UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

RESEARCH TRIANGLE PARK, NC 27711 

SEP 2 5 2009 

OFFICE OF 

MEMORANDUM AIR QUALITY PLANNING 

AND STANDARDS 

SUBJECT: 

FROM: 

TO: 

Guidance on SIP Elements Required Under Sections 11 O(a)(1) and (2) 

for the 2006 24-Hour Fine Particle (PM2.5) National Ambient Air Quality 

Standards (NAAQS) 

William 

Air Quality 

T. Harnett, 

Policy Division 

Director 

(C539-

{J)~ 0l) T: ~ 

Regional Air Division Directors, Regions 1-X 

The purpose of this memorandum is to provide guidance on addressing the 

"infrastructure" elements for State Implementation Plans (SIPs) required under sections 

110(a)(l) and 110(a)(2) ofthe Clean Air Act (CAA) for the 2006 24-hour PM2.s NAAQS (71 FR 

61144). On December 18,2006, EPA revised the 24-hour average PM2.s primary and secondary 

NAAQS from 65 micrograms per cubic meter ()lg/m3

) to 35 ~tg/m . Under sections 11 O(a)(1) 

and 11 O(a)(2) of the CAA, after promulgation of a new or revised NAAQS, each state is required 

to submit a plan to provide for the implementation, maintenance, and enforcement of that 

NAAQS. 

States are r~quired to address basic SIP requireme.nts (see Attachment A), to assure 

attainment and maintenance ofthe standards. By law, SIPs to address sections 110(a) (1) and 

11 0( a)(2) are to be submitted by states within 3 years after promulgation of a new or revised 

standard. 1 In many cases the section 11 0( a)(2) SIPs for the 1997 PM2.s NAAQS may already be 

adequate to implement the 2006 24-hour PM2.s NAAQS. Many of the required section 11 0( a)( 1) 

and 11 0( a)(2) SIP elements relate to the general information and authorities that constitute the 

" infrastructure" of a state's air quality management program, and these have been in place since 

the initial SIPs were submitted in response to the ·1970 Clean Air Act. However, it is still the 

responsibility of each state to make this determination for each new or revised NAAQS. 

Determining Completeness of State Submittals 

As required by section 110(a)(l), states will have to review and revise, as appropriate, 

their existing particulate matter SIPs to ensure that they are adequate to address the 2006 24-hour 

PM2.s NAAQS. States should, in consultation with EPA Regional Offices, refer to applicable 

EPA regulations governing SIP submittals in 40 CFR Part 51 - e.g., Subpart H ("Prevention of 

1 Although the rule for the revised PM2.5 standard has an effective date of December 18, 2006, the rule was signed 

by the Administrator and publically disseminated on September 21, 2006. Therefore, the deadline for submittal of 

11 0(a) SIPs for the 2006 24-hour PM25 NAAQS is September 21, 2009 based on the signature date. 

Internet Address (URL) • http://www.epa.gov 

Recycled/Recyclable • Printed wHh Vegetable Oil Based Inks on Recycled Paper (Minimum 25% Postconsumer) 
2 

Air Pollution Emergency Episodes"), Subpart I ("Review of New Sources and Modifications"), 

Subpart J (Ambient Air Quality Surveillance), Subpart K (Source Surveillance), Subpart L 

(Legal Authority), Subpart M ("Intergovernmental Consultation"), Subpart 0 (Miscellaneous 

Plan Content Requirements), Subpart I' ("Protection of Visibility"), and Subpart Q ("Reports"). 

If a state determines that its existing SIP is adequate, then the state needs to certifY through a SIP 

submittal (e.g., a letter to the Agency fi·om the Governor or his/her designee) that demonstrates 

the existing SIP contains provisions addressing all requirements of the section II O(a)(2) 

infi·astructure elements as applicable for the 2006 24-hour PM2,; NAAQS. For purposes of the 

2006 24-hour PM2.5 NAAQS, in cases where a state believes that it meets the requirements of 

sections II O(a)(l) and 11 O(a)(2) without further revision of its SIP, EPA believes it is 

appropriate for the state to submit a certification letter without holding an additional public 

hearing. Because prior submissions for infi·astructure requirements will have met the statutory 

requirements for notice and public hearing, EPA believes that such process is not required now. 

The public will have an opportunity to review the certification when EPA takes action on the 

submittal through the notice-and-comment rulemaking process. 

In order for EPA to determine that a submittal for a SIP is complete, the submittal must 

affirmatively address all required elements/sub-elements, and should include documentation 

demonstrating a correspondence between each infrastructure element and an equivalent state 

statutory or regulatory authority in the existing or submitted SIP. At a minimum, a complete 

submission is a letter fi·om an appropriate state official (i.e., Governor or designee) certifying 

compliance with each element and with a specific description of how compliance with each 

element is achieved. Submissions lacking a detailed explanation for how the state's SIP meets 

each applicable requirement of section II O(a)(2) should be deemed incomplete. Submissions 

that address some but not all elements/sub-elements should not be deemed complete for the 

unaddressed elements/sub-elements, but will result in findings of failure to submit fur only the 

unaddressed elements/sub-elements. After EPA makes a finding of failure to submit, the state 

would only be required to submit those elements that were found not to have been submitted in 

order for EPA to make a determination that the SIP is fully complete. Letters stating that the 

state will submit a SIP revision some time in the future are not complete. 

A finding that the submittal is complete does not mean that the submittal is approvable 

because the completeness review only addresses whether the state has provided information 

sufficient to warrant formal EPA review for approvability. Once EPA determines a SIP 

submission to be complete , or after six months when that submission is deemed complete by 

operation oflaw, EPA has up to I year to take action on (i.e., to approve or disapprove) the 

submission. EPA must promulgate a Federal Implementation Plan (PIP) for the state if EPA 

takes any of the following final actions associated with the required SIP: (I) determines that a 

state has failed to make a SIP submission, (2) determines that a state has made an incomplete 

submission, or (3) disapproves a SIP submission. Any of these actions starts a two year PIP 

clock. In order to stop or rescind a PIP, the state must submit, and EPA must approve, a SIP 

submission that meets the applicable requirements. 
3 

Guidance for Satisfying the Section 110(a)(2)(D) Requirement 

Compliance with CAA section 11 O(a)(2)(D) requires that states address 4 separate 

elements. 

1. SIP Submissions from States pertaining to the "significant contribution" 

t·equirement of section 110(a)(2)(D)(i). 

Section 11 O(a)(2)(D)(i)(I) specifically provides that each state's SIP must contain 

adequate provisions to prohibit air pollutant emissions fl"om within the state that significantly 

contribute to nonattainment of the NAAQS in any other state. Therefore, the state's submission 

must explain whether or not emissions from the state have this impact and, if so, address the 

impact. 

The state's conclusion must be supported by an adequate technical analysis. Information to 

support the state's determination with respect to significant contribution to nonattainment might 

include, but is not limited to, information concerning emissions in the state, meteorological 

conditions in the state and the potentially impacted states, monitored ambient concentrations in 

the state and the potentially impacted states, the distance to the nearest area that is not attaining 

the NAAQS in another state, and air quality modeling. The EPA believes that it would be 

appropriate for states to make this assessment by considering the impact of current or future 

emissions on nearby nonattainment areas, and evaluating the air quality impact and potential 

mitigation strategies.2 Using these kinds of evaluations, it is EPA's intention to complete a rule 

to address interstate pollution transport in the eastern half of the continental United States. 

EPA is currently working on a new rule to replace the CAIR rule that will address issues 

raised by the court in North Carolina v. EPA, 531 F. 3d 896 (D.C. Cir. 2008). That new rule will 

assist states with obligations to address interstate transport that significantly contributes to 

nonattainment in another state. However, all states must submit complete 110 SIPs at this time 

that address the requirements of section 11 O(a)(2)(D) for the 2006 24-hour PM2.5 NAAQS, and 

states cannot wait for the CAIR replacement rule without getting a finding of failure to submit at 

this time. In addition, even if the CAIR rule were not remanded by the court, states cannot rely 

on the current CAIR rule for this submission for the 2006 24-hour PM2.5 NAAQS because the 

CAIR rule does not address this NAAQS. 

2. SIP Submissions ft·om States pertaining to the "interfere with maintenance" 

requirement of section 110(a)(2)(D)(i). 

Section 11 O(a)(2)(D)(i)(I) specifically provides that each state's SIP must contain 

adequate provisions to prohibit air pollutant emissions fl"om within the state that interfere with 

maintenance of the NAAQS in any other state. States' submissions must address this 

independent requirement of the statute. This provision requires evaluation of impacts on areas of 

other states that are meeting the 2006 24-hour PM2.5 NAAQS, not merely areas formerly 

2 If assessing future emissions the state should attempt to represent a future year that is no further in the future than 

the year in which attainment of the NAAQS is required in the downwind state. In most cases we expect the 

attainment date to be no later than 5 years from the date ofnonattainment designations. Since designations are 

expected to be issued in 2009, the maximum attainment date would be 2014. 
4 

designated nonattainment that are subject to a maintenance SIP. Therefore, the state's 

submission must explain whether or not emissions fi:om the state have this impact and, if so, 

address the impact. 

A state's submission for this requirement should provide the technical information which the 

state deems appropriate to supp01t its conclusions. Suitable information might include, but is not 

limited to, information concerning emissions in the state, meteorological conditions in the state 

and the potentially impacted states, monitored ambient concentrations in the state and the 

potentially impacted states, and air quality modeling. 

Using these kinds of evaluations, it is EPA's intention to complete a rule to address interstate 

pollution transp01t in the eastern half of the continental United States. However, all states must 

submit complete II 0 SIPs at this time that address the requirements of section I I O(a)(2)(D) for 

the 2006 24-hour PM2.s NAAQS and states cannot wait for the CAIR replacement rule without 

getting a finding of failure to submit at this time. 

3. SIP submissions pertaining to the "prevention of significant deteriomtion" 

requirement of section IIO(a)(2)(D)(i). 

Section II O(a)(2)(D)(i)(II) contains a requirement for all states to submit SIPs that 

contain adequate provisions prohibiting" .... any source or other type of emission activity within 

the state fi'01n emitting any air pollutant in amounts which will interfere with measures required 

to be included in the applicable implementation plan for any other state .... to prevent significant 

deterioration of air quality ... " 

EPA believes this requirement is satisfied for PM2.5 if a state's SIP includes 

preconstruction review programs for major sources that satisfy the requirements of 40 CFR 

51.165(b)(l) and 40 CFR 51.166 (i.e., New Source Review for major stationary sources locating 

in attainment areas when the source will cause or contribute to a violation of the NAAQS, and 

Prevention of Significant Deterioration (PSD), respectively). Unless the area has known 

outstanding permit program deficiencies, it is not necessary, at this time, for states to make a SIP 

submission containing rule changes specifically to address section II O(a)(2)(D)(i)(II) for the 

2006 24-hour PM2.5 NAAQS. If this is the case, the state can submit an appropriate ce1tification 

as described previously in this guidance. 

All areas are currently required to have some form ofpreconstruction permitting program 

for PM2v This program may include a transitional program or a program that conforms with the 

minimum requirements ofEPA's May 2008 final rule on implementation of the NSR program 

for PM2.5• 73 Fed. Reg. 28321. In this action, EPA issued new final rules for certain 

components ofPM2.s preconstruction permitting programs Rll' attainment and nonattainment 

areas. States are currently required to revise their preconstruction review permit programs to 

incorporate these new requirements into an approved SIP by May 20 I I. However, this provision 

under the May 2008 rules has been challenged and is now under a petition for reconsideration 

whereby EPA has agreed to reconsider the schedule tor revising state PSD programs for PM2 5. 

Accordingly, EPA may revise the schedule for submitting the revised PSD SIPs un· EPA 

approval. For the present time, however, the deadline for adopting and submitting PM2.5 SIPs for 

NSR/PSD is May 201 I. Thus, states are not required to adopt the May 2008 rules for the 
5 

purposes of satisfying the section llO(a) SIP requirement by September 2009 and may rely 

instead on implementing a transitional program for PM2.5, For example, the state's PSD program 

would satisfy the requirements of 40 CFR 51.166 at this time if the applicable rule defines the 

pollutants subject to regulation, e.g., "regulated NSR pollutant," in such way as to automatically 

include any new NAAQS, e.g., 24-hour PM2.s NAAQS, that EPA may promulgate. 

States with PSD F!Ps in place generally are required under a delegation agreement with 

EPA to implement .PSD in accordance with the federal PSD program, which provides for the 

automatic protection of any new NAAQS that EPA may promulgate. These states must ensure 

that their delegation agreement clearly authorizes them to implement the federal PSD program 

requirements as amended in May 2008. If a delegation agreement is def!eient in this regard, the 

state should work with EPA to modify the agreement to enable implementation ofPM2 5 

requirements. 

In addition to the PSD permitting program, a state's SIP may include additional measures 

as necessary to prevent air pollution in excess of the PSD increment that defines significant 

deterioration for each area. 40 CFR 51.166(a). However, EPA has not yet established PSD 

increments for PM2.5. Without these components of a PSD program, it is difficult for states to 

determine if additional measures are needed to prevent significant deterioration within the state. 

Likewise, a neighboring state cannot determine whether its SIP would interfere with such 

additional measures in another state's SIP. However, notwithstanding the absence ofPSD 

increments for PM2.5, EPA believes that at this time states may continue to rely on their existing 

PSD and NNSR permitting programs to prevent significant deterioration of air quality within 

their own boundaries and in adjacent states until such increments are established. 

4. SIP Submissions from States pertaining to the "protect visibility" requirement of 

section 110(a)(2)(D)(i). 

Section II O(a)(2)(D)(i)(Il) also contains a requirement for all states to submit SIPs that 

contain adequate provisions prohibiting " ... any source or other type of emission activity within 

the state fi·om emitting any air pollutant in amounts which will interfere with measures required 

to be included in the applicable implementation plan for any other state .... to protect visibility." 

EPA believes this requirement can be satisfied by an approved SIP addressing reasonably 

attributable visibility impairment (RA VI), if required, and an approved SIP addressing regional 

haze. EPA promulgated regulations in 1980 to address RA VI in Class I areas that is caused by 

the emissions of air pollutants fi·om one source, or a small number of sources. See 45 FR 80084 

(December 2, 1980) and current 40 CFR 51.300-51.307. A state must take specified steps to 

address RA VI after a Federal Land Manager at any time certifies that RA VI exists at a specific 

Class 1 Area. 40 CFR 51.302(c)(l). 

Under the 1980 regulations, 35 states and the U.S. Virgin Islands were required to submit 

SIPs to address RA VI. EPA issued F!Ps to address the requirements ofRAVI for those states 

that had failed to submit SIPs. See 50 FR 28544 (July 12, 1985) and 52 FR 45132 (November 

24, 1987). EPA is not aware of any certification by a Federal Land Manager of existing RA VI 

that remains unaddressed by a currently approved SIP or FIP. Accordingly, we believe that 

states for which EPA has approved into the state's current SIP some or all RAY! elements, 
6 

should be able to make a relatively simple SIP submission verifying tbat no source within the 

state emits pollutants that interfere with RAVI measures included in the applicable 

implementation plan (SIP or FIP) of any other state. As noted above for PSD, those states 

having full or partial F!Ps in place will not satisfy the independent section II O(a)(2)(D)(i)(II) 

requirement unless they submit, and EPA approves into the SIP, all required RAVI elements. 

In 1999, EPA issued regulations requiring states to address regional haze impacting 

visibility in Class I areas. See 64 FR 35714 (July I, 1999) and current 40 CFR 51.308 - 51.309. 

Regional haze is visibility impairment that is produced by a multitude of sources and activities 

which emit visibility-impairing pollutants and their precursors and which are located across a 

broad geographic area. States are currently under an obligation to submit SIPs that contain 

measures to address regional haze, including a long-term strategy to address visibility 

impairment for each Class I area which may be affected by emissions Ji·om a state. These SIP 

submissions were due on December 17, 2007. In January 2009, EPA found that 37 states, the 

District of Columbia, and the U.S. Virgin Islands had failed to make all or patt of the required 

SIP submissions to address regional haze. See 74 FR 2392 (January 15, 2009). These findings 

require EPA to issue F!Ps within 2 years, by January, 2011, unless the states submit SIPs and 

EPA approves them before that date. States that intend to rely on the required regional haze SIPs 

to satisfy this element of their section II O(a) SIP but have not formally indicated this intention in 

a SIP submission, or have not yet submitted the regional haze SIP, may receive an additional 

finding of failure to submit this element of their section IIO(a) SIP. EPA will be able to fully 

approve the submittal as satisfying section II O(a)(2)(D)(i)(II) only after we have taken final 

action approving the regional haze SIP. 

Guidance for Satisfying the Section 110(a)(2)(G) Requirement 

To address the section II O(a)(2)(G) element, states with air quality control regions 

identified as either Priority I, Priority lA, or Priority II by the "Prevention of Air Pollution 

Emergency Episodes" rules at 40 CFR 51.150, must develop emergency episode contingency 

plans. Currently, those regulations do not specifically address PM2.5• 

Until the Agency finalizes changes to the emergency episode regulations to establish for 

PM2.s specific levels for classifying areas as Priority I, lA, and II tor PM2.s, and to establish a 

significant harm level (SHL), EPA recommends that states through their public processes set 

Priority levels and emergency action levels for PM2.s necessary to develop emergency episode 

plans consistent with the requirements in 40 CFR 51.150 through 51.153. We fmther 

recommend that states consider the levels discussed in the February 12, 2007 EPA issue paper 

titled "Revising the Air Quality Index and Setting a Significant Harm Level for PM2.5" and to 

Attachment B to this guidance in establishing Priority levels and emergency action levels, 

including' a SHL. 3 Using the recommendations in Attachment B, for the purposes of satisfying 

the requirements of section 110(a)(2)(G), states would develop emergency episode plans for any 

area that has monitored and recorded 24-hour PM2.s levels greater than 140.4 )lg/m since 2006. 

If this level was never exceeded in any area of the state, the state can certify that it has 

appropriate general emergency powers to address PM2.5-related episodes, and that no specific 

3 The issue paper can be found at http://www.epa.gov/ttn/caaa/qen/aqi issue paper 020707.pdf 
7 

emergency episode plans are necessary at this time, given the existing monitored levels 4 States 

should develop submissions to meet this requirement through appropriate public processes. 

In submittals addressing the 1997 PM2.s NAAQS, several states committed to make SIP 

submittals addressing section II O(a)(2)(G) only after EPA completed a rulemaking to establish a 

SHL for PM2. 5• We understand the motivation for taking this approach, and EPA is working to 

complete this rulemaking. Nevertheless, under section II O(k)(l )(B), EPA cannot find such 

submittals to be complete. It is for this reason that EPA is providing the recommendations in this 

memorandum as guidance for states to make submittals to address section II O(a)(2)(G). The 

SHL, Priority levels, and emergency action levels recommended in Attachment B are relevant 

for both the 1997 PM2.5 NAAQS and the 2006 PM2.5 NAAQS. If a state elects not to make a 

submittal that addresses section II O(a)(2)(G) for the 2006 24-hour PM2.s NAAQS in accordance 

with the Agency's recommendations or otherwise meeting the statutory requirements, EPA will 

have reason to make a finding of failure to submit fi.Jr this NAAQS. 

For Further Information 

If you have any questions concerning this guidance, please contact David Sanders at 

(919) 541-3356. Please ensure that the appropriate air agency officials for states in your Region 

are made aware of this guidance. 

Attachments 

cc: Brian McLean, OAP 

Kevin McLean, OGC 

Margo Oge, OT AQ 

Steve Page, OAQPS 

Peter Tsirigotis, OAQPS 

Richard Wayland, OAQPS 

Lydia Wegman, OAQPS 

4 Under these conditions the contingency plan portion of section llO(a)(2)(G) for the 1997 PM2.; NAAQS, lor 

which we issued a finding for failure to submit in October 2008, may also be resolved (73 FR 62902). 
Attachment A: Required Section 110 "Infrastructure" SIP Elements5 

Section 110(a)(2)(A)- Emission limits and other control measures: requires SIPs to include 

enforceable emission limits and other control measures, means, or techniques, and schedules for 

compliance. 

Section 110(a)(2)(B)- Ambient air quality monitoring/data system: requires SIPs to provide 

for establishment and operation of ambient air quality monitors, collection and analysis of 

ambient air quality data, and to make these data available to EPA upon request. 

Section 110(a)(2)(C)- Program for enforcement of control measures: requires SIPs to 

include a program providing for enforcement of all SIP measures and the regulation of 

construction of new and modified stationary sources as necessary to assure that the NAAQS are 

achieved, including a permit program as required in parts C and D. 

Section 110(a)(2)(D)- Interstate transport pi"Ovisions: requires SIPs to contain adequate 

provisions prohibiting emissions generated within the state fi·om contributing significantly to 

nonattainment in, or interfering with maintenance by, any other state with respect to the 

NAAQS, or fi"Om interfering with measures required to be included in the SIP of any other state 

to prevent significant deterioration or to protect visibility. 

Section 110(a)(2)(E)- Adequate resources: requires SIPs to provide necessary assurances tor 

adequate personnel, funding, and authority under state law to carry out its SIP, to contain 

requirements addressing potential conflicts of interest, and to provide necessary assurances that 

the state retains responsibility fbr ensuring adequate implementation of the SIP where the state 

relies on a local or regional government f(Jr implementation of any SIP provision. 

Section 110(a)(2)(F)- Stationary source monitoring system: requires SIPs to establish a 

system to monitor emissions from stationary sources, to submit periodic emissions reports, to 

correlate the emissions rep01ts with the corresponding SIP emission limits and standards, and to 

make emissions repotis available to the public. 

Section 110(a)(2)(G)- Emergency episodes: requires SIPs to provide for authority to address 

activities causing imminent and substantial endangerment to public health and to provide for 

adequate contingency plans to implement such authority. 

Section 110(a)(2)(H)- Future SIP revisions: requires SIPs to provide for SIP revisions in 

response to changes in the NAAQS, or availability of improved methods fbr attaining the 

NAAQS, and in response to an EPA finding that the SIP is substantially inadequate. 

Section llO(a)(2)(J)- Consultation with government officials, public notitication, PSD and 

visibility protection: requires states to provide a process for consultation with local 

governments and Federal Land Managers carrying out NAAQS implementation requirements; 

5 The specific nonattainment area plan requirements of sections IIO(a)(2)(C) and IIO(a)(2)(1) are subject to the 

timing requirement of section 172, not the timing requirement of section II O(a)( I), and therefore not considered 

required elements of the "infi·astructure SIP." 
requires SIPs to notify the public ifNAAQS are exceeded in an area and to enhance public 

awareness of measures that can be taken to prevent exceedances; and requires SIPs to meet 

applicable requirements of part C related to prevention of significant deterioration and visibility 

protection. 

Section 110(a)(2)(K)- Air quality modeling/data: requires SIPs to provide for the performance 

of air quality modeling for predicting effects on air quality of emissions of any NAAQS pollutant 

and the submission of such data to EPA upon request. 

Section 110(a)(2)(L)- Permitting fees: requires SIPs to require each major stationary source to 

pay permitting fees to cover the cost of reviewing, acting upon, implementing and enforcing a 

permit until such fee requirement is superseded by EPA approval of a fee program under title V 

of the Clean Air Act. 

Section 110(a)(2)(M)- Consultation/participation by affected local entities: requires SIPs to 

provide toi· consultation and pmiicipation in SIP development by local political subdivisions 

affected by the SIP. 
Attachment B: Recommended Interim Significant Hum Level, Pl"iority Levels, and Action 

Levels for PMz.sEmergency Episode Plans (EEPs) 

Current AQI - PMz.s AQI Under Recommended Recommended Consideration - EEP Priority EEP Action 24-honr Region Level 

Index 24-hom· Average Classification .Category Avera~e ** Values (~-tglm )t * (~-tg!m·) 

Good 0-50 0.0-15.4 0.0-15.4 

. Moderate 51-100 15.5-40.4 15.5-35.4 

Unhealthy tor 101-150 40.5-65.4 35.5-55.4 Sensitive Groups 

Unhealthy 151-200 65.5-150.4 55.5-140.4 

Very Unhealthy 201-300 150.5-250.4 140.5-210.4 Priority Level II Alert 

Hazardous 1 301-400 250.5-350.4 210.5-280.4 Priority Level Warning I and !A 

Hazardous 2 401-500 350.5-500 280.5-350.4 Emergency 

Significant Harm Level (SHL) 350.5 

t For a discussion of possible revisions to the AQI and SHL, see the EPA issue paper found 

at hl1p:j/',yw)Y~.£!2'l·gslvfttJ . .JLcamJ{ggnLi!Sli. i'!ol!~~Jl-ill29L. 0 2_Q7 OlJLqJ * Based on historical incidence of24-hour average concentrations using the most recent 3 

calendar years of data. 

**See 40 CFRPmt 51 Appendix L "Example Regulations for Prevention of Air Pollution 

Emergency Episodes" tor an example of the application of emergency action levels.