Air Quality Index Reporting

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