussed in the section above, the results of the focus groups
indicate that, above the level of the standard, the combination of
colors and descriptors proposed by us effectively communicates the
intended health effects message. The comments of focus group
participants (SAIC, 1998) support the generally accepted view that the
color red sends a strong cautionary message. We believe that this color
is most appropriate to use when effects are likely to occur in the
general population, and when more serious effects are likely in members
of sensitive groups. We believe that the combination of the use of
orange and red for the two categories above the level of the standard
appropriately conveys a gradation of concern that is consistent with
our understanding of the likely public health effects associated with
these categories. We note that the numerical levels of the 8-hour
average O3 NAAQS and the 24-hour average PM NAAQS were set
in conjunction with specific forms of these standards which have the
effect of allowing multiple days a year during which the level of the
standard can be exceeded. These combinations of levels and forms
provide the requisite degree of public health protection, even when
some days reach air quality levels above the level of the standards.
Thus, it is consistent with the selection and definition of these NAAQS
that a gradation of colors be used, and that the color red be specified
for the PSI category with a stronger cautionary message.
As an alternative to requiring the use of specified colors, we are
soliciting comment on the option of recommending, rather than
requiring, the use of these colors when reporting agencies choose to
report the PSI in color format. In soliciting comment on this
alternative, we are seeking to allow communities maximum flexibility in
PSI reporting, while still preserving a nationally uniform air quality
index. We therefore request that commenters addressing this issue
discuss how this more flexible approach would satisfy the statutory
language requiring a nationally uniform air quality index if different
colors may be used across the nation to represent the same range of air
quality.
b. Reporting requirements. We propose to change 40 CFR part 58.50
to require reporting of the PSI in all Metropolitan Statistical Areas
(MSAs) 8 with a population over 350,000, instead of all
urbanized areas with a population over 200,000. This change is being
proposed for consistency with the other monitoring regulations in part
58, which are or will be based on MSAs. This change does not, however,
have a significant impact on who is required to report, since virtually
the same number of cities would be covered under the proposed reporting
requirement as are covered under the existing requirement.
---------------------------------------------------------------------------
\8\ A complete list of MSAs and their boundaries can be found in
the Statistical Abstract of the United States (1998).
---------------------------------------------------------------------------
Consistent with early input from State and local agencies, we are
proposing to change the rounding conventions used to calculate index
values corresponding to pollutant concentrations at and above the
numerical level of the NAAQS to be consistent with the rounding
conventions used in defining the NAAQS for each pollutant. This will
avoid situations where a health advisory could be issued that describes
the air as unhealthy, when in fact the numerical level of the standard
has not been exceeded. The revised rounding conventions are presented
below in the proposed appendix G--Uniform Air Quality Index and Daily
Reporting.
The proposed rule retains the requirements to identify the area for
which the PSI is being reported, the time period covered by the report,
the ``critical'' pollutant for which the reported PSI value was
derived, the PSI value, and the associated category descriptor. The
proposed rule adds two requirements, (1) to report the associated
category color if a color format is used and, (2) to report all PSI
values greater than 100. Because different sensitive groups are at-risk
from different pollutants, issuing advisories for all sensitive groups
who may be affected at PSI values greater than 100 clearly improves
public health protection. The proposed rule continues to encourage, but
does not require, that PSI reports include the PSI for sub-divisions of
the MSA (if there are important differences in air quality across sub-
divisions of the MSA), the actual pollutant concentrations, possible
causes for high index values, and appropriate health effects and
cautionary statements (based on the guidance discussed in section
II.C.3 below). These topics are also discussed in our updated
``Guideline for Public Reporting of Daily Air Quality--Pollutant
Standards Index (PSI)'' (EPA 1998b).
The proposed rule emphasizes the importance of forecasting the PSI
by specifying that forecasted values should be reported, when possible,
but does not require that forecasted values be reported. Given the
importance of the O3 sub-index in a large number of MSAs,
and the use of an 8-hour averaging time for calculating the
O3 sub-index value, forecasting the O3 index
value is now more beneficial than before. For a health advisory system
to be effective, people need to be notified as early as possible to be
able to avoid exposures of concern. Because the proposed O3
sub-index is based on the 8-hour O3 NAAQS, forecasting
O3 concentrations clearly would have increased value in
providing cautionary statements to the public. In the past, when a
health advisory was issued because the PSI value of 100 had been
exceeded for the 1-hour O3 NAAQS, people potentially had
time to avoid exposures of concern because O3 levels tend to
remain elevated for several hours during the day. With an 8-hour
standard, however, this would not be the case, since by the time the
level of the 8-hour NAAQS has been exceeded and a health advisory
issued, the potential for exposures of concern would likely have passed
for that day. Forecasting 8-hour maximum O3 concentrations
would facilitate the risk-reduction function of the PSI by giving
people time to limit or avoid exposures of concern. We recognize that
many State and local air agencies are already issuing health advisories
based on forecasted O3 concentrations. Since we have
determined that forecasting would add much to the benefits of PSI
reporting, we will be making available guidance on starting a
forecasting program (EPA 1999) in an area or MSA where forecasting is
not presently done. Included in the document will be guidance on using
hourly O3 concentrations as predictors for 8-hour averages.
c. Index name. Many State and local agencies have encouraged us to
change the name of the PSI to the Air Quality Index, or AQI, since many
agencies already use the name AQI when reporting the PSI value to the
public. Most participants in the focus groups preferred the name AQI,
commenting that it more clearly identified the index as relating to the
quality of the air rather than to environmental pollution in general.
On the other hand, we note that changing the name may result in
confusion due to historical familiarity and usage, not only in the U.S.
but
[[Page 67828]]
internationally, since the PSI has been used by many countries
throughout the world for many years. Based on these considerations, we
are soliciting comment on changing the name of the Pollutant Standards
Index (PSI) to the Air Quality Index (AQI).
2. What Are the Proposed Changes to the Sub-Indices?
To conform to the proposed general changes to the PSI discussed
above, and to reflect the recent revisions to the O3 and PM
NAAQS, we are proposing changes to the sub-indices for O3,
PM, CO, and SO2; no conforming changes are necessary for the
NO2 sub-index. The proposed sub-indices are summarized below
in Table 2, in terms of pollutant concentrations that correspond to
breakpoints in the index, and are discussed in the following sections.
These sub-indices are presented in more detail in the proposed appendix
G to reflect the proposed changes to the numerical rounding conventions
for calculating index values.
Table 2.--Breakpoints for O3, PM2.5, PM10, CO, and SO2 Sub-indices
----------------------------------------------------------------------------------------------------------------
O3 PM
-----------------------------------------------------------------
PSI value PM2.5, 24-hr PM10, 24-hr CO, 8-hr (ppm) SO2, 24-hr
8-hr (ppm) 1-hr (ppm) (g/ (g/ (ppm)
m3) m3)
----------------------------------------------------------------------------------------------------------------
50............ 0.07 .............. 15 50 4 0.03
100............ 0.08 0.12 65 150 9 0.14
150............ 0.10 0.16 100* 250 12 0.22
200............ 0.12 0.20 150* 350 15 0.30
300............ 0.40 (1-hr) 0.40 250* 420 30 0.60
400............ 0.50 (1-hr) 0.50 350* 500 40 0.80
500............ 0.60 (1-hr) 0.60 500* 600 50 1.00
----------------------------------------------------------------------------------------------------------------
*If a different SHL for PM2.5 is promulgated, these numbers will change accordingly.
a. Ozone sub-index. On July 18, 1997, we revised the O3
primary NAAQS to replace the 1-hour standard with a new standard with
an 8-hour average at a level of 0.08 ppm and a form based on the 3-year
average of the annual fourth-highest daily maximum 8-hour average
O3 concentrations measured at each monitor within an area
(62 FR 38856-38896). These revisions were based on findings from the
most recent review of the NAAQS indicating that the new primary
standard will provide increased protection to the public, especially
children active outdoors and other sensitive groups, against a wide
range of O3-induced health effects, including decreased lung
function; increased respiratory symptoms; hospital admissions and
emergency room visits for respiratory causes, among children and adults
with pre-existing respiratory disease such as asthma; inflammation of
the lung; and possible long-term damage to the lungs. In setting this
standard, we recognized that there is no discernible threshold below
which health effects do not occur, that the standard is not risk free,
and, thus, that exposures of concern are possible below the numerical
level of the standard for some extremely sensitive individuals.
Based on feedback on the staff draft, above a PSI value of 100, we
propose to adopt the revisions to the O3 sub-index that were
presented in the staff draft, and to make changes to the staff draft
below that value. The proposed revisions to the O3 sub-index
above the level of the standard, and the rationale for these proposed
revisions, are discussed above in section II.B.2. Below the level of
the standard, at a PSI value of 50, we propose that 0.07 ppm, 8-hour
average, be the breakpoint between the good and moderate categories. As
in the staff draft, this concentration is judged by staff as an
appropriate breakpoint for starting to convey a limited health message
for extremely sensitive individuals. This breakpoint was adopted
because comments received indicated that the draft subcategories within
the moderate category created confusion, and that having a distinct
subcategory within moderate with no health message was unnecessary. We
recognize that this breakpoint defines a category with a somewhat
narrower range of concentrations. However, we believe this breakpoint
makes an important distinction to emphasize the limited health message
for extremely sensitive individuals. The effect of this range on
forecasting is addressed in the forecasting guidance. Beyond this
issue, comments received on the staff draft O3 sub-index,
discussed in section II.B.4, have been generally positive and have
focused on the presentation of the sub-index through the Ozone Mapping
Project and on the wording of associated cautionary statements included
as guidance. These proposed revisions are consistent with the proposed
general changes to the PSI discussed above in section II.C.1.a.
These proposed revisions reflect the new 8-hour O3 NAAQS
and will in almost all areas result in a more health protective index
than the current index based on the 1-hour O3 standard.
However, we recognize that a very small number of areas in the U.S.
have atypical air quality patterns, with very high 1-hour daily peak
O3 concentrations relative to the associated 8-hour average
concentrations. In such areas, the use of the current 1-hour sub-index
may be more health protective on a given day than the proposed 8-hour
sub-index. To allow for the reporting of the more health protective
sub-index value, we also propose to retain the 1-hour sub-index at and
above PSI values of 100 and to allow the reporting of the higher of the
two O3 sub-index values. Thus, both the new 8-hour and the
current 1-hour sub-indices, as shown in Table 2, are included in the
proposed appendix G. To conform to the proposed general changes to the
PSI, a breakpoint of 0.16 ppm, 1-hour average, has been added to the 1-
hour sub-index at a PSI value of 150. This value is the mid-point of
the breakpoints at PSI values of 100 and 200. Since for the large
majority of areas the 8-hour sub-index will be more health protective,
we are not proposing to require all areas to calculate both sub-index
values. Rather, we are proposing to allow areas the flexibility to
calculate both sub-index values and, when both sub-index values are
calculated, to require that the higher value be reported. We are
specifically soliciting comment on this proposed approach.
b. PM sub-index. On July 18, 1997, we revised the PM NAAQS by
adding a new set of standards for fine particles, or PM2.5,
set at levels of 15 g/m3 (annual) and 65
g/m3 (24-hour average) (62 FR 38652-38760). These
revisions were based on findings from the most recent review of the PM
NAAQS that recently published studies have
[[Page 67829]]
indicated that serious health effects were more closely associated with
the levels of the smaller particle subset of PM10. These
health effects include premature mortality and increased hospital
admissions and emergency room visits, primarily in the elderly and
individuals with cardiopulmonary disease; increased respiratory
symptoms and disease in children and individuals with cardiopulmonary
disease such as asthma; decreased lung function, particularly in
children and individuals with asthma; and alterations in respiratory
tract defense mechanisms. In addition, PM10 standards were
retained at the same levels of 50 g/m\3\ (annual) and 150
g/m\3\ (24-hour average) to continue to provide protection
against health effects associated with the coarse particle subset of
PM10, including aggravation of asthma and respiratory
infections. To reflect these revisions to the PM NAAQS, we are
proposing to add a new sub-index for PM2.5, and to make
conforming changes to the sub-index for PM10, consistent
with the proposed general changes to the PSI described above in section
II.C.1.a. These proposed sub-indices are summarized above in Table 2
and discussed below.
New PM2.5 sub-index. Consistent with the basic structure
of the PSI, an index value of 100 corresponds to the level of the 24-
hour PM2.5 NAAQS, 65 g/m\3\, and an index value of
50 corresponds to the level of the annual NAAQS, 15 g/
m\3\. Also consistent with the basic structure of the PSI, the upper
bound index value of 500 corresponds to the SHL, established in section
51.16 of the CFR under the Prevention of Air Pollution Emergency
Episodes program. The SHL is set at a level that represents an imminent
and substantial endangerment to public health. In mid-1999, we will
propose revisions to the Prevention of Air Pollution Emergency Episodes
program, which will include an SHL for PM2.5. In advance of
proposing an SHL for PM2.5, we are now proposing to
establish a PM2.5 concentration 9 to be
associated with a PM2.5 index value of 500.
---------------------------------------------------------------------------
\9\ Should the final SHL for PM2.5, when promulgated,
be different from this concentration, we will revise this
PM2.5 sub-index accordingly.
---------------------------------------------------------------------------
In proposing to establish this PM2.5 concentration to be
associated with a PM2.5 index value of 500, the primary
focus is on evidence linking mortality with increases in PM
concentration. The current SHL for PM10 (600 g/
m\3\) was established on the basis of the increased mortality found
during historical wintertime pollution episodes in London, where PM
concentrations, measured as British Smoke, were in the range of 500 to
1000 g/m\3\ (52 FR 24687-24688). We believe that these studies
still provide the best scientific support for significant harm levels
for PM. British Smoke provides an approximate measurement of fine
particles, since it is considered to measure PM with a cut-point of
approximately 4.5 microns. While some coarse mode particles are
included, it has been found that mainly fine mode particles are
collected using the British Smoke method. In establishing the SHL for
PM10, we used an assumption that a concentration of
PM10 can be estimated by adding 100 to a concentration
measured in terms of British Smoke (52 FR 24688). For the purposes of
proposing to establish a PM2.5 concentration to be
associated with a PM2.5 index value of 500, we are assuming
that particle mass concentration measured by the British Smoke method
is approximately equivalent to a PM2.5 mass concentration.
For intermediate breakpoints in the PSI between values of 100 and
500, PM2.5 concentrations are proposed that generally
reflect a linear relationship between increasing index values and
increasing PM2.5 values. The available scientific evidence
of health effects related to population exposures to PM2.5
concentrations between the 24-hour NAAQS level and the proposed SHL
suggest a continuum of effects in this range, with increasing
PM2.5 concentrations being associated with increasingly
larger numbers of people likely experiencing serious health effects (62
FR 38675; Staff Paper, p. VII-27) The proposed generally linear
relationship between PSI values and PM2.5 concentrations in
this range, rounded to increments of 50 g/m3 to
reflect the approximate nature of such a relationship, is consistent
with this evidence.
Conforming changes to the PM10 sub-index. Consistent
with the retention of the levels of the PM10 NAAQS, we are
proposing to retain the PM10 sub-index generally and to add
a new breakpoint at an index value of 150 to conform to the proposed
additional PSI category. We propose that this breakpoint be set at a
PM10 24-hour average concentration of 250 g/
m3, the mid-point between the breakpoints associated with
index values of 100 and 200. We believe that the PM10 sub-
index, with this conforming change, remains appropriate for the public
health protection purposes of the PSI.
c. Conforming changes to the CO and SO2 sub-indices.
Since the current PSI sub-indices reflect the current NAAQS for CO and
SO2, the only change being proposed today for these sub-
indices is to add a breakpoint to each sub-index at an index value of
150 to conform to the proposed additional PSI category. We propose that
these breakpoints be set at concentrations at the mid-points between
the breakpoints associated with index values of 100 and 200, consistent
with the approach described above for conforming changes to both the 1-
hour O3 sub-index and the PM10 sub-index. These
proposed breakpoints are summarized in Table 2 and presented in more
detail in appendix G to reflect the proposed changes to the numerical
rounding conventions used to calculate index values. These sub-indices
will be reviewed in conjunction with the future reviews of the CO and
SO2 NAAQS.
3. What are the Changes to Related Informational Materials?
We have edited related informational materials on O3
prepared in conjunction with the staff draft O3 sub-index,
such as the cautionary statements, to reflect the input from the focus
groups and from national, State and local agencies and associations.
The edits include some of the wording changes suggested to the
cautionary statements, as well as clarification of the health/air
quality message associated with the moderate category. In the
``unhealthy'' and ``very unhealthy'' categories, there are distinct
cautionary statements for members of sensitive groups and the general
public. In addition, because different conditions make individuals and
groups susceptible to the effects of different air pollutants, we have
developed pollutant-specific health effects and cautionary statements
for the other pollutants in the index, including PM2.5,
PM10, CO, SO2, and NO2. The health
effects and cautionary statements may be found on AIRLINKS (http://
www.epa.gov/airlinks). Our draft guidance on PSI reporting, ``Guideline
for Public Reporting of Daily Air Quality--Pollutant Standards Index
(PSI)'' (EPA 1998b), which includes the health effects and cautionary
statements, is available in the docket and on AIRLINKS.
The brochure ``The Pollutant Standards Index'' (EPA 1994), contains
information about the general health effects associated with each
category, and precautions that sensitive groups and the general public
should take to avoid exposures of concern. Currently, it contains one
set of health effects and cautionary statements that are generally
applicable to all of the pollutants currently included in the PSI, and
does not identify specific sensitive groups for each of the pollutants.
In changes to this
[[Page 67830]]
brochure, we will revise the categories and descriptors to be
consistent with final revisions to the PSI, identify sensitive groups
in the health effects statements for each of the pollutants, and will
include the pollutant-specific health effects and cautionary statements
discussed above.
The booklet, ``SMOG--Who Does It Hurt?,'' was developed using
health effects information from the review of the standard and
therefore already incorporates the concepts of sensitive groups and a
continuum of effects to background levels of O3. Revisions
to this booklet will be based on final revisions to the PSI,
information from the focus groups, and comments from national, State
and local agencies and associations. Based on these comments, the
distinction between stratospheric and ground-level O3 will
be made clearer, and the section ``What does exertion have to do with
O3-related health effects?'' will include clarification of
the effect of individual conditioning on exertion levels. In addition,
we are planning to develop a shorter, summary brochure about
O3 health effects to complement the ``SMOG--Who Does It
Hurt?'' booklet, to translate both ``SMOG--Who Does It Hurt?'' and the
shorter summary booklet into Spanish, and to develop informational
materials about O3 health effects for primary care
providers. All of these documents will be made available when revisions
to the PSI are final, including on the AIRNOW web site.
III. Regulatory and Environmental Impact Analyses
A. Executive Order 12866: OMB Review of ``Significant Actions''
Under Executive Order 12866, the Agency must determine whether a
regulatory action is ``significant'' and, therefore, subject to Office
of Management and Budget (OMB) review and the requirements of the
Executive Order. The order defines ``significant regulatory action'' as
one that may:
(1) Have an annual effect on the economy of $100 million or more or
adversely affect in a material way the economy, a sector of the
economy, productivity, competition, jobs, the environment, public
health or safety, or State, local, or tribal governments or
communities;
(2) create a serious inconsistency or otherwise interfere with an
action taken or planned by another Agency;
(3) materially alter the budgetary impact of entitlements, grants,
user fees, or loan programs or the rights and obligations or recipients
thereof; or
(4) raise novel legal or policy issues arising out of legal
mandates, the President's priorities, or the principles set forth in
the Executive Order. The OMB has advised us this proposal should be
construed as a ``significant regulatory action'' within the meaning of
Executive Order 12866. Accordingly, this action was submitted to the
OMB for review. Any changes made in response to OMB suggestions or
recommendations will be documented in the public record and made
available for public inspection at EPA's Air and Radiation Docket
Information Center (Docket No. A-98-20).
B. Regulatory Flexibility Analysis/Small Business Regulatory
Enforcement Fairness Act
Under the Regulatory Flexibility Act (RFA), 5 U.S.C. 601 et seq.,
EPA must prepare a regulatory flexibility analysis assessing the impact
of any proposed or final rule on small entities. Under 6 U.S.C. 605(b),
this requirement may be waived if EPA certifies that the rule will not
have a significant economic impact on a substantial number of small
entities. Small entities include small businesses, small not-for-profit
enterprises, and governmental entities with jurisdiction over
populations less than 50,000 people.
Today's proposal to revise the PSI program modifies existing air
quality reporting requirements for MSA's with populations over 350,000
people. Today's proposal, if promulgated, will not establish any new
regulatory requirements affecting small entities. On the basis of the
above considerations, EPA certifies that today's proposal will not have
a significant economic impact on a substantial number of small entities
within the meaning of the RFA. Based on the same considerations, EPA
also certifies that the new small-entity provisions in Section 244 of
the Small Business Regulatory Enforcement Fairness Act (SBREFA) do not
apply.
C. Unfunded Mandates Reform Act
Title II of the Unfunded Mandates Reform Act of 1995 (UMRA), P.L.
104-4, establishes requirements for Federal agencies to assess the
effects of their regulatory actions on State, local, and tribal
governments and the private sector. Under section 202 of the UMRA, EPA
generally must prepare a written statement, including a cost-benefit
analysis, for proposed and final rules with ``Federal mandates'' that
may result in expenditures to State, local and tribal governments, in
the aggregate, or to the private sector, of $100 million or more in any
1 year.
EPA has determined that today's proposal, if promulgated, would not
include a Federal mandate that may result in estimated costs of $100
million in any 1 year to either State, local, or tribal governments, in
the aggregate, or to the private sector. Accordingly, EPA has
determined that the provisions of section 202 of the UMRA do not apply
to this rulemaking.
D. Paperwork Reduction Act
Today's proposal does not establish any new information collection
requirements beyond those which are currently required under the
Ambient Air Quality Surveillance Regulations in 40 CFR part 58 (OMB
#2060-0084, EPA ICR No. 0940.15). Therefore, the requirements of the
Paperwork Reduction Act do not apply to today's action.
E. Executive Order 13045: Children's Health
Executive Order 13045, entitled ``Protection of Children from
Environmental Health Risks and Safety Risks'' (62 FR19885, April 23,
1997), requires Federal agencies to ensure that their policies,
programs, activities, and standards identify and assess environmental
health and safety risks that may disproportionately affect children. In
today's proposal, EPA identified children as one of the sensitive
groups which may be at increased risk of experiencing the effects of
concern following exposure to ozone. The proposed PSI categories,
descriptors, and cautionary statements all take into consideration the
increased health risk to children which may result from such exposures.
Therefore, today's action does comply with the requirements of E.O.
13045.
F. Executive Order 12848: Environmental Justice
Executive Order 12848 requires that each Federal agency make
achieving environmental justice part of its mission by identifying and
addressing, as appropriate, disproportionately high and adverse human
health or environmental effects of its programs, policies, and
activities on minorities and low-income populations in the United
States.
The nature of today's action is to inform the general public,
including minorities and low-income populations, about the nature of
the air pollution in the areas they live. Today's action establishes a
uniform tool for States to use to develop programs which will caution
particularly sensitive people to minimize their exposures and educate
the public about general health effects
[[Page 67831]]
associated with exposure to different pollution levels. States may also
use information established as part of the PSI to trigger programs
designed to reduce emissions to avoid exceedances of the NAAQS.
Therefore, today's action will help facilitate public participation,
outreach, and communication in areas where environmental justice issues
are present.
G. Executive Order 12875: Enhancing Intergovernmental Partnerships
Under Executive Order 12875, EPA may not issue a regulation that is
not required by statute and that creates a mandate upon a State, local
or tribal government, unless the Federal government provides the funds
necessary to pay the direct compliance costs incurred by those
governments, or we will consult with those governments. If EPA complies
by consulting, Executive Order 12875 requires us to provide to OMB a
description of the extent of our prior consultation with
representatives of affected State, local and tribal governments, the
nature of their concerns, copies of any written communications from the
governments, and a statement supporting the need to issue the
regulation. In addition, Executive Order 12875 requires us to develop
an effective process permitting elected officials and other
representatives of State, local and tribal governments ``to provide
meaningful and timely input in the development of regulatory proposals
containing significant unfunded mandates.''
Today's rule implements requirements specifically set forth by the
Congress in section 319 of the Act without the exercise of any
discretion by us. Accordingly, the requirements of section 1(a) of
Executive Order 12875 do not apply to this rule.
H. Executive Order 13084: Consultation and Coordination with Indian
Tribal Governments
Under Executive Order 13084, EPA may not issue a regulation that is
not required by statute, that significantly or uniquely affects the
communities of Indian tribal governments, and that imposes substantial
direct compliance costs on those communities, unless the Federal
government provides the funds necessary to pay the direct compliance
costs incurred by the tribal governments, or EPA will consult with
those governments. If EPA complies by consulting, Executive Order 13084
requires us to provide to OMB, in a separately identified section of
the preamble to the rule, a description of the extent of our prior
consultation with representatives of affected tribal governments, a
summary of the nature of their concerns, and a statement supporting the
need to issue the regulation. In addition, Executive Order 13084
requires us to develop an effective process permitting elected
officials and other representatives of Indian tribal governments ``to
provide meaningful and timely input in the development of regulatory
policies on matters that significantly or uniquely affect their
communities.''
Today's rule implements requirements specifically set forth by the
Congress in section 319 of the Act without the exercise of any
discretion by us. Accordingly, the requirements of section 3(b) of
Executive Order 13084 do not apply to this rule.
I. National Technology Transfer and Advancement Act
As noted in the proposed rule, Section 12(d) of the National
Technology Transfer and Advancement Act of 1995 (NTTAA), Pub L. No.
104-113, Sec. 12(d) (15 U.S.C. 272 note) directs EPA to use voluntary
consensus standards in its regulatory activities unless to do so would
be inconsistent with applicable law or otherwise impractical. Voluntary
consensus standards are technical standards (e.g., materials
specifications, test methods, sampling procedures, and business
practices) that are developed or adopted by voluntary consensus
standards bodies. The NTTAA directs EPA to provide Congress, through
OMB, explanations when the Agency decides not to use available and
applicable voluntary consensus standards. This action does not involve
technical standards. Therefore, EPA did not consider the use of any
voluntary consensus standards.
IV. References
EPA, (1994) ``Measuring Air Quality: The Pollutant Standards
Index,'' U.S. Environmental Protection Agency, Office of Air Quality
Planning and Standards (MD-10), Research Triangle Park, NC, 27711, EPA
451/K-94-001.
EPA, (1997) Review of the National Ambient Air Quality Standards
for Particulate Matter: Policy Assessment of Scientific and Technical
Information, OAQPS Staff Paper, Office of Air Quality Planning and
Standards, Research Triangle Park, NC 27711, EPA-452/R-96-013.
EPA, (1998a) Community Action Programs: Blueprint for Program
Design, U.S. Environmental Protection Agency, Office of Mobile Sources,
Ann Arbor, MI, EPA 420-R-98-003.
EPA, (1998b) Guideline for Public Reporting of Daily Air Quality--
Pollutant Standards Index (PSI), U.S. Environmental Protection Agency,
Office of Air Quality Planning and Standards, Research Triangle Park,
NC, 27711, draft document.
EPA, (1999) Guideline for Starting an Air Pollution Forecasting
Program, U.S. Environmental Protection Agency, Office of Air Quality
Planning and Standards, Research Triangle Park, NC, 27711, in
preparation.
Science Applications International Corporation, (1998) Report of
Eight Focus Groups on the Ozone Map, the Pollutant Standards Sub-Index
for Ozone, and the Ozone Health Effects Booklet, Science Applications
International Corporation, McLean, VA.
U.S. Department of Commerce, Statistical Abstract of the United
States, 1998, U.S. Bureau of the Census.
Whitfield, R.G.; Biller, W.F.; Jusko, M.J.; Keisler, J.M. (1996) A
probabilistic assessment of health risks associated with short-term
exposure to tropospheric ozone . Report prepared for U.S. EPA, OAQPS.
Argonne National Laboratory; Argonne, IL.
Wolff, G.T., (1995) Letter from Chairman of Clean Air Scientific
Advisory Committee to the EPA Administrator, dated November 30, 1995.
EPA-SAB-CASAC-LTR-96-002.
List of Subjects in 40 CFR Part 58
Environmental protection, Air pollution control, Air quality
surveillance and data reporting, Ambient air quality monitoring network
design and siting, Intergovernmental relations, pollutant standards
index, Quality assurance program.
Dated: December 1, 1998.
Carol M. Browner,
Administrator.
For the reasons set forth in the preamble, chapter I of title 40 of
the Code of Federal regulations is proposed to be amended as follows:
PART 58--AMBIENT AIR QUALITY SURVEILLANCE
1. The authority citation of part 58 continues to read as follows:
Authority: 42 U.S.C. 7410, 7601(a), and 7619.
2. Section 58.50 is revised to read as follows:
Sec. 58.50 Index reporting.
(a) The State shall report to the general public through prominent
notice an air quality index in accordance with the requirements of
appendix G to this part.
(b) Reporting is required by all Metropolitan Statistical Areas
with a population exceeding 350,000.
[[Page 67832]]
(c) The population of a Metropolitan Statistical Area for purposes
of index reporting is the most recent decennial U.S. census population.
3. Appendix G is revised to read as follows:
Appendix G--Uniform Air Quality Index and Daily Reporting
General Requirements
1. What is the PSI?
2. Why report the PSI?
3. Must I report the PSI?
4. What goes into my PSI report?
5. What colors do I use when I report the PSI?
6. Is my PSI report for my MSA only?
7. How do I get my PSI report to the public?
8. How often must I report the PSI?
9. May I make exceptions to these reporting requirements?
Calculation
10. How does the PSI relate to air pollution levels?
11. Where do I get the pollutant concentrations to calculate the
PSI?
12. Do I have to forecast the PSI?
13. How do I calculate the PSI?
14. How do I use Table 2 and Equation 1 to calculate the PSI?
Background and Reference Materials
15. What additional information should I know?
16. References
General Requirements
1. What Is the PSI?
The Air Quality Index (PSI) is a tool that simplifies reporting
air pollution to the general public. The PSI incorporates into a
single index concentrations of 5 criteria pollutants: ozone
(O3), particulate matter (PM), carbon monoxide (CO),
sulfur dioxide (SO2), and nitrogen dioxide
(NO2). The scale of the index is divided up into general
categories that are associated with health messages.
2. Why Report the PSI?
The PSI offers various advantages:
a. It is simple to create and understand.
b. It conveys the health implications of air quality.
c. It promotes uniform use throughout the country.
3. Must I Report the PSI?
You must report the PSI daily if yours is a metropolitan
statistical area (MSA) with a population over 350,000.
4. What Goes Into My PSI Report?
Your PSI report must contain the following:
a. The reporting area(s) (the MSA or subdivision of the MSA).
b. The reporting period (the day for which the PSI is reported).
c. The critical pollutant (the pollutant with the highest index
value).
d. The PSI (the highest index value).
e. The category descriptor and index value associated with the
PSI and, if reported in a color format, the associated color. Use
only the following descriptors and colors for the six PSI
categories:
------------------------------------------------------------------------
PSI Descriptor Color
------------------------------------------------------------------------
0 to 50..................... ``Good''.............. Green.
51 to 100................... ``Moderate''.......... Yellow.
101 to 150.................. ``Unhealthy for Orange.
Sensitive Groups''.
151 to 200.................. ``Unhealthy''......... Red.
201 to 300.................. ``Very Unhealthy''.... Purple.
301 and above............... ``Hazardous''......... Maroon.
------------------------------------------------------------------------
When appropriate, your PSI report may also contain the
following:
a. The name and index value for other pollutants, particularly
those with an index value greater than 100.
b. The index values for sub-areas of the reporting area.
c. Actual pollutant concentrations.
d. Causes for unusual PSI values.
5. What Colors Do I Use When I Report the PSI?
If reporting in color format, you must use the colors listed
above. More specifically the colors you must use are defined in the
following table for both red, green, blue (RGB) and cyan, magenta,
yellow, and black (CMYK) color formulas.\1\
Table 1.--Color Formulations for Reporting the PSI.\2\
--------------------------------------------------------------------------------------------------------------------------------------------------------
Color R G B C M Y K
--------------------------------------------------------------------------------------------------------------------------------------------------------
Green........................................................ 0 228 0 224 0 224 30
Yellow....................................................... 255 255 0 0 0 255 0
Orange....................................................... 255 126 0 0 132 255 0
Red.......................................................... 255 0 0 255 255 0 0
Purple....................................................... 153 0 76 0 153 80 102
Maroon....................................................... 76 0 38 0 76 38 179
--------------------------------------------------------------------------------------------------------------------------------------------------------
\2\ The color models are based on a 0-255 scale (e.g., 50 percent is 126).
6. Is My PSI Report for My MSA Only?
Generally, your PSI report applies to your MSA only. However,
your report does not apply to just your MSA in two situations:
a. If a significant air quality problem exists (PSI greater than
100) in areas next to your MSA but not in it (for example
O3 concentrations are often highest downwind and outside
an urban area), your PSI report should apply to these areas also.
b. If different PSI categories apply to different definable
parts of your MSA, you should report a separate PSI for each part of
your urban area.
---------------------------------------------------------------------------
\1\ The RGB model is traditionally used for TV or computer
monitor colors while CMYK is traditionally used for color printers.
---------------------------------------------------------------------------
7. How Do I Get My PSI Report to the Public?
You must furnish the daily report to the appropriate news media
(radio, television, and newspapers). You may make the daily report
publicly available at one or more places of public access, or you
may disseminate it by a recorded phone message or a public Internet
site.
8. How Often Must I Report the PSI?
You must report the PSI at least 5 days per week. Exceptions to
this requirement are in Section 9 below.
9. May I Make Exceptions to These Reporting Requirements?
If the index for a particular pollutant remains below 50 for a
season or year, then you may exclude the pollutant from your
calculation of the PSI in Section 13.
If the PSI remains below 50 for a year, then you may report the
PSI at your discretion.
Calculation
10. How Does the PSI Relate to Air Pollution Levels?
For each pollutant, the PSI transforms ambient concentrations to
a scale from 0 to 500. The PSI is related to the National Ambient
Air Quality Standard (NAAQS) for each pollutant. The index value of
100 is always associated with the numerical level of the standard
for each pollutant. The index value of 50 is associated with annual
standards (if they exist) for each pollutant. Higher categories of
the index are based on increasingly serious health effects and
increasing proportions of the population that are affected. The EPA
relates the index to other air pollution concentrations through
linear interpolation based on these levels. The PSI is equal to the
highest of the numbers corresponding to each pollutant. The
pollutant responsible for the highest number (the reported PSI) is
called the ``critical'' pollutant.
11. Where Do I Get the Pollutant Concentrations To Calculate the
PSI?
You must use concentration data for four of the five PSI
criteria pollutants from the State/Local Air Monitoring Station
(SLAMS) or parts of the SLAMS required under 40 CFR
[[Page 67833]]
58.20. For PM, you need only calculate and report the PSI on days
for which you have measured air quality data (e.g., particulate
monitors often report values only every sixth day). You may use
particulate measurements from monitors that are not reference or
equivalent methods if you can relate these measurements by linear
regression to reference or equivalent method measurements.
12. Do I Have to Forecast the PSI?
You should forecast the PSI at least 24-hours in advance using
the most accurate and reasonable procedures considering meteorology,
topography, availability of data, and forecasting expertise. Since
ozone is a dominant pollutant in air pollution and the form of the
ozone standard is an 8-hour average, the timing of how the public is
informed is an important issue. In order for affected people to take
advantage of this information, it is necessary to consider at least
a short term forecast or prediction of 8-hour ozone levels for the
purposes of reporting the PSI. Guidance to this appendix suggest
ways to do this which require less resources than 24-hour advance
forecasts (EPA 1999).
13. How Do I Calculate the PSI?
The PSI is the highest value calculated for each pollutant as
follows:
a. Truncate the pollutant concentration from the monitor
recording the highest concentration in the reporting area to one
more than the significant digits used in the NAAQS for that
pollutant. This is equivalent to the rounding conventions used in
the NAAQS.
b. Using Table 2, find the two breakpoints that contain the
concentration.
c. Using Equation 1, calculate the index.
d. Round the index to the nearest integer.
Table 2.--Breakpoints for the PSI
--------------------------------------------------------------------------------------------------------------------------------------------------------
These breakpoints--
-------------------------------------------------------------------------------------------------------
PM10 PM2.5 (3 (ppm) 8-hour O3 (ppm) 1- (g/ m>g/m3) CO (ppm) SO2 (ppm) NO2 (ppm) PSIs
hour 1 m3)
--------------------------------------------------------------------------------------------------------------------------------------------------------
0.000-0.069..... - 0-54 0.0-15.4 0.0-4.4 0.000-0.034 (2) 0-50 Good.
0.070-0.084..... - 55-154 15.5-65.4 4.5-9.4 0.035-0.144 (2) 51-100 Moderate.
0.085-0.104..... 0.125-0.164 155-254 65.5-100.4 5 9.5-12.4 0.145-0.224 (2) 101-150 Unhealthy for sensitive groups.
0.105-0.124..... 0.165-0.204 255-354 100.5 5-150.4
5 12.5-15.4 0.225-0.304 (2) 151-200 Unhealthy.
0.125-0.374..... 0.205-0.404 355-424 150.5 5-250.4
5 15.5-30.4 0.305-0.604 0.65-1.24 201-300 Very unhealthy.
(0.155-0.404) 4.
(3)............. 0.405-0.504 425-504 250.5 5-350.4
5 30.5-40.4 0.605-0.804 1.25-1.64 301-400
(3)............. 0.505-0.604 505-604 350.5 5-500.4
5 40.5-50.4 0.805-1.004 1.65-2.04 401-500 Hazardous.
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Areas are required to report the PSI based on 8-hour ozone values. However, there are areas where a PSI based 1-hour ozone values would be more
protective. In these cases, the index for both the 8-hour and the 1-hour ozone values may be calculated and the maximum PSI reported.
\2\ NO2 has no short-term NAAQS and can generate a PSI only above a PSI value of 200.
\3\ 8-hour O3 values do not define higher PSI values (301). PSI values of 301 or higher are calculated with 1-hour O3 concentrations.
\4\ The numbers in parentheses are associated 1-hour values to be used in this overlapping category only.
\5\ If a different SHL for PM2.5 is promulgated, these numbers will change accordingly.
If the concentration is equal to a breakpoint, then the index is
equal to the corresponding index in Table 2. However, Equation 1 can
still be used. The results will be equal. If the concentration is
between two breakpoints, then calculate the index of that pollutant
with Equation 1. You must also note that in some areas, the PSI
based on 1-hour O3 will be more protective than using 8-
hour values (see footnote 1 to Table 2). In these cases you may use
1-hour values as well as 8-hour values to calculate the index and
then use the maximum PSI value as the index for O3.
[GRAPHIC] [TIFF OMITTED] TP09DE98.040
Equation 1
Where Ip = the index for pollutant p
Cp = the truncated concentration of pollutant
p
BPHi = the breakpoint that is greater than or equal
to Cp
BPLo = the breakpoint that is less than or equal to
Cp
IHi = the PSI value corresponding to BPHi
Ilo = the PSI value corresponding to BPLo.
If the concentration is larger than the highest breakpoint in
Table 2 then you may use the last two breakpoints in Table 2 when
you apply Equation 1. If your O3 values (1-hour and 8-
hour) are in the overlapping category (very unhealthy, see footnote
4 to Table 2) then you must use Equation 1 for both values and use
the larger index value for O3.
14. How Do I Use Table 2 and Equation 1 To Calculate the PSI?
If you observe a 1-hour O3 value of 0.156 ppm, an 8-
hour O3 value of 0.130 ppm, and a PM10 value
of 210 g/m\3\, then do this:
a. Find the breakpoints for PM10 at 210
g/m\3\ as 205 g/m\3\ and 354 g/m\3\
corresponding to index values 151 and 200;
b. Find the breakpoints for 1-hour O3 at 0.156 ppm as
0.155 ppm and 0.404 ppm corresponding to index values 201 and 300;
c. Find the breakpoints for 8-hour O3 at 0.130 ppm as
0.125 ppm and 0.374 ppm corresponding to index values 201 and 300;
d. Apply Equation 1 for 210 g/m\3\, PM10:
[GRAPHIC] [TIFF OMITTED] TP09DE98.041
e. Apply Equation 1 for 0.156 ppm, 1-hour O3:
[GRAPHIC] [TIFF OMITTED] TP09DE98.042
f. Apply Equation 1 for 0.130 ppm, 8-hour O3:
[GRAPHIC] [TIFF OMITTED] TP09DE98.043
g. Find the maximum, 203. This is the PSI.
Background and Reference Materials
15. What Additional Information Should I Know?
The EPA has developed a computer program to calculate the PSI
for you. The program works with Windows 95, it prompts for inputs,
and it displays all the pertinent information for the PSI (the
index, color, category, health effects, and cautionary language).
You can download the program at www.epa.gov/airnow. The EPA also
publishes a brochure on the PSI that explains the index in detail
(EPA 1999b), guidance that provides associated health effects and
cautionary statements (EPA 1998), and guidance that explains the
steps necessary to start an air pollution forecasting program (EPA
1999a).
16. References
EPA, (1998) Guideline for Public Reporting of Daily Air Quality-
Pollutant Standards Index (PSI), U.S. Environmental Protection
Agency, Office of Air Quality Planning and Standards, Research
Triangle Park, NC, 27711, draft document.
EPA, (1999a) Guideline for Starting an Air Pollution Forecasting
Program, U.S. Environmental Protection Agency, Office of
[[Page 67834]]
Air Quality Planning and Standards, Research Triangle Park, NC,
27711, in preparation.
EPA, (1999b) Measuring Air Quality: The Pollutant Standards
Index, Printing Management Office, U.S. Environmental Protection
Agency, 401 M Street, SW, Washington, DC 20460, in preparation.
[FR Doc. 98-32571 Filed 12-8-98; 8:45 am]
BILLING CODE 6560-50-P