Appendix A 

Policy Memoranda 
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Policy Memoranda i 

Charlotte, Raleigh/Durham & Winston-Salem Appendix A 

CO Limited Maintenance Plan August 2, 2012 

TABLE OF CONTENTS 

Guidance Memorandum: 6/18/1990, William G. Laxton, “Ozone and Carbon Monoxide Design 

Value Calculation” ...............................................................................................................1 

Letter: 3/15/1991, Gov. James G. Martin to G. C. Tidwell, “North Carolina’s Nonattainment 

Boundary Recommendation for Ozone and Carbon Monoxide” .........................................5 

Guidance Memorandum: 10/6/1995, Joseph W. Paisie, “Limited Maintenance Plan Option for 

Nonclassifiable CO Nonattainment Areas” .........................................................................8 
Policy Memoranda ii 

Charlotte, Raleigh/Durham & Winston-Salem Appendix A 

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You are here: EPA H om e Air & Radiation TTN W eb - Technology Transfer N etw ork > N ational Am bient Air

Q uality Standards > O zone Im plem entation > Technical Resources > O zone and CO D esign Value Calculations 

Ozone and Carbon Monoxide 

Design Value Calculations

 UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

 Office of Air Quality Planning and Standards

 Research Triangle Park, North Carolina 27711

 June 18, 1990

MEMORANDUM

SUBJECT: Ozone and Carbon Monoxide Design Value Calculations

FROM: William G. Laxton, Director

 Technical Support Division (MD-14)

TO: See Below

 In discussions related to the Clean Air Act legislation, design

values for ozone and carbon monoxide are receiving particular

attention. Previously, it sufficed to designate areas as either

attainment or nonattainment but now areas will be further classified

into different categories based upon the magnitude of the appropriate

design value. This additional classification step places added

emphasis on the need to accurately determine these design values. The

classification will be done according to concentration cutpoints, and

on a schedule, specified in the legislation.

 Obviously, once this process is set in motion we will be working

very closely with you to develop these design values. However, I

thought it would be appropriate to reiterate our design value

computation procedures in advance to help people anticipate the types

of data review questions that may arise. The computation procedures

stated here are consistent with our previous methods. There are

differences between the procedures for ozone and carbon monoxide

because the National Ambient Air Quality Standard (NAAQS) is

structured in terms of expected exceedances while the carbon monoxide

NAAQS uses the older "once per year" format. The most apparent

difference is that the CO design values are based upon 2 years of data

while design values for ozone use 3 years. Another difference is that

the ozone NAAQS uses the daily maximum ozone value while the CO NAAQS 

considers running 8-hour averages so that, even though they must be

non-overlapping, it is possible to have more than one CO exceedance per

day. Because of these differences, it is convenient to discuss each

pollutant separately. With respect to terminology, you may hear the CO

design value approach referred to as "the highest of the second highs',

while the ozone design value is frequently simplified as "the fourth

high in 3 years."

 One point to remember is that all locations within an area have to

meet the standard (NAAQS). Therefore, when we do our evaluations, we

look at each individual site to make sure that every site meets the

standard. A separate design value is developed for each site that does

not meet the NAAQS, and the highest of these design values is the

design value for the area.

Technology Transfer N etw ork / N AAQ S

O zone Im plem entation

http://w w w .epa.gov/ttn/naaqs/ozone/ozonetech/laxton.htm

Last updated on M onday, N ovem ber 19, 2007

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Carbon Monoxide

 CO design values are discussed in terms of the 8-hour CO NAAQS,

rather that the 1-hour NAAQS, because the 8-hour NAAQS is typically the

standard of concern. However, a 1-hour design value would be computed

in the same manner. For 8-hour CO, we simply look at the maximum and

second maximum (non-overlapping) 8-hour values at a site for the most

recent 2 years of data. These values may be readily found on an AIRS

AMP450, "Quick Look", printout. Then we choose the highest of the

second highs and use this as our design value for that site. We then

look at all design values within an area and the highest of these

serves as the design value for the area. Note that, for each site,

individual years of CO data are considered separately to determine the

second maximum for each year - CO data are not combined from different

years. It is probably worth commenting on this. The CO NAAQS requires

that not more than one 8-hour average per year can exceed 9 ppm

(greater than or equal to 9.5 ppm to adjust for rounding). We evaluate

attainment over a 2-year period. If an area has a design value greater

that 9 ppm, it means there was a monitoring site where the second

highest (non-overlapping) 8-hour average was greater that 9 ppm in at

least 1 year. Therefore, there were at least two values above the

standard during 1 year at that site and thus the standard was not met.

 Hypothetical Case (two CO sites in an area)

 (8-Hour Averages)

 MAX 2nd High

 SITE 1 1987 14.6 8.9

 1988 13.9 10.9

 10.9 is the Design Value

 for Site 1

 (8-Hour Averages)

 MAX 2nd High

 SITE 2 1987 12.2 11.1

 1988 10.8 10.4

 11.1 is the Design Value

 for Site 2

 11.1 ppm would be the design value for the area.

Ozone

 The form of the ozone NAAQS requires the use of a 3-year period to

determine the average number of exceedances per year. In its simplest

form, the ozone standard requires that the average number of

exceedances over a 3-year period, cannot be greater than 1.0. An area

with four exceedances during a 3-year period, therefore, does not meet

the ozone standard because four exceedances in 3 years averages out to

more than once per year. Now, if the fourth highest value was equal to

the level of the ozone standard, i.e. 0.12 ppm, then the area would

have no more than three exceedances during the 3-year period and the

average number of exceedances per year would not be greater 3

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than one. This assumes no missing data and is how the fourth high

value in 3-years came to be used as the design value. Actually, an

adjustment is specified in the ozone NAAQS to account for missing data

in determining the expected exceedances for ozone. Because of

considerations associated with control strategy modeling, the following

basic approach for ozone design values has been in use since 1981. If

there are 3 complete years of ozone data, then the fourth highest daily

maximum during the 3-year period is the data, then the fourth highest

daily maximum during the 3-year period is the design value for that

site. If only 2 complete years of data are available, then the third

highest is used and, if only one complete year is available, then the

second highest is used. In this approach, a year of ozone data is

considered complete if valid daily maximums are available for at least

75 percent of the ozone season. Note that because of the form of the

ozone NAAQS, data are combined over multiple years but they are not

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combined from different sites.

 Hypothetical Case (two O3 sites in an area, each year at 

 least 75% complete) 

 FOUR HIGHEST DAILY MAXIMUM VALUES

 Max 2nd Hi 3rd Hi 4th Hi

 SITE 1 1986 .127 .123 .122 .110

 1987 .129 .124 .121 .116

 1988 .142 .136 .134 .115

 The design value for Site 1 is 0.129 ppm, the fourth highest

 daily maximum value during the three year period.

 FOUR HIGHEST DAILY MAXIMUM VALUES

 Max 2nd Hi 3rd Hi 4th Hi

 SITE 2 1986 .110 .100 .095 .090

 1987 .110 .100 .095 .090

 1988 .180 .175 .160 .110

 The design value for Site 2 is 0.110, the fourth highest

 value during the three year period.

 0.129 ppm would be the design value for the area.

 There are a few additional comments warranted on the ozone

example. First, note that data from each site was treated

independently in computing the design value for that site. Assuming no

missing data, the second site would meet the ozone NAAQS but the area

would not because the other site shows that the NAAQS is not being met. 

Also, it should be noted that the high

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values for a year are considered even if the data for that year did not

satisfy the 75 percent data completeness criterion. For example, if a

site had 2 years of data that met the 75 percent data completeness

requirement and 1 year that did not, then the third highest value

during the 3-year period would be the design value because there were

only 2 complete years of data but the data from all 3 years would be

considered when determining the third highest value. This ensures that

valid high ozone measurements in a particular year are not ignored

simply because other data in that year were missing. When computing

data completeness, the number of valid days can be increased to include

days that may be assumed to be less than the standard level as stated

in the ozone NAAQS. Also, for new sites that have just come on line,

the 75 percent data completeness requirement for the start-up year may

be applied beginning with the first day of actual monitoring as long as

the data set is at least 75 percent complete for June through August.

 A final practical complication that must be addressed in

determining ozone design values is the case where a site reports data

but has no year that meets the 75 percent data completeness

requirement. Admittedly, this is an unusual situation but, for the

sake of completeness, it needs to be addressed. At the same time,

however, the reason for this consistent data completeness problem

should be examined because ozone monitoring data completeness is

typically greater that 90 percent. In general, if a site has no

complete years of data and fewer than 90 days of data during the 3-year

period, the design value will be determined on a case by case basis. 

In such cases, the data base is so sparse that it would be extremely

difficult to describe general rules that would apply and a careful

evaluation would have to be made to determine why this situation

occurred and what is the most appropriate way to use the data. For a

site without a single complete year of data but at least 90 days of

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data during the 3-year period, the following steps are followed in

determining the ozone design value:

 1. Divide the number of valid daily maximums during the 3-year

 period by the required number of monitoring days per year. 

 As noted earlier, the number of valid days can be increased

 by including the number of days that may be assumed to be

 less than the standard level as specified in the ozone NAAQS.

 2. Add 1.0 to the above total and then use the integer portion

 of the result as the rank of the design value.

 These steps are not as complicated as they may initially appear. 

For example, suppose a site with a required ozone monitoring season of

214 days each year reports 0, 121, and 130 valid days of ozone data

during the 3-year period. Step 1 would give (0+121+130)/214=1.17. In

step 2, 1.0 is added to this total giving 2.17. The integer portion of

2.17 is 2 and so the design value is the second highest value during

the three year period. Again, this type of situation should not occur

that often and the reasons for the data completeness problems should be

identified.

 When discussing data completeness for ozone, it is important to

recognize that monitoring sites are occasionally discontinued for valid

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practical reasons. In such cases, if data are available from another

site that is representative of the same situation, then data from the

discontinued site may be superceded by data from the other site. The

intent is to ensure that a single year of data from a monitor that was

discontinued 2 years ago, does not dictate the design value if data are

available from another, equally representative, site. This is not

intended to eliminate the missing data penalty when a site is

discontinued and there is no data available from a similar monitor.

 I have not discussed certain basic data handling

conventions, such as computing 8-hour CO averages with missing

data, determining the non-overlapping second maximum 8-hour

average, or the definition of a valid daily maximum 1-hour ozone

daily maximum. All of these conventions have been in place since

the 1970's and are routinely incorporated into AIRS outputs so I

have not bothered to discuss these points.

Addressees:

Director, Environmental Services Division, Regions I-VIII, X

Director, Office of Policy and Management, Region IX

Director, Air Management Division, Region III

Director, Air and Waste Management Division, Region II

Director, Air, Pesticides and Toxics Management Division, Regions

 I and IV

Director, Air and Radiation Division, Region V

Director, Air, Pesticides and Toxics Division, Region VI

Director, Air and Toxics Division, Regions VII, VIII, IX, and X

cc: J. Calcagni (MD-15)

 R. Campbell (MD-10)

 T. Curran (MD-14)

 D. DeVoe (ANR-443)

 J. Farmer (MD-13)

 T. Helms (MD-15)

 W. Hunt (MD-14)

 S. Meiburg (MD-11)

 R. Ossias (LE-132A)

------------------------- end of original document -----------------

Note to reader:

This copy of the Laxton memo is a retyped version of the original. As

a result, the page breaks had to be forced after the last word on each

page on the original document.

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Policy Memoranda 5 

Charlotte, Raleigh/Durham & Winston-Salem Appendix A 

CO Limited Maintenance Plan August 2, 2012 

JAMES C MARTJN 

CO'IERNOR 

Mr. Greer C. ~~d~ell 

R~qion~l Ad~inistrator 

STATE OF NORTH CAROLINA 

OFF!CO OF THE GOVERNOR 

R~.EJ~H "OOH001 

><arch lS, lHl 

U, S. Env>ronmental Prote~tion Agency 

Region IV 

345 Courtland Street, N, E. 

Atlanu, Geor~ia 30:365 

In response to your letter o:!' F~bruary S, H~l, invi-tJ.ng North 

Caro;ina to provi~e designations of ozone and carbon monoxide 

nonatuin~.ent areao, the State of North CaroHM chooses to make 

the following desi9notions. 

North Carolina proposes carbon rnonoxicle nonatUhment areas as 

fo:lows, 

11 Wi.thin the Greer.sboro/W~nston-Sqlern/High Poir.t 

MetropolHan Statistical Area {><5!\l we propose Fonyth 

County. 'l'l>e level o= nonattainner.t is class1f1ed as 

mo~erate. 

Within the 

counties. 

~oderate. 

Raleigh/OUhZLrn MSI< we propose l<oke apd D~rharn 

'!'he level of no~att~inmer.t J.s claositierl as 

3) Meckler.burg c~~~ty oontin~es to ~e cl.assified as a 

nonottaintnent ore• by previous designotJ.on. We expect 

an attoin<neM rle<nonstntion to be s~bmitted soon aftH 

EPA issues new guirlonce. 

() l\11 other a.eo• of the ;5tate are consi<lere<l to be in 

attainment of the standa::"O fer carbon monoxi<!e. 

I 
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Charlotte, Raleigh/Durham & Winston-Salem Appendix A 

CO Limited Maintenance Plan August 2, 2012 

N~. Greer C. T;dw~ll 

Page 2 

/<arch 15, 1991 

• 

North Carolina propos~s o•on<> noMttainrnent areas as follows: 

II Ne propose the following counties in the North Carolina 

portion of the Cllarlotte/Gastonia/Rock HHl MSA wHh a 

classHioation of modeute, Gaston and >locklenburg, 

2) We propose the following counties in the Greensboro/ 

Winston-Salem/High Point MSA with a classification of rnoder~te: Davidson, Forsyth and Guilford, 

3) we propose the following counties in th~ Raleigh/Durham 

MSA with a classification o£ rnoOerate: DUrham and Wake. 

4) All other areas of the State are consJ:dered to be in 

attainment of tl>e stondard for ozone, 

In ad<litiO>"t to these nonattainment counties, North Carolina 

-proposes to expand its inspect!.on and maintenance program for 

vehicles into four more counties - caba;;rus, Union, Randolph, and 

Orange. 'l'hh wJ.ll further reduce emissions which contribute to o~one formation because of the large nurnl>er of commuters from 

these ~cu~ties to the saven p~opos~d for nonattainment 

designation. 

l\ttache<l is · l<anagemen t, llir 

were evaluated. 

a report from 

Quality section, 

the Division of Environmental 

which explains how these areas 

we llave submitted, or have in the hearing process and expect 

to submit before May 15, 1991, all corrections of Rl\C'l' 

<leficienoies noted in the Moy 26, 1~88, an<l Novembers, 1989, 

letters. 

we have implemented the December 27, l9BB, inspection/ 

maintenance corrective action pl~n, including use of tampered 

undercover vehicles and the imminent use of lll\R-90 anaLy•ers. 

"When new EP/'. poHcy requirements for inspection/rnaintenanc<> 

programs are issue<l, w~ expe-ct to adjust our program as 

apprcniate. 

I 
Policy Memoranda 7 

Charlotte, Raleigh/Durham & Winston-Salem Appendix A 

CO Limited Maintenance Plan August 2, 2012 

Mr. GreH C. Tidwell 

"age 3 

March 15, 1991 

The implementation coSt£ of the Clean M.r Act /l<llenCments wil.l 

be substantial, but we are rnovir.g to secure the necessary funding 

and staff. Thank you for the opportunity to make these 

designations as ~n early step in meeting the Clean Air Act requ~rements, 

JGM/WWCjr. 

Attachments 

cc: willhm w. Coh,y, Jr. 

George T, Everett 

Lee A, Paniel 

' 

I 
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UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

RESEARCH TRIANGLE PARK. NC 277 1'1 

OFFICE OF 

October 6, 1995 AIR QUALITY PLANNING 

AND STANDARDS 

MEMORANDUM 

SUBJECT: 

FROM: 

TO: 

Limited Maintenance Plan Option for Nonclassifiable CO 

Nonattainment Areas . . 

Joseph~- Paisie, Group Leader ~~ ft 

Integrated Policy and Strategies~Gtoup (MD-15) 

Air Branch Chiefs, Regions I-X 

On November 16, 1994, EPA issued guidance regarding a 

limited maintenance plan option for nonclassifiable ozone 

nonattainment areas in a memorandum from Sally L . Shaver, 

Director, Air Quality Strategies and Standards Division, to 

Regional Air Division Directors. EPA believes that such an 

option is also appropriate for nonclassifiable CO nonattainment 

areas and the f ollowing questions and answers set ·forth EPA's 

. guidance regarding the availability of this option for such 

areas. As this is guidance; final and binding determinations 

regarding the eligibility of areas for the limited maintenance 

plan option will only be made in the context of notice and 

comment rulemaking actions regarding specific redesignation 

requests. 

If there are any questions concerning the limited 

maintenance plan option for nonclassifiable CO areas, please 

contact me at (919) 541- 5556 or Larry Wallace at (919) 541-0906. 

Attachment 

cc: E. Cummings, OMS 

K. McLean, OGC 

c. Oldham 

L. Wallace Received: 

in the Air Quality Branch 
Policy Memoranda 

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', 

10/6/95 

Limited Mai n tenance Plan Option for Nonclassifiable CO 

Nonattainment areas 

1. Question: 

What requirements must . CO nonclassifiable areas, which are 

attaining the co NAAQS with a design value that is 

signific antly below the NAAQS, meet in order to have an 

approvable maintenance plan under section 175A of the Act? 

Answer: 

Nonclassifiable CO nonattainment areas seeking redesignation 

to attainment whose design values are at or below 7 . 65ppm 

(85 percent of exceedance levels of the CO NAAQS) at the 

time of redesignation may choose to submit a less rigorous 

maintenance plan than was formerly re~ired. This new 

option is being termed a limited maintenance plan. 

Nonclassifiable co areas with design values greater than 

7.65ppm will continue to be subject to full maintenance plan 

requirements described in the September 4, 1992 memorandum, 11Procedures for Processing Requests to Redesignate Areas to 

Attainment," £rom John Calcagni, former Director of the 

OAQPS Air Quality Management Division to the Regional Air 

Division Directors. 

The EPA now believes that it is j 'ustifiable and appropriate 

to apply a different set of maintenance plan requirements to 

a nonclassifiable CO nonattainment areas whose monitored air 

quality is equal to or less than 85 percent of exceedance 

·levels of the ozone NAAQS . The EPA does not believe that 

the full maintenance plan requirements need be applied to 

these areas because ·they have achieved . air quality levels 

well below the standard without the application of control 

measures required by the Act for moderate and serious 

nonattainment areas. Also, these areas do not have either a 

recent histor¥ of monitored violation of the CO NAAQS or a 

long prior history of monitored air quality problems. The 

EPA believes that the continued applicability of prevention 

of significant deterioration (PSD) requirements, any control 

measures already in the SIP, and Federal measures (such as 

the Federal motor vehicle control program) should provide 

adequate assurance of maintenance for these areas. 
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·,_ 

2 

2. Question: 

Besides having a design value that is equal to or less than 

85% of the CO NAAQS what other requirements are necessary 

for a _nonclassifiable CO nonattainment area to qualify for 

the limited maintenance plan option? 

Answer: 

To qualify for the limited maintenance plan option, the CO 

design value for the area, based on the 8 consecutive 

quarters (2 years of data) used to demonstrate .attainment, 

must be at or below 7.65ppm (85 .percent of exceedance levels 

of the ozone NAAQS). Additionally, the design value for the 

area must continue to be at or below 7 . 65ppm until the time 

of final EPA action on the redesignation. The method for 

calculating design valries is pr~sented in th~ June 18, 1990 

memorandum, "Ozone and Carbon Monoxide Design Value 

Calculations," from William G. Laxton, former Director of 

the OAQPS Technical Support Division to Regional Air 

·Directors. The memorandum foquses primarily on determining 

design values for nonattainment areas in order to classify 

the areas as moderate or serious for co. Therefore, the 

document discusses determining the design value for an area 

based on the monitors which are exceeding the standard. In 

the case of a nonattainment area seeking redesignation to 

attainment, all monitors must be meeting the standar d. To 

assess. whether a nonclassifiable area meets the 

applicability cutoff for the limited maintenance plan, a 

separate design value must be developed for every monitoring 

·site. The highest of these design values is the design 

value for the whole area . If the area .design value ' is ·at or 

below 7.65ppm, the State may select the limited maintenance 

plan option for the first 10-year maintenance period under 

section 175A. If the design value for the area exceeds 

7.65ppm prior to final EPA action on the redesignation, the 

area no longer qualifies for the limited maintenance plan 

and must instead submit a full maintenance plan, as 

indicated in the September 4, 1992 memorandum. 
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·, 

3 

3. Question: 

What elements must be contained in a section 175A 

maintenance plan for nonclassifiable CO areas which qualify 

for t~e limi ted maintenance plan option? 

Answer: 

Following is a list of core provisions which should be 

included in the limited maintenance plan for CO 

nonclassifiable areas. Any final ~PA determination 

regarding the adequacy of a limited maintenance plan will be 

made following review of the plan submittal in light of the 

particular circumstances facing the area proposed for 

redesignation and based on all relevant available 

information. 

a. Attainment I n ventory 

~ .. 

The State should develop an attainment emissions inventory 

to identify a level of emissions -in the area which is 

sufficient to attain the NAAQS. This inventory should be 

consistent with EPA's most recent guidance1 on emissions 

inventories ·for nonattainment areas available at the time 

and should represent emissions during the time period 

associated with the monitoring data· showing attainment. The 

inventory should be based on actual "typical winter day" 

emissions of CO. 

b. Maintena n ce Demonstration 

The maintenance demonstration requirement is considered to 

be satisfied for nonclassifiable areas .if the monitoring 

data show that the area is meeting the air quality criteria 

for limited maintenance areas (7.65ppm or. 85% of the CO 

NAAQS) . There is no requirement to project emissions over 

the maintenance period. The EPA- believes if the area begins 

the maintenance period at or below 85 percent of exceedance 

levels, the air quality along with the continued 

applicability of PSD requirements, any control measures 

already in the SIP, and Federal measures, should provide -

·adequate assurance of maintenance over the initial 10-year 

1The EPA's current guidance on the preparation of emissions 

inventories for ozone areas is contained in the following 

documents: "Procedures for the Preparation of Emission Inventories 

for Carbon Monoxide and Precursors of Ozone: Volume I" (EPA-450/4-

91- 016) , . "Emission Inventory ' Requirements for Ozone State 

Implementation Plans" (EPA-450/4-91 -010) , and "Procedures for 

Emission Inventory Preparation: Volume IV, Mobile Sources" (EPA450/4-8l-026d). 
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4 

maintenance period. 

When EPA approves a limited maintenance plan, EPA is 

c on c luding that an emissions budget may be treated as 

essentially not constraining for the length of the 

maintenance period because it is unreasonable to expect that 

such an area will experience so much growth in that period 

that a violation of the co NAAQS would result . · 

c. Monitoring Network/Verification of Continued Attainment 

To verify the attainment status of :the area over the 

maintenance period, the maintenance plan should contain 

provisions for continued operation of an appropriate, EPAapproved air quality monitoring network, in accordance with 

40 CFR part 58. This is particularly important for areas 

u sing a limited maintenance plan because there will be no 

cap on emissions. 

d . Contingency Plan 

·-. Section 1 75A of the Act requires that a maintenance plan 

include contingency provisions, as necessary, to promp tly 

correct any violation of the NAAQS that occurs after 

redesignation of the area. These contingency measures do 

not have to be fully adopted at the time of redesignation. 

However, . the contingency plan is considered to be an 

enforceabl~ part of the SIP and should .ensure that the 

contingency measures are adopted expeditiousl y once they are 

triggered by a specified event. The contingency plan should 

identify the measures to be promptly adopted and provide a 

dule and procedure for adoption and implementation of 

the measures. The State should also identify specific 

indicators, or triggers, which will be used to determine 

when the contingency measures need to be implemented. While 

a violation of the NAAQS is an acceptable trigger, States 

may wish to choose a pre- violation action level as a 

trigger, such as an exceedance of the NAAQS. By taking 

early action, a State may be able to prevent any actual 

violation of the NAAQS and, therefore, eliminate any need on 

the part of EPA to redesignate an area back to 

nonattainment. 

e. Conformity Determinat'ions Under · Limited Maintenance 

Plans 

The transportation conformity rule (58 FR 62188; 

November 24, 1993) and the general conformity rule (58 FR 

63214; November 30, 1993) apply to nonattainment areas and 

main-tenance areas operating under maintenance plans. Under 

e i ther rule, one means of demonstrating confo rmity of 

Federal actions is to indicate th~t expected· emissions from 
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5 

planned actions are consistent with the emissions budget for 

the area. Emissions budgets in limited maintenance plan 

areas may be treated as essentially not constraining for the 

length of the initial maintenance period because it is 

unreasonable to expect that such an area will experience so 

much growth i~ that period that a violation of the CO NAAQS 

would result. In other words, EPA would be concluding that 

emissions need not be capped for the maintenance period. 

Therefore, in areas with approved limited maintenance plans, 

Federal actions reqUiring conformity determinations. under 

the transportation conformity rule could be considered to 

satisfy the "budget test" required· in sections 93.118, 

93.119, and 93.120 of the rule. · Similarly, in these areas, 

Federal actions subject to the general conformity rule could 

be considered to satisfy the "budget test" specified in 

section 93 . 158(a) (5} (i} (A} of the rule.