Federal Register/Vol. 72, No. 55 / Thursday, March 22, 2007/Rules and Regulations

ENVIRONMENTAL PROTECTION

AGENCY

40 CFR Parts 50 and 51

[EPA-HO-OAR-2005-0159; FRL-8 289-5]

RIN 2060-AN40

Treatment of Data Influenced by

Exceptional Events

AGENCY: Environmental Protection

Agency (EPA).

ACTION: Final rule.

SUMMARY: This action finalizes a rule to

govern the review and handling of air

quality monitoring data influenced by

exceptional events. Exceptional events

are events for which the normal

planning and regulatory process

established by the Clean Air Act (CAA)

is not appropriate. In this rulemaking

action, EPA is finalizing the proposal to:

Implement section 319(b)(3)(B) and

section 107(d)(3) authority to exclude

air quality monitoring data from

regulatory determinations related to

exceedances or violations of the

National Ambient Air Quality Standards

(NAAQS) and avoid designating an area

as nonattainment, redesignating an area

as nonattainment, or reclassifying an

existing nonattainment area to a higher

classification if a State adequately

demonstrates that an exceptional event

has caused an exceedance or violation

of a NAAQS. The EPA is also requiring

States to take reasonable measures to

mitigate the impacts of an exceptional

event.

DATES: This final rule is effective May

21, 2007.

ADDRESSES: The EPA has established a

docket for this action under Docket ID

No. EPA-HQ-OAR-2005-0159. All

documents in the docket are listed on

the http://www.regulations.goir Web

site. Although listed in the index, some

information is not publicly available,

i.e., confidential business information

(CBI) or other information whose

disclosure is restricted by statute.

Certain other material, such as

copyrighted material, is not placed on

the Internet and will be publicly

available only in hard copy form.

Publicly available docket materials are

available either electronically through

http://www.regulations.gov or in hard

copy at the OAR Docket, EPA/DC, EPA

West, Room 3334, 1301 Constitution

Ave., NW., Washington, DC. The Public

Reading Room is open from 8:30 a.m. to

4:30 p.m., Monday through Friday,

excluding legal holidays. The telephone

number for the Public Readjig Room is

(202) 566-1744, and the telephone

number for the Air and Radiation

Docket and Information Center is (202)

566-1742'.

FOR FURTHER INFORMATION CONTACT:

General questions regarding the final

rule should be addressed to Mr. Larry D.

Wallace, PhD, Office of Air Quality

Planning and Standards, Air Quality

Policy Division, Mail Code C539-01,

Research Triangle Park, NC 27711;

telephone (919) 541-0906, and e-mail

address wallace.larry@epa.gov.

Questions concerning technical and

analytical issues related to this final rule

should be addressed to Mr. Neil Frank,

Office of Air Quality Planning and

Standards, Air Quality Assessment

Division, Mail Code C304-01, Research

Triangle Park, NC 27711; telephone

(919) 541-5560, and e-mail address

fraik.neil@epa.gov.

SUPPLEMENTARY INFORMATION:

I. General Information

A. Does This Action Apply to Me?

Regulated Entities. This final rule will

affect State and local air quality

agencies. This rule may also affect

Tribal air quality agencies that have

implemented air quality monitoring

networks or have authority to

implement air quality programs.

This list is not intended to be

exhaustive, but rather provides a guide

for readers regarding entities likely to be

regulated by this action. This list gives

examples of the types of entities EPA is

now aware could potentially be

regulated by this action. Other types of

entities not listed could also be affected.

To determine whether your facility,

company, business, organization, etc., is

regulated by this action, you should

examine the applicability criteria in

section IV of this preamble. If you have

any questions regarding the

applicability of this action to a

particular entity; consult the people

listed in the preceding section.

B. How Is This Preamble Organized?

Table of Contents

The following is an outline of the

preamble.

I.General Information

A. Does This Action Apply to Me?

B. How Is This Preamble Organized?

II. Preamble Glossary of Terms and

Acronyms

III. Background and Purpose of This

Rulemaking

A. Legislative Requirements

B. Historical Experience Concerning

Exceptional and Natural Events

IV. This Final Action

A. to Whom and to What Pollutants Does

This Rule Apply?

B. How Does This Rule Relate to Indian

Tribes?

C. Comments Submitted on the Proposed

Rule

D. What Is an Exceptional Event?

E. Examples of Exceptional Events

1. Chemical Spills and Industrial

Accidents

2. Structural Fires

3. Exceedances Due to Transported

Pollution

-4. Exceedances Due to a Terrorist Attack

5. Natural Events

a. Natural Disasters and Associated CleanUp Activities

b. Volcanic and Seismic Activities

c. High Wind Events

d. Wildland Fires

e. Stratospheric Ozone Intrusions

6. Prescribed Fire

V. The Management of Air Quality Data

Affected by Exceptional Events

A. Flagging of Data in the AQS Database

1. Background

2. Final Rule

3. Comments and Responses

B. What Does It Mean for an Event to

"Affect Air Quality"?

1. Background

2. Final Rule

3. Comments and Responses

C. Use of a "But For" Test

1. Background

2. Final Rule

3. Comments and Responses

D. Schedules and Procedures for Flagging

and Requesting Exclusion of Data

1. Background

2. Final Rule

3. Comments and Responses

E. Exclusion of Entire 24-Hour Value as

- Opposed to a Partial Adjusfment of the

24-Hour Value

1. Background

2. Final Rule

3. Comments and Responses

F. What Should States Be Required To

Submit in Their Exceptional Events

Demonstrations?

1. Background

2. Final Rule

3. Comments and Responses

G. Public Availability of Air Quality Data

and Demonstrations Related to

Exceptional Events

1. Background

2. Final Rule

3. Comments and Responses

VI. Additional Requirements

A. Requirements for States To Provide

Public Notification, Public Education,

and Appropriate and Reasonable

Measures To Protect Public Health

1. Background

2. Final Rule

3. Comments and Responses

VII. Special Treatment of Certain Exceptional

Events Under This Final Rule

A. Volcanic and Seismic Activities

1. Background

2. Final Rule

B. High Wind Events

1. Background

2. Final Rule

C. Stratospheric Ozone Intrusion

1. Background

2. Final Rule

VIII. Treatment of Fireworks Displays

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A. Background

B. Final Rule

C. Comments and Responses

IX. Statutory and Executive Order Reviews

A. Executive Order 12866: Regulatory

Planning and Review

B. Paperwork Reduction Act

C. Regulatory Flexibility Act

D. Unfunded Mandates Reform Act

E. Executive Order 13132: Federalism

F. Executive Order 13175: Consultation

and Coordination With Indian Tribal

Governments

G. Executive Order 13045: Protection of

Children From Environmental Health

and Safety Risks

H. Executive Order 13211: Actions That

Significantly Affect Energy Supply,

Distribution, or Use

I. National Technology Transfer

Advancement Act

J. Congressional Review Act

K. Petitions for Judicial Review

II. Preamble Glossary of Terms and

Acronyms

The following are abbreviations of

terms used in the preamble.

ARM Approved Regional Methods.

AQS Air Quality System.

BACM Best Available Control

Measures.

CAA Clean Air Act.

CAAA Clean Air Act Amendments.

EPA Environmental Protection

Agency.

FEM Federal Equivalent Methods.

FIP Federal Implementation Plan.

FR Federal Register.

FRM Federal Reference Methods.

NAAQS National Ambient Air Quality

Standards.

NEAP Natural Events Action Plan.

NEPA National Environmental Policy

Act.

NTTA National Technology Transfer

Advancement Act of 1995.

OAQPS Office of Air Quality Planning

and Standards.

OMB Office of Management and

Budget.

PM Particulate matter.

PM10 Particles with a nominal mean

aerodynamic diameter less than or

equal to 10 micrometers.

PM 10-2.5 Particles with a nominal

mean aerodynamic diameter greater

than 2.5. micrometers and less than or

equal to 10 micrometers.

PM2.

5 Particles with a nominal mean

aerodynamic diameter less than or

equal to 2.5 micrometers.

RACM Reasonably Available Control

Measures.

SIP State Implementation Plan.

SAFE-TEA-LU Safe Accountable

Flexible Efficient-Transportation

Equity Act-A Legacy for Users.

SMP Smoke Management Program.

TAR Tribal Authority Rule.

TIP Tribal Implementation Plan.

UMRA Unfunded Mandates Reform

Act.

USDA U.S. Department of Agriculture.

VCS Voluntary Consensus Standards.

Ill. Background and Purpose of This

Rulemaking

A. Legislative Requirements

We 1 are finalizing a rule to govern the

revieW and handling of air quality

monitoring data influenced by

exceptional events. As discussed below,

these are events for which the normal

planning and regulatory process

established by the CAA is not

appropriate. Section 319 of the CAA, as

amended by section 6013 of the Safe

Accountable Flexible EfficientTransportation Equity Act: A Legacy for

Users (SAFE-TEA-LU) of 2005,

required EPA to publish the proposed

rule in the Federal Register no later

than March 1, 2006.2 Further; EPA must

issue this final rule no later than 1 year

from the date of proposal. The EPA -

published the proposed rule on March

10, 2006 (See 71 FR 12592).

In this final rule, EPA is establishing procedures and criteria related to the

identification, ealuation,

interpretation, and use of air quality

monitoring data related to any NAAQS

where States petition EPA to exclude

data that are affected by exceptional

events.

Section 319 defines an event as an

exceptional event if the event affects air

quality; is an event that is not

reasonably controllable or preventable;

is an event caused by human activity

that is unlikely to recur at a. particular

location or a natural event; and is

determined by EPA to be an exceptional

event. The statutory definition of

exceptional event specifically excludes

stagnation of air masses or

meteorological inversions; a

meteorological event involving high

temperatures or lack of precipitation; or

air pollution relating to source

noncompliance.

Section 319(b)(3)(B)(i) requires a State

air quality agency to demonstrate

through "reliable, accurate data that is

promptly produced" that an exceptional

event occurred.3 Section 319(b)(3)(B)(ii)

requires that "a clear causal

I The U.S. Environmental Protection Agency.

2 All subsequent references to section 319 of the

CAA in this proposal are to section 319 as amended

by SAFE-TEA-LU .unless otherwise noted.

3 While this dfcument refers primarily to States

as the entity responsible for flagging data impacted

by exceptional events, other agencies, such as local

or Tribal government agencies, may also have

standing to flag data as being affected by these types

of events, and the criteria and procedures that are discussed in this rulemaking also apply to these

entities.

relationship" be established between a

measured exceedance of a NAAQS and

the exceptional event demonstrating

"that the exceptional event caused a

specific air pollution concentration at a

particular location." In addition, section

319(b)(3)(B)(iii) requires a public

process to determine whether an event

is an exceptional event. Finally, section

319(b)(3)(B)(iv) requires criteria and

procedures for a Governor to petition

the Administrator to exclude air quality

monitoring data that is directly due to

exceptional events from use in

determinations with respect to

exceedances or violations of the

NAAQS.

The term exceedance refers to a

measured or modeled concentration

greater than the level of one or more for

a pollutant. The NAAQS are also set

with particular averaging periods (e.g., 3

years for ozone and PM2.

5) such that a

violation of the NAAQS for ozone and

PM2.5 requires an average annual

concentration level specified by

appendix I and N to 40 CFR 50 to be

greater than the level of the NAAQS.

Public comments favored the

consideration of data contributing to

both exceedances and violations for data

exclusion under this Rule. As discussed

in section V.C, exceedances of any

NAAQS will be eligible for

considerhtion for data exclusion and

any data contributing to violations of

daily or sub-daily standards will also be

eligible for consideration (e.g. 8-hour or

24-hour standards). Data .contributing to

annual violations without being

exceedances themselves are considered

too close to background air quality

levels for exclusion under this Rule.

Section 319 also contains a set of five

principles for EPA to follow in

developing regulations to implement

section 319:

(i) Protection of public health is the highest

priority;

(ii) Timely information should be provided

to the public in any case in which the air

quality is unhealthy;

(iii) All ambient air quality data should be

included in a timely manner in an

appropriate Federal air quality database that

is accessible to the public;

(iv) Each State must take necessary

heasures to safeguard public health

regardless of the source of the air pollution;

and

(v) Air quality data should be carefully

screened to ensure that events not likely to recur are represented accurately in all

monitoring data and analyses (42 U.S.C.

7619(b)(3)(A).

In adopting revisions to section 319,

Congress sought to provide statutory

relief to States to allow them to avoid

being designated as nonattainment or to

avoid continuing to be designated.

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nonattainment as a result of exceptiona

events in appropriate circumstances. Ti

accomplish this goal, Congress

enumerated certain minimum

requirements for this rulemaking. In

addition, Congress provided certain

statutory principles for EPA to follow i]

promulgating regulations to exclude

data affected by exceptional events.

B. Historical Experience Concerning

Exceptional and Natural Events

Since 1977, EPA guidance and

regulations have either implied or documented the need for a flagging

system for data affected by an

exceptional event. The first EPA

guidance related to the exclusion or

discounting of data affected by an exceptional event was an Office of Air

Quality Planning and Standards

(OAQPS) guidance document entitled,

"Guideline for the Interpretation of Air

Quality Standards," Guideline No. 1.2-

008 (revised February 1977).4

In July 1986, EPA issued the guidanci

entitled, "Guideline On the

Identification and Use of Air Quality

Data Affected By Exceptional Events"

(the Exceptional Events Policy). The

Exceptional Events Policy provided

criteria for States to use in making

decisions related to identifying data tha

have been influenced by an exceptional

event.

In addition to the Exceptional Events

Policy, on July 1, 1987, EPA

promulgated the NAAQS for PM10

(particulate matter With an aerodynami

diameter of 10 micrometers or less),

which also addressed the issue of

excluding or discounting data affected

by exceptional events. 5 Appendix K of

that rule allows for special

consideration of data determined to be

affected by an exceptional event.

Section 2.4 of appendix K authorizes

EPA to discount from consideration in

making attainment or nonattainment

determinations air quality data that are

attributable to "an uncontrollable event

caused by natural sources" of PM,. or

"an event that is not expected to recur at a given location." Section 2.4 of

appendix K, together with EPA

guidance contained in the Exceptional

Exients Policy, describes the steps that

4 "Guideline for Interpretation of Air quality

Standards," U.S. Environmental Protection Agency

Office of Air quality Planning and Standaids,

Research Triangle Park, N.C. OAQPS No. 1.2-008

(Revised February 1977). The guidance indicated

the need for a data flagging system which would

require the submittal of detailed information

establishing that a violation was due to

uncontrollable natural sources and that the

information could be used in decision making

related to the feasibility of modifying control

strategies.

5 Federal Register (52 FR 24667), July 1, 1987.

I should be taken for flagging PM 0 data

o that a State believes are affected by an

exceptional or natural event. "

In 1990, section 188(f was added to

the CAA. This section of the CAA

provided EPA authority to waive either.

n a specific attainment date or certain

planning requirements for serious PM10

nonattainment areas that are affected by

nonanthropogenic sources. In response

to section 188(f), and in consideration of

the CAA consequences for areas affected

by elevated concentrations caused by

natural events, in 1996 EPA issued a

policy toaddress data affected by

natural events entitled, "Areas Affected

by PM10 Natural Events," (the PM10

Natural E-ents Policy).6

.On July 18, 1997, EPA issued a

revised NAAQS for ozone and a new

NAAQS addressing PM 2.

5. For ozone,

the revised NAAQS provided for an 8-

hour averaging period (versus 1 hour for

the previous. NAAQS), and the level of

the standard was changed from 0.12

e ppm to 0.08 ppm (62 FR 38856). For the

PM2.

5 NAAQS, EPA established both a nbw 24-hour standard and a new annual

standard. In that Federal Register, EPA

also promulgated appendices I and N to

40 CFR 50. Appendices I and N

provided the methodologies for

t determining whether an area is in

attainment of the 8-hour ozone and

PM2.5 NAAQS respectively, using

ambient air quality data. Section 1.0 of

appendix I, related to the ozone

standard, addresses the treatment of

data determined to be influenced

natural events, and section 1.0(b) of

appendix N, related to the PM2.

5

standard, providesthat EPA may give

special consideration to data

determined to be affected by an

exceptional or natural event.

Appendices K, I, and N, which are parts of the NAAQS for the affected

pollutants as described above, provide

that, while States must submit all valid

ambient air quality data to EPA's Air

Quality System (AQS) database for use

in making regulatory decisions, in some

cases it may be appropriate for EPA to

exclude, discount, weight, or make

adjustments to data that have been

appropriately flagged from calculations

in determining whether or not an area

has attained the standard. These

decisions are to be made on a case-bycase basis using all available

information related to the event in

question, and are required to be made

available to the public for review. It

should also be noted that, while it

e Memorandum from Mary D. Nicols, Assistant

Administrator for Air and Radiation, to EPA

Regional Offices entitled, "Areas Affected-by PM1o

Natural Events," May 30, 1996.

would be desirable to be able to adjust

the daily value to exclude only those

portions of the data that are attributable

to the exceptional event, due to

technical limitations, such subtraction

has not been possible, and EPA's

historical practice has been to exclude

a daily measured value in its entirety

when that value is found to be largely

caused by an exceptional event.

Following the promulgation of the 8-

hour ozone and the PM2.

5 NAAQS, EPA

provided additional guidance to States

on how to address data affected by

exceptional and natural events.7 Thatguidance directed the States to follow

three specific EPA guidance documents

in making determinations related to data

influenced by exceptional and natural

events: (1) The Exceptional Events

Policy; (2) The PM10 Natural Events

Policy; and (3) The Interim Air Quality

Policy on Wildland and Prescribed

Fires, Memorandum from Richard D.

Wilson, Acting Assistant Administrator

for Air and Radiation, to EPA Regional

Administrators, May 15, 1998. The

nterim Air Quality Policy on Wildland

and Prescribed Fires addressed the

treatment of air quality monitoring data

that are affected by wildland and

lrescribed fires that are managed for

resource benefits.8

IV. This Final Action

A.-To Whom and to What Pollutants

Does This Rule Apply?

Under the statutory scheme•

established by the CAA, States are

primarily responsible for the

administration of air quality

management programs within their

borders. This includes the monitoring

and analysis of ambient air quality and

submission of monitoring data to EPA,

which are then stored in EPA's AQS

database. The EPA retains an important

oversight responsibility for ensuring

compliance with CAA requirements.

With respect to the treatment of air

quality monitoring data, States are

responsible for ensuring data quality

and validity and for identifying

measurements that they believe warrant

special consideration, while EPA is

7 "Guideline on Data Handling Conventions for

the PM NAAQS," United States Environmental

Protection Agency, Office of Air Quality Planning

and Standards, Research Triangle Park, NC 27711,

EPA-454/R-98-017, December 1998.

8 Following the promulgation of this rule, it is

EPA's intention to begin the process to revise the

"Interim Air Quality Policy on Wildland and

Prescribed Fires" in calendar year 2007 to update

the policy and to ensure that the policy is

consistent with'this final rulemaking action. In

addition, it is EPA's intent that agricultural

prescribed burning will be addressed when tlis

policy is updated and will also address basic smoke

management practices.

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responsible for reviewing and approving

or disapproving any requests for such

consideration. Therefore, this final rule

applies to all States; to local air quality

agencies to whom a State has delegated

relevant responsibilities for air quality

management, including air quality

monitoring and data analysis; and, as

discussed below, to Tribal air quality

agencies where appropriate. This rule

governs EPA's actions in reviewing and

.approving or disapproving the relevant

actions taken or requested by States.

Where EPA implements air quality

management programs on Tribal lands,

this rule would govern those actions as

well.

At present, only the NAAQS for ozone

and particulate matter (PM) contain

provisions which allow for the special

handling of air quality data affected by

exceptional and natural events (40 CFR

part 50, appendices K, I, and N). The

language of section 319 of the CAA is

broad in terms of making its provisions

applicable to events that "affect air

quality" and to exceedances or

violations of "the national ambient air

quality standards" (42 U.S.C.

7619(b)(1)(A)(i), (b)(3)(B)(iv)). Thus, its

provisions can apply to the NAAQS for

any criteria pollutant. Because the

NAAQS established for other criteria

pollutants do not currently contain

provisions permitting the discounting or

exclusion of data due to exceptional

events, we are only applying the

provisions of this rule initially to ozone

and PM.9 As we review and consider the

need for revisions to the NAAQS for

other pollutants,we will include

provisions to address exceptional events

in those NAAQS in accordance with

section 319, as appropriate at that time.

Because issuance of a new or revised

NAAQS will necessitate the initiation of

the designation process, EPA believes

that the NAAQS rules are an .

appropriate place to make provisions for

exceptional events in the evaluation of

air quality data. In the interim, where

exceptional events result in exceedances

or violations of NAAQS that do not

currently provide for special treatment

of the data, we intend to use our

discretion as outlined under section

9 Section IV.G of the preamble to the Proposed

Rule discussed special considerations relevant to a

new NAAQS for PMIo-2 .s proposed by EPA on

December 20, 2005. This proposed standard would

have drawn a distinction between coarse particles

of urban versus non-urban origin, which raised new

issues about the handling of exceedances of the

coarse particle standard caused by exceptional

events. However, in EPA's final rule on the PM

NAAQS, issued September 21, 2006, EPA retained

the existing 24-hour PM,o standard instead of

promulgating the proposed PMo 2.5 standard. Thus,

section IV.G of the preamble to the Proposed Rule

is no longer relevant and has been removed from

this Preamble.

107(d)(3) not to redesignate affected

areas as nonattainment based on these

events. We also intend to use our

discretion under this rule to address

determinations for the ozone standard

related to the treatment of data

influenced by both exceptional and

natural events. Currently, appendix I,

only addresses the treatment of data

determined to be influenced by a

stratospheric ozone intrusion and other

natural events, but does not address the

handling of data influenced by other

exceptional events.

B. How Does This Rule Relate to Indian

Tribes?

Under the CAA and the Tribal

Authority Rule (TAR), eligible Indian

Tribes may develop and submit Tribal

Implementation Plans (TIPs) for EPA

approval, to administer requirements

under the CAA on their reservations and

other areas under their jurisdiction.

However, Tribes are not required to

develop TIPs or otherwise implement

relevant programs under the CAA. The

EPA has stated that it will continue to

ensure the protection of air quality

throughout the nation, including in

Indian country, and will issue Federal

Implementation Plans (FIPs) as

necessary or appropriate to fill gaps in

program implementation in affected

areas of Indian country (63 FR 7254,

7265; February 12, 1998).

In cases where a Tribal air quality

agency has implemented an air quality

monitoring network, which is affected

by emissions from exceptional events;

the criteria and procedures identified in

this final rule may be used to exclude

or discount data for regulatory purposes.

Certain Tribes may implement all

relevant components of an air quality

program for purposes of meeting the

various requirements of this rule. In

some cases, however,'a Tribe may

implement only portions of the relevant

program and may not be in a position

to address each of the procedures and

requirements associated with excluding

or discounting emissions data (e.g., a

particular Tribe may operate a

monitoring network for purposes of

gathering and identifying appropriate

data, but may not implement relevant

programs for the purpose of mitigating

the effects of exceptional events

required under this rule). The EPA

intends to work with Tribes on the

implementation of this rule, which may

include appropriate implementation by

EPA of program elements ensuring that

any exclusion or discounting of data in

Indian country areas with air quality

affected by exceptional events comports

with the procedures and requirements

of this rule.

C. Comments Submitted on the

Proposed Rule

The proposed rule on the "Treatment

of Data Influenced by Exceptional

Events" was issued on March 10, 2006

(71 FR 12592). We received 98 letters

from commenters representing 587 .

comments from private citizens, State

and local governments, industry,

environmental groups" and Federal

agencies. Sections V, VI, VII, and VIII of

this notice describe the primary

elements and requirements concerning

the process for the handling of data

influenced by exceptional events. Each

section summarizes the relevant issues

and options discussed in the proposed

rule and provides the final decisions

related to the issues for each section. In

this preamble, we have provided

responses to certain significant

comments to elaborate or provide

clarification for EPA's decision on an

issue discussed in the relevant section

of the rule. We have developed a

response to comments document which

addresses all of the timely comments

received on the proposed rule.

Following the promulgation of this rule,

the response to comments document

will be placed into the docket of this

rulemaking action for public review

(See Docket No. EPA-HQ-OAR-2005-

0159).

D. What Is an Exceptional Event?

In accordance with the language in

section 319, EPA is defining the term

"exceptional event" to mean an event

that:

(i) Affects air quality;

(ii).Is not reasonably controllable or preventable;

(iii) Is an event caused by human activity

that is unlikely to recur at a particular

location or a natural event; and

(iv) Is determined by EPA through the

process established in these regulations to be

an exceptional event.

It is important to note that natural

events, which are one form of

exceptional events according to this

definition, may recur, sometimes

frequently (e.g., western wildfires). For

the purposes of this rule, EPA is

defining "natural event" as an event in

which human activity plays little or no

direct causal role to the event in

question. We recognize that over time,

certain human activities may have had

some impact on the conditions which

later give rise to a "natural" air

pollution event. However, we do not

believe that small historical human

contributions should preclude an event

from being deemed "natural." In

adopting section 188(f) of part D,

subpart 4, of the 1990 amendments to

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the CAA, Congress recognized and

provided for distinctions between these

types of events with respect to waiver of

applicable requirements and the

extension of otherwise applicable

attainment dates for the PMio standard.

In approving section 188(f) of the CAA,-

the House committee of jurisdiction

discussed a circumstance in which

recurring emissions from a source

should be considered to be

anthropogenic. The House report noted

EPA statements that, in the cited case,

high concentrations of dust from a

lakebed were due to human activity, i.e.,

the long-term diversion of water from a

lake. (See Pub. L. 101-549, CAA

Amendments of 1990 House Report No.

101-290(1), May 17, 1990; and

discussion of Mono Lake, California

therein). Also, EPA recognized, in

recently acting to retain PM10 as a

measure of coarse particulate, that in

some instances exceedances of this

NAAQS "may be caused in whole or in

part, by exceptional events, including

natural events such as windstorms.

* * *. (and that) an exceedance may be

treated as an exceptional event even

though anthropogenic sources such as

agricultural and mining emissions

contribute to the exceedance." (71 FR

61216; October 17, 2006).

In this final rule, EPA also defines the

term "exceedance" with respect to

compliance with the NAAQS and

establishes criteria for determining

when an event can be said to "affect air

quality." We are not finalizing more

detailed requirements for determining

when an event is "not reasonably

,controllable or preventable" because we

believe that such determinations will

necessarily be dependent on specific

facts and circumstances that cannot be

prescribed by rule.

E. Examples of Exceptional Events

The EPA believes that the following

types of events meet the definition of

exceptional events, as defined above.

This means that air quality data affected

by these types of events may qualify for

exclusion under this rule provided that

all other requirements of the rule are

met. By providing the examples listed

below, EPA is not determining that such

events are the only types of events that

may qualify for exclusion under the rule

as exceptional events. Other events that

meet the statutory criteria for an

exceptional event as defined in this rule

may also qualify for exclusion. The AQS

user documentation contains a list of

other similar events that may be flagged

for special consideration. (http://

www.epa.gov/ttn/airs/airsaqs/man uals/

qualifiers.htm),10

In addition, in the sections below, we

have provided responses to certain

significant comments received during

the comment period for the proposed

rule regarding the examples of events

that may meet the definition of an

exceptional event in order to elaborate

upon or provide clarification about what

constitutes an exceptional event.

1. Chemical Spills and Industrial

Accidents

Emissions that result from accidents

such as fires, explosions, power outages,

train derailments, vehicular accidents,

or combinations of these may be flagged

as an exceptional event.

Comments and Responses

Comment: Several commenters stated

that "Chemical Spills and Industrial

Accidents" should generally not be

considered exceptional events.

Commenters stated that most industrial

accidents and chemical spills are

reasonably controllable and preventable

with proper planning and mitigation

efforts. These commenters stated that -

allowing for accidents or spills that

could have been avoided is inconsistent

with the CAA.

Response: It is EPA's belief that air

quality data that has been affected by

emissions from chemical spills,

industrial accidents, or structural fires

may be flagged by a State as an

exceptional event and reviewed by EPA

for exclusion on a case-by-case basis to

determine whether it meets the criteria

for exceptional events as defined in this

rule. In particular, data influenced by

chemical spills or industrial accidents

- must be demonstrated to have "affected

air quality" and must be demonstrated

-to be due to circumstances that were not

reasonably controllable or preventable

and are .events that are unlikely to recur

in a particular location. The EPA agrees -

with the commenters that industrial or

point source emissions due to

malfunctions or non-compliance would

not be considered exceptional events

and should be addressed through the

normal State Implementation Planning

process.

2. Structural Fires

Structural fires include any accidental

fire involving a manmade structure.

Comments and Responses

Comment: Several commenters

indicated that "Structural Fires" should

1o The EPA will be revising the list of events

contained in the AQS database following the

promulgation of this rule to ensure that the list is

consistent with the requirements of the rule.

generally not be considered exceptional

events.. Commenters stated that these

types of events should be considered as

emissions from anthropogenic sources

and handled within the form of the

respective air quality standards where a

certain number of exceedances of the

standards are allowed over a 3-year

period. Commenters assert that

structural fires, lasting for several hours,

are unlikely to cause an area to reach

the level of nonattainment. In cases

where structural fires are determined to

be the cause of a monitored violation of

the NAAQS, commenters stated that

EPA should adopt a case-by-case review

of these events.

Response: The definition of structural

fires under this rule pertains to any

accidental fire involving a manmade

structure. The EPA believes that

structural fires could be an exceptional

event under this rule, provided all other

requirements of the rule are met,

because they could "affect air quality,"

could be an event that is not

"reasonably controllable" or "preventable," and could be events that

are caused by human activity that are

unlikely to recur at the same location.

However, EPA agrees with the

commenters that these types of events,

as well as other similar types of events,

should be reviewed on a case-by-case

basis to determine whether they meet

the criteria for an exceptional event as

defined by this rule.

3. Exceedances Dtie to Transported

Pollution

Transported pollution, whether

national or international in origin, and

whether from natural or anthropogenic

sources, may cause exceedances eligible

for exclusion under this rule, as long as

all of the criteria and requirements

related to exceptional events are met as

defined in this rule. For example, States

may flag, and EPA may exclude, data

associated with fires occurring outside

of the borders of theijUnited States, such

as forest fires in Mexico, Central

America, and Canada; or transport

events such as African dust and Asian

dust which contribute significantly to

ambient concentrations of a pollutant in

an area, leading to exceedances or

violations of a NAAQS. An example of

interstate transported emissions which

may be flagged as due to an exceptional

event would be emissions due to smoke

from wildfires or wildland fire use fires

which cause exceedances or violations

of the NAAQS at monitoring sites in

other States. Other examples could

include data affected by emissions from

mining and agricultural activities when

such emissions are subjected to longrange transport, and the criteria and

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requirements related to an exceptional

event are met as defined in this rule. In

general, events due to transported

pollution may be considered on a caseby-case basis.

Comments and Responses

Comment: Several commenters

expressed concern over EPA allowing

the exceptional events rule to be used to

excl ide data that has been affected by

emissions emanating from sources

outside the borders of the United States.

Response: States may flag data that

has been affected by sources emanating

from outside the United States that meet

the criteria for an exceptional event as

defined under this rule, including

requirements for causation and

documentation. In cases where an area

is impacted by emissions from sources

outside of the United States which do

not meet the criteria for an exceptional

event under this rule, and these

emissions contribute to an area being

designated as nonattainment, the

emissions may be addressed under

section 179B of the CAA related to

"International Border Areas." Section

179B provides that where a State is

required to submit a State

Implementation Plan (SIP) to address

issues related to a nonattainment "

designation, EPA may approve the SIP

for the area provided that the plan (1)

meets all the applicable requirements

called for under the CAA, other than the

requirement that the plan demonstrate

attainment or maintenance of the

NAAQS, and (2) the'SIP must

demonstrate that the affected area

would be able to attain the standard by

the applicable attainment date "but for"

emissions emanating from outside the

United States.

4. Exceedances Due to a Terrorist Attack

Emissions that result from a terrorist

attack such as smoke from fires, dust,

explosions, power outages, train

derailments, vehicular accidents, or

combinatibns of these may be flagged as

an exceptional event.

Comments and Responses

No comments were received. on this

topic.

5. Natural Events

The natural events addressed by this'

final rule are: (1) Natural disasters and

associated cleanup activities; (2)

volcanic and seismic activities; (3) high

wind events; (4) wildfires and wildland

fire use fires; and (5) stratospheric ozone

intrusions. The EPA will consider other

types of natural events on a case-by-case

basis.

a. Natural Disasters and Associated

Clean-Up Activities

For the purpose of flagging, major

natural disasters such as hurricanes and

tornadoes for which State, local, or

Federal relief has been granted and

clean-up activities associated with these

events, may be considered exceptional

events. The EPA believes that for a

major natural disaster, a timeframe up to

12 months is a reasonable time period

to allow for. clean-up activities

associated with these types of activities.

In cases where the damage caused by

the event is so substantial that a 12-

month period is inadequate to address

the clean up that- is necessary, a State

may submit a request to EPA for an

extension of the 12-month time period.

The EPA will grant requests for

extensions of the time period related to

such events on a case-by-case basis if

the States submit adequate supporting

information concerning the reason for

the extension as well as the length of

time being requested for the extension.

Comments and Responses

Comment: Several commenters

indicated that EPA should limit the time

period associated with clean-up ,

activities due to a natural disaster. One

commenter indicated that the

exceptional events rule as proposed

would allow States to apply the term

"natural disaster" very broadly to

include circumstances that would

circumvent the intent of the CAA. For

example, declaring an episode of high

summer temperatures to be a natural

disaster could potentially allow a State

to exclude high ozone levels which

commonly occur during hot weather.

Response: A time period up to 12

months for clean-up activities is

permitted for major natural disasters,

such as hurricanes and tornadoes, for

which State, local, or Federal relief has

been granted, may be flagged for

exclusion as exceptional events under

this rule. The clean-up activities associ ated wihths 4ypso eet

may also be flagged for exclusion as

being due to an exceptional event.

Given the nature of a major natural

disaster, the 12-month time period

allowed for clean-up activities following

such disaster is a reasonable time

period, and is consistent with the time

period being allowed for volcanic and

seismic activities under this rule. The

period of high summer temperatures

noted in the comment would not

represent a major natural disaster, as

described above, subject to the 12-

month clean-up period.

b. Volcanic and Seismic Activities

Ambient concentrations of particulate

matter for which volcanic or seismic

activity caused or significantly

contributed to high levels of particulate

matter in an affected area will be treated

as natural events. While generally not

occurring frequently, volcanic and

seismic activity can affect air quality

data related to the particulate matter

NAAQS for an extended period of time

after an event. Volcanic activities can

contribute to ambient concentrations in

several ways: it may influence

concentrations of particulate matter due

to primary emissions (e.g., ash), and

emissions of precursor pollutants (e.g.,

sulfur dioxide) that contribute to the

secondary formation of particulate

matter. Seismic activity (e.g.,

earthquakes) can also contribute to

ambient particulate matter

concentrations by shaking the ground,

causing structures to collapse, and

otherwise raising dust which may lead

to exceedances or violations of the

NAAQS.

Comments and Responses

Comment: Several commenters

indicated that the rule should provide

sufficient flexibility for data to be

excluded where the duration of the

event may last for a long period of time.

An example of such an event is where

volcanic activities last for several days.

Response: The EPA agrees with the

commenters and notes that the rule

allows for States to flag data and jubmit

documentation related to events such as

long-term volcanic and seismic

activities. States may also submit

requests to EPA to extend the time

period up to 12 months for major

natural disasters, for clean-up activities

following volcanic and seismic events.

States are encouraged to submit

supporting information related to the

reasons for the requested extension and

the length of time being requested for

the extension.

c. High Wind Events

High wind events are events that

affect ambient particulate matter

concentrations through the raising of

dust or through the re-entrainment of

material that has been deposited. In

some locations, concentrations of coarse

particles like PM10 are most likely

affected by these types of events,

although PM2.

5 standards may be

exceeded under such circumstances as

well. Section VII.B. also includes a

discussion of this issue.

Comments and Responses

. Comment: Several commenters

suggested that EPA replace the term

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"high winds" with the term "windgenerated dust" because (1) it places the

emphasis on the natural mechanism, (2)

dust may become entrained at relatively

low wind velocities, and (3) the change

will eliminate confusion between the

wind speeds associated with a natural

event and wind speeds needed to

qualify for a "high wind" exceptional

event under EPA's 1986 guidance.

Response: The EPA is retaining the

term "high wind" event because it

accurately connotes the type of natural

event that should be excluded under

this rule, as well as the action which

caused the exceedance or violation of

the standard. The term also serves as an

indicator concerning the level of wind

which caused the exceedance or

violation of the standard and indicates

that it was unusually high for the

affected area during the time period that

the event occurred. Therefore, States

must provide appropriate

documentation to substantiate why the

level of wind speed associated with the

event in question should be considered

unusual for the affected area during the

time of year that the event occurred. The

EPA will evaluate such instances on a

case-by-case basis, including factors

such as historically typical windspeed

levels for the season of the year that the

event is claimed.l

d. Wildland Fires

Federal land managers have afforded

recognition to several different types of

wildland fires (i.e., wildfire, wildland

fire use fire and prescribed fire),

depending on their causal

circumstances and the role that such

fires play in the affected ecosystems.

Prescribed fire is addressed more fully

in the following section.

The question of what is a natural

versus an anthropogenic fire has

particular significance when

considering the impacts of wildland

fires (wildfire, wildland fire use fire and

prescribed fire) on air quality and how

these impacts should be regarded under

this rule. A "wildfire" is defined as an

unplanned, unwanted wildland fire

"As described elsewhere in the preamble, EPA

is adopting a weight of evidence approach to

demonstrate that an exceptional event caused an

exceedance or violation. Therefore, in instances

where the level of the wind speed results in

exceedances or violations of particulate matter, for

data affected by these events to be considered for

exclusion under the weight of evidence approach,

a clear causal relationship must be demonstrated

between the exceedances measured at the air

quality monitoring site and the high wind event in

question. EPA will consider in the weight of

evidence analysis winds that produce emissions

contributed to by anthropogenic activities that have

been controlled to the extent possible through use

of all reasonably available reasonable and

appropriate measures.

(such as a fire caused by lightning), and

include unauthorized human-caused

fires (such as arson or acts of

carelessness by campers), escaped

prescribed fire projects (escaped control

due to unforeseen circumstances),

where the appropriate management

response includes the objective to

suppress the fire. In contrast, a "wildland fire use" fire is the

application of the appropriate

management response to a naturallyignited (e.g., as the result of lightning)

wildland fire to accomplish specific

resource management objectives in

predefined and designated areas where

fire is necessary and outlined in fire

management or land management plans.

Using these definitions, we believe

that both wildfires and wildland fire use

fires fall within the meaning of "natural

events" as that term is used in section

319. Therefore, ambient particulate

,matter and ozone concentrations due to

smoke from a wildland fire will be

considered for treatment as an

exceptional event if the fire is

determined to be either a wildfire or

wildland fire use fire.

Comments and Responses

Comment: In general, commenters

strongly supported exempting wildfires

as exceptional events under the rule.

Response: The EPA acknowledges

support for the proposal to classify

wildfires as a potential exceptional

event. As noted above, the Agency states

that wildland fires will be excluded as

exceptional events if they meet the

criteria and requirements of the

exceptional events rule.

Comment: The Agency received

comments both supporting and

opposing the proposal allowing

wildland fire use fires to qualify as an

exceptional evefit.

Response: After reviewing Congress'

revisions to section 319, the various

Agency policies cited in the proposal,

and comments received, the Agency has

deterntined that wildland fire use fires

may also qualify as an exceptional

event. However, these types of fires

must also meet certain criteria. For

example, these fires must occur on

lands .that have been designated in fire

management or land management plans

as areas where fires are necessary and

desirable to accomplish specific

resource management objectives.

Comment: Many commenters

supported EPA's commitment to update

the 1998 Interim Air Quality Policy on

Wildland and Prescribed Fires to be

consistent with this rule.

Response: The Agency plans to begin

revising this policy in 2007 as part of its

* overall Fire Strategy after promulgation

of this rule.

e. Stratospheric Ozone Intrusions

Stratospheric ozone intrusion is

considered to be a natural event. A

stratospheric ozone intrusion occurs

when a parcel of air originating in the

stratosphere, which is at an average

height of 20 km or 12.4 miles, is

transported directly to the surface of the

earth. Stratospheric ozone intrusions are

very infrequent, localized events of

short duration. They are typically

associated with strong frontal passages

and, thus, may occur primarily during

the spring season.

Comments and Responses

Comment: One commenter stated that

EPA should update its approach to

stratospheric events, establish criteria

by which such events may be

determined, and credit States for the

impact of intrusion events on noncompliant ozone monitor readings.

Response: Stratospheric ozone

intrusion is identified as a natural event

under 40 CFR part 50, appendix I, for

ozone, and will be considered for

treatment as an exceptional event.

6. Prescribed Fire

A "prescribed fire" is defined as any

fire ignited by management actions to

meet specific resource management

objectives. According to existing Federal

policy, prior to ignition a prescribed fire

must have an approved prescribed fire

plan and must meet the National

Environmental Policy Act (NEPA)

requirements (where applicable)(see

National Wildiand Fire Coordination

Group Glossary of Wildland Fire

Terminology, 2003). For purposes of

section 319, a prescribed fire cannot be

classified as "natural," given the extent

of the direct human causal connection,

however, a prescribed fire may meet the

statutory criteria defined in section 319

of "affect[ing] air quality," being "unlikely to recur at a particular

location" and is "not reasonably

controllable or preventable." The

determination of whether a prescribed

fire can be considered an exceptional

event showld be made on a case-by-case

basis taking into account the factors

* described below.

A prescribed fire carried out for

resource management objectives is

frequently designed to restore essential

ecological processes of fire and mimic

fire under natural conditions. As such,

a prescribed fire's expected frequency

can vary widely, depending on the

natural fire return interval of a

particular landscape or wildland

ecosystem. The natural firereturn

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interval can range from once every year

to less frequently than once in more

than 200 years. Thus, in many, though

not all cases, it may be possible to

demonstrate that the likelihood of

recurrence is sufficiently small enough

to show that a prescribed fire under

these conditions meets the "unlikely to

recur at a particular location"

requirement of the statutory language.

A prescribed fire may also meet the

condition of "not reasonably

controllable or preventable" by

examining whether there are reasonable

alternatives to the use of fire in light of

the needs and objectives'to be served by

it. For instance, there may be a

significant build-up of forest fuels in a

particular area that if left unaddressed

would pose an unacceptable risk of

catastrophic wildfire, which could

result in adverse impacts of much

greater magnitude, duration, and

severity than would result from careful

use of prescribed fire. A particular

ecosystem may also be highly

dependent on a natural fire return

interval to maintain a sustainable

natural species composition.

Alternatively, pest or disease outbreaks

in an area may be such that there are no

reasonable alternatives to prescribed

fire. In some cases, other legal

requirements may preclude the use of

mechanical fuel reduction methods

such as in designated wilderness or

National Parks. Where such ecological

conditions exist, or where mechanical

or other treatments are not reasonably

feasible for reasons that include, but are

not limited to, a lack of access, or severe

topography, we believe that prescribed

fire qualifies as being "not reasonably

controllable or preventable." Thus, we

believe that a prescribed fire, conducted

by Federal, State, Tribal or private

wildland managers or owners, under the

conditions described above may qualify

as an exceptional event.

In addition, one of the principles

contained in SAFE-TEA-LU, section

6013(b)(3)(A), includes the principle

that States must take necessary

measures to safeguard public health

regardless of the source of air pollution.

We believe it reasonable to tie the

qualifying criteria for an

anthropogenically generated prescribed

fire to State accountability for public

health protection. Consistent with

historical practice governed by the

guidance contained in the "Interim Air

Quality Policy on Wildland and

Prescribed Tires," issued on May 15,

1998, EPA approval of exceedances

linked to a prescribed fire used for

resource management purposes is

contingent on the State certifying that it

has adopted and is implementing a

Smoke Management Program (SMP) as

described in that policy. A State SWP

establishes a basic framework of

procedures and requirements for

managing smoke from a prescribed fire

managed for resource benefits: A SMP is

typically developed by a State or Trilje

with cooperation and participation by

wildland managers, both public and

private, and the general public. As

reflected in the Interim Air Quality

Policy on Wildland and Prescribed

Fires, States are provided flexibility on

the structure of a SMP. Thus, a SMP can

be extensive and detailed, or simply

identify the basic smoke management

practices for minimizing emissions, and

controlling impacts from a prescribed

fire.12 In the proposal to this rule, EPA

proposed to continue the use of that

approach. We also proposed to expand

the criteria for contingent approval to a

-prescribed fire where, in lieu of a SMP,

basic smoke management practic'es, that

minimize emissions and control

impacts, are being employed by burners.

In order to protect public health in areas

where a SMP has not been adopted, in

the final rule, the Agency has elected to

expand, on a case-by-case basis, the

qualifying criteria by which a prescribed

fire may qualify as an exceptional event.

In those cases, the Agency will judge on

a case-by-case basis whether the State

has ensured that appropriate basic.

smoke management practices have been

employed in determining whether the

prescribed fire qualifies as an

exceptional event. If an exceptional

event occurs using the basic smoke

management practices approach, the

State must undertake a review of their

approach to ensure public health is

being protected and must include

consideration of development of a SMP.

Comments and Responses

Comment: Several commenters

supported classifying prescribed fire as

qualifying as an exceptional event.

However, some commenters indicated

that there should be limitations placed

on when this type of fire should be

considered as an exceptional event. A

number of commenters also

disapproved of allowing prescribed fire

to be considered as an exceptional event

because they believe that this type of

12 Basic smoke management practices could

include, among other practices, steps that will

minimize air pollutant emissions during and after

the burn, evaluate dispersion conditions to

minimize exposure of sensitive populations, actions

to notify populations and authorities at sensitive

receptors and contingency actions during the fire to

reduce exposure of people at such receptors,

identify steps taken to monitor the effects of the fire

on air quality, and identify procedures to ensure

that burners are using basic smoke management

prictices.

fire is anthropogenic and does not meet

the statutory definition of exceptional

event. Some commenters'also favored

expanding the criteria for contingent

approval to include instances where

basic smoke management practices are

used in lieu of a SMP, while other

commenters did not favor this

expansion.

Response: The EPA believes that a

prescribed fire may be excluded as an

exceptional event under this rule only

in cases where the event meets the

criteria for an exceptional event as

defined in this rule, if documentation is

submitted to show that the fire meets

the requirement, as described above, of

"affect[ing] air quality," being "not

reasonably controllable or preventable"

and "unlikely to recur at location" and

provided the other requirements of the

rule including, among others, the

schedules and procedures for flagging

and demonstration are met. In those

instances where a prescribed fire meets

the criteria for an exceptional event, the

State must also provide appropriate

documentation to show that a certified

SMP was in place or that the burner

employed basic smoke management

practices and that the appropriate

practices were being followed at the

time that the event occurred. Because a

prescribed fire is an anthropogenic

source of emissions for purposes of

section 319, even 'though it may qualify

as an exceptional event, a State can

attempt to limit the health impact of a

prescribed fire through the thoughtful

development and implementation of a

SMP or ensuring that basic smoke

management practices were -employed

that minimize emissions and control

impacts from prescribed fires.

V. The Management of Air Quality Data

Affected by Exceptional Events

The EPA proposed that, in order to

exclude air quality data from

consideration for regulatory purposes,

States must follow the procedures,

timelines, and other requirements

described in the proposed rule. Under

the Final Rule, if an event is determined

to be a qualifying exceptional event

according to section IV.D, a State, Tribe,

or designated local agency may petition

EPA to classify the event as exceptional

and submit a demonstration to justify

data exclusion.' 3 For data exclusion,

States must clearly identify, or "flag,"

13 Although a single qualifying exceptional event

may affect air quality for multiple days and at

multiple monitors, the discussions below consider

an individual demonstration as justifying exclusion

of a single AQS data point. The EPA encourages

State submittals to package demonstrations about

single exceptional events to expedite the review

process.

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data they believe to be influenced by

such events. The demonstration to

justify data exclusion shall provide

evidence that: (a) The event qualifies in

accordance with section IV.D and with

EPA policies and guidance for certain

events as described in section IV.E, (b)

there is a clear causal relationship

between the measurement under

consideration and the event that is

claimed to have affected the air quality

in the area, (c) the event is associated

with an unusual measured

concentration beyond typical

fluctuations including background, and

(d) that there would have been no

exceedance or violation but for the

event.

The SAFE-TEA-LU requirements for

exclusion of data from exceptional

events are: (1) The occurrence of the

exceptional event must be demonstrated

by reliable and accurate data; (2) the

State must show that there is a "clear

causal relationship" between the

NAAQS exceedances and the event; (3)

there must be a public review process

related to the exceptional event

determination; and (4) the rule must set

criteria and procedures for States to

petition EPA to exclude data directly

affected by an exceptional event. The

sections below describe how each of

these requirements must be met.

The sections below address the

flagging of data as exceptional events

that are determined to have affected air

quality, submittal of demonstrations to

request data exclusion, public review,

and the schedule and timing for these

processes. After an exceptional event occurs (judged according to section

IV.D) and an agency determines that the

event affected ambient air quality,

flagging may occur according to section

V.A. Section V.B describes the

evaluation of whether or not the event

affected ambient air quality. Section V.C

describes the necessary "but-for" test

that data would have complied with the

applicable standard but for the

occurrence of the exceptional event.

Section V.D explains the schedules and

procedures for the flagging and

demonstration submittals, section V.E

discusses the applicability to hourly

readings, section V.F states the

requirements for determination

submittals if the agency requests EPA to

exclude the data from consideration for

regulatory purposes, and section V.G

describes the public review.

requirements. Some commenters

suggested that all data occurring from

exceptional events should be flagged,

and EPA will allow these flags for

informational purposes, even if the data

do not qualify for exclusion. If EPA concurs on the exclusion of data from

qualifying exceptional events, the data

will be excluded from regulatory

consideration but will still count toward

data capture requirements.

A. Flagging of Data in the AQS Database

1. Background

Air quality data are required,

pursuant to 40 CFR 58.15, to be

submitted to EPA by each State on a

calendar quarterly basis, with

submissions due not later than 90 days

after the end of a quarterly reporting

period. Once air quality data have been

submitted to EPA, it is possible to "flag"

specific values for various purposes.

"Data flagging" refers to the act of

making a notation in a designated field

of an electronic data record. The

principal purpose of the data flagging

system in the AQS database is to

identify those air quality measurements

for which special attention or treatment

is warranted. These include, but are not

limited to, those measurements that are

influenced by exceptional events.

The preamble to the proposed rule

stated: "In the case of exceptional

events, States place the initial flag on

the data in the AQS database. Following

an evaluation of the supporting

documentation, EPA will decide

whether to concur with the flag;

concurrence will be marked by the

placement of a second flag in the AQS

database by EPA. Once EPA has

concurred on the flag, the data will be

excluded from regulatory decisions such

as determinations of attainment or

nonattainnient." a "While the flagging of data by the

State is the first step in an exceptional

events demonstration, it is insufficient

by itself to allow for the exclusion of

data. In order to have EPA- concur on a

flag, States must meet the additional

requirements described below. As stated

previously, the State has the

responsibility to document both the

occurrence of the event and the causal

connection to the monitoring data under

consideration. Because the initial step of

flagging the data is a relatively simple

one, States may flag many more days

than the number of days for which they

ultimately submit documentation to

support exclusion."

2. Final Rule

In the case of exceptional events,

States and Tribes place the initial flag

on the data in the AQS database, but

EPA determines the available flags.14

States may also delegate authority to

14 It is EPA's intention, for purposes of

consistency with this rule, to review the list of

exceptional events that are currently in the AQS

database following the promulgation of the rule.

local agencies to submit flags and

documentation. In-any event, States

should work with their local agencies

for the identification and review of

exceptional events and consider

requests to flag data from those

agencies. At the time the flag is inserted

into the AQS database, the State must

also provide an initial description of the

event in the AQS comment field. This

initial description should include such

information as the direction and

distance from the event to the air quality

monitor in question, as well as the

direction of the wind on the day in

question. The flags, and the initial event

description, must be inserted into the

AQS database prior to July 1st following

the year in which the event occurred.

Schedules for demonstrations are

discussed in section V.D.

Following an evaluation of the

supporting documentation, EPA will

make a decision concerning whether to

concur with the flag; concurrence will

be marked by the placement of a second

flag in the AQS database by EPA. If EPA

has concurred on the flag, the data will

be excluded from regulatory

determinations such as determinations

related to attainment or nonattainment,

or determinations concerning SIP

development. The EPA will use the

second flag to indicate the following

conditions: EPA concurrence, EPA nonconcurrence, and documentation

submitted with EPA decision pending.

While flagging of the data in the AQS

database by the affected State, local, or

Tribe authority is-the first step in an

exceptional events demonstration, it is

insufficient in and of itself to allow for

the exclusion of data. In order for EPA

to concur on an exceptional events flag,

States, Tribes, and local agencies must

meet the additional requirements

described below. As explained, the

State, Tribe, or local agency has the

responsibility to document the

occurrence of the event in question, to

demonstrate that the event qualifies as

an exceptional event in accordance with

section IV.D, is consistent with EPA

policies and guidance for certain events

as described in section IV.E, has

provided for public review in

accordance with section V.G, and to

document the causal connection

between the measurement under

consideration and the event that is

claimed to have affected the air quality

in the area. The State, Tribe, or local

agency must also demonstrate that the

event is associated with an unusual

measured concentration beyond typical

fluctuations including background, and

that there would have been no

exceedance or violation "but for' the

event. Because the initial step of

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flagging the data is a relatively simple

one, States, Tribes, and local agencies

may flag more days than the number of

days for which they ultimately intend to

submit demonstrations to justify data

exclusion.

3. Comments and Responses

Comment: One commentei supported

flagging data related to any fire that

caused an exceedance.

Response: This Rule does not

preclude a State, Tribe, or Local-agency

from flagging any data allegedly

influenced by exceptional events.

However, for the data to qualify as an

exceptional event and to exclude it from

regulatory decisions, the data must meet

all of the criteria described in this Rule

and all the procedures delineated must

be followed.

B. WHat Does It Mean for an Event To

"Affect Air Quality"?

1. Background

It is Important to recognize that any

emissions-producing event has the

potential to have some influence on

downwind air quality. Indeed, on any

given day, measured air quality at any

given location will reflect the influences

of a variety of activities, including both

natural and anthropogenic emissions

from both local as well as remote

upwind sources. Given the directive in

section 319(b)(3)(B)(ii), that a clear

causal connection must exist between

the "measured exceedances" and the

exceptional event, EPA believes that it

would be unreasonable to exclude data

affected by an exceptional event simply

because of a trivial contribution of an

event to air quality. Furthermore, we

believe that it would be unreasonable to

exclude more significant, but routine

background air quality impacts, as this

would disregard an important part of

the public's exposure to air pollution

upon which EPA's air quality standards

are based. The effect of such exclusion

would be an inappropriate reduction in

the stringency of the NAAQS, rather

than providing specific relief under the

circumstances provided in section 319

for which States should not be

designated nonattainment or be required

to prepare costly SIP control strategies.

Neither section 319, nor its legislative

history, provides precise guidance on

what should be considered when

determining whether an event "affects

air quality" and thus qualifies to be

considered for exclusion or special

treatment. However, section

319(b)(3)(B)(ii) and (iv) provides that

there must be a "clear causal

relationship" between a measured

exceedance of a standard and the event

to show that the event "caused a

specific air pollution concentration;"

and it must be shown that the data in

question are "directly due" to an

exceptional event. Moreover, one of the

principles provided by section

319(b)(3)(A) indicates that the

protection of public health is the highest

priority. For these reasons, we proposed

three conditions under which an event

may qualify as "exceptional" for

purposes of special regulatory

consideration: Its air quality impactmust (1) fall both above the level of the

applicable standard (i.e., must be an "exceedance" as required by section

319), (2) be significantly beyond the

normal fluctuating range of air quality,

including background air quality

concentrations, and (3) should be large

enough such that without it there would

have been no exceedance.

We next provided several alternative

approaches to determining whether and

when air quality is "affected by"

exceptional events and requested

comment on which of these approaches was most suitable for demonstrating

such impacts. These approaches

primarily applied to condition (2)

above. Two of the approaches involved

statistical comparisons of existing

flagged data. The final rule most closely

reflects the third proposed option with

some modifications. This option

considered a case-by-case evaluation of

the data against historical, seasonally

adjusted air quality levels. Finally, the

proposed rule provided details

regarding what is meant by an

exceedance (1) and the "but-for"

condition (3). These are discussed in

detail in section V.C.

2. Final Rule

Under the Final Rule, the

demonstration to justify data exclusion

must provide a justification that: (a) The

event qualifies in accordance with

section IV.D. and if applicable, with

EPA policies and guidance for certain

events as described in section IV.E, (b)

there is a clear causal relationship

between the measurement under

consideration and the event that is

claimed to have affected the air quality

in the area, (c) the event is associated

with an unusual measured

concentration beyond typical

fluctuations including background, and

(d) there would have been no

exceedance or violation but for the

event (discussed in section V.C). The

second and third criteria establish that

the event affected air quality.

The second criterion that the event

caused an air quality impact may be

shown through a number of methods

includi.ng, but not limited to, modeling

and speciation analysis. The third

criterion distinguishes common events

from those that are exceptional and may

be accomplished through the

presentation of historical evidence.

The final rule permits a case-by-case

evaluation, without prescribed

threshold criteria, to demonstrate that

an event affected air quality. This

demonstration would be based on the

weight of available evidence, but must

consider the historical frequency of

such measured concentrations. While a

State may determine the specific

approach to use for such analysis, it

must compare contemporary

concentrations with the distribution of

all measured data during the past

several years. The evidence that an

event affected air quality may be

presented on a seasonal or other

temporal basis to best compare

contemporary concentrations with the

distribution of historical values. For

consistency with data reporting and

computation of NAAQS statistics, a

calendar quarter basis is suggested.

Baseline data may also be defined

differently for each event type (e.g.,

April and May data may be the most

relevant information for statistical

comparison with certain dust events).

The general statistical approach of

using all measured data during the past

several years is independent of

historical flagging practices and allows

States to accurately represent events not

likely to recur by including all

monitoring data in analyses.

In addition, the magnitude of the

measured concentration on days

affected by exceptional events relative

to historical, temporally adjusted air

quality levels can guide the level of

necessary analysis and documentation

to demonstrate that the event affected

air quality. For extremely high

concentrations relative to historical

values (e.g., concentrations greater than

the 95th percentile), a lesser amount of

documentation or evidence may be

required to demonstrate that the event

affected air quality. The closer the event

concentration is to typical levels (e.g.,

values less than the historical 75th

percentile), the stronger the necessary

evidence would have to be to justify

exclusion of data for regulatory

purposes. This weight of evidence

approach is most nearly analogous to

our historical treatment of exceptional

events.

3. Comments and Responses

Comment: One commenter noted that

EPA's proposed rule concedes that the

third option would "provide the least

definitive guidance to assist States in

their evaluations," and "may make it

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* difficult for EPA regions to be consistent

when determining whether to concur on

a flag." Moreover, "the case-by-case

approach allows for consideration of

days with ambient concentrations -

which are not necessarily among the

highest concentrations that have been

historically observed. While such days

are unlikely to impact short-term

standards, discounting such days can

certainly have an impact on an annual

average concentration." The commenter

asserted that EPA's description of the

proposed case-by-case evaluation makes

the case for rejecting that option because

it fails to provide the guidance

mandated by section 319, and is so

vague as to be arbitrary.

Response: The EPA disagrees with the

commenter that this option fails to

provide guidance and is so vague as to

be arbitrary. The EPA has explained

above the criteria that it will use in

making its-case-by-case evaluations. The

commenter's concern that the event

must represent concentrations that are

not typically observed is addressed by

the third criterion that the event must be

associated with an unusual measured

concentration beyond typical

fluctuations including background.

Demonstration of the magnitude of the

measured concentrations with respect to

historical frequency under similar

conditions will provide a new level of

consistency across monitoring locations.

Comment: If an area exceeds the

NAAQS, one commenter stated that use

of a 95th percentile criterion better

ensures that the definition of an

exceptional event is met (i.e., unlikely

to recur at a particular location).

Response: The EPA recognizes that

extreme concentrations (e.g.,

corresponding to values greater than the

95th percentile of historical values) are

more likely associated with exceptional

events. With the final rule, we are not

assuming that such values are definitely

exceptional. In fact, some extreme

concentrations may be associated with

various emission sources and

atmospheric conditions which are

unrelated to a causal connection to the

claimed exceptional event. Instead, the

frequency of occurrence relative to

historical concentrations would be used

as an important part of the overall

weight of evidence to demonstrate the

exceptional nature of the claimed air

quality impact.

C. Use of a "But For" Test

1. Background

There may be instances in which

exceptional events may have a

significant impact on air quality on days

when concentrations are already above

the applicable standard in the absence

of the influence of such events. In such

cases, it is important to preserve and

consider all valid air quality data

influenced by such activities, which

properly fall within the responsibilities

of States to manage for purposes of air

quality attainment and maintenance.

For this reason, we proposed to require

that air quality data may not be

excluded except where States show that

exceedances or violations of applicable

standards would not have occurred "but

for" the influence of exceptional events.

In other words, to the extent that it is

possible to determine that the resulting

air quality concentrations and

appropriate design values for an area

would be above the level of the

standards even withofit the influence of

the exceptional event, the air quality

data for the day(s) in question should

not be excluded. However,

consideration of the impacts of

exceptional events on air quality values

for control strategy planning purposes

may be appropriate, and States are

encouraged to consult with the

appropriate EPA regional office to

further discuss this issue.

2. Final Rule

The EPA will maintain the proposed

"but-for" requirement that air quality

data may not be excluded except where

States, Tribes, or local agencies show

that exceedances or violations of

applicable standards would not have

occurred "but for" the influence of'

exceptional events. Through analyses, it

is possible to demonstrate that an

exceedance or violation would not have

occurred but for the event [See sample

"but-for" analysis in memo to docket,

Husar et 01. 2006 (http://

www.regulations.gov, EPA-HQ-OAR2003-0061-0733 thru 0733.5)]. This

analysis does not require a precise

estimate of the estimated air quality

impact from the event. The weight of

evidence demonstration can present a

range of possible concentrations which

is not as technically demanding as

justifying a specific adjustment to a

measured value.

Because there are two standards for

PM2.5, clarification is needed regarding

the measurements that contributed to an

exceedance or a violation -that are

eligible to be excluded. This rule is

limited to values above the annual

standard for PM2.

5 because this

simplifies the process for determining

which values are eligible for flagging

according to the intent of section 319.

The short-term PM2.5 NAAQS is based

on a 3-year average of the annual 98th

percentile of 24-hour values. Therefore,

it is possible that one or two of these

annual concentration values may be

below the level of the NAAQS whilethe

3-year average is above the level of the

NAAQS. Because three annual q8th

percentile concentration values are

included in the determination of a

short-term PM2.5 NAAQS violation,

individual measurements below the

NAAQS may contribute to a violation.

On the other hand, the annual PM2.5

NAAQS is also a standard based on a 3-

year average. However, violations of the

annual standard that are caused by

measurements which are not

exceedances of that standard will be

difficult to distinguish from typical air

quality concentrations including

background. To accommodate the 3-year

form of the PM2.

5 NAAQS, this rule will

allow measurements whose

concentrations are greater than the level

of the annual NAAQS to be flagged as

being affected by exceptional events for

the purposes of contributing to an

exceedance or violation of the PM2.

5

NAAQS. Thus, we provide the -.

following clarification that individual

measured values greater than the annual

PM2.5 NAAQS will be considered

"exceedances" under this rule and

therefore eligible to be considered for

exclusion for comparisons to either the

annual or 24-hour NAAQS.

3. Comments and Responses

Comment: One commenter stated that,

while some of those measurements may

not individually be above the NAAQS,

taken together they might be sufficient

to put an area in violation of an annual

standard. Any "but for" determination

must take into account the aggregate of

exceptional events that occurred within

the applicable NAAQS period.

Response: The rule acknowledges that

it is possible that an event can affect

multiple days. The "but for" provision

allows for data exclusion if but for the

entire event there would have been no

exceedance or violation. Therefore, for

those events that can be shown to affect

air quality on multiple consecutive

days, measurements for the entire

period are eligible for data exclusion,

provided that at least one measurement

day during the episode is an exceedance

as defined by this rule and the air

quality impact on each day are

considered exceptional.

Comment: One commenter cautioned

EPA about using the phrase "to the

extent it is possible to determine"

because a "bright line" distinction

between the contribution from natural

and anthropogenic sources often does

not exist.

Response: We agree with this

comment and for this reason we will -

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approach to demonstrate that there

would not have been an exceedance or

violation but for the event.

D. Schedules and Procedures for

Flagging and Requesting Exclusion of

Data

1. Background

In establishing procedures and time

tables for States to request, and EPA to

grant, exclusion of data affected by

exceptional events, we are guided by

two competing considerations: Ensuring

States have adequate time and

opportunity to compile and evaluate all

relevant and available information in

support of such requests; and making

determinations in a timely manner so

that all pertinent and valid air quality

data would be appropriately considered

in regulatory determinations. To assist

EPA in determining the best approach to

managing the data flagging process and

submissions of demonstrations for the

final rule, we proposed three

alternatives for public review and

commient. Public comments showed that

each option had desirable aspects, and

these are incorporated into the final

rule.

2. Final Rule

A multi-step process will be

established for identification of data and

submission of demonstrations. The

process is designed to ensure that

States, Tribes, and local agencies have

adequate opportunity to compile and -

present evidence of exceptional and

natural events but also ensures timely

submittals in order to make regulatorydecisions and ensure the protection of

human health through NAAQS

determinations. The steps include State

flagging, annual State submission of an

initial event description, State

submission of a demonstration to justify

data exclusion and EPA review followed

by approval or disapproval. Where air

quality in an area is influenced by a

relatively small set of emission sources

with well-defined emission profiles and

limited pollutant species, a

demonstration that an air quality

measurement influenced by a particular

event merits exclusion may be relatively

simple to make. In other cases, such as

where the number and types of sources

contributing to measured air quality

concentrations are extremely complex

and varied, making it more difficult to

distinguish between the effects of

routine activities and unusual ones,

more time and effort will be needed for

a State, Tribe, or local agency to provide

an adequate demonstration in support of

its request.

States, Tribes, and local agencies are

encouraged to flag the data that they

believe to be affected by exceptional

events at the time of submission of the

air quality data to EPA's AQS database,

in accordance with the schedule

described in 40 CFR 58.16, which is

generally no later than 90 days after the

end of the calendar quarter. This

includes both flagging of data and

insertion of the initial event description

into the AQS comment field. This

constitutes notification of the

appropriate EPA Regional Office

concerning the State's intention to seek

exclusion of data. This approach would

ensure that the flagging process remains

consistent with the timeline set forth in

rules governing data submission

requirements. The EPA recognizes that

laboratory analyses may delay these

submissions and therefore is extending

the required time period for submission

to 180 days after the end of the calendar

year (i.e., all flags, along with initial

event descriptions, for a calendar year

must be reported by July 1 of the

following year).

We encourage States, Tribes, and local

agencies to submit the demonstration to

justify data exclusion annually for

exceedarices of short-term NAAQS by

July 1. However, the demonstration to

justify'data exclusion must also be

submitted no later than 12 months prior

to a regulatory decision. For all flagged

events, the demonstration to justify data

exclusion must be submitted within 3

years of the calendar quarter following

an event, but nolater than 12 months

prior to a regulatory decision. This

period should be used primarily to

support NAAQS compliance with

annual averages and violations of the

short-term standard that were not

anticipated. For nonattainment

designations, this would occur with the

Governor's letter recommending the list

of nonattainment ares. We also

recognize that special circumstances

could dictate more expedited data

delivery, flagging, and minimal

demonstrations (e.g., PM2.

5 designations

using 2002-2004 data). The submitted

deshonstration to justify data exclusion

as well as the EPA responses and the

rationale for the EPA decision will be

made'publicly available through EPA.

The reason for providing the 3-year

timeframe is that for ozone and PM,

decisions regarding whether or not an

area is attaining the applicable standard

are based on the most recent 3 years of

air quality data. Providing 3 years for

submission of demonstrations would

provide States, Tribes, and local

agencies with an opportunity to

evaluate whether the influence of one or

more exceptional events will be relevant

to determinations of attainment or

nonattainment before undertaking the

effort of preparing and submitting

demonstrations.

Once EPA receives a State's

demonstration, EPA generally will

undertake to review the demonstration

and provide a concurrence or

nonconcurrence on the flag in the AQS

database within 60 days. The EPA

expects that, in most cases, this time

period should be enough time to review

and provide a concurrence or nonconcurrence related to a State's request

to exclude data affected by an

exceptional event. However, for more

complex demonstrations, EPA may

require additional time to make its

decision and will notify the State of the

additional time required.

3. Comments and Responses

Comment: One commenter supported

arguments on why the proposed rule

must include a procedure for

retrospective flagging that addresses the

full set of the State's needs so that the

end result is that the State can flag any

and all events impacted by natural

events.

Response: With the Final Rule, EPA

requires annual submittal of flags. States

may, if they so choose, submit them

sooner. This schedule ensures that data

are collected And retained shortly after

the event and identification of potential

(non-routine) events is done in a timely

fashion to ensure that appropriate

corrective actions can be taken. States

would only maintain minimal

documentation supporting the decision

to flag the data. The full demonstrations,

however, can come later, in order to

allow States time to focus efforts on

those events that are determined to have

an impact on attainment. The Agency

notes that the-Exceptional Events Rule

does not apply to routine natural events

that are part of background air quaity

Comment: One commenter was

concerned that a State may have failed

to flag data impacted by a natural event

because the data values were below the

current NAAQS, only to find the State

threatened with nonattainment after

NAAQS revisions.

Response: For data collected before

the effective date of this rule, States may

include a demonstration to justify data

exclusion with the Governor's

recommendation letter on

nonattainment areas, provided that

there was notice and opportunity for

public comment. After. considering this

and other comments, for PM2.

5 data

collected during calendar years 2004-

2006, that the State identifies as

resulting from an exceptional event,

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EPA is permitting the State to flag and

submit an initial description of the

event provided that these are submitted

no later than October 1, 2007. In cases

where the State is able to show that this

time period is inadequate, a State may

submit a request for an extension and

EPA will grant this request for an

'extension up to but no later than

December 1, 2007. This procedure

should accommodate States concerned

about potential PM2.5 nonattainment

areas using the 2004-2006 data sets. The

EPA may consider a similar exemption

of the schedules for submittal of data for

future revision of standards.

Comment: One commenter stated that

EPA should also make allowances for

those situations when a State neglects to

flag a value or submit documentation

within the equired timeframes. In these

cases, the commenter asserted that EPA

should provide some type of petitioning

process.

Response: If a State fails to meet the

schedule for flagging or.document

submittal, late petitions will not be

considered. Policy decisions, SIP

planning, and dissemination of data

should not be delayed or altered based

on a State's failure to submit

documentation or follow the regulatory

procedures in a timely manner.

E. Exclusion of Entire 24-Hour Value as

Opposed to a Partial Adjustment of the

24-Hour Value

1. Background

In general, EPA's historical practice

has been to exclude a daily measured

value in its entirety when Ian

exceptional event causes that value, and

we retained this approach in the

proposed rule. With this approach, a

determination is made that emissions

from the event are largely responsible

for the resultant ambient air pollutant

concentration. For example, if the

observed concentration is 200 gg/m 3 for

PM2.

5 and is associated with a nearby

forest fire, then EPA is likely to concur

with the claim that the event was

responsible for the ambient

concentration. The measured value

would be excluded in its entirety from

the data used to judge attainment (as per

40 CFR 50, appendix N), although the

measurement would still count towards

meeting minimum data capture

requirements.

We believe it would be desirable to

adjust the daily value to exclude only

those portions of the data that are

attributable to the exceptional event in

question, and to retain the remainder of

the day's measurement if appropriate

and accurate methods were available to

make such adjustments. For example, if

an area affected by. a wildfire had a

measured 24-hour PM2.

5 concentration

of 50 pg/m 3 and the estimated event

impact was 30 gg/m 3, then the expected

value that would have occurred but for

the event would have been 20 gg/m3.

Normal air quality -for this location

might be 16 pg/m 3 and, therefore, the

"but-for" concentration of 20 pg/m 3 is

above average. Discounting the entire

event day could, therefore,

inappropriately bias a determination of

nonattainment with the annual PM2.

5

NAAQS (currently set at 15 pg/m3). We

are currently seeking to develop and

evaluate new analytical methods that.

would allow us to discount only the

portion of the daily value attributable to

the excdptional event. However, at

present, we are not aware of the

existence of precise and universally

applicable techniques that are

administratively and technically

feasible and that could support partial

adjustment of air quality data except

perhaps in limited cases, such as where

the number and type of pollutant

species and contributing sources are

relatively less complex or potentially

when sufficient spatial, temporal,

meteorological and chemical data are

available [See memo to docket, Husar et

al. 2006, (http://www.regulations.gov,

EPA-HQ-OAR-2003-0061-0733 thru

0733.5)]. When wedetermine that

techniques for adjustment of air quality

data are sufficiently well-demonstrated

for -use in exceptional events

determinations, we will publish a notice

of proposed rulemaking to seek

comment on the appropriateness and

scope of such use and its impact on the

requirements set forth in this rule for

determining an exceptional event.

2. Final Rule

We are retaining in this rule EPA's

historical practice to exclude a daily

measured value in its entirety when that

value is found to be caused by a

qualifying exceptional event that

affected air quality in accordance With

the conditions described in sections V.B

and V.D. If precise and universally

applicable techniques that are

administratively and technically

feasible and that could support partial

adjustment of air quality data become

available in the future, EPA will,

through a rulemaking, propose, and as

appropriate, finalize a technique for

partial adjustment of data as well as any

other matters in this rule which may be

affected by the availability of this

technology.

One exception may be made to this

exclusion of the entire daily value for

monitoring locations with hourly

measurements by Federal Reference

Methods (FRM), Federal Equivalent

Methods (FEM), and/or Approved

Regional Methods (ARM) where such

data are submitted routinely to AQS.

For example, in cases where

stratospheric ozone intrusion occurs,

those hourlj (but not sub-hourly).

measurements affected by the intrusion

may be excluded in order to calculate

the ozone measurements for the day.

The individual hours are to be excluded'

however, if the resulting calculated

NAAQS averaging time value exceeds

the level of the standard, not just if the

individual hourly values exceed that

level. Thus, in the case of ozone, the

resulting 8-hour average must exceed

0.08 ppm, and the resulting 24-hour

average must exceed 15.0 pg/m 3 for

PM2 5. Incomplete data substitution

protocols shall also be considered when

evaluating the original and revised

NAAQS averaging time value. In other

words, an 8-hour ozone period is

considered valid when fewer than six

valid hours are present if one half the

minimum detection limit can be

substituted for the missing hours and

the resultant 8-hour value still exceeds

0.08 ppm; a daily (24-hour) PM2.5 value

is consideied valid when fewer than

eighteen valid hours are present if

zeroes can be-substituted for the missing

hours and the resultant 24-hour value

still exceeds 15.0 gg/m 3

.

3. Comments and Responses

Comment: One commenter supported

value adjustment rather than exclusion

when, and only when, such adjustment

can be accomplished by the application

of various quantitative or semiquantitative approaches. When this is

not possible, the value in question

should be replaced with a long-term

seasonal mean value.

Response: The EPA will consider

such analyses as part of the weight of

evidence to judge "but-for," but will not

make quantitative adjustments to

reported measured values because EPA

does not believe sufficient quantitative

methods are available at this time.

F. What Should States Be Required To

Submit in Their Exceptional Events

Demonstrations?

1. Background

.Section 319 requires that, in order to

have a flagged value excluded from

regulatory determinations, a State must

make an affirmative demonstration that

an event occurred (as shown by reliable

and accurate data that is promptly

produced) and that there is a clear

causal relationship between measured

exceedances or violations of a standard

and the exceptional event in question to

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."demonstrate that the exceptional event

caused a specific air pollution

concentration" (42 U.S.C.

7619(b)(3)(B)(ii), (iv)). Section 319 also

indicates that regulations promulgated

under the section should provide for

criteria and procedures to exclude air

quality monitoring data "directly due to

exceptional events from use in

determinations by the Administrator

with respect to exceedances or

violations of the national ambient air

quality standards."

Therefore, after flagging data in the

AQS database, States are expected to

develop appropriate documentation to

support each individual flag. As a

general matter, we believe that such

demonstrations should include

documentation showing that the event

in fact occurred and that emissions

related to the event were transported in

the direction of the monitor(s) where

measurements were recorded; the size of

the area affected by the transported

emissions; the relationship in time

between the event, transport of

emissions, and recorded concentrations;

and, as appropriate, pollutant speciesspecific information supporting a causal

relationship between the event and the

measured concentration. The latter

information could be based on available

data provided by routine speciation,

monitoring'networks, or from selective

laboratory analysis of archived

particulate matter filters for the day

thought to be impacted by specific

events. In certain situations, such data

might be useful for evaluation of

impacts from exceptional events, e.g., to

distinguish between impacts caused by

natural fires versus impacts caused by

industrial sources. States also need to

show that appropriate mitigation actions

were taken at the time that the event

occurred, or after an event occurred in

order to protect public health.

The-following examples are intended

to further illustrate the kinds of

information that States could consider

in preparing their demonstrations:

9 Information demonstrating the

occurrence of the event and its

subsequent transport to the affected

monitors. This could include, for

instance, documentation from land

owners/managers, satellite-derived

pixels (portions of digital images)

indicating the presence of fires; satellite

images of the dispersing smoke and

smoke plume transport or trajectory

calculations (calculations to determine

the direction of transport of pollutant

emissions from their point of origin)

connecting fires with the receptors.

* Identification of the spatial pattern

of the affected area (the size, shape, and

area of geographic coverage). This could

include, for instance, the use of satellite

or surface measurement data.

* Information about temporal patterns

(e.g., the time and duration of an event

in relation to measured downwind

concentrations, air quality trends over

time and space). This could include, for

instance, observed sequential

concentration spikes at multiple

locations in a downwind direction.

* Identification of the chemical

composition of measured

concentrations. This could include, for

instance, organic or crustal material in

excess of typically observed quantities

to differentiate from other high

concentration events.

* High wind speeds relative to

historically typical levels for the season

of the year in which the claimed event

occurred.

This list is not exhaustive and not all

of these kinds of information and/or

documentation will need to be provided

in every instance. A particular instance

may require more or less

documentation, depending on the

particular facts or circumstances in that

instance. The simplest demonstrations

could consist of newspaper accounts or

satellite images to demonstrate that an

event occurred together with daily and

seasonal average ambient concentrations

to demonstrate an unusually high

ambient concentration level, which is

clearly indicative of an exceptional

impact. Such is the case with events

such as volcanic eruptions. and nearby

forest fires. In one instance, we

determined that wildfires upwind of the

San Diego area very likely caused high

concentrations of particulate matter

measured in October 2003 based on the

actual physical damage caused by fire to

the ambient monitor. Depending on the

nature of the event, meteorological

conditions, severity and spatial extent of

measured ambient concentrations

(including relevant chemical

components when available) relative to

what typically occurs in the area, and

on emissions of pollutants from the

exceptional event which have similar

characteristics to those of other sources

in the area, additional showings could

be required on a case-by-case basis. In

particular, we anticipate that

significantly more effort will be needed

to establish that an exceptional event

caused a particular concentration in an

urban area in which there are numerous

and-diverse sources and complex

meteorology and topography, and where

the emissions from the event in question

may well be similar to those from other

sources contributing to measured

concentrations, as compared to an area

that has relatively few sources, simple

terrain and less complex meteorology,

and where emissions associated with

the event are both substantially greater

than and different in composition from

those of other nearby sources.

2. Final Rule

The demonstration to justify data

exclusion will address specific monitor

readings reported to the AQS database.

As stated in the previous sections, a

complete demonstration shall justify

that: (a) The event qualifies in

accordance with section IV.D. and with

EPA policies and guidance for certain

events as described in section IV.E, (b)

there is a clear causal relationship

between the measurement under

consideration and the event that is

claimed to have affected the air quality

in the area, (c) the event is associated

with an unusual measured

concentration beyond typical

fluctuations including background, (d)

there would have been no exceedance or

violation but for the event, and (e) the

State has provided an opportunity for

the public to comment as required

under section V.G. The level of

documentation may vary by the type of

event and can be guided in part by the

relative magnitude of the observed

concentrations. To obtain concurrence,

EPA must determine that the

demonstration is complete and provides

a reasonable technical demonstration.

Because of the variability in the

nature of exceptional events and the

resulting demonstration requirements,

States should consult with the

appropriate EPA Regional Office early

in the process of preparing their

demonstrations. We are not specifying

what will be required as a minimum

level of documentation in all cases

because facts and circumstances:will

vary significantly based on, among other

things, geography, meteorology and the

relative complexity of source

contributions to measured

concentrations in any particular

location. We believe, however, that at a

minimum, the elements of such a

demonstration should include a

showing that an event occurred at a time

when meteorological conditions were

conducive to transporting emissions

from the event downwind to the

monitor recording a high concentration

of one or more criteria pollutants.

Acceptable documentation -will be

determined through consultation with

the EPA regional offices. However,

certain minimum requirements (e.g.,

"but for" test) will be necessary as

discussed in the earlier sections of this

rule.

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3. Comments and Responses

Comment: In cases where high wind

data cannot be found, one commenter

stated that EPA should use a "weight of

evidence" approach, and should

recognize that not accepting a

demonstration that such exceedances

are exceptional events is equivalent to a

determination that the exceedances

were caused by recurring anthropogenic

sources.

Response: The EPA agrees that a

weight of evidence approach is the most

appropriate for demonstrations of

exceptional impact..

Comment: One commenter asserted

that States should be allowed to choose

not to submit any demonstration, if the

flagged value does not impact a

regulatory determination or if more

detailed investigation indicates that the

value may not have been caused by an

exceptional event after all. In these

cases, the agency should have the

option to remove the flag.

Response: We agree that the flag can

be removed in these circumstances or

left for informational purposes only.

Comment: One commenter stated that

EPA must provide a reasonable

explanation and documentation for their

decision to deny any request for the

flagging of data.

Response: The EPA regional offices

will work with the States, Tribes, and

local agencies fo ensure that proper

documentation is submitted to justify

data exclusion. The EPA will make the

response and associated explanation

publicly available.

Comment: One commenter stated that

EPA must establish a'technically-based

appellate process for States to follow

when Regional Offices do not concur

with a data flag.

Response: The EPA does not believe

that an appellate process is necessary

because we anticipate that the States

and Regional Offices will be working

closely through the data and

documentation submission process.

G. Public Availability of Air Quality

Data and Demonstrations Related to

Exceptional Events

1. Background

Section 40 CFR part 58.16 of EPA's air

quality monitoring rules state that all

ambient air quality data and associated

quality assurance data, including

metadata records and information

specified, by the AQS Data Coding

Manual epa.gov/ttn/airs/airsaqs/

manuals/manuals.htm must be reported

to EPA via AQS. This information

includes exceptional event flags.

2. Final Rule

We are requiring that all relevant

flagged data, along with the reasons for

the data being flagged, and a

demonstration that the flagged data are

caused by exceptional events be made

available by the State for 30 days of

public review and comment. The State

or designated local agency should

consider the public comments prior to

the final demonstration being submitted

to EPA for a decision concerning

whether to exclude the data from

regulatory consideration. Notice and

availability of such data and

demonstrations must be adequate and

consistent with States' administrative

procedures governing similar

submissions. The EPA does not require

that public hearings be held on

exceptional events demonstrations but

leaves this matter to the States'

discretion consistent with their

administrative procedures. With the

submission of the demonstration, the

State should document that the public

comment process was followed.

3. Comments and Responses

Comment: One commenter stated that

any new rules related to the flagging of

exceptional events should be consistent

with prior EPA policies and provide

sufficient-time for States to engage the

public in the process prior to data being

flagged in the AQS.

Response: The EPA believes that the

data demonstration requirements of the

final rule provide sufficient time to

engage the public. Not only does the

final rule require that the public be

accorded an opportunity to comment on

the State's findings, but in some

instances there will be further

opportunities for public review and

comment at the time that EPA proposes

*to base specific actions, e.g., approval, or

disapproval of SIP revisions. Thus, we

do not believe that additional public

review and comment provisions are

necessary or appropriate.

VI. Additional Requirements

Pursuant to section 319, EPA is

finalizing this rule to address data that

has been influenced by exceptional

events. Also, EPA is finalizing one.of

four options put forth in the proposed

rule to address the issue of whether, and

to what extent, States are required to

adopt specific mitigation plans or

measures to protect the public from

emissions-due to exceptional events.

Section 319 states that in promulgating

regulations under the section, EPA shall

follow certain, enumerated principles

and that regulations must contain

certain requirements. Section

319(b)(3)(A) contains five principles,

including the principle that each State "must take necessary measures to

safeguard public health regardless of the

source of air pollution." In order to

address this principle, EPA is finalizing

its proposal to exclude trivial and more

routine air quality impacts from

qualifying as an exceptional event and

is also finalizing a "but for" test as a

precondition to qualification as an

exceptional event (See: section V.C

above).

A. Requirements for States To Provide

Public Notification, Public Education,

and Appropriate and Reasonable

Measures To Protect Public Health

1. Background

The EPA proposed one approach and

took comments on three alternative

options concerning what actions a State

should take in anticipation of, or in

response to, the occurrence of an

exceptional event. The options that

were proposed ranged from being very

detailed and prescriptive to being very

flexible and less prescriptive in terms of

the actions that States should take to

mitigate the impact of an exceptional

event on the public. While EPA does not

believe that section 319(b)(3)(A)

explicitly requires, in and of itself, that

States must develop mitigating

measures or plans, EPA solicited

comment in the proposed rule on

whether this subparagraph.supports the

use of other legal authority to require

mitigating actions or plans when an

exceptional event occurs, and solicited

comment on issues regarding its legal

authority to require mitigation measures

and plans, and the legal basis for not

requiring mitigation measures or plans.

Option 1 in the proposed rule

provided that in cases where

exceedances of a NAAQS are caused by

an exceptional event, once a State.

becomes aware that an exceptional

event is occurring, is predicted to occur,-

or has occurred, the State must take

reasonable and appropriate actions to:

e Provide notice to the public of the

event. This may include, but is not

limited to, using the media to alert the

public of the event.

e Provide public education

concerning the potential health risks

associated with being exposed to high

ambient concentrations of pollutant(s)

related to the event. This may include,

but is not limited to, providing

information to sensitive populations

related to the health risks associated

with the event.

e Take appropriate and reasonable

measures to abate or minimize the

exposure of the public to high

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concentrations of air pollution

associated with the exceptional event.

This may include, but is not limited to,

taking reasonable and appropriate

actions to implement control measures

on significant contributing

anthropogenic sources to reduce

potential'exposure of the public to

emissions associated with natural

events. States must review the need to

implement controls on contributing

anthropogenic sources on a case-by-case

basis. For example, in the case of

volcanic or seismic activity, this may

include, but is not limited to, prdiriding

for prompt clean-up of the ash deposits

related to the event to prevent reentrainment.

Under option 1, EPA also proposed

that, where a State is requesting that air

quality data be excluded as an

exceptional event, the State must

submit, as a part of its demonstration,

appropriate documentation to show that

the State provided public notice and

public education concerning the event

in question, and that the State took

reasonable and appropriate measures to

abate or minimize the exposure of the

public to the emissions from the event,

where appropriate.

Option 2 in the proposed rule

provided that, States are required to

adopt a general mitigation plan to

address exceptional events before the

occurrence of an event as a part of the

State's SIP required under section

110(a)(1) of the CAA. Section 110(a)(1)

requires States to adopt and submit to

EPA, within 3 years following the

promulgation of a new or revised

NAAQS, a plan which provides for the

implementation, maintenance, and

enforcement of the standard in each air

quality region within the State. Under

this option, States would be required to

develop and adopt the general

requirements and procedures necessary

for the implementation of a mitigation

plan to address exceptional events as a

part of its section 110(a)(1) SIP to

address a new or revised NAAQS. The.

general plan related to exceptional

events would include provisions

providing for public notice, public

education related to an event, and

provide a requirement for a State to take

reasonable and appropriate measures to

mitigate the public health impacts of an

exceptional event. Under this option, in

cases where control measures are

required to address the impacts

associated with an exceptional event,

the State would be required to

implement appropriate measures on an

episodic basis, meaning in response to

a specific event that affects the air

quality of a particular area.

Option 3 in the proposed rule

required that, where appropriate, EPA

would require a State to develop and

implement a mitigation plan for an area

following the occurrence of an

exceptional event. This is in contrast to

option 2 above, which would require

each State to adopt a plan under section

110(a)(1) of the CAA which would

contain the general provisions of a

mitigation plan in advance of the

occurrence of any exceptional event.

Under option 3, the mitigation plan

would only be developed by the State

following the occurrence of an

exceptional event for which the State

requested exclusion of the air quality

data, and would not be submitted as a

part of the SIP. The mitigation plan

would be required to address the actions

that would be taken by the State related

to future similar events. The mitigation

plan under this option would have the

same provisions as required of plans

developed under Option 2 above,

including the requirements to notify the

public that an event is expected to

occur, or is occurring, or has occurred,

to provide for public education related

to the health effects associated with the

event, and to identify the actions that

would be taken by the State to mitigate

the impact of any recurrence of the

event on public health.

Option 4 provided that EPA would

not require a State to develop and

implement a mitigation plan for

exceptional events, or to take specific

mitigation measures as described in

options 1-3 in order for EPA to exclude

data from regulatory consideration. This

approach proposed to allow States to

have the maximum degree of flexibility

in determining what actions should be

taken to mitigate the impacts of

exceptional events, e.g., public

notification, public education, efforts to

reduce exposures, or other necessary

measures to safeguard public health.

Thus, under this proposed option States

would not be obligated to take any

particular actions to mitigate exposures

such as those contained in Option 1, to

develop and implement a formal

mitigation plan as part of the SIP such

as those contained in Option 2, or to

develop a more formal plan with

requirements not a part of the SIP such

as those contained in Option 3.

2. Final Rule

The EPA is adopting a modified

version of Option 1 from the proposed

rule, as described above. This option

does not require States to submit formal

mitigation plans; however, States must

provide public notice, public education,

and must provide for implementation of

reasonable measures to protect public

health when an event occurs.

3. Comments and Responses

Comment: Several commenters

supported option I because they stated

that it provides more flexibility for

States to determine the appropriate

measures to be implemented related to

the occurrence of an exceptional event.

Other commenters supported option 1

for well defined, well understood events

that are non-recurring or unlikely to

recur. The majority of the commenters

who commented on option 2 strongly

opposed that option. The commenters

indicated that option 2 would waste

scarce local resources in developing a

mitigation plan. Other commenters

stated that issues concerning

exceptional events should be dealt with

outside the SIP process and section 110

of the CAA. With regard to Option 3,

one commenter indicated that a

preemptive plan similar to a Natural

Events Action Plan (NEAP) (which

includes Reasonably Available Control

Measures (RACM)/Best Available

Control Measures (BACM) is necessary

to mitigate the poor air quality impacts

associated with exceptional events. The

commenter stated that BACM, not

RACM, must be implemented on all

contributing anthropogenic sources

related to an exceptional event. Several

commenters supported option 3 for

addressing public health impacts related

to recurring natural events. The

commenters stated that mitigation plans

should include BACM for contributing

anthropogenic sources, not RACM. The

majority of commenters who

commented on option 4.stated that they

supported the implementation of option

4 because it allows States the most

flexibility for developing and tailoring.

programs for public notification of

exceptional events, the implementation

of education programs on exceptional

events, and implementation of

reasonable measures to protect public

health.

Response: States have an inherent

responsibility to protect its citizens and

as such to provide appropriate and

reasonable actions to mitigate the

impact of exceptional events on the

public health. This includes alerting the

public when such events occur,

.providing public education concerning

the health effects of such events, and

implementing reasonable measures to

mitigate the impact of such events on

public health. Consistent with this

inherent responsibility, it is EPA's belief

that States are in a better position to

make decisions concerning what actions

should be taken to protect the public

when an exceptional event occurs. This

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being the case, States should have the

necessary flexibility to take appropriate

actions when exceptional events occur.

The EPA is adopting a modified version

of its proposed preferred option 1,

which requires States to provide public

notification, public education, and

provides that States should take

"reasonable and appropriate measures"

to protect public health related to the

occurrence of an event. Because States

are inherently responsible for the public

health of its citizens, and are capable of

making the determinations of what

actions shbuld be taken to mitigate the

impact of such events on the public

when they occur. The EPA has modified

option 1 from the proposed rule and

will not be requiring States to submit

documentation concerning the actions

that it took to mitigate the impact of

exceptional events, in order for EPA to

exclude data from regulatory

consideration. As proposed in option 1,

States may still make determinations

regarding reasonable measures in a

particular instance, which may or may

not include the implementation of

control measures on contributing

anthropogenic sources related to an

event, and are not limited to any

particular measure. Therefore, under

this option the implementation of

RACM or BACM is not required, but a

State has the necessary flexibility to

determine if, and what, controls should

be implemented following an event, as well as the level of control that is

required. The EPA believes that this"

modified option 1 provides suitable

flexibility to allow States to take those

actions that it deems necessary and

appropriate to protect public health.

While section 319, as revised by SAFETEA-LU, does not specifically provide

that States must implement mitigation

plans, in developing the exceptional

events rule, EPA is required to consider

the enumerated principles including the

principle that States must take

necessary measures to protect public

health regardless of the source of air

pollution. Therefore, under the

modified version of option 1 adopted in

this final rule, States must take

reasonable and appropriate actions to

protect public health.

Comment: Several commenters stated

that the exceptional events rule should

be consistent with the current

-requirements under existing policies

with respect to the need for a NEAP to

address recurring natural events such as

high wind events.

Response: The EPA believes that it is

advantageous for States to keep NEAPs

in place that are currently being

implemented in order to address the

public health impacts associated with

recurring natural events such as high

wind events. However, following the

promulgation of this rule, States will no

longer be required to keep NEAPs in

place that were not approved as a part

of a SIP for an area. Where a NEAP, as

well as BACM, has been approved as a

part of a nonattainment SIP for an area,

the NEAP, as well as the associated

BACM, must remain in place. States

may, however, submit a request to EPA

to remove the NEAP and BACM from

the SIP. The request must contain an

approvable demonstration, as required

by section 110(1), which shows that the

removal of the NEAP and BACM will

not interfere with any applicable

requirement concerning attainment or

maintenance of the NAAQS for an area,

reasonable further progress, or any other

applicable requirement for the area.

VII. Special Treatment of Certain

Exceptional Events Under This Final

Rule

As stated in section IV.D above, this

final rule applies to data affected by

natural events (which are a subset of

exceptional events) at air quality

monitoring sites where it has been

determined that concentrations due to

these events have caused, or

substantially contributed to,

exceedances of the NAAQS in an

affected area. This final rule applies to

several types of natural events,

including, but not limited to, volcanic

and seismic activities, natural disasters,

high wind events, certain fires, and

stratospheric ozone intrusions. It also

applies to transported pollution

originating from national and

international sources that otherwise

meets the criteria and requirements for

exceptional events. Some types of

exceptional events have unusual

characteristics that require special

consideration in the context of this final

rulemaking. We discuss each of these

special issues, and the necessary

accommodations, below.

A. Volcanic and Seismic Activities

1. Background

Volcanic and seismic activities may

affect air quality for an extended period

of time after the initial occurrence of the

event in question. Therefore, EPA

believes that it is appropriate to

consider an extended timefrane for

flagging and exclusion of data

associated with such events.

Specifically, EPA believes that

emissions attributed to anthropogenic

activities associated with clean-up that

re-entrain volcanic ash and dust from

seismic activit4r during the first year (12

months) following an event will be

treated as due to the natural event.

2. Final Rule

The EPA is finalizing its proposal

with regards to volcanic and seismic

activities. The EPA will allow up to 12

months for the clean-up of ash deposits

due to volcanic/seismic events. During

that time period, emissions of reentrained dust due to anthropogenic

activities associated with cleanup may

be treated as exceptional events. In

cases where the damage caused by the

event is so substantial that a 12-month

period is inadequate to address the

clean-up that is necessary, a State may

submit a request for an extension of the

12-month time period to EPA. As stated

elsewhere in this rule, EPA will grant

requests for extensions of the time

period related to such events on a caseby-case basis. States are encouraged to

submit supporting information

concerning the reason for the extension

and the length of time being reqiested

for the extension.

B. High Wind Events

1. Background

Where high wind events result in

exceedances or violations of the

particulate matter standards, EPA

proposed that they be treated as natural

events if there is a clear causal

relationship demonstrated between the

exceedances measured at the air quality

monitoring site and the high wind event

in question, and if anthropogenic

activities which contribute to

particulate matter emissions in

conjunction with the high wind event

are reasonably well-controlled.

2. Final Rule

The EPA's final rule concerning high

wind events states that ambient

particulate matter concentrations due to

dust being raised by unusually high

winds will be treated as due to

uncontrollable natural events where (1)

the dust originated from

nonanthropogenic sources, or (2) the

dust originated from anthropogenic

sources within the State, that are

determined to have been reasonably

well-controlled at the time that the

event occurred, or from anthropogenic

sources outside the State. These events

are also discussed in section IV.E.5.c

above. In cases where anthropogenic

sources are determined to have

contributed to exceedances or violations

due to high wind events at air quality

monitoring sites, per our decision in

this rulemaking concerning the action

that States must take to mitigate the

impact of exceptional events on public

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health (See section VI above), States

must take reasonable and appropriate

measures to mitigate the impact

associated with the event on publiq

health. As stated in section VI of this

rule, States have the flexibility to

implement reasonable measures to

protect public health when an

exceptional event occurs. These actions

may or may not include the

implementation of controls on

contributing anthropogenic sources

related to an event. However, where

anthropogenic sources have contributed

to the exceedances of the PM NAAQS at

an air quality monitoring site due to a

high wind event, a State must take

reasonable and appropriate measures to

protect public health.

Since the conditions that cause or

contribute to high wind events vary

from area to area with soil type,

precipitation, and the speed of wind

gusts, States should provide appropriate

documentation which indicates what

types of circumstances contributed to

the exceedances or violations at the

monitoring site in question. 15 In this

rule, EPA is not identifying a specific

wind speed which should be considered

when making a determination

concerning whether an event should

qualify as exceptional. Instead, EPA is

requiring that States submit appropriate

documentation which demonstrates

why a particular event should be

considered exceptional for the affected

area. The EPA will review the

documentation submitted by States

concerning high wind events and will

make decisions concerning whether to

exclude the data as being influenced by

15 Section 319(b)(1)(B) states: "In this subsection,

the term 'exceptional event' does not include (i)

stagnation of air masses or meteorological

inversions; (ii) a meteorological events involving

high temperatures or a lack of precipitation; or (iii)

air pollution relating to source noncompliance." In

terms of the exclusion related to "a meteorological

event involving high temperatures or a lack of

precipitation" EPA believes that this statutory

language prohibits EPA from treating a typical dry

day(s) or a dry season for an area as an exceptional

event. However, EPA believes that Congress did not

intenud that the above quoted language to prevent a

State from submitting compelling documentation

which shows that severe drought conditions may

have contributed to an exceptional event, but

instead was designed to prevent the indiscriminate

exclusion of data on days characterized by "high

temperature and a lack of precipitation." Therefore,

EPA is permitting States to submit documentation

which shows that "severe drought" conditions may

have contributed to the occurrence of a high wind

event. The documentation must, however, be

compelling enough to show that the conditions

present at the time of the event were more

substantial than. a typical dry day(s) or dry season

for the area in question, but were related to severe

drought conditions. The EPA will review this

information and make decisions concerning the

exclusion of the data related to the event on a caseby-case basis.

an exceptional event on a case-by-case

basis.

C. Stratospheric Ozone Intrusion.

1. Background

Consideration of stratospheric ozone

intrusions applies only to the 8-hour

ozone standard. The occurrence of such

intrusions are extremely difficult to

measure or document given currently

measured meteorological parameters

and the locations of these

measurements. The infrequency, short

durations, and localized nature of such

events makes it difficult to use currently

available, general meteorological data,

which are usually collected at isolated

locations such as airports, to determine

whether a stratospheric ozone intrusion

has occurred. The EPA believes that it

is important to differentiate between

stratospheric ozone intrusion, which is

an exceptional event for the purpose of

flagging data, and other non-exceptional

meteorological events. Although-data

have been identified in the past showing

the result of stratospheric ozone

intrusion, no standard definition or

criteria have been established for

concrete identification. Therefore, EPA's

determination of whether a

stratospheric ozone intrusion has

occurred is a case-by-case decision

based on reasonable judgment

considering the season of the year, time

of day, persistence, duration, type and

severity of accompanying

meteorological conditions associated

with the ozone measurement in

question, and other data showing that

conditions were not conducive to local

high ozone production but for this

intrusion.

2. Final Rule

The EPA is finalizing its rule as

proposed. The EPA's determination of

whether a stratospheric ozone intrusion

has occurred will be made on a case-bycase basis based on reasonable judgment

considering the criteria as noted above.

It is our intention to review this type of

exceptional event during the next

review ofthe NAAQS for ozone. A

review of historical data related to the

flagging of stratospheric ozone intrusion

as an exceptional event shows that the

event hal only been flagged on a few

isolated occasions.

VIII. Treatment of Fireworks Displays

A. Background

The EPA proposed to treat emissions

due to fireworks displays in a manner

similar to exceptional events. Some

national and/or cultural traditions, such

as July 4th Independence Day and the

Chinese New Year, have long included

fireworks displays as important

elements of their observances. While

this issue is not specifically covered in

CAA section 319, EPA believes that

Congress did not intend to require EPA

to consider air quality violations

associated with such cultural traditions

in regulatory determinations.

We are not aware of any information

showing adverse air quality impacts

caused by individual use of fireworks in

relatively small quantities. However,

analyses of monitoring data collected on

July 4th and July 5th indicates that large

fireworks displays, in combination with

other sources, can in some

circumstances be potentially significant

sources of air pollutant emissions. For

this reason, States are encouraged to

take reasonable precautions to minimize

exposures to emissions from fireworks

displays, to explore the use of lower

emitting fireworks, as well as to manage

associated activities that may also have

significant air quality impacts in the

areas where these events are held. Such

precautions may include alerting the

public to the potential for short-term air

quality impacts that may result from the

discharge of fireworks at large displays,

monitoring prevailing winds, and

locating displays downwind of

concentrations of people. For these

reasons, where States can show that the

use of fireworks displays was integral to

significant traditional national, ethnic,

or other cultural events, we proposed

that air quality data associated with

such.events could be excluded similar

to exceptional events under this rule.

B. Final Rule

The EPA is finalizing the approach as

stated in the proposed rule to treat

emissions from fireworks similar to the

treatment of exceptional events in the

final rule provided that the event meets

the other criteria as stated in this

rulemaking. For example, the event

must be determined to have affected air

quality. Where a State can show that the

use of fireworks is significantly integral

to traditional national, ethnic, or other

cultural events (e.g., July Fourth

celebrations, Chinese New Year

celebrations, Diwali, etc.), EPA will

exclude data from regulatory

determinations for monitoring stations

whose exceedances or violations has

been determined to be caused by

emissions from fireworks displays on a

case-by-case basis. As stated in other

parts of the rule, .States must assure that

reasonable measures were taken to

protect the public from the emissions

created by the fireworks display. Under

this rule, States are also strongly

encouraged to institute educational

programs that alert the public to the

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health effects associated with exposure

to emissions from fireworks displays.

C. Comments and Responses

Comment: The majority of

commenters who commented on this

issue agreed that emissions from

fireworks should be treated as an

exceptional event. However, some

commenters disagreed with EPA's

proposal to treat fireworks as an

exceptional event. Several commenters

believed that fireworks are neither an

exceptional event nor a natural event

and that EPA should not make

provisions for fireworks to be excluded

as an exceptional event.

Response: In considering the intent of

the SAFETEA-LU legislation, it is EPA's

belief that Congress did not intend to

prohibit the exclusion of data affected

by emissions from fireworks related to

celebrations of national or cultural

traditions. It is EPA's belief that data

influenced by fireworks displays should

be subject to the same provisions as

other exceptional events identified

under this rule. Therefore, the

mitigation actions described in sebtion

VI.A above would also apply to

emissions related to fireworks displays.

IX. Statutory and Executive Order

Reviews

A. Executive Order 12866: Regulatory

Planning and Review

Under Executive Order 12866 (58 FR

51735, October 4, 1993), this action is a

significant regulatory action because it

raises novel legal or policy issues

arising out of legal mandates.

Accordingly, EPA submitted this action

to the Office of Management and Budget

(OMB) for review under Executive

Order 12866 and any changes made in

response to 0MB recommendations

have been documented in the docket for

this action.

B. Paperwork Reduction Act

This action does not impose an

information collection burden. The information being requested under this

rule is consistent with current

requirements related to information

needed to verify the authenticity of

monitoring data submitted to EPA's

AQS database, and to justify data that

has been flagged as being affected by

exceptional or natural events. However,

the OMB has previously approved the

information collection requirements

regulations for ambient air monitoring

contained in 40 CFR part 58,-subparts A

through E, under the provisions of the

Paperwork Reduction Act, 44 U.S.C.

3501 et seq. and assigned OMB control

number 2060-0084, EPA ICR number

940.17. A cOly of the OMB approved

Information Collection Request (ICR)

may be obtained from Susan Auby,

Collection Strategies Division; U.S.

Environmental Protection Agency

(2822T); 1200 Pennsylvania Ave., NW.,

Washington, DC 20460 or by calling

(202) 566-1672.

Burden means that total time, effort,

or financial resources expended by

persons to generate, maintain, retain, or

disclose or provide information to or for

a Federal agency. This includes the time

needed to review instructions; develop,

acquire, install, and utilize technology

and systems for the purposes of

collecting, validating, and verifying

information, processing and

maintaining information, and disclosing

and providing information; adjust the

existing ways to comply with any

previously applicable instructions and

requirements; train personnel to be able

to respond to a collection of

information; search data sources;

complete and review the collection of

information; and transmit or otherwise

disclose the information. An Agency

may not conduct or sponsor, and a

person is not required to respond to a

collection of information unless it

displays a currently valid OMB control

number. The OMB control numbers.for

EPA's regulations in the CFR are listed

in 40 CFR part 9.

C. Regulatory Flexibility Act

I. The Regulatory Flexibility Act

generally requires an agency to prepare a regulatory flexibility analysis of any

rule subject to notice and comment

rulemaking requirements under the

Administrative Procedures Act or any

other statute unless the 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

organizations, and small governmental

jurisdictions. For the purpose of

assessing the impacts of this final rule

on small entities, small entity is defined

as: (1) A small business as defined by

the Small Business Administration's

regulations at 13 CFR 121.2.01; (2) a

small governmental jurisdiction that is a

government of a city, county, town,

school district or special district with a

population of less than 50,000; and (3)

a small organization that is any not-forprofit enterprise which is independently

owned and operated and is not

dominate in its field.

Courts have interpreted the RFA to

require a regulatory flexibility analysis

only when small entities will be subject

to the requirements of the rule. See,

Michigan v. EPA, 213 F.3d 663, 668-69

(DC Cir., 2000), cert. den., 532 U.S. 903

(2001). This rule would not establish

requirements applicable to small

entities. Instead, this rule provides the

criteria necessary for State, local, or

Tribal air quality agencies to meet in

order to properly flag data as being

influenced by an exceptional or natural

event. The rule also provides

information concerning what action.

should be taken by a State, local, or

Tribal air quality agency to protect

public health during and following an

exceptional or natural event. Because

affected States would have discretion to

implement controls on sources that may

need to be regulated due to

anthropogenic contribution in the area

determined to be influenced by an

exceptional or natural event, EPA could

not predict the effect of the rule on

small entities.

After considering the economic

impacts of this final rule on small

entities, I certify that this rule will not

have a significant economic impact on

a substantial number of small entities.

D. Unfunded Mandates Reform Act

Title II of the Unfunded Mandates

Reform Act of 1995 (UMRA), Public

Law 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

governments, in the aggregate, or to the

-private sector, of $100 million or more in any 1 year. Before promulgating an

EPA rule for which a written statement

is needed, section 205 of the UMRA

generally requires EPA to identify and

'consider a reasonable number of

regulatory alternatives and adopt the

least costly, most cost-effective or least

burdensome alternative that achieves

the objectives of the rule. The

provisions of section 205 do not apply

when they are inconsistent with

applicable law. Moreover, section 205

allows EPA to adopt an alternative other

than the least costly, most cost-effective

or least burdensome alternative if the

Administrator publishes with the final

rule an explanation of why that

alternative was not adopted. Before EPA

establishes any regulatory requirements

that may significantly or uniquely affect

small governments, including Tribal

governments, it must have developed

under section 203 of the UMRA a small

government agency plan. The plan 'must

provide for notifying potentially

affected small governments to have

meaningful and timely input in the

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development of EPA regulatory

proposals with significant Federal

intergovernmental mandates, and

informing, educating, and advising

small government on compliance with

regulatory requirements.

We have determined that this rule

does not contain a Federal mandate that

may result in expenditures of $100

million or more for State, local, and

Tribal governments, in the aggregate, or

the private sector in any 1 year. This

action simply provides the criteria for

State, local, or Tribal air quality

agencies to flag data to be discounted for

regulatory purposes that is being

influenced by exceptional or natural

events. Thus, this rule is not subject to

the requirements bf sections 202, 203,

and 205 of the UMRA.

E. Executive Order 13132: Federalism

Executive Order 13132, entitled

"Federalism" (64 FR 43255, August 10,

1999), requires EPA to develop an

accountable process to ensure

"meaningful and timely input by State

and local officials in the development of

regulatory policies that have federalism

implications." "Policies that have

federalism implications" is defined in

the Executive Order to include

regulations that have "substantial direct

effects on the States, or the relationship

between the national government and

the States, or on the distribution of

power and responsibilities among the

various levels of government."

This final rule does not have

federalism implications. It will not have

substantial direct effects on the States,

on the relationship between the national

government and the States, or on the

distribution of power and

responsibilities among the various

levels of government, as specified in

Executive Order 13132. The CAA

establishes the scheme whereby States

take the lead in developing plans to

meet the NAAQS. Thus, Executive

Order 13132 does not apply to this rule.

F. Executive Order 13175: Consultation

and Coordination With Indian Tribal

Governments

Executive Order 13175, entitled

"Consultation and Coordination with

Indian Tribal Governments" (65 FR

67249, November 9, ?000), requires EPA

to develop an accountable process to

ensure "meaningful and timely input by

Tribal officials in the development of

regulatory policies that have Tribal

implications." This final rule does not

have "Tribal implications" as specified

in Executive Order 13175. The rule

provides information concerning what

action should be taken by a State, local,

or Tribal. air quality agency

implementing.relevant air quality

programs to protect public health once

EPA has provided a concurrence on data

that has been flagged as being

influenced by an exceptional or natural

event. The CAA and the Tribal

Authority Rule (TAR) give Tribes the

opportunity to develop and implement

CAA programs, but it leaves to the

discretion of the Tribe whether to

develop these programs and which

programs, or appropriate elements of a

program, the Tribe will adopt through

the Tribal Implementation Plan (TIP).

This rule does not have Tribal

implications as defined by Executive

Order 13175. It does not have a

substantial direct effect on one or more

Indian Tribes, because no Tribe has

implemented a TIP related to the PM or

the 8-hour ozone NAAQS at this time.

Furthermore, this rule does not affect

the relationship or distribution of power

and responsibilities between the Federal

government and Indian Tribes. The

CAA and the TAR establish the

relationship of the Federal government

and Tribes in developing plans to attain

the NAAQS, and this rule does nothing

to modify that relationship. Because this

rule does not have Tribal implications,

Executive Order 13175 does not apply.

However, even though we found that

this rule does not have Tribal

implications, we nevertheless were

aware of Tribes that had an interest in

this rule. Therefore, We conducted

communications and outreach related to

the rule with the Tribes through

discussions via conference calls with

the Tribal Association. We also

provided information to the Tribes on

the rule via the Quarterly Tribal Air

Newsletter.

G. Executive Order 13045: Protection of

Children From Environmental Health

and Safety Risks

Executive Order 13045: "Protection of

Children From Environmental Health

anqd Safety Risks" (62 FR 19885, April

23, 1997) applies to any rule that (1) is

determined to be "economically

significant" as defined under Executive

Order 12866, and (2) concerns an

environmental health and safety risk

that EPA has reason to believe may have

a disproportionate effect on children. If

the regulatory action meets both criteria,

EPA must evaluate the environmental

health or safety effects ofthe planned

rule on children, and explain why the

planned regulation is preferable to other

potentially effective and reasonably

-feasible alternatives considered by EPA.

This action is not subject to Executive

Order 13045 because it is not

economically significant as defined in

Executive Order 12866, and because

EPA does not have reason to believe that

the environmental health risks or safety.

risks addressed by this rule present a

disproportionate risk or safety risk to

children. The rule provides information

concerning what action should be taken

by a State, local, or Tribal ait quality

agency to protect public health once

EPA has provided a concurrence on data

that has been flagged as being

influenced by an. exceptional or natural

event.

H. Executive Order 13211: Actions That

Significantly Affect Energy Supply,

Distribution, or Use

This rule is not a "significant energy

action" as defined in Executive Order

13211, "Actions That Significantly

Affect Energy Supply, Distribution, or

Use," (66 FR 28355, May 22, 2001)

because it is not likel to have a

significant adverse effect on the supply,

distribution, or use of energy. Further,

we have concluded that this rule is not

likely to have any adverse energy

effects.

L National Technology Transfer

Advancement Act

Section 12(d) of the National

Technology Transfer Advancement Act

of 1995 (NTTAA), Public Law No. 104-

113, section 12(d) (15 U.S.C. 272 note)

directs EPA to use voluntary consensus

standards (VCS) in its regulatory

activities unless to do. so would be

inconsistent with applicable law or

otherwise impracticable. Voluntary

consensus standards are technical

standards (e.g., materials specifications;

test methods, sampling procedures, and

business practices) that are developed or

adopted by VCS bodies. The NTTAA

directs EPA to provide Congress,

through OMB, explanations when EPA

decides not to use available and

applicable VCS.

This action does not involve technical

standards. Therefore, EPA did not

consider the use of any VCS.

J. Congressional Review Act

The Congressinnal Review Act, 5

U.S.C. 801 et seq., as added by the Small

Business Regulatory Enforcement

Fairness Act of 1996, generally provides

that before a rule may take effect, the

agency promulgating the rule must

'submit a rule report, which includes a

copy of the rule, to each House of the

Congress and to the Comptroller General

of the United States. The EPA will

submit a report containing this rule and

other required information to the U.S.

Senate, the U.S. House of

Representatives, and the Comptroller

General of the United States prior to

publication of the rule in the Federal

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Register. A major rule cannot take effect

until 60 days after it is published in the

Federal Register. This action is not a "major rule" as defined by 5 U.S.C.

804(2). This rule will be effective May

21, 2007.

K. Petitions for Judicial Review

Under section 307(b)(1) of the CAA,

petitions for judicial review of this

action must be filed in the United States

Court of Appeals for the District of

Columbia Circuit by May 21, 2007.

Filing a petitioi for reconsideration by

the Administrator of this final rule does

not affect the finality of this rule for the

purposes of judicial review nor does it

extend the time within which a petition

for judicial review must be filed, and

shall not postpone the effectiveness of

such rule or action. This action may not

be challenged later in proceedings to

enforce its requirements. See CAA

Section 307(b)(2).

List of Subjects

40 CFR Part 50

Environmental protection, Air

pollution control, National parks,

Wilderness areas.

40 CFR Part 51

Environmental protection, Air

pollution control, Administrative

practice and procedure, Reporting and

recordkeeping requirements.

Dated: March 14, 2007.

Stephen L. Johnson,

Administrator.

m In consideration of the foregoing, the

Environmental Protection Agency

amends 40 CFR parts 50 and 51 as

follows:

PART 50-NATIONAL PRIMARY AND

SECONDARY AMBIENT AIR QUALITY

STANDARDS

0 1. The authority citation for part 50

continues to read as follows:

Authority: 42 U.S.C. 7401 et seq.

* 2. Amend § 50.1 to add paragraphs (j)

and (k) to read as follows:

§ 50.1 Definitions.

(j) Exceptional event means an event

that affects air quality, is not reasonably

controllable or preventable, is an event

caused by human activity that isunlikely to recur at a particular location

or a natural event, and is determined by

the Administrator in accordance with 40

CFR 50.14 to be an exceptional event. It

does not include stagnation of air

masses or meteorological inversions, a

meteorological event involving high

temperatures or lack of precipitation, or

air pollution relating to source

noncompliance.

(k) Natural event means an event in

which human activity plays little or no

direct causal role.

(1) Exceedance with respect to a

national ambient air quality standard

means one occurrence of a measured or

modeled concentration that exceeds the

specified concentration level of such

standard for the averaging period

specified by the standard.

* 3. Add § 50.14 to read as follows:

§50.14 Treatment of air quality monitoring

data Influenced by exceptional events.

(a) Requirements. (1) A State may

request EPA to exclude data showing

exceedances or violations of the

national ambient air quality standard

that are directly due to an exceptional

event from use in determinations by

demonstrating to EPA's satisfaction that

such event -caused a specific air

pollution concentration at a particular

air quality monitoring location.

(2) Demonstration to justify data

exclusion may include any reliable and

accurate data, but must demonstrate a clear causal relationship between the

measured exceedance or violation of

such standard and the event in

accordance with paragraph (c)(3](iii) of

this section.

(b) Determinations by EPA. (1) EPA

shall exclude data from use in

determinations of exceedances and

NAAQS violations where a State

demonstrates to EPA's satisfaction that

an exceptional event caused a specific

air pollution concentration in excess of

one or more national ambient air quality

- standards at a particular air quality

monitoring location and otherwise

satisfies the requirements of this

section.

- (2) EPA shall exclude data from use

in determinations of exceedances and

NAAQS violations where a-State

demonstrates to EPA's satisfaction that

emissions from fireworks displays

caused a specific air pollutionconcenttation in excess of one dr more

national ambient air quality standards at

a particular air quality monitoring

location and otherwise satisfies the

requirements of this section. Such data

will be treated in the same manner as

exceptional events under this rule,

provided a State demonstrates that such.

use of fireworks is significantly integral

to traditional national, ethnic, or other

cultural events including, but not

limited to July Fourth celebrations

which satisfy the requirements of this

section.

(3) EPA shall exclude data from use

in determinations of exceedances and

NAAQS violations, where a State

demonstrates to EPA's satisfaction that

emissions from prescribed fires caused

a specific air pollution concentration in

excess of one or more national ambient

air quality standards at a particular air

quality monitoring location and

otherwise satisfies the requirements of

this section provided that such

emissions are from prescribed fires that

EPA determines meets the definition in

§ 50.1(j), and provided that the State has

certified to EPA that it has adopted and

is implementing a Smoke Management

Program or the State has ensured that

the burner employed basic smoke

management practices. If an exceptional

event occurs using the basic smoke

management practices approach, the

State must undertake a review of its

approach to ensure public health is

being protected and must include

consideration of development of a SMP.

(4) [Reserved] - (c) Schedules and Procedures. (1)

Public notification.

(i) All States and, where applicable,

their political subdivisions must notify

the public promptly whenever an event

occurs or is reasonably anticipated to

occur which may result in the

exceedance of an applicable air quality

standard.

(ii) [Reserved.]

(2) Flagging of data.

(i) A State shall notify EPA of its

intent to exclude one or more measured

exceedances of an applicable ambient

air quality standard as being due to an

exceptional event by placing a flag in

the appropriate field for the data record

of concern in accordance with the

schedules for submission of data to the

AQS database in 40 CFR 58.16.

(ii) Flags placed on-data in accordance

with this section shall be deemed

informational only, and the data shall

not be excluded from determinations

with respect to exceedances or

violations of the national ambient air

quality standards unless and until,

following the State's submittal of its

demonstration pursuant to paragraph

(c)(3) of this section and EPA review,

EPA notifies the State of its concurrence

by placing a concurrence flag in the

appropriate field for the data record in

the AQS database.

(iii) Flags placed on data as being due

to an exceptional event together with an

initial description of the event shall be

submitted to EPA not later than July 1st

of the calendar year follo wing the year

in which the flagged measurement

occurred, except as alloWed under

paragraph (c)(2)(iv) of this section.

(iv) For PM2.

5 data collected during

calendar years 2004-2006, that the State

identifies as resulting from an

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exceptional event, the State must notify

EPA of the flag and submit an initial

description of the event no later than

October 1, 2007. EPA may grant an

extension, if a State requests an

extension, and permit the State o

submit the notification of the flag and

initial description by no later than

December 1, 2007.

(v) When EPA sets a NAAQS for a

new pollutant, or revises the NAAQS for

an existing pollutant, it may revise or

set a new schedule for flagging data for

the initial designation of areas for those

NAAQS.

(3) Submission of demonstrations.

(i) A State that has flagged data as

being due to an exceptional event and

is requesting exclusion of the affected

measurement data shall, after notice and

opportunity for public comment, submit a demonstratioh to justify data

exclusion to EPA not later than the

lesser of, 3 years following the end of

the calendar quarter in which the

flagged concentration was recorded or,

12 months prior to the date that a

regulatory decision must be made by

EPA. A State must submit the public

comments it received along with its

demonstration to EPA. - (ii) A State that flags data collected

during calendar years 2004-2006,

pursuant to paragraph (c)(2)(iv) of this

section, must adopt the procedures and

requirements specified in paragraph

(c)(3)(i) of this section and must include

a demonstration to justify the exclusion

of the data not later than the submittal

of the Governor's recommendation letter

on nonattainment areas.

(iii) The demonstration to justify data

exclusion shall provide evidence that:

(A) The event satisfies the criteria set

forth in 40 CFR 50.1(j);

(B) There is a clear causal relationship

between the measurement under

consideration and the event that is

claimed to have affected the air quality

in the area;

(C) The event is associated with a

measured concentration in excess of

normal historical fluctuations, including

background; and

(D) There would have been no

exceedance or violation but for the

event. (iv) With the submission of the

demonstration, the State must document

that the public comment process was

followed.

(v) [Reserved.]

(A) [Reserved]

PART 51-NATIONAL PRIMARY AND

SECONDARY NATIONAL AMBIENT AIR

QUALITY STANDARDS

I 4. The authority citation for part 51

continues to read as follows:

Authority: 23 U.S.C. 101; 42 U.S.C. 7401-

7671q.

* 5. Adding Subpart Y consisting of

§ 51.930 to read as follows:

Subpart Y-Mitigation Requirements

§51.930 Mitigation of Exceptional Events.

(a) A State requesting to exclude air

quality data due to exceptional events

must take appropriate and reasonable

actions to protect public health from

exceedances or violations of the

national ambient air quality standards.

At a minimum,-the State must:

(1) Provide for prompt public

notification whenever air quality

concentrations exceed or are expected to

exceed an applicable ambient air quality

standard;

(2) Provide for public education

concerning actions that individuals may

take to reduce exposures to unhealthy

levels of air quality during and

following an exceptional event; and

(3) Provide for the implementation of

appropriate measures to protect public

health from exceedances or violations of

ambient air quality standards caused by

exceptional events.

(b) [Reserved]

[FR Doc. E7-5156 Filed 3-21-07; 8:45 am]

BILUNG CODE 6560-50-P

13581

HeinOnline -- 72 Fed. Reg. 13581 2007