Specifically, we proposed that an area would be eligible for the first 1 year extension under section 172( a)( 2)( C) and under 181( a)( 5) if, for the attainment year, the area's 4th highest daily 8 hour average is 0.084 ppm or less. The area will be eligible for the second extension if the area's 4th 94 highest daily 8 hour value, averaged over both the original attainment year and the first extension year, is 0.084 ppm or less.

b. Summary of final rule. We are adopting the interpretation that we proposed on June 2, 2003. Under both sections 172( a)( 2)( C) and 181( a)( 5), an area will be eligible for the first of the 1 year extensions under the 8

hour NAAQS if, for the attainment year, the area's 4th highest daily 8 hour average is 0.084 ppm or less. The area will be eligible for the second extension if the area's 4th highest daily 8 hour value, averaged over both the original attainment year and the first extension year, is 0.084 ppm or less.

We believe that it would be absurd to apply section 181( a)( 5) as written for purposes of the 8 hour ozone NAAQS.

This section was written with the form of the 1 hour NAAQS in mind. For purposes of the 1 hour NAAQS, an area is violating the NAAQS if it has more than three exceedances of the NAAQS at a monitor over a 3 year period. Thus, if an area is averaging more than one exceedance per year at a monitor, it is violating the NAAQS. For the 1 hour NAAQS,

it makes sense to consider whether there has been more than one exceedance in the attainment year for purposes of granting an extension because two or more exceedances indicate a significant likelihood the area will not be able 95 to attain the NAAQS with a 1 year extension of the attainment date since four exceedances over a 3 year period mean the area is violating the NAAQS.

For the 8 hour NAAQS, violations are determined based on the concentration as determined by averaging the 4th highest reading at a monitor over a 3 year period. Thus,

for each monitor ( with complete data), the fourth highest readings for each of 3 consecutive years are averaged to determine whether an area is violating the NAAQS. If the average of those readings is at or above 0.085, then the area is violating the 8 hour ozone NAAQS. Unlike the 1 hour NAAQS, an area could have several exceedances of the 8 hour NAAQS in the attainment year and still be on track to attain the NAAQS the following year since attainment is based on an average of the fourth highest reading. For this reason, and as we proposed, we believe it makes sense to allow for the two 1 year attainment date extensions under section 181( a)( 5), based on the 4th highest reading at a monitor rather than based on the number of exceedances. We are interpreting the phrase " minimal number of exceedances" in section 172( a)( 2)( C) to apply in the same manner.

c. Comments and response COMMENT: The commenters generally supported EPA's proposed interpretation for granting up to two 1 year attainment date extensions. One commenter requested clarification that the 96 4th highest daily average 8 hour ozone concentration would be used to grant the first extension and the 4th highest daily average 8 hour ozone concentration of the attainment year and first extension year would be used to determine eligibility for the second 1 year attainment date extension.

The commenter further expressed support for this approach since it is consistent with how EPA determines whether an area is violating the 8 hour NAAQS.

RESPONSE: No commenters opposed this aspect of EPA's proposal. However, we are re stating that the 4th highest daily average 8 hour ozone concentration would be used to grant the first 1 year extension and the 4th highest daily average 8 hour ozone concentration of the attainment year and first extension year would be used to determine eligibility for the second 1 year attainment date extension.

C. How will EPA implement the transition from the 1 hour to the 8 hour NAAQS in a way to ensure continued momentum in States' efforts toward cleaner air? ( Section VI. C. of the proposal; see 68 FR 32818; 51.905 of draft rule)

There are two key issues that EPA considered together regarding the transition from the 1 hour NAAQS to the 8 hour NAAQS: ( 1) when will the 1 hour NAAQS no longer apply ( i. e.,

be " revoked"); and ( 2) what protections are in place to ensure that, once the 1 hour NAAQS is revoked, air quality will not degrade and that progress toward attainment will 97 continue as areas transition from implementing the 1 hour NAAQS to implementing the 8 hour NAAQS. As in the proposed rule, the second key issue has three components: ( 1) what requirements that applied based on an area's classification for the 1 hour NAAQS must continue to apply to that area;

( 2) for how long; and ( 3) in what geographic area. Below,

we set forth our final transition approach in four parts:

( 1) when will the 1 hour NAAQS no longer apply ( i. e., when will it be revoked); ( 2) what 1 hour obligations should continue to apply once the 1 hour NAAQS is revoked; ( 3) how long should those requirements continue to apply; and ( 4)

what is the geographic area subject to the requirement?

1. When will EPA revoke the 1 hour NAAQS? ( section VI. C. 2. of proposal; see 68 FR 32819; section 50.9. b. of proposed and final rules)

a. Background. In the proposed rule ( 68 FR 32819), EPA provided an in depth discussion of the background of the transition rule ( 40 CFR 50.9( b)) and policy as established in July 1997 and as subsequently revised in response to the ongoing litigation over the 8 hour ozone NAAQS and court decisions ( 68 FR 32818 19). In short, at the time the 8

hour NAAQS was promulgated in 1997, EPA anticipated that areas would implement the 8 hour ozone NAAQS under subpart 1. Areas that were not meeting the 1 hour NAAQS were obligated to continue to meet that NAAQS and would remain 28 In addition, in June 2003, we stayed our authority to apply the revocation rule pending our reconsideration in this rulemaking of the basis for revocation. ( 68 FR 38160, June 26, 2003).

98 subject to most of the requirements that applied due to the area's 1 hour classification, including obligations under subpart 2 ( 62 FR 38873). Although EPA concluded in the NAAQS rulemaking that the 1 hour NAAQS was not necessary to protect public health and that the 8 hour NAAQS would replace the 1 hour NAAQS ( 62 FR 38863), we determined to delay revocation of the 1 hour NAAQS for areas not yet meeting that NAAQS in order to facilitate continued implementation of the 1 hour obligations ( 62 FR 38873).

Thus, we promulgated a rule providing for the phase out of the 1 hour ozone NAAQS on an area by area basis based upon a determination by EPA for each area that it had met the 1

hour NAAQS ( 40 CFR 50.9( b), as promulgated at 62 FR 38894)

(" revocation rule").

Subsequently, because the pending litigation over the 8 hour NAAQS created uncertainty regarding the 8 hour NAAQS and our implementation strategy, we placed two limitations on our authority to apply the revocation rule: ( 1) the 8

hour NAAQS must no longer be subject to legal challenge, and ( 2) it must be fully enforceable. 28 ( 65 FR 45182, July 20,

2000).

Ultimately, the Supreme Court struck down the 99 implementation strategy provided for in the preamble to the final NAAQS rule. Although the Court agreed with EPA's conclusion that the statute was ambiguous as to how a revised, more stringent ozone NAAQS should be implemented,

the Court found unreasonable the implementation strategy EPA anticipated at the time the 8 hour NAAQS was promulgated.

Because EPA believes the time at which the 1 hour NAAQS should no longer apply is inextricably linked to the overall implementation strategy, EPA determined that it should reconsider 40 CFR 50.9( b) in the context of this rulemaking.

( 68 FR 32818 19).

Consistent with the decision of the Supreme Court, our proposed June 2003 implementation rule anticipated that some, if not all, 8 hour ozone nonattainment areas would implement that NAAQS under subpart 2 of the CAA. There was no longer the clear cut dichotomy that we anticipated in 1997   i. e., that 8 hour implementation would occur under subpart 1 and 1 hour implementation would continue to occur under subpart 2. Thus, the approach from 1997   where we retained the 1 hour NAAQS for areas that had not met it in order to make clear that such areas retained subpart 2 obligations   merited reconsideration. In addition, we indicated that the area by area approach to revocation of the NAAQS was needlessly burdensome and that it made more sense to promulgate one rule establishing the date of 100 revocation of the 1 hour NAAQS for all areas.

With respect to the time at which the 1 hour NAAQS should no longer apply to areas, we sought comment on two options. Under Option 1, we would revoke the 1 hour NAAQS in full 1 year after the effective date of designations for the 8 hour NAAQS. The key consideration for when the NAAQS would be revoked was the time at which areas designated nonattainment for the 8 hour NAAQS would be subject to conformity requirements for the 8 hour ozone NAAQS and our concern that areas not be subject to conformity for both the 8 hour and the 1 hour NAAQS at the same time. We believed that since our proposed anti backsliding provisions would ensure that progress toward clean air continued and would obligate areas to continue to meet the control obligations associated with the area's 1 hour classification, there was no need to retain the NAAQS and the associated designations and classifications.

Under Option 2, we proposed to retain the NAAQS itself ( and the associated designations and classifications) for limited purposes ( viz., those identified and discussed in section VI. C. 3. of the proposed rule, which are the same obligations that would continue to apply under Option 1).

For all remaining purposes, we would revoke the 1 hour NAAQS and the associated designations and classifications 1 year after the effective date of designations for the 8 hour 101 NAAQS. This approach would not create a different substantive result than Option 1; under both Options, areas would remain subject to the same obligations that applied based on their 1 hour classification. Rather, Option 2 was based on a somewhat different legal rationale than Option 1.

b. Summary of final rule. We are adopting Option 1. We will revoke the 1 hour NAAQS in full, including the associated designations and classifications, 1 year following the effective date of the designations for the 8 hour NAAQS. However, we are adopting strong antibacksliding provisions which preserve control obligations mandated by subpart 2 for an area's classification for the 1 hour NAAQS. In light of the anti backsliding provisions,

the deciding factor supporting the schedule for revocation is the conformity obligation for areas. We believe it is unnecessary to require areas to meet conformity for both the 1 hour and 8 hour NAAQS at the same time; equally important,

however, is the need to ensure that there is no time when conformity stops applying for areas that are subject to it under the 1 hour NAAQS and designated nonattainment for the 8 hour NAAQS. Thus, we are adopting a regulation that provides for revocation of the 1 hour NAAQS 1 year following the effective date of the designation of the area for the 8

hour NAAQS since that is the time an area designated as nonattainment for the 8 hour NAAQS will be subject to 102 conformity requirements for the 8 hour NAAQS.

Our final anti backsliding provisions will ensure that mandatory subpart 2 control measures that applied due to an area's classification under the 1 hour NAAQS will continue to apply after the 1 hour NAAQS is revoked in full.

Many commenters believed, and we agree, that Option 1 is a clearer approach than Option 2. Since both options would lead to the same substantive result, we are adopting the clearer approach. Many commenters recommended alternatives other than those proposed by EPA. Our basis for rejecting these approaches is provided below and in the RTC document.

c. Comments and responses COMMENT: Most of the comments we received addressed the issue of when we should revoke the 1 hour NAAQS. About half of the commenters favored revocation of the 1 hour NAAQS in full 1 year after the effective date of the 8 hour designations ( proposed Option 1). Only a handful of commenters favored partial revocation of the 1 hour NAAQS ( proposed Option 2). Almost a third of the commenters who addressed this issue opposed revocation of the 1 hour NAAQS.

Many of the commenters in this group insisted that EPA should retain the 1 hour NAAQS because it is necessary to protect public health and some noted that it may be more protective of public health than the 8 hour NAAQS in several 103 areas such as the South Coast and Houston. A number of these commenters also suggested that revocation would be contrary to the CAA and Congressional intent. Several commenters recommended alternative means or timing for the revocation of the 1 hour NAAQS, including a recommendation to revoke the 1 hour NAAQS immediately upon designations for the 8 hour NAAQS.

RESPONSE TO MAJOR COMMENTS: Several commenters opposed revocation at all because they believe the 1 hour NAAQS is necessary to protect public health. The issue of whether the 1 hour NAAQS is necessary to protect public health is a standard setting issue that was resolved in 1997. At that time, EPA determined that it was not necessary to retain the 1 hour NAAQS as a NAAQS in order to protect public health.

In setting the 8 hour NAAQS in 1997, we concluded that replacing the current 1 hour NAAQS with an 8 hour NAAQS is appropriate to provide adequate and more uniform protection of public health from both short term ( 1 to 3 hours) and prolonged ( 6 to 8 hours) exposures to ozone in the ambient air ( 62 FR 38863). The sole issue here is how and when the transition from implementation of the 1 hour NAAQS to implementation of the 8 hour NAAQS should occur.

We believe the strong anti backsliding provisions in section 51.905 will ensure that not only will controls already adopted under the 1 hour NAAQS continue to be 104 implemented until an area attains the 8 hour ozone NAAQS,

but also that there will be no or minimal delay in obtaining additional emissions reductions comparable to those that would have been required had the 1 hour NAAQS remained in place. Although attainment of the 1 hour NAAQS would no longer be a goal, the provisions of section 51.905 would retain the ROP obligations that would have been required under the 1 hour NAAQS. Furthermore, the provisions of section 51.905 also would retain an area's obligation to either expeditiously complete the 1 hour attainment demonstration or obtain emissions reductions toward meeting the 8 hour NAAQS that substitute for those that would have been required had an area completed its attainment demonstration on a schedule more expeditious than that required solely for the 8 hour NAAQS. Thus, retaining the 1 hour NAAQS itself would become largely superfluous from the standpoint of obtaining timely emissions reductions.

We disagree with comments that recommended that EPA revoke the 1 hour NAAQS immediately upon a nonattainment designation for the 8 hour NAAQS. We believe that such timing would create a gap when conformity would not apply in the year following designation under the 8 hour NAAQS ( since conformity does not apply for the 8 hour NAAQS until 1 year after designation).

COMMENT: A major concern raised by commenters was that if 105 the NAAQS were revoked, areas would no longer have to meet the SIP budgets established for the 1 hour NAAQS for conformity purposes. These commenters were concerned that 8 hour ozone nonattainment areas that were nonattainment or maintenance for the 1 hour NAAQS would be able to determine conformity using another less protective test, such as the " build/ no build" test. One commenter said that if conformity is weakened, billions of dollars will be spent on transportation without accountability for public health impacts. To avoid these results, commenters suggested that conformity requirements for the 1 hour NAAQS continue to apply until some other point, such as when budgets for the 8 hour NAAQS are available, when areas have an approved maintenance plan for the 8 hour NAAQS, or the end of areas'

1 hour maintenance planning periods ( assuming these periods would remain as they are, and would not be affected by revocation of the 1 hour NAAQS).

RESPONSE: The EPA proposed conformity regulations for the new 8 hour ozone NAAQS and new fine particulate matter NAAQS on November 5, 2003 ( 68 FR 62690). We proposed that new 8

hour ozone nonattainment areas that have 1 hour ozone SIPs would meet one of several tests, and the menu of options we offered differed depending on how the 8 hour area boundary relates to the 1 hour area boundary. We will consider the issues raised by commenters and provide a full response in 106 the context of that rulemaking.

However, at this point EPA can respond to the suggestions to revoke the 1 hour NAAQS at a later point such as when 8 hour budgets are available, or the end of the 1

hour maintenance planning period. Under these scenarios,

there would be a period of years where conformity would have to be determined for both NAAQS at the same time: a result that EPA believes could lead to confusion and additional burden for transportation and air quality planners. The EPA believes it is sufficient that conformity be determined for one ozone NAAQS at a time. Since the 8 hour NAAQS is the health based standard and it is more stringent than the 1

hour NAAQS, we believe conforming to the 8 hour NAAQS will be sufficient.

COMMENT: One commenter recommended that we provide an option that allows States to submit an 8 hour conformity budget early and suspend the 1 hour conformity requirements at the time the 8 hour budget is determined to be adequate.

A second commenter suggested something similar, that EPA require States to expedite budgets for the 8 hour standard in areas where the 8 hour boundary is larger.

RESPONSE: The EPA did not propose to revoke the 1 hour NAAQS earlier than 1 year after designations, in part because we did not believe that areas would be able to submit an 8 hour SIP earlier than 1 year following 107 designation. Furthermore, EPA's proposal was intended to align the revocation of the 1 hour NAAQS with the application of conformity requirements for the 8 hour NAAQS 1 year after the effective date of 8 hour nonattainment designations. The EPA continues to believe it is unlikely that areas will have adequate budgets that address the 8

hour NAAQS before EPA revokes the 1 hour NAAQS. Such budgets cannot stand alone but have to be associated with adopted control measures and demonstrations of either attainment or RFP, and we believe developing these SIPs will take States some time. Once the SIPs are submitted, EPA must find them adequate, a process which EPA intends to complete within 90 days of receiving a SIP. It is unlikely that States will be able to complete the work to submit 8

hour ozone SIPs 1 year from the effective date of 8 hour ozone area designations, and less likely that States will have submitted them sufficiently in time for EPA to find them adequate before the 1 hour NAAQS is revoked.

Given these facts and the fact that EPA did not propose an option for revoking the standard earlier than 1 year after 8 hour designations are effective, EPA does not intend to provide for early revocation of the 1 hour NAAQS, nor will EPA require 8 hour areas to expedite development of their 8 hour SIP for this purpose. All areas must submit SIPs as soon as practicable, and EPA wants States to develop 108 quality SIPs to support attainment demonstrations and conformity determinations. Prior to the revocation of the 1 hour NAAQS, new transportation plan and transportation improvement plan must conform to the applicable SIP budgets for the 1 hour NAAQS.

COMMENT: Some commenters rebutted EPA's assertion that revoking the 1 hour NAAQS is necessary so that agencies can focus on planning for the 8 hour NAAQS. These commenters stated that neither the revocation of the 1 hour NAAQS ( or the budgets) is justified on this basis with respect to transportation and emissions modeling, because under either NAAQS, similar work in establishing base year inventories,

and future forecasts of travel and emissions must be done.

Once the resources are in place to make future forecasts,

commenters thought that the level of effort in both time and money to produce analyses to different regional boundaries is relatively small, and ample resources are available to pay for the additional analyses needed to determine conformity to both NAAQS.

The EPA also received comments of the opposite opinion.

A number of commenters supported EPA's proposal that conformity apply for one NAAQS at a time. One commenter stated that determining conformity for two separate ozone NAAQS would result in undue administrative burden, create confusion about requirements in the public process and make 109 synchronization of the air quality and transportation planning processes more difficult. A couple of commenters argued that having to determine conformity for both ozone NAAQS would drain limited resources in transportation and environmental agencies. One of these commenters contended that demonstrating conformity for two ozone NAAQS could in fact delay progress, due to the high administrative burdens.

RESPONSE: While these comments focus solely on the resources necessary to determine conformity for both NAAQS,

EPA believes a discussion of resources should include all aspects of attainment planning. Under EPA's proposal, with revocation of the 1 hour NAAQS, conformity will no longer apply for that NAAQS as a matter of law. Therefore, in order for conformity to apply for both NAAQS as one commenter requests, both NAAQS have to be implemented at the same time, i. e., the 1 hour NAAQS would have to be implemented in addition to the 8 hour NAAQS. This would mean continuation of the requirements to demonstrate attainment and maintenance of the 1 hour as well as the 8

hour NAAQS. The EPA believes that it would be a substantial increase in burden for States to plan for attainment of both NAAQS, which includes conformity but also includes creating inventories for each source sector, determining feasible control measures, writing rules to implement control measures, permitting stationary sources, establishing ROP 110 plans, running iterations of air shed modeling, and demonstrating attainment.

In 1997, EPA determined that the 1 hour NAAQS is not necessary to protect public health. Where they are not required by anti backsliding provisions, EPA does not believe that the additional burden States would undertake in planning to achieve both the 1 hour and the 8 hour NAAQS is necessary to protect public health.

2. What requirements that applied in an area for the 1

hour NAAQS continue to apply after revocation of the 1 hour NAAQS for that area? ( Section VI. C. 3. of proposal; 68 FR 32820; section 51.905( a) of the draft and final rules)

a. Background. In this section of the June 2, 2003 proposed rule ( 68 FR 32820), we considered what obligations from subpart 2 that applied to an area based on its classification for the 1 hour ozone NAAQS should continue to apply to such area after it has been designated for the 8

hour NAAQS and the 1 hour NAAQS has been revoked. We proposed that the continuity of particular obligations may vary depending on the attainment status of an area for the 8 hour NAAQS. The proposed rule addressed two categories of areas: ( 1) areas that are designated nonattainment for the 8 hour NAAQS and that were designated nonattainment for the 1 hour NAAQS on or after November 15, 1990; and ( 2) areas that are designated attainment for the 8 hour NAAQS and that 111 were designated nonattainment for the 1 hour NAAQS on or after November 15, 1990. Furthermore, we divided the types of obligations into four categories for purpose of our analysis: 1) mandatory control measures ( e. g., NOx RACT,

I/ M, and fuel programs); 2) discretionary control measures ( e. g., control measures or other obligations the State selected and adopted into the SIP for purposes of attainment, ROP or any other goal to benefit air quality,

but which are not specifically mandated by subpart 2); 3)

growth management ( NSR); and 4) planning activities ( attainment and maintenance demonstrations and RFP plans).

We addressed conformity separately because it is a subpart 1 requirement. In addition, we addressed the NOx SIP Call separately since this obligation applies statewide and without respect to the designation status of areas within the State.

In the draft regulatory text released in August 2003,

for areas designated nonattainment for the 8 hour NAAQS, we broke into two groups the areas designated nonattainment for the 1 hour NAAQS on or after November 15, 1990: ( 1) areas that remain designated nonattainment for the 1 hour NAAQS at the time of revocation of the 1 hour NAAQS; and ( 2) areas that were designated nonattainment for the 1 hour NAAQS but that have been redesignated to attainment for the 1 hour NAAQS ( i. e., " maintenance areas") at the time of revocation 29The draft regulatory text did not accurately reflect the preamble discussion which distinguished maintenance areas at the time of designation for the 8 hour NAAQS from those that remained designated nonattainment at the time of 8 hour designation. For the final rule, we use the time of 8 hour designations rather than the time the 1 hour NAAQS is revoked.

112 of the 1 hour NAAQS. 29 In response to comments on the proposed rule and draft regulatory text, the final regulation creates the same sub categorization for areas designated attainment for the 8 hour NAAQS. In the final rule and in the preamble discussion below, we also break into the same two groups the areas designated attainment for the 8 hour NAAQS. Thus, in the preamble and rule we consider the obligations that continue to apply for four categories of areas: ( 1) areas that remain designated nonattainment for the 1 hour NAAQS at the time of designation as nonattainment for the 8 hour NAAQS; ( 2) areas that are maintenance areas for the 1 hour NAAQS at the time of designation as nonattainment for the 8 hour NAAQS; ( 3)

areas that remain designated nonattainment for the 1 hour NAAQS at the time of designation as attainment for the 8

hour NAAQS; and ( 4) areas that are maintenance areas for the 1 hour NAAQS at the time of designation as attainment for the 8 hour NAAQS. Both the preamble and the rule may use the following terms to discuss these four categories: ( 1) 8

hour NAAQS nonattainment/ 1 hour NAAQS nonattainment ( 2) 8 113 hour NAAQS nonattainment/ 1 hour NAAQS maintenance; ( 3) 8

hour NAAQS attainment/ 1 hour NAAQS nonattainment ( 4) 8 hour NAAQS attainment/ 1 hour NAAQS maintenance. Under each of these sections in the preamble, we address how the final rule treats the four types of obligations identified in the proposed rule: ( 1) mandatory control measures; ( 2)

discretionary control measures; ( 3) growth; and ( 4) planning obligations.

b. Summary of final rule. The approach we are adopting in the final rule is summarized below under the individual sections discussing each category of area and type of control obligation.

c. Section 51.905( a)( 1): 8 hour NAAQS nonattainment/ 1 Hour NAAQS nonattainment ( i) Mandatory control measures. ( Section VI. C. 3. a. i.

of proposed rule; see 68 FR 32820; sections 51.900( f) and 51.905( a)( 1) of the draft and final rules.)

( A) Background. For areas designated nonattainment for the 1 hour NAAQS at the time they are designated nonattainment for the 8 hour NAAQS, we proposed that, to the extent the area has met a mandatory SIP obligation under the CAA that is included as part of the approved SIP, the State may not modify or remove that measure except to the extent that it may have modified or removed that measure for purposes of the 1 hour NAAQS ( 68 FR 32820). For example, if 114 an area was classified as serious for the 1 hour ozone NAAQS and required to have an enhanced I/ M program as part of its SIP, the State cannot remove the enhanced I/ M program for that area even though it may be classified as marginal or moderate for the 8 hour ozone NAAQS. However, under the proposal, the State may modify the enhanced I/ M program consistent with EPA's enhanced I/ M regulations, just as it may have done for purposes of the 1 hour NAAQS. ( We address below when the obligation to retain such control measures as active control programs no longer applies, the geographic area in which the obligation applies, and the demonstration a State must make at that point to modify the SIP.)

For control measures that the State has not yet adopted, we proposed that the State remains obligated to adopt and submit such control measures. And, once adopted into the approved SIP, the State may not modify or remove such measures except to the same extent that it could have modified or removed them for purposes of the 1 hour NAAQS.

Our draft regulatory text referred to these obligations as " applicable requirements" and we identified the subpart 2 mandatory control measures in the definitions section under " applicable requirements."

( B) Summary of final rule. We are adopting the approach we proposed. ( See sections 51.905( a)( 1)( i) and 51.900( f) of the final rule.) All areas designated 115 nonattainment for the 8 hour ozone NAAQS and designated nonattainment for the 1 hour ozone NAAQS at the time of designation for the 8 hour NAAQS remain subject to control measures that applied by virtue of the area's classification for the 1 hour NAAQS.

As we stated in the preamble to the proposed rule ( 68 FR 32819), there are a number of provisions in the CAA that we believe are evidence of Congress' intent that these obligations continue to apply despite EPA's determination that the 1 hour NAAQS is no longer necessary to protect public health. For example, at the time of the 1990 Amendments to the CAA, Congress designated and classified existing ozone nonattainment areas ( and classified all other ozone nonattainment areas) as a matter of law. Congress also provided that areas could not remove from the SIP controls mandated by subpart 2 even after the area attains the NAAQS and is redesignated to attainment. At most, the State could move such controls to the contingency plan provisions of the SIP. See CAA section 175A( d). Also significant is that in 1990, Congress enacted a provision specifying States' obligations with respect to control measures for a NAAQS after EPA revised that NAAQS to be less stringent. In section 172( e), Congress specified that if EPA revises a NAAQS and makes it less stringent, EPA must promulgate regulations applicable to areas that have not yet 116 attained the original NAAQS to require controls that are no less stringent than the controls that applied to areas designated nonattainment prior to such relaxation. We believe that, if Congress intended areas to remain subject to the same level of control where a NAAQS was relaxed, they also intended that such controls not be weakened where the NAAQS is made more stringent. Finally, we noted that the Supreme Court cautioned against making subpart 2 " abruptly obsolete." For areas designated nonattainment in 1990,

Congress intended the mandatory requirements of subpart 2 to apply ( as implemented controls or contingency measures) for a significant period of time. We believe if we allowed areas to remove those mandated controls from their SIPs it would render those provisions prematurely obsolete, contrary to Congressional intent. We adopt in full the analysis provided at 68 FR 32819, 1st and 2nd columns.

The final rule also reflects, with several exceptions,

the table in appendix B of the June proposal which identified the applicable requirements. The definition of " applicable requirements" in section 51.900( f) of the draft regulatory text erroneously excluded some of the requirements included in appendix B. The requirements that weren't included in the proposed regulatory text definition of applicable requirement but are included in the definition in the final rule are: 30In addition, aAppendix E of the June 2, 2003 proposal treats 1 hour NSR as an applicable requirement after the 1 hour standard is revoked. Under the final rule, 1 hour NSR would not applybe a required implementation plan element after the 1 hour standard is revoked. At that point, a State may remove from the SIP the NSR provisions applicable to the 1 hour NAAQS if the State makes a demonstration under Section 110( l) that the revision would not interfere with 117 ° Enhanced ( ambient) monitoring under section 182( c)( 1)

of the CAA.

° Transportation controls under section 182( c)( 5) of the CAA.

° Vehicle miles traveled provisions of section 182( d)( 1)

of the CAA.

° NOx requirements under section 182( f) of the CAA.

One exception in which the final rule does not reflect appendix B of the proposal concerns the requirement for reformulated gasoline ( RFG). Appendix B erroneously included RFG as an applicable requirement under subpart 2.

As discussed below under " Comments and responses," it is not an applicable requirement under subpart 2 and is not included as such in section 51.900( f) of the final rule. In addition, Appendix B listed NSR ( major source applicability and offets) as " applicable requirements" under subpart 2.

Although these would be applicable requirements under subpart 2 for the 8 hour standard, they would not be applicable requirements under subpart 2 for the 1 hour standard after the 1 hour standard is revoked. 30 attainment or reasonable further progress. Instead, NSR under the 8 hour NAAQS will apply.

118 ( C) Comments and responses COMMENT: Concerning the June 2, 2003 proposal, several commenters believed that not all control requirements required by an area's 1 hour classification would necessarily help achieve the 8 hour NAAQS and therefore opposed the proposed anti backsliding provisions. Other commenters supported the proposal.

Concerning the draft regulatory text, commenters generally reiterated their comments from the June 2, 2003 notice in commenting on the draft regulatory text.

RESPONSE: As we noted above and in the preamble to the proposed rule, we examined the CAA as a whole to discern Congressional intent since Congress did not specifically address anti backsliding where EPA promulgated a more stringent NAAQS. After considering the " as a matter of law"

designation and classification for the 1 hour NAAQS, section 172( e), and the CAA's redesignation provisions, we believe that Congress intended these areas to continue to implement requirements that applied in the area for the 1 hour NAAQS.

COMMENTS: The EPA's June 2 proposal listed RFG in appendix B as an " applicable requirement" for severe and above ozone nonattainment areas; it was also listed as an " applicable requirement" in the draft regulatory text under section 119 51.900( f). The EPA received a number of comments addressing RFG requirements. Some commenters argued that the program was of no environmental benefit in certain locations, and should not be required. One commenter suggested that where it is estimated that the costs per ton of VOC removal would be around $ 36 million per daily ton removed or around $ 100,000 per annual ton removed, with no measurable benefit to ozone levels, that requiring use of RFG would be an " absurd result" justifying a waiver of the RFG requirement.

One commenter argued that the rules providing for ozone nonattainment areas to opt in to the RFG program should be liberalized, to allow additional areas to avail themselves of the benefits of RFG. Other commenters argued against such liberalization, on the basis that the fuels industry is already burdened with implementation of far reaching fuels regulations and does not need the additional difficulties that would be associated with the proliferation of RFG optins

RESPONSE: The EPA has decided that it is not appropriate to list RFG as an " applicable requirement" in the final rule in section 51.900( f). The RFG program is not adopted as a State program in SIPs, as are the other " applicable requirements" listed in today's final rule. Rather, RFG is required under a Federal program. It is prescribed in some instances by statute, and in other instances States are 120 allowed to opt in and opt out of the program in accordance with Federal statutory prescriptions and EPA rules. The EPA recognizes that the scope and applicability of the RFG program during and after implementation of the new 8 hour ozone standard raises various issues that need further clarification. However, such clarification is more appropriately provided in a separate undertaking. Since Federal RFG does not appear on the final rule's list of " applicable requirements" in subpart 2, there is no need to respond in this rulemaking to the comments regarding implementation of the RFG program. Therefore, while not an " applicable requirement" under today's rules, the RFG requirement is nonetheless applicable under the CAA for certain areas, and EPA will determine in the future whether this requirement would change for these areas when they attain the ozone NAAQS.

COMMENT: One commenter noted that the language in the draft regulatory text is based upon the date of revocation of the 1 hour ozone NAAQS, which is at least one year later than that specified in the proposed rule. The date of revocation is also highly uncertain compared to the date of designation, which is driven by the Consent Decree. The Draft Regulatory Text therefore conflicts with the proposed rule language. The commenter prefers use of the date of designation for these and other applicable requirements. 121 RESPONSE: The regulatory text has been revised to key the requirement from the effective date of designation for the 8 hour NAAQS.

COMMENT: One commenter believed there was a conflict between the June 2, 2003 notice and the draft regulatory text concerning the timing of the 1 hour NSR obligation. The draft section 51.905( a)( 1) provision would apply for areas designated nonattainment for the 1 hour NAAQS at the time of revocation of the 1 hour NAAQS, but the June 2, 2003 notice provision would apply to areas designated nonattainment for the 1 hour NAAQS at the time of designation of the 8 hour NAAQS. The commenter recommended that the rule be based on the date of designation for the 8 hour NAAQS.

RESPONSE: We agree there was a conflict in the draft regulatory text on this matter. However, as discussed below, the final differs from the proposal in that after the 1 hour NAAQS is revoked, NSR under the 1 hour standard would not be retained after the 1 hour standard is revokedNAAQS will no longer be a required implementation plan element in areas that are 8 Hour NAAQS nonattainment/ 1 Hour NAAQS nonattainment. Instead, NSR under the 8 hour NAAQS will apply.

( ii) Discretionary control measures. This discussion of discretionary measures includes how we plan to treat enforceable commitments approved into the SIP. ( section 31 For purposes of the preamble to this rulemaking, whenever we state that a State must make the demonstration required under section 110( l) to modify its SIP, we also mean that the State must make the required demonstration under section 193 to the extent the affected area is designated nonattainment and the SIP requirement the State is modifying was a control requirement in effect or required to be in effect prior to November 15, 1990.

122 VI. C. 3. a. ii. of proposed rule, see 68 FR 32821, and section VI. C. 3. a. v. of proposed rule; see 68 FR 32822; Section 51.905( d) of draft and final rules; there is no parallel provision in the final rule.)

( A) Background. Many approved SIPs contain control measures that are not specified under subpart 2 for the area, but that the State chose to adopt as part of the demonstration of attainment or part of the ROP requirement for the 1 hour NAAQS. For these kinds of measures, we proposed that States retain the discretion they now have to modify these requirements in their SIPs. For purposes of the 1 hour NAAQS, States may currently revise or remove those requirements so long as they make a demonstration consistent with section 110( l) that such removal or modification would not interfere with attainment of or progress toward the 1 hour ozone NAAQS ( or any other applicable requirement of the CAA). 31 Once the 1 hour standard is revoked, for purposes of the 8 hour NAAQS, the same discretion to modify a SIP would apply except the State would need to make the demonstration required by section 123 110( l) with respect to the 8 hour NAAQS, not the 1 hour NAAQS. See 68 FR 32821 for an example of how this would work.

We also proposed that States remain obligated to meet enforceable commitments approved into a SIP to the same extent as if they were adopted measures ( 68 FR 32822). This includes enforceable commitments to perform a mid course review. The only way a State may modify or remove such a commitment is through a SIP revision making the required demonstration under section 110( l).

( B) Summary of final rule. We are adopting the approach we set forth in our proposed rule. A State may revise or remove discretionary control measures ( including enforceable commitments) contained in its SIP for the 1 hour NAAQS so long as the State demonstrates consistent with section 110( l) that such removal or modification will not interfere with attainment of or progress toward the 8 hour ozone NAAQS ( or any other applicable requirement of the CAA). Under the rule, States remain obligated to meet any SIP approved commitment to perform a mid course review.

These SIP commitments generally do not bind the States to take any specific action in response to the results of the mid course review. The EPA anticipates that rather than using these reviews to ensure areas meet the 1 hour NAAQS ( which will have been revoked), States and EPA can use these 124 reviews to ensure progress is being made consistent with needs for the 8 hour NAAQS.

Note, however, that since general provisions for modifying or removing control measures in a SIP are already provided in the statute ( sections 110( l) and 193), we do not believe there is a need to have a duplicative provision in this final rule. Therefore, even though the draft regulatory text contained such a provision ( section 51.905( d)), the final rule does not contain that provision.

( C) Comments and responses COMMENT: Several commenters supported the proposal regarding discretionary control measures. Other commenters believed that States should not be held to commitments to submit the mid course review required under their 1 hour SIP. Some commenters objected to the provision in draft regulatory text for allowing " relaxations" of the SIP under sections 110( l) and 193 of the CAA.

RESPONSE: Sections 110( l) and 193 allow States to modify the discretionary controls in their SIPs if the provisions of those sections are met. While we believe it is important to prevent backsliding consistent with the statutory provisions, we do not believe it is appropriate to further restrain the discretion Congress granted to States in determining the appropriate mix of controls in the SIP. We believe that a State may revise discretionary controls 125 approved in its SIP as long as it meets the criteria specified in sections 110( l) and 193. We believe the tests provided in sections 110( l) and 193 will prevent the adverse effects envisioned by the commenter.

( iii) Measures to address growth. ( section VI. C. 3. a. iii of proposed rule; see 68 FR 32821; sections 51.900( f) and 51.905( a)( 1) of the draft and final rule.)

( A) Background. In general, the SIP provisions in the CAA include one provision to address growth   nonattainment NSR. We discuss conformity for all areas in a later section.

For areas that are 8 hour NAAQS nonattainment/ 1 hour NAAQS nonattainment, we proposed in the June 2, 2003 notice that the major source applicability cut offs and offset ratios for nonattainment NSR that applied for an area's 1

hour classification continue to apply.

( B) Summary of final rule. The final rule treats 1

hour NSR as a requirement that will no longer apply once the 1 hour NAAQS is revoked. We provide a more thorough discussion of the approach in our final rule and the rationale in the section below discussing 1 hour NAAQS obligations that no longer apply as of revocation of the 1

hour NAAQS.

( C) Comments and responses. Comments and responses are included in the section below discussing 1 hour NAAQS 32 In this rulemaking, we use " ROP" to refer to the rate of progress requirement for the 1 hour NAAQS and " RFP" to refer to both the rate of progress requirement under subpart 2 and the reasonable further progress requirement under subpart 1 for the 8 hour ozone NAAQS.

126 obligations that no longer apply as of revocation of the 1

hour NAAQS.

( iv) Planning SIPs.

( A) Outstanding ROP obligation. ( section VI. C. 3. a. iv of proposal; 68 FR 32822; Section 51.905( a)( 1) of the draft and final rules)

( 1) Background. In the June 2, 2003 proposal, we proposed that States remain obligated to address separately 1 hour ROP requirements that do not overlap with RFP obligations for the 8 hour NAAQS. 32 Where outstanding ROP and RFP obligations overlap, the area need not submit a separate ROP plan for the 1 hour NAAQS but must show that the 8 hour ROP plan is no less stringent than the 1 hour ROP requirement. For ROP provisions already adopted into the SIP, we proposed that the State may remove or revise control measures needed to meet the ROP milestone if such control measures were discretionary ( i. e., not mandated by subpart 2 for the area's 1 hour classification), as discussed above,

and the State makes a demonstration under section 110( l)

including a demonstration that the revision will not interfere with meeting the 1 hour ROP and 8 hour RFP goals. 127 ( 2) Summary of final rule. We are adopting the approach set forth in our proposed rule for areas that are 8 hour NAAQS nonattainment/ 1 hour NAAQS nonattainment.

States remain obligated to meet the CAA mandated ROP emission reduction targets that applied for the 1 hour NAAQS, but discretionary measures adopted to meet those targets may be modified, if the State makes the necessary showing under section 110( l).

In addition, we are providing further clarification regarding how this obligation applies. Areas that have an outstanding obligation for an approved 1 hour ROP SIP for one or more of the ROP periods ( e. g., 1999 2002, 2002 2005,

2005 2007) must still develop and submit to EPA ( if they have not already done so) all outstanding 1 hour ROP plans.

Where a 1 hour ROP obligation overlaps with an 8 hour RFP requirement, the State's 8 hour RFP measures can be used to satisfy the 1 hour ROP obligation.

The State may choose to show that both the 8 hour and 1 hour ROP obligations are met through a single 8 hour plan submittal. To prevent backsliding, the State must ensure that the 8 hour RFP emission plan is at least as stringent as the 1 hour ROP emission target, for the year in which 1

hour ROP must be met. The State may do this by first establishing an RFP emission target for the entire 8 hour ozone nonattainment area, for the 1 hour ROP target year. 33Op cit.

128 If the 8 hour RFP emission target for the 8 hour area for the same period is more stringent than the 1 hour ROP emission target for the 1 hour area ( assuming the 8 hour area includes the entire 1 hour area), the State is not obligated to submit a separate 1 hour ROP plan, but can rely solely on the 8 hour RFP plan and emission target to demonstrate that the 1 hour target will be met. However,

the State must ensure that the emission target will be met for the same period as for 1 hour ROP ( e. g., 2003 2005).

The State may rely on any control measure to meet both ROP for the 1 hour NAAQS and RFP for the 8 hour NAAQS. Appendix A below provides an example of how this might work.

In the June 2, 2003 proposal ( 68 FR 32835), we proposed that the Agency's Clean Data Policy33 would remain effective under the 8 hour ozone NAAQS, and we therefore intend to apply this policy in implementing this final rule for areas that achieve the 8 hour NAAQS. Thus, if an area attains the 8 hour ozone NAAQS, under the Agency's " Clean Data Policy,"

EPA may waive the 1 hour RFP obligation for the area based on a determination that the area has attained the 8 hour NAAQS. Under that policy, the State will not be subject to the 1 hour RFP requirement for so long as the area remains in attainment with the 8 hour NAAQS. ( The EPA will address 129 the applicability of the Clean Data Policy for 8 hour ozone nonattainment areas in Phase 2 of the implementation rule.)

We believe that there is ambiguity in the statute regarding whether areas should remain subject to the requirement to submit planning SIPs, such as the 1 hour ROP plans. Unlike control obligations, we do not believe there is as strong an argument that Congress intended areas to continue to submit planning SIPs for a NAAQS that EPA has determined is no longer necessary to protect public health.

Section 172( e), which applies when EPA relaxes a NAAQS, only requires EPA to ensure that control measures are no less stringent than they were for the more stringent NAAQS that has been replaced. It does not indicate a Congressional intent that areas remain obligated to plan for and meet a NAAQS as it existed before it was revised. However, both attainment demonstrations and ROP plans result in the adoption of control obligations. And, if EPA determined that these planning requirements did not apply at all, areas currently designated nonattainment for the 1 hour NAAQS that have not met these obligations might be subject to less stringent controls than would have otherwise applied. Thus,

in considering how to treat this obligation, we balanced the need to ensure the same level of control with the difficulties associated with meeting this obligation.

For purposes of ROP, the exercise of calculating the 130 reductions necessary to meet ROP is relatively simple.

Moreover, as provided above, even if the State must calculate ROP separately for the 1 hour and 8 hour NAAQS, it may still rely on one or more of the same control measures to meet both those obligations. Additionally, we believe that most of the areas with an outstanding 1 hour ROP obligation will be able to demonstrate that the 8 hour RFP targets for the same time period will be more stringent and thus will not be required to prepare a separate 1 hour ROP plan. Finally, we note that States have already submitted and, EPA has already approved 1 hour ROP plans for most 1

hour nonattainment areas. Thus, the anti backsliding provisions regarding the continued obligation to adopt and submit 1 hour ROP plans will affect only a handful of areas.

For these reasons, we are adopting a regulation that requires areas that are 8 hour NAAQS nonattainment/ 1 hour NAAQS nonattainment to continue to adopt and achieve the level of ROP reductions mandated by Congress under the CAA for that NAAQS.

( 3) Comments and responses COMMENTS ON JUNE 2, 2003 PROPOSAL: Few commenters submitted comments on the portion of the proposed rule discussing the anti backsliding requirements applicable to 1 hour ROP.

Several commenters generally opposed any continued planning obligations under the 1 hour NAAQS, but did not raise 131 specific concerns with respect to ROP. Similarly, a number of other commenters opposed revocation of the 1 hour NAAQS and urged retention of all 1 hour planning and control obligations; but again, these commenters did not raise concerns specific to the proposed anti backsliding approach for ROP.

One commenter, addressing section 51.905( a)( 1)( iii) of the draft regulatory text, argued that States should have the ability to modify ROP measures if it can be demonstrated that they are not needed for purposes of meeting requirements under the 8 hour NAAQS or if measures are no longer appropriate due to updated technical information regarding emissions inventory and control strategy effectiveness. Another commenter objected to retaining the 1 hour ROP requirement, primarily because areas recently reclassified to a higher classification would have a continuing obligation for ROP even if they were not required to develop an RFP plan under the 8 hour NAAQS. Another commenter believed the 1 hour ROP requirement should only be required where it is demonstrated to be needed for attainment of the 8 hour NAAQS.

RESPONSE: As provided above, we believe Congress intended areas to continue to have control measures no less stringent than those that applied for the 1 hour NAAQS. Because the ROP obligation results in control obligations, we believe 132 areas should remain obligated to adopt outstanding ROP obligations to ensure that the ROP milestones are met. If a State believes adopted controls are not the best fit for the 8 hour NAAQS, the State retains full discretion to revise those controls so long as the revision doesn't interfere with the ROP milestones.

Without this provision, an area with an unmet obligation to submit and implement a ROP plan under the 1 hour NAAQS could experience backsliding by being released from the obligation to have controls in place that achieve a specified level of emissions reductions during the interim period prior to implementation of the SIP required for the 8 hour NAAQS. In other words, if the 1 hour NAAQS were not revoked, the area would have been required to continue to ensure emissions would be reduced by specified levels in specific timeframes. If the final rule contained no provision comparable to section 51.905( a)( 1)( i), achievement of those emissions reductions would almost certainly be delayed. Because we are transitioning to a more stringent and protective air quality NAAQS. we see no reason why there should be provisions that would provide less protection to public health.

( B) Unmet attainment demonstration obligations ( section VI. C. 3. a. iv of proposal; see 68 FR 32822; section 51.905( a)( 1)( ii) of the draft and final rules) 133 ( 1) Background. Most areas designated nonattainment for the 1 hour ozone NAAQS have fully approved attainment demonstrations for the 1 hour NAAQS. Because there are so few areas without approved attainment demonstrations, in the proposed rule we identified the two types of situations of which we were aware and solicited comment on how to handle those situations. First, there are a few areas that do not have a fully approved attainment demonstration because the area has not acted in accordance with the timelines provided under the CAA. The second situation is an area which has a future obligation to submit an attainment demonstration. In general, these are areas that, over the past several years,

have been reclassified ( i. e., " bumped up") to a higher classification. In the preamble to the proposal, we discussed the policy reasons that would support retention of the obligation to submit an attainment demonstration and the policy reasons that would counsel against retention of that obligation ( 68 FR 32822). For both these groups of areas,

we solicited comment on whether to retain the obligation to develop a 1 hour attainment demonstration. In addition, we solicited comment on two alternatives that would address many of the policy concerns we noted.

Alternative 1 would require that areas with a current or past due obligation to submit a new or revised attainment demonstration instead be required to submit a SIP revision 134 that would obtain an advance increment of local emissions reductions toward attainment of the 8 hour ozone NAAQS within a specified, short term timeframe; 5 percent and 10 percent were suggested possibilities for the increment.

Under Alternative 2, areas with a current or past due obligation to submit a 1 hour attainment demonstration would be required to submit their 8 hour ozone attainment demonstration early in lieu of being required to submit a 1 hour attainment demonstration. The draft regulatory text was developed using the first alternative, and used a 10 percent increment.

( 2) Summary of final rule. In the final rule, we are allowing the States to choose among three options that are tailored after the approaches addressed in the proposed rule. Thus, rather than establishing one mandatory approach, we are adopting a rule that will allow States to choose any one of the following three options:

° Option 1. Submit a 1 hour attainment demonstration.

° Option 2. Submit, no later than 1 year after the effective date of the 8 hour designations, an early increment of progress plan toward the 8 hour NAAQS which provides:

° A 5 percent increment of reduction from the 2002 emissions baseline ( NOx and/ or VOC). The control measures for achieving this increment must be in 34The amount of which will depend on the ROP option in the final rule and the classification of the area.

135 addition to measures ( or enforceable commitments to measures) in the SIP as of the effective date of designation and in addition to national or regional measures. ( The State can take credit for this increment of reduction toward its RFP requirement under the 8 hour NAAQS.)

° For achievement of the emissions reductions within 2 years after submittal ( i. e., 3 years after designation).

° Option 3. Submit an early 8 hour ozone attainment demonstration SIP 1 year after the effective date of designation for the 8 hour NAAQS that:

° Demonstrates attainment of the 8 hour NAAQS by the area's attainment date,

° Provides for 8 hour RFP consistent with the area's classification out to the area's attainment date, and ° Ensures that the first segment of RFP34 between the end of 2002 and the end of 2008 is achieved early   by the end of 2007.

With respect to Option 2, the final rule specifies a 2002 baseline year for calculating the early increment of progress whereas the draft regulatory text did not provide a 136 specific baseline year.

As noted above in the ROP section, we believe the statute is ambiguous regarding the need for States to address planning for a NAAQS no longer needed to protect public health. However, since these planning SIPs result in the adoption of control measures, which we believe Congress intended be no less stringent, we examined what approaches would ensure controls are adopted and implemented without unnecessarily obligating States to plan for a NAAQS not needed to protect public health.

Unlike planning for ROP, preparing an attainment demonstration involves complex modeling and analyses that can be resource intensive both in terms of workload and cost. We don't believe it is appropriate or necessary to mandate that States perform the attainment demonstration for a NAAQS that is not needed to protect public health. But we also do not believe it is appropriate to waive in total this obligation in light of the need to ensure there is no delay in achieving emissions reductions to protect public health.

We are adopting an approach that provides States with options because it provides maximum flexibility to States that have outstanding attainment demonstration obligations while continuing to obtain in a timely fashion many or all of the emissions reductions that should occur under those obligations, effecting an orderly transition to planning 137 under the 8 hour NAAQS. In addition, we do not believe it is equitable to relieve these areas of this obligation where other areas have already adopted controls to meet these obligations and will not be able to modify or remove such controls unless the State can demonstrate that such action is consistent with section 110( l).

Thus, in balancing Congressional intent to ensure no backsliding, equitable treatment of all areas, the need for areas to begin planning for the 8 hour NAAQS and the limited planning resources that States have available, we believe the best approach is to provide States with several alternatives, each of which will achieve emissions reductions on a timeframe similar to when they would have been achieved for the 1 hour NAAQS through a 1 hour attainment demonstration SIP. The State may choose the option that is least burdensome in light of activities already performed. For example, States with a 1 hour attainment demonstration that is past due or is due in the next several months may have already made significant progress in developing a 1 hour attainment demonstration SIP. Thus, these State may choose the first option. We are aware that one or more States have already begun the process of developing 8 hour attainment demonstrations for some 1

hour nonattainment areas. These States may choose to submit an early 8 hour attainment demonstration SIP. Other areas, 138 which have not yet made significant progress on 1 hour or 8

hour attainment planning, may wish to reserve more time for the attainment demonstration process, which can involve complex modeling, and thus choose the third option   to achieve an early increment of progress.

For the second option available to States, we chose 5   rather than 10   percent as the amount of reduction. Under this option, States must achieve the 5 percent emission reduction from local controls ( not currently required by the SIP) and within 3 years of designation for the 8 hour NAAQS.

In light of the quick timeframe in which to achieve the reductions following designations and the limitation that such reductions cannot be from regional or national controls or from measures already in the SIP, we concluded that 10 percent was unduly burdensome. The States that choose this option will need to identify and adopt appropriate controls within a 1 year timeframe and require sources to implement the controls within a short time thereafter. These limitations will restrict the control choices available to States. In addition, because of the limited timeframe for adoption and submission of the controls to EPA, we do not believe it is reasonable to require the State to obtain a level of reduction that would force the States to concentrate its resources on the early ROP reduction rather than on an 8 hour attainment plan. However, because the 35Memorandum of May 10, 1995, " RFP, Attainment Demonstration, and Related Requirements for Ozone Nonattainment Areas Meeting the Ozone National Ambient Air Quality Standard," from John S. Seitz, Director, Office of Air Quality Planning and Standards. Available at: http:// www. epa. gov/ ttn/ oarpg/ t1/ memoranda/ clean15. pdf.

139 State will not be able to rely on national or regional controls, we are confident that the 5 percent requirement will achieve the anti backsliding goal.

Finally, as with the 1 hour ROP requirement, we note that EPA may waive the 1 hour attainment demonstration requirement for areas based on a determination that the area has attained the 8 hour NAAQS. The EPA's Clean Data Policy35 provides that if EPA has determined that an area has attained the 1 hour NAAQS, it will not be obligated to submit a 1 hour attainment demonstration for so long as it maintains the 1 hour NAAQS. Thus, extending this policy to the 8 hour NAAQS, if EPA determines that an area has attained the 8 hour ozone NAAQS before the time the area is obligated to make a submission under this portion of EPA's 8 hour implementation regulations, EPA would waive this requirement for so long as the area remains in attainment with the 8 hour NAAQS. ( The EPA will address the applicability of the Clean Data Policy for 8 hour ozone nonattainment areas in Phase 2 of the implementation rule.)

( 3) Comments and responses COMMENT: Several commenters advocated retaining the 140 planning obligations under the 1 hour NAAQS, expressing the belief that momentum will be lost in implementing controls if these obligations are not retained. In general, most of these commenters also opposed revocation of the 1 hour NAAQS and believed Congress intended the 1 hour NAAQS to be planned for and met. Some commenters opposed retaining the attainment demonstration requirements under the 1 hour NAAQS after the NAAQS is revoked on the basis that State resources are limited and should be focused on developing plans for implementing the 8 hour rather than the 1 hour NAAQS. A few commenters favored the alternative of requiring an early plan with an advance increment of emissions reductions toward progress of the 8 hour NAAQS in lieu of the attainment demonstration SIP revision. A few other commenters favored the alternative of requiring States to submit an early attainment demonstration SIP for the 8 hour NAAQS.

Only one commenter believed that 10 percent was the appropriate amount under Alternative 1 for an advance increment of progress; several others opposed 10 percent,

claiming that it appeared to be punitive, that there was no technical support for that amount, and that it may be more than what was needed for attainment of the 8 hour NAAQS.

Some commenters recommended that exceptions be made for any area that made good faith efforts to develop and submit 141 its plan, such as those with a submitted and approved plan that may have been challenged and overturned by a court.

RESPONSE: We have designed the final rule such that an area without an approved attainment demonstration or ROP plan would still be required to submit and implement a ROP plan and an attainment demonstration or substitute plan as required for the 1 hour NAAQS. We believe this approach will ensure there are no delays in achieving emissions reductions as we transition to the more stringent 8 hour ozone NAAQS.

We believe that areas that have not met their planning obligations under the 1 hour NAAQS   if relieved of that obligation after the 1 hour NAAQS is revoked   would provide emissions reductions on a more protracted time schedule than areas that had met their 1 hour NAAQS planning obligations.

For example, an area that is classified severe 15 for the 1 hour NAAQS would have to obtain RFP reductions and any additional reductions needed for attainment by the end of 2005, whereas if that same area is moderate under the 8 hour NAAQS, it would not be required to obtain reductions under the RFP provisions until 2008 and additional reductions for attainment by some time in 2009. We believe that the provisions of the final rule   by offering three alternative means of meeting the 1 hour attainment demonstration obligation   allow sufficient flexibility for a State in 142 these circumstances to choose the most appropriate means to achieve these reductions in the time intended by Congress.

d. Section 51.905( a)( 2): 8 hour NAAQS Nonattainment/ 1 hour NAAQS Maintenance In the June 2003 proposal, we discussed the requirements for areas designated as attainment for the 1

hour NAAQS with a maintenance plan at the time of designation for the 8 hour NAAQS in the same sections discussing the requirements for areas designated nonattainment for the 1 hour NAAQS at the time of 8 hour designations. However, in the draft regulatory provisions,

we created a separate subparagraph addressing these areas.

Below, we indicate briefly where the obligations for these areas, i. e., maintenance areas at the time of designation,

are the same as for areas designated nonattainment for the 1 hour NAAQS at the time of 8 hour designations. We discuss in more detail where the obligations differ.

( i) Mandatory Control Measures. ( section VI. C. 3. a. i.

of proposed rule; see 68 FR 32821; sections 51.900( f) and 51.905( a)( 2) of draft and final rules)

( A) Background. In the June 2003 proposal, we proposed that all areas designated nonattainment for the 8

hour NAAQS and that were nonattainment or maintenance for the 1 hour NAAQS at the time of 8 hour designations would be required to continue to implement mandatory measures adopted 36In order to redesignate these areas to attainment, EPA had to determine these areas had met all obligations under part D. See CAA Section 107( d)( 3)( E).

143 into the approved SIP. We did not distinguish between areas designated nonattainment for the 1 hour NAAQS at the time of designation for the 8 hour NAAQS and areas that are maintenance for the 1 hour NAAQS at the time of designation for the 8 hour NAAQS. However, in the draft regulatory text, we created a separate provision for maintenance areas because these areas do not have an outstanding obligation to adopt mandatory control obligations for the 1 hour NAAQS. 36 Thus, the draft regulatory provision for maintenance areas did not address the future adoption of controls; it simply provided that these areas would be required to continue to implement the applicable requirements ( as defined in the regulatory text) in the approved SIP.

We also provided in the June 2003 proposal and the draft regulatory text that if a maintenance area had previously shifted a mandatory control measure to the contingency provisions, the area would not be required to begin implementation of that measure based on the 8 hour nonattainment designation. However, the measure would need to remain as a contingency measure for the area and could not be removed from the SIP.

( B) Final Rule. We are adopting the approach we took 144 in the proposal and the draft regulatory text. Areas that are maintenance for the 1 hour NAAQS at the time of 8 hour designations and are designated nonattainment for the 8 hour NAAQS, must continue to implement mandatory control requirements ( i. e., " applicable requirements") that have been approved into the SIP. However, since maintenance areas do not have any outstanding obligation to adopt mandatory control measures for the 1 hour NAAQS, the provision only addresses implementation, not adoption. In addition, this section recognizes that maintenance areas had the flexibility to move mandatory controls to the contingency measures portion of their maintenance plan. The area would not be required to implement these measures unless it is required to do so for the area's classification for the 8 hour NAAQS. However, the measures would need to remain as contingency measures and could not be removed from the SIP.

We are adopting the requirement that 1 hour maintenance areas are required to continue to implement mandatory controls for the same reasons we provided with respect to 8

hour NAAQS nonattainment/ 1 hour NAAQS nonattainment areas above. With respect to mandatory measures that the State has moved to the contingency portion of the maintenance plan, we do not believe that Congress intended to require areas to begin implementing such measures again based on the 145 promulgation of a revised NAAQS unless required based on the area's classification for the revised NAAQS. These areas have fully complied with the process that Congress established   attainment of the ( then existing) NAAQS and redesignation to attainment for that NAAQS based on a plan demonstrating that the area will maintain the NAAQS. While we believe these areas should not " backslide" from existing control levels, we do not believe that for purposes of the 8 hour NAAQS they should be required to begin implementing once more measures that the State has chosen to place in the contingency measures portion of the SIP.

( ii) Discretionary Control measures. ( Section VI. C. 3. a. ii. of proposed rule, see 68 FR 32821, Section 51.905( a)( 2) of draft regulatory text; there is no parallel provision in the final rule.)

( A) Background. The June 2, 2003 proposal did not discuss the requirements for these areas independent of all areas that were designated nonattainment for the 1 hour NAAQS on or after November 15, 1990. The draft regulatory text ( section 51.905( a)( 2)), however, did provide for this situation separately but did not directly address discretionary measures.

( B) Summary of final rule. As with discretionary control measures for 8 hour NAAQS nonattainment/ 1 hour NAAQS nonattainment areas, 1 hour NAAQS maintenance/ 8 hour NAAQS 37 If an area located in the Ozone Transport Region was redesignated to attainment, section 184( b)( 2) of the CAA required it to retain a nonattainment NSR program. In addition, it is possible that one or more areas still has a nonattainment NSR program in place because of the way the State wrote the SIP.

146 nonattainment areas will retain the discretion to modify any discretionary control measures upon a demonstration under section 110( l). We are not promulgating regulatory text because, as described above, sections 110( l) and 193 of the CAA govern such SIP revisions.

( iii) Measures to address growth. ( Section VI. C. 3. a. iii of proposed rule; see 68 FR 32821; sections 51.900( f) and 51.905( a)( 1) of the draft and final rules)

( A) Background. In the proposal, we recognized that 1 hour maintenance areas generally are subject to the prevention of significant deterioration ( PSD) program and are no longer implementing the nonattainment NSR program for their previous 1 hour ozone designation and classification. 37 For areas where the NSR program no longer applies under the SIP, we proposed that the areas would not need to revert back to the NSR program they had for purposes of the 1 hour NAAQS. The proposal provided examples of how this would work ( 68 FR 32821).

( B) Summary of final rule. We are adopting the approach we proposed but our rationale relies on the final rule's provision that NSR under the 1 hour standard will no 147 longer apply as of revocation of the 1 hour standard. If an area has been redesignated to attainment for the 1 hour NAAQS as of the effective date of the 8 hour nonattainment designation and is no longer required to implement a nonattainment NSR program, the area will not be required to revert back to the program it had for purposes of the 1 hour ozone NAAQS. As noted elsewhere, NSR offset ratios and source applicability provisions under the 1 hour standard are not being defined as " applicable requirements" after the 1 hour standard is revoked.

As provided in more detail below for 8 hour NAAQS nonattainment/ 1 hour NAAQS nonattainment areas, we have determined that 1 hour NAAQS NSR should not continue to apply once the 1 hour NAAQS is revoked for those areas. It would not be reasonable to require these areas to begin those 1 hour programs again for the 1 year between designation for the 8 hour NAAQS and revocation of the 1

hour standard. Moreover, Congress did not intend the nonattainment NSR program to continue to apply to most areas once they are redesignated to attainment. Rather, such areas are subject to the PSD program. For an area that has met the clean air goals for the 1 hour NAAQS, we see no reason to require such area to revert back to its 1 hour NSR program. These areas will be required to implement the nonattainment NSR program that applies based on their 148 classification for the 8 hour ozone NAAQS.

( iv) Planning SIPs. ( Section VI. C. 3. a. iV. of proposed rule, see 68 FR 32822; no specific provision in draft regulatory text or final rule.)

( A) Background. In the June 2003 proposal, we did not discuss maintenance areas separate from 8 hour NAAQS nonattainment/ 1 hour NAAQS nonattainment areas. However,

the preamble discussion focused on areas with an outstanding obligation to submit a 1 hour ROP or attainment plan and the obligation to ensure that the ROP percentage reduction obligations in the approved SIP are achieved. Maintenance areas for the 1 hour NAAQS do not have an outstanding obligation to submit ROP or attainment plans for the 1 hour NAAQS. Thus, the draft regulatory text did not include language similar to that in 51.905( a)( ii) and ( iii) for maintenance areas. The draft regulatory text did reflect ROP as an applicable requirement for maintenance areas,

indicating that these areas must ensure that any SIP revision does not interfere with an approved ROP milestone.

( B) Summary of final rule. We are adopting the approach taken in the draft regulatory text. In redesignating an area to attainment, EPA must conclude that the area has met all requirements applicable under section 110 and part D. Thus, maintenance areas do not have continuing progress and attainment demonstration 149 requirements, and the final rule does not establish requirements for maintenance areas related to outstanding attainment demonstration and ROP plans. The final rule does identify the ROP percent reduction requirement as an applicable requirement. However, we note that the ROP periods for areas redesignated to attainment for the 1 hour NAAQS have already passed and thus any revision to the SIP should not affect ROP reductions for the periods required for the 1 hour NAAQS.

( C) Comments and responses COMMENT: One commenter believed that 1 hour maintenance areas designated nonattainment under the 8 hour NAAQS should not have to submit updates to the 1 hour maintenance plan,

since they will be developing 8 hour attainment plans that will subsume the requirements of the maintenance plan previously in effect.

RESPONSE: The rule provides that after the 1 hour ozone NAAQS is revoked, areas are relieved of responsibilities to submit updates to their 1 hour maintenance plans. The State may submit a revision to the SIP to remove the provisions that require the update to the maintenance plan.

COMMENT: One commenter noted that draft Section 51.905( a)( 2) would limit shifting of an applicable requirement to the contingency measure portion of an area's maintenance plan. Under the proposal, a State may only make 150 such a shift prior to the revocation of the 1 hour NAAQS;

States may only make subsequent shifts by satisfying the requirements of Section 110( l) of the CAA. The commenter believes that this criterion for shifting measures to the maintenance plan is more stringent and burdensome than the requirements in Section 175A of the CAA for maintenance plans. In the alternative, the commenter recommends that in lieu of the showing required by Section 110( l), that States,

instead, be allowed to substitute a control measure with equivalent emissions reductions for the measures they propose to remove from their plan.

RESPONSE: We agree with the commenter that section 51.905( a)( 2) will limit the authority of an area that was maintenance for the 1 hour standard at the time of designation as nonattainment for the 8 hour standard.

However, we disagree with the commenter regarding the statutory provisions that apply for purposes of SIP revisions. The commenter is incorrect that section 110( l)

does not apply to revisions to maintenance plans. Prior to being designated nonattainment for the 8 hour NAAQS, such an area could move adopted measures to the contingency measures portion of the maintenance plan based on a demonstration under section 110( l) that such a revision would not interfere with attainment, maintenance or any other applicable requirement of the CAA. Our rule provides that 151 upon designation as nonattainment for the 8 hour NAAQS, a 1

hour maintenance area will not be able to shift adopted mandatory controls ( i. e., those identified as " applicable requirements" in the regulation) to contingency measures as those obligations are now defined as " applicable requirements." Once the area is redesignated to attainment for the 8 hour NAAQS, such obligations will no longer be defined as " applicable requirements" and the State can move them to contingency measures based on a demonstration that to do so would not interfere with attainment or maintenance of the 8 hour NAAQS or any other applicable requirement of the CAA. For adopted control measures that are not identified as " applicable requirements" in the regulation,

the State will continue to have the same authority it currently has for shifting adopted controls to contingency measures, based on a demonstration under section 110( l).

COMMENT: One commenter noted that in section 51.905( a)( 2),

the clause "... except to the extent required under its 8

hour obligations..." could be interpreted to imply that contingency measures in the 1 hour maintenance plan become 8 hour measures by default. The commenter suggested language to avoid an incorrect interpretation.

RESPONSE: The final rule reflects this recommended language change with some slight modifications.

e. Section 51.905( a)( 3): 8 Hour NAAQS Attainment/ 1 Hour 38These two options were: 1) when the area attains the 1 hour NAAQS, or ( 2) when the area attains the 8 hour NAAQS.

152 NAAQS Nonattainment ( i) Mandatory control obligations. ( Section VI. C. 3. b.

of proposal see 68 FR 32823; section 51.905( a)( 3)( i) of the draft and final rule)

( A) Background. The proposal noted that the issue of what obligation remains with respect to mandatory control measures approved into the SIP or required under the CAA is based on the CAA's requirements for maintenance plans. We proposed that if EPA determined that these areas were required to develop maintenance plans pursuant to section 175A, then they would need to keep ( or to adopt and then keep) those control measures in the SIP, though they could shift them to contingency measures.

For an area that was never redesignated to attainment for the 1 hour standard and never had a section 175A maintenance plan, we proposed that if the area wants to revise any part of its current 1 hour SIP, the area must first adopt and submit a maintenance plan consistent with section 110( a)( 1) ( discussed below). We proposed that these obligations would remain in place but in a later section of the preamble proposed options as to when this obligation would no longer apply. 38 ( B) Summary of final rule. 153 We are adopting an approach consistent with our proposed rule. As we discuss later in this preamble, we have determined that mandatory control obligations will no longer apply once an area attains the 8 hour NAAQS. Thus,

because these areas are attaining the 8 hour NAAQS, the State may request that obligations under the applicable requirements of section 51.900( f) be shifted to contingency measures once the 1 hour NAAQS is revoked, consistent with sections 110( l) and 193 of the CAA. However, the State cannot remove the obligations from the SIP.

Because these areas are in attainment with the healthbased NAAQS, we believe that Congress   as with areas redesignated from nonattainment to attainment   did not intend the areas to retain these controls as implemented measures if the area can demonstrate maintenance without the controls. As with areas redesignated to attainment, the rule provides that the State cannot remove the measures from the SIP, but rather may move them to the contingency measures portion of the SIP. We did not receive comments directly addressing mandatory control obligations for this category of areas outside the context of maintenance plans for these areas discussed below.

( ii) Discretionary control obligations. ( Section VI. C. 3. b. iii. of proposal; 68 FR 32823; section 51.905( d) of draft regulatory text; no parallel provision in final rule.) 39If an area located in the Ozone Transport Region was redesignated to attainment, section 184( b)( 2) of the CAA 154 Areas designated nonattainment for the 1 hour NAAQS that are designated attainment for the 8 hour ozone NAAQS will retain the ability to modify any discretionary controls upon a demonstration under section 110( l). However, such controls must remain in the SIP as contingency measures. We are not promulgating regulatory text because, as described above, sections 110( l) and 193 of the CAA govern such SIP revisions. As with mandatory measures, we look to the maintenance plan provision of section 175A to see what Congress' intent may have been for these areas. Because these areas were nonattainment for the 1 hour NAAQS, we believe Congress intended them to retain the measures in the SIP, but could shift them to contingency measures if the area demonstrates it will maintain the 8 hour NAAQS if the measure is no longer implemented. We did receive comments directly addressing discretionary control obligations for this category of areas outside the context of maintenance plans for these areas discussed below.

( iii) Measures to address growth. ( Section VI. C. 3. b. i. of proposal; 68 FR 32823; no provision in draft or final rule.)

( A) Background. The proposal explained that NSR applies only in nonattainment areas. 39 Since these areas required it to retain a nonattainment NSR program. In addition, it is possible that one or more areas still has a nonattainment NSR program in place because of the way the State wrote the SIP.

155 would be designated attainment for the 8 hour NAAQS   the only ozone NAAQS that exists for the area once the 1 hour NAAQS is revoked   they would be subject to PSD, not NSR,

once the 1 hour NAAQS is revoked.

( B) Summary of final rule. We are adopting the approach we set forth in our proposed rule for areas designated attainment for the 8 hour NAAQS and designated nonattainment for the 1 hour NAAQS at the time of designation for the 8 hour NAAQS. After the 1 hour NAAQS is revoked, the CAA requires such areas to comply with PSD, not NSR. ( The States may need to modify their SIPs so that it provides for PSD rather than NSR in such areas.) We do not see a basis for mandating that such areas retain a nonattainment NSR program and do not believe that Congress intended such a result. As an initial matter, once the 1

hour NAAQS is revoked, these areas are meeting the only ozone NAAQS that is in place. Congress specified that PSD shall apply in areas not designated nonattainment ( section 161 of the CAA). In addition, as provided in more detail below for 8 hour NAAQS nonattainment/ 1 hour NAAQS nonattainment areas, we have determined that 1 hour NAAQS NSR should not continue to apply once the 1 hour NAAQS is 40Memorandum from Mary Nichols to Regional Air Division Directors dated October 14, 1994, entitled " Part D New Source Review ( part D NSR) Requirements for Areas Requesting Redesignation to Attainment."

156 revoked for those areas.

Note that for these areas, the NSR provisions may be removed from the SIP and need not be shifted to contingency measures. 40 We have never interpreted section 175A of the CAA to mandate that nonattainment NSR be retained as a contingency measure in the SIP after an area is redesignated from nonattainment to attainment because we do not interpret NSR to be a control measure. ( See, e. g., May 12, 2003; 68 FR 25436.)

( C)

COMMENT: Some commenters believed that the 1 hour NAAQS should remain in effect, and therefore NSR would continue to apply until the area attains the 1 hour NAAQS and is redesignated to attainment for that NAAQS regardless of the area's status for the 8 hour NAAQS. Other commenters generally agreed with the proposal.

RESPONSE: We address the broader legal and policy issues regarding revocation of the 1 hour NAAQS in the revocation section of this rule.

( iv) Planning SIPs. ( Section VI. C. 3. b( ii) of proposed rule; see 68 FR 32823; Section 51.905( a)( 3)( ii) of draft and final rule.) 157 ( A) Background. In the June 2, 2003 proposed rule,

we proposed that any outstanding SIP planning requirements ( ROP plans and attainment demonstrations) that applied for purposes of the 1 hour NAAQS would not continue to apply to areas designated attainment for the 8 hour NAAQS for as long as they continue to maintain the 8 hour NAAQS. If such an area violates the 8 hour NAAQS prior to having an approved maintenance plan meeting the requirements of section 110( a)( 1) the obligation to have a 1 hour attainment demonstration and ROP plan would once again apply in the same manner that they apply for 8 hour NAAQS nonattainment/ 1 hour NAAQS nonattainment areas.

The draft regulatory text ( section 51.905( a)( 3))

contained specific provisions addressing the obligation for an area designated attainment for the 8 hour NAAQS that subsequently violates the 8 hour NAAQS prior to having an approved maintenance plan under section 110( a)( 1). If the area was required to and does not have an approved attainment demonstration or ROP plan for the 1 hour NAAQS,

the State would be required to submit a plan providing for a 10 percent emission reduction as a substitute for the attainment demonstration and to adopt and submit any outstanding ROP emission reductions.

( B) Summary of final rule. We are adopting our proposal with some modification. As an initial matter, 41We discuss the obligation for these areas to adopt a section 110( a)( 1) maintenance plan below.

158 section 51.905( a)( 3) now only addresses 8 hour NAAQS attainment/ 1 hour NAAQS nonattainment areas. We have created a new section 51.905( a)( 4) that addresses 8 hour NAAQS attainment/ 1 hour NAAQS maintenance areas. The section addressing that second category of areas is discussed below. An area that is 8 hour NAAQS attainment/ 1

hour NAAQS nonattainment will not be required to develop and submit outstanding attainment demonstration and ROP plans for the 1 hour NAAQS for so long as the area continues to maintain the 8 hour NAAQS. However, if the area violates the 8 hour NAAQS prior to having an approved 8 hour maintenance plan under section 110( a)( 1), the area will be required to submit a SIP revision to address outstanding ROP and attainment demonstration plans as follows. 41 ( 1) ROP Plans. For an outstanding 1 hour ROP plan,

the State must submit a SIP providing for any outstanding ROP and the 3 year periods for achieving those reductions will begin January 1 of the year following the 3 year period on which EPA bases its determination. For example, if an area was required to and does not have an approved SIP providing for a 9% reduction in emissions from 1996 1999,

the obligation to have such a SIP is deferred unless the area violates the 8 hour NAAQS prior to having an approved 159 maintenance plan for the 8 hour NAAQS. If EPA determines in August 2007 that the area violated the 8 hour NAAQS based on ambient air quality data from 2004 2006 and at that time the area does not have an approved maintenance plan for the 8

hour NAAQS, the area will be required to submit a SIP providing for a 9 percent reduction in emissions for the 3

year period of January 2007  December 2009. The State may rely on national and regional controls for purposes of meeting this increment of reduction and the 9 percent should be calculated using the 1990 baseline. ( The 1 hour ROP requirement is calculated from a 1990 baseline, not a 2002 baseline, as is the 8 hour RFP requirement.) We have clarified the language in the final regulation to make clear that the requirement to submit the plan for additional emission reductions applies only to the extent that an area had not met its prior planning obligations. For example, if an area was classified as serious for the 1 hour NAAQS and had an approved 15 percent ROP plan and an approved 9 percent ROP plan for 1996 1999, then the area does not have any outstanding ROP obligation that must be met under this provision. However, if the same area only had an approved 15 percent ROP plan, but not an approved 9 percent ROP plan for 1996 1999, then the area has an outstanding 9 percent ROP plan for the 1996 1999 period. If the State had submitted the ROP plan to EPA, but EPA had not yet acted on 160 the submission, the State may notify EPA that it wishes to rely on the previously submitted SIP or it may elect to submit a new or revised SIP.

We believe this approach makes sense as it ensures that the level of emission reduction that the area was required to achieve, but was not yet enforceable under the SIP, will be achieved expeditiously after a violation of the 8 hour NAAQS occurs.

( 2) Attainment Demonstration. For an outstanding 1

hour attainment demonstration, the final rule requires the State to either: ( 1) submit an 8 hour maintenance plan that addresses the violation and demonstrates maintenance through EPA approved modeling; or ( 2) submit a plan to achieve a 3 percent increment of progress within 3 years after EPA determines the area has violated the NAAQS. The 3 percent increment of progress must be in addition to measures ( or enforceable commitments to measures) in the SIP at the time of the effective date of designation and in addition to national or regional measures.

This approach differs from both the June 2003 proposal and the draft regulatory text in that we do not establish precisely the same requirement for these areas that we establish for areas that are 8 hour NAAQS nonattainment/ 1

hour NAAQS nonattainment. For areas that are 8 hour NAAQS 161 nonattainment/ 1 hour NAAQS nonattainment, section 51.905( a)( 1)( ii) provides three options for the State. The first option available is that States may choose to submit their 1 hour SIP. We do not believe this option makes good policy sense for an area designated attainment for the 8

hour NAAQS to spend resources to develop a plan to achieve the 1 hour NAAQS ( which is likely to have been revoked by that time), when the area will already be in the process of developing the section 110( a)( 1) maintenance plan for the area discussed elsewhere in this preamble.

The second and third options under section 51.905( a)( 1)( ii) available to areas that are 8 hour NAAQS nonattainment/ 1 hour NAAQS nonattainment are analogous but not identical to the two options we provide for areas designated attainment for the 8 hour NAAQS. Both types of areas are provided with the option of achieving a specified increment of progress. For areas that are 8 hour NAAQS nonattainment/ 1 hour NAAQS nonattainment, we established an increment of 5 percent and for those designated attainment for the 8 hour NAAQS, we established a 3 percent increment.

In general, we believe that those areas initially designated attainment for the 8 hour NAAQS will have a less significant 8 hour problem   these areas tend to record values within a few parts per billion of the NAAQS. Thus, since the increment of progress is limited to controls not already 162 adopted into the SIP or required by federal or regional controls, the 5 percent reduction requirement would likely be excessive for purposes of addressing that small deviation from the NAAQS.

The third option available to areas that are 8 hour NAAQS nonattainment/ 1 hour NAAQS nonattainment is to submit an early 8 hour attainment demonstration. Since areas designated attainment for the 8 hour NAAQS are not required to develop attainment demonstrations, it did not make sense to carry this option over. Rather, we determined it made more sense to allow the area to address the violation in the context of the obligation that it does have, i. e., to develop a maintenance plan for the 8 hour NAAQS. Thus, for these areas, we created the option of performing a more rigorous maintenance demonstration   a demonstration based on EPA approved modeling.

( C) Comments and responses.

COMMENT: Some commenters on draft regulatory text objected to continuing the obligation for areas to submit ROP plans and/ or attainment demonstrations for the 1 hour NAAQS after the 1 hour NAAQS is revoked. Some of the comments reflected the fact that the regulatory text may have been unclear regarding what the requirement entailed and which areas were affected.

RESPONSE: We have designed the final rule such that an area 163 with an unmet planning obligation would still be required to submit and implement a rate of progress plan and an attainment demonstration ( or substitute plan) under the 1 hour NAAQS if the area violates the 8 hour NAAQS before it has an approved maintenance plan. These are areas that have historically had an ozone problem and, in general, have 8

hour design values within a few parts per billion of the 8

hour NAAQS. Once these areas have an approved 110( a)( 1)

maintenance plan with contingency measures, that plan will address future violations of the 8 hour NAAQS and the 1 hour obligations will no longer apply. However, until that plan is in place, we believe that Congress would have intended these requirements to still have significance if the area violates the health based NAAQS.

The final regulatory text was modified to clarify that the provision applies to areas that do not have approved ROP plans and/ or attainment demonstrations under the 1 hour NAAQS and that violate the 8 hour NAAQS before having an approved 8 hour maintenance plan under section 110( a)( 1).

The regulatory text also clarifies the obligation that will apply.

( v) Maintenance Plans for the 8 hour NAAQS. ( Section VI. C. 3. b( iii) of proposed rule; see 68 FR 32823; Section 51.905( a)( 3)( iii) of draft and final rules)

( A) Background 164 In the June 2003 proposal, we proposed that areas designated attainment for the 8 hour NAAQS and designated nonattainment for the 1 hour NAAQS on or after November 15,

1990, must adopt and submit a maintenance plan consistent with section 110( a)( 1) within 3 years of designation as attainment for the 8 hour NAAQS. The maintenance plan should provide for continued maintenance of the 8 hour NAAQS for 10 years following designation for the 8 hour NAAQS and must include contingency measures. Areas with approved 1 hour maintenance plans under section 175A would be able to modify those maintenance plans consistent with their obligation to have a maintenance plan for the 8 hour NAAQS under section 110( a)( 1). Such areas could remove from their maintenance SIPs ( a) the obligation to submit a maintenance plan for the 1 hour NAAQS 8 years after approval of their initial 1 hour maintenance plan; and ( b) the requirement to implement contingency measures upon a violation of the 1 hour ozone NAAQS.

The draft regulatory text reflected the description in the June 2003 proposal.

( B) Summary of final rule We are adopting the approach we proposed. However, as noted above, we have now created separate subsections in the rule addressing areas that were designated nonattainment for the 1 hour NAAQS at the time of designation for the 1 hour 165 NAAQS and areas that were maintenance areas for the 1 hour NAAQS at the time of designation for the 8 hour NAAQS.

Section 51.905( a)( 3)( iii) applies only to areas designated nonattainment for the 1 hour NAAQS at the time of designation for the 8 hour NAAQS. Section 51.905( a)( 4)( ii)

establishes the same requirement for areas that are maintenance for the 1 hour NAAQS at the time of designation for the 8 hour NAAQS. These two provisions provide that 1

hour NAAQS nonattainment/ 8 hour NAAQS attainment ( section 51.905( a)( 3)( iii)) and 8 hour NAAQS attainment/ 1 hour NAAQS maintenance ( section 51.905( a)( 4)( ii)) areas must adopt and submit a maintenance plan consistent with section 110( a)( 1)

within 3 years of designation as attainment for the 8 hour NAAQS. The maintenance plan should provide for continued maintenance of the 8 hour NAAQS for 10 years following designation for the 8 hour NAAQS and should include contingency measures. We provide additional detail below regarding maintenance areas for the 1 hour NAAQS.

Section 110( a)( 1) requires all areas to demonstrate that they will attain and maintain the relevant NAAQS. Most of the areas addressed by this provision of the regulation have historically had problems meeting and/ or remaining in attainment of the ozone NAAQS. We think it is important for States to ensure that these areas will continue to have clean air so that the health of citizens will be protected. 166 ( C) Comments and responses COMMENT: A number of commenters who addressed this issue in comments on the June 2, 2003 proposal did not support the section 110( a)( 1) maintenance plan requirement. Some commenters believed the 1 hour NAAQS should remain in effect and with it any existing 1 hour SIP requirements, including section 175A maintenance plan requirements ( which would require conformity determinations). One commenter objected to the proposed requirement, alleging the requirement was unnecessary and not required. Two commenters agreed with the requirement.

In commenting on the draft regulatory text one commenter supported this provision. One commenter recommended that we provide more specific guidance on preparation of section 110( a)( 1) maintenance plans and also not require modeling for them. Two commenters objected to maintenance plans under section 110( a)( 1) because they would not require conformity ( as would maintenance plans under section 175A) for areas that currently have maintenance plans under the 1 hour NAAQS. The commenters believed the maintenance planning should be done under section 175A.

Another commenter believed that section 110( a)( 1) of the CAA requires neither contingency measures nor a 10 year plan;

the commenter suggested that the section 110( a)( 1)

maintenance plan merely be a continuation of the provisions 167 of the existing maintenance plan.

RESPONSE: Because the 1 hour NAAQS would be revoked, the requirements of section 175A would not apply to these areas ( areas initially designated attainment for the 8 hour NAAQS but that were designated nonattainment for the 1 hour NAAQS at the time of enactment of the 1990 CAA Amendments.)

Section 175A applies to redesignations, not to initial designations. After the 1 hour NAAQS is revoked, we believe that an area that was previously designated nonattainment for the 1 hour NAAQS or was designated attainment with a maintenance plan and that initially is designated attainment for the 8 hour ozone NAAQS, should be required to demonstrate maintenance only for the 8 hour NAAQS at that point. The area was not " redesignated" attainment for the 8 hour NAAQS, and therefore the section 175A maintenance plan requirement does not apply. We believe that the section 110( a)( 1) maintenance provisions   as required in section 51.905   will provide adequate assurance of maintenance of the 8 hour NAAQS. The EPA always retains the authority to require a State that fails to maintain the NAAQS to revise its SIP to provide additional maintenance measures or to redesignate the area nonattainment and require an attainment demonstration.

We do not agree with commenters that opposed a provision requiring a maintenance plan under section 168 110( a)( 1) for these areas. We believe that the CAA requires that SIPs continue to provide for maintenance of the applicable NAAQS under section 110( a)( 1). Because these areas have historically experienced ozone problems and generally are close to violating the 8 hour NAAQS, we believe it is prudent to require a demonstration of how they will maintain the 8 hour NAAQS. We think this requirement will benefit citizens by providing better assurance that the air will remain clean and will benefit industry by minimizing the likelihood the area will violate the standard and be redesignated to nonattainment.

f. Section 51.905( a)( 4): 8 Hour NAAQS Attainment/ 1 Hour NAAQS Maintenance As noted above, in the preamble to the proposed rule,

EPA addressed in the same section 1 hour nonattainment areas and 1 hour maintenance areas that are designated nonattainment for the 8 hour NAAQS. Comments on the proposed regulatory text noted that section 51.905( a)( 3)

only addressed 8 hour attainment areas that were designated nonattainment for the 1 hour ozone NAAQS and not areas that were maintenance for that NAAQS. Thus, the draft rule did not address all aspects of the proposal since it did not include provisions for areas that are maintenance for the 1

hour NAAQS at the time of designations.

We considered revising paragraph 51.905( a)( 3) to 169 include 1 hour maintenance areas. However, that subsection included certain requirements not relevant for 1 hour maintenance areas, such as requirements concerning outstanding attainment demonstration and ROP plans. Thus,

in the final rule, we created section 51.905( a)( 4) to apply to areas designated attainment for the 8 hour NAAQS and that were maintenance areas for the 1 hour NAAQS at the time of designation for the 8 hour NAAQS.

( i) Obligations in an approved SIP. ( 51.905( a)( 4)( i)).

This subsection is identical in structure to section 51.905( a)( 3)( i). Our reasons are explained in our discussion of section 51.905( a)( 3)( i), above.

( ii) Maintenance plan. ( 51.905( a)( 4)( ii). As provided above in the discussion of section 51.905( a)( 3)( iii), we are adopting in our final rule our proposed interpretation regarding maintenance plans for areas designated nonattainment for the 1 hour NAAQS on or after November 15, 1990 ( i. e., areas that remain designated nonattainment for the 1 hour NAAQS as well as maintenance areas for the 1 hour NAAQS at the time of designation for the 8 hour NAAQS). Specifically, these areas must adopt a maintenance plan under section 110( a)( 1) within 3 years of designation for the 8 hour NAAQS. The provision for maintenance areas is the same as for areas designated nonattainment for the 1 hour NAAQS. However, for 170 maintenance areas, section 51.905( e), discussed below,

cross references this provision and addresses the relationship between the existing 1 hour maintenance plan and the 8 hour maintenance plan.

Our reasons for adopting this provision are discussed above. Although these areas already have maintenance plans,

those plans only address maintenance of the 1 hour NAAQS.

It is important for these areas to ensure that they have a plan addressing maintenance of the 8 hour NAAQS. These areas may evaluate their existing plan and demonstrate how it will ensure maintenance of the 8 hour NAAQS, or may modify their existing plan, or may adopt a new plan, as appropriate.

COMMENT: One commenter argued that it makes little sense to require the State to continue to expend the effort and resources to update and extend these maintenance plans. The commenter questioned why a newly designated marginal area under the 8 hour NAAQS should be exempt from implementation plan requirements, while an area previously nonattainment for the 1 hour NAAQS, but now in attainment for both NAAQS,

should be required to continue with 8 additional years of maintenance plan requirements.

RESPONSE: The final rule ( section 51.905( a)( 4)) clarifies that these areas ( areas that are initially designated attainment for the 8 hour NAAQS but were attainment areas 171 under the 1 hour NAAQS with approved maintenance plans) are relieved of the requirement to update their maintenance plan under section 175( A), but must submit a maintenance plan under section 110( a)( 1) that provides for maintenance for 10 years. It should be noted that marginal areas under the 8

hour NAAQS are not " exempt" from implementation plan requirements; they are still subject to nonattainment new source review and conformity requirements, for instance.

Furthermore, if a marginal area does not attain the NAAQS by its attainment date, the CAA requires that the area be bumped up in classification, which would require the area to submit a revised SIP with an attainment demonstration and control measures required under subpart 2 for the area's new classification. In addition, once the area attains the 8

hour NAAQS, it will be subject to the more stringent maintenance plan provision in section 175A, which requires the areas to demonstrate maintenance for 20 years.

3. For how long do these obligations continue to apply?

( Section VI. C. 4 of proposed rule; see 68 FR 32824; section 51.905( b) of draft and final rules)

a. Background. In the June 2, 2003 proposed rule, we proposed two options for when the State would no longer be required to continue implementing SIP approved control obligations required for an area's 1 hour classification.

At that time, these requirements could be relegated to the 172 contingency measures portion of the SIP if the State demonstrated that implementation of the controls was not necessary to attain or maintain the 8 hour NAAQS ( consistent with section 110( l)). For simplification, we refer to this as the time control obligations may be shifted to the contingency measures. We clarified that the term " control obligations" was intended to refer to the obligations which we determined would continue to apply under the preceding sections of the proposal, including the NOx transport rules.

Under Option 1, control obligations could be shifted to contingency measures when the area achieves the level of the 1 hour ozone NAAQS ( even if the area has not yet attained the 8 hour NAAQS). Under Option 2, control obligations could be shifted to contingency measures once the area attains and is redesignated to attainment for the 8 hour NAAQS ( regardless of when, if ever, the area attains the 1 hour NAAQS). The draft regulatory text was developed using Option 1 ( when the area achieves the level of the 1

hour ozone NAAQS).

b. Summary of final rule. We are adopting Option 2   control obligations an area is required to retain in the approved SIP for an area's 1 hour classification must continue to be implemented under the SIP until the area attains and is redesignated to attainment for the 8 hour NAAQS. At that time, the State may relegate such controls 173 to the contingency measure portion of the SIP if the State demonstrates in accordance with section 110( l) that doing so will not interfere with maintenance of the 8 hour NAAQS or any other applicable requirement of the CAA. If at the time the area is redesignated to attainment for the 8 hour NAAQS the State has an outstanding obligation to adopt a control requirement under the 1 hour NAAQS, it remains obligated to do so, but may adopt it as a contingency measure. As discussed above, under EPA's Clean Data Policy, certain obligations such as the requirement to submit ROP plans and attainment demonstrations may be suspended based on a determination that the area has attained the 8 hour NAAQS and will no longer apply if the area is redesignated to attainment. However, if an area experiences a violation of the 8 hour NAAQS prior to being redesignated to attainment the requirements would once again apply.

We are adopting this option because, as noted in the June 2, 2003 proposal, the 8 hour NAAQS is the NAAQS that we have determined will protect public health and the environment. Only once an area demonstrates it has met and can maintain the health protective NAAQS do we believe it will be appropriate to shift these obligations to the contingency measures portion of the SIP. This scheme is consistent with what Congress intended. The CAA 174 contemplates under subpart 2 that States must implement certain mandated requirements. Under the maintenance plan provision of the CAA ( section 175A), such requirements may be shifted to the contingency measure portion of the SIP upon or after redesignation to attainment. Since the relevant NAAQS is now the 8 hour NAAQS, we believe it is appropriate to require these mandated controls to remain as part of the implemented SIP until an area attains the 8 hour NAAQS and is redesignated to attainment. On or after that date, a State may move such obligation to the contingency measures portion of the SIP consistent with sections 175A and 110( l). Moreover, we believe it is appropriate to use attainment of the 8 hour NAAQS rather than attainment of the 1 hour NAAQS because, as provided elsewhere in this rulemaking, EPA will no longer be making determinations of whether an area has attained the 1 hour NAAQS and areas will not be required to demonstrate attainment or maintenance of the 1 hour NAAQS. Some areas may never attain the 1 hour NAAQS, as there will be no obligation to do so once it is revoked.

The final rule covers the continued applicability of the NOx transport rules under section 51.905( f), rather than as an " applicable requirement" for purposes of section 110( l) because the NOx rules apply regardless of an area's attainment or nonattainment status for the 8 hour ( or the 1 175 hour) NAAQS.

c. Comments and responses COMMENT: Of the few commenters who addressed this issue in response to the June 2, 2003 proposal, several favored Option 1, and several favored Option 2. Of those who commented on the draft regulatory text, one commenter opposed the provision, and one comment was unclear as to the commenter's concerns. One other commenter supported the provision. Several commenters had clarifying questions.

RESPONSE: Our rationale for the choice of Option 2 is presented above. A more detailed response to these and other comments appears in the RTC document.

4. Which portions of an area designated for the 8 hour NAAQS remain subject to the 1 hour NAAQS obligations?

( Section VI. C. 2 and 3 of proposal; see 68 FR 32820 32821;

51.905( c) of the draft and final rules)

a. Background. In the June 2, 2003 notice, we proposed that the obligation to retain or to adopt and retain a mandatory control obligation applies only to the part of the 8 hour ozone nonattainment area that was designated nonattainment for the 1 hour ozone NAAQS. The proposal also provided an example of how this would work.

The draft regulatory text provided additional specificity concerning geographic applicability of the antibacksliding provisions. The draft text provided that with 176 two exceptions only the portion of the designated area for the 8 hour NAAQS that was required to adopt the applicable requirements in 51.900( f) for purposes of the 1 hour NAAQS is subject to the obligations identified in paragraph ( a) of this section with several exceptions. The first exception is an area that is designated nonattainment for the 8 hour NAAQS but that was nonattainment for the 1 hour NAAQS with an unmet obligation to submit an attainment demonstration;

for these areas, the draft regulatory text provided that the entire area designated nonattainment for the 8 hour ozone NAAQS would be subject to the 10 percent advance increment of reduction. The second exception is an area that is attainment for the 8 hour NAAQS but that was nonattainment under the 1 hour NAAQS with an unmet obligation to submit an attainment demonstration; for these areas, the 110( l)

maintenance plan would have to demonstrate maintenance for the entire 8 hour ozone attainment area.

b. Summary of final rule. The final rule incorporates most aspects of the approach as that contained in the proposal and in the draft regulatory text. The final rule provides that only the portion of the designated area for the 8 hour NAAQS that was designated nonattainment for the 1 hour NAAQS is required to comply with the obligations in subparagraph 51.905( a), except if the State elects to provide an early increment of progress or an early 8 hour attainment 177 demonstration in lieu of an outstanding 1 hour attainment demonstration ( for an 8 hour NAAQS nonattainment area/ 1 hour NAAQS nonattainment area under 51.905( a)( 1)( ii)( B) and ( C)),

the increment of progress or early 8 hour attainment plan must apply for purposes of the entire 8 hour nonattainment area.

The final rule does not follow the approach in the proposal for the maintenance plan requirement for 8 hour attainment areas. The maintenance plans required under section 51.905( a)( 3)( iii) and ( 4)( ii) must demonstrate maintenance only for the area designated nonattainment for the 1 hour NAAQS at the time of designation of the 8 hour NAAQS. We received comment that recommended this obligation apply only to the area that was originally designated nonattainment for the 1 hour NAAQS. After considering this comment and our discussion in the preamble to the proposed rule, we agree with the commenter. In many States,

attainment areas are identified county by county rather than identifying a group of counties as an attainment area.

Thus, a State may have one or more groups of counties listed as a nonattainment area and then the remaining counties in the State are each identified individually as " attainment."

See e. g., 40 CFR 81.311 ( Georgia); 81.329 ( Nevada). Because the area that historically had a problem attaining the ozone NAAQS is the area that was previously designated 178 nonattainment for the 1 hour NAAQS, we believe it makes the most sense to require the maintenance plan for the area previously designated nonattainment for the 1 hour NAAQS.

We will set forth in 40 CFR Part 81, Subpart E, an identification of the boundaries of areas and the area designations and classifications for the 1 hour NAAQS at the time of the 8 hour designations.

c. Comments and responses COMMENTS ON JUNE 2, 2003 PROPOSAL: With regard to limiting the applicability of 1 hour obligations to that portion of the 8 hour nonattainment area that was also part of the 1

hour nonattainment area, one commenter supports this policy,

especially for the enhanced I/ M program. The commenter believes that the environmental benefit of requiring an extension of the enhanced I/ M program to areas recently added to the CMSA and designated nonattainment for the 8

hour NAAQS to be minimal, costly, and disruptive of the continued implementation of the enhanced I/ M program in the current 1 hour nonattainment area.

One commenter objected to requiring the substitute planning requirement ( 10 percent advance increment of emission reductions) that applies to areas with an outstanding attainment demonstration for the entire 8 hour ozone nonattainment area. Instead, the commenter recommended it should only apply to the 1 hour nonattainment 179 area.

RESPONSE: The final rule provides for retaining applicable emission control requirements for an area's 1 hour classification in only the original 1 hour nonattainment area.

As noted in the final rulemaking notice, we are now allowing the State to meet its unmet 1 hour attainment demonstration obligation by submitting the outstanding attainment demonstration or by taking one of two early actions for 8 hour planning: achieve a 5 percent advance increment of emission reductions or submit an early 8 hour attainment demonstration. The advance increment of emission reductions is applied throughout the entire 8 hour nonattainment area because, although it is being submitted in lieu of the 1 hour requirement, it is intended to address the 8 hour nonattainment problem. Similarly, the 8 hour attainment demonstration is intended to address attainment for the full 8 hour area. Because these alternatives to the 1 hour attainment demonstration are intended to address attainment and progress toward the 8 hour NAAQS, the State would need to apply these requirements, if selected, to the entire 8 hour nonattainment area. We developed these alternatives in response to concerns that areas focus on the 8 hour NAAQS rather than on the 1 hour NAAQS and that continued planning obligations for the 1 hour NAAQS would 180 burden State resources. States still have the flexibility to choose to develop the 1 hour attainment demonstrations for the 1 hour area if they would like to restrict the unmet planning obligation to the old area.

5. What obligations that applied for the 1 hour NAAQS will no longer apply after revocation of the 1 hour NAAQS for an area? ( Section VI. C. 3. d. of proposal; see 68 FR 32824;

Section 51.905( e) of proposed and final rules)

a. Background In the June 2, 2003 proposed rule ( 68 FR 328224), we proposed that once the 1 hour NAAQS is revoked,

EPA would no longer make findings of failure to attain that NAAQS and, therefore, we would not reclassify areas based upon a finding that the area failed to attain the 1 hour NAAQS. We indicated areas should focus their resources on attainment of the 8 hour NAAQS and stated that we believed it would be counterproductive to establish new obligations for States with respect to the 1 hour NAAQS after they have begun planning for the 8 hour NAAQS. In addition, we noted that the attainment dates for areas classified as marginal,

moderate and serious had passed and that the CAA does not provide for reclassification of severe areas. We also noted other mechanisms that are available to make sure that States continue to make progress toward attaining the 8 hour NAAQS.

In addition, we indicated that conformity requirements would no longer apply for the 1 hour NAAQS once the NAAQS is 181 revoked. The June 2, 2003 proposal explains that, under section 176( c) of the CAA, conformity applies to areas designated nonattainment or subject to the requirement to develop a maintenance plan pursuant to section 175A. Once the 1 hour NAAQS is revoked, areas would no longer be designated nonattainment for the 1 hour NAAQS or subject to the obligation to develop a maintenance plan under section 175A for the 1 hour NAAQS and thus would no longer be subject to the obligation to demonstrate conformity ( either transportation conformity or general conformity) for that NAAQS.

The draft regulatory text incorporated these concepts and also provided that, at the time of revocation of the 1

hour NAAQS, any provisions of applicable SIPs that require conformity determinations in such areas for the 1 hour NAAQS will no longer be enforceable as a matter of law pursuant to section 176( c)( 5) of the CAA.

Additionally, the draft regulatory text reflected the discussion in the preamble to the proposed rule regarding what portions of a 1 hour maintenance plan could be revised or removed once the 1 hour NAAQS was revoked ( 68 FR 32823).

The draft regulatory text provided that areas with approved 1 hour maintenance plans could modify those plans to remove the obligation to submit a maintenance plan for the 1 hour NAAQS eight years after approval of the initial 1 hour 182 maintenance plan and to remove the obligation to implement contingency measures upon a violation of the 1 hour NAAQS.

The draft regulatory text provided, however, that these requirements would remain enforceable until EPA approved a SIP removing or revising them and also provided that EPA would not approve such revisions until EPA approves an 8

hour attainment demonstration for an area designated nonattainment for the 8 hour NAAQS or an 8 hour maintenance plan for an area designated attainment for the 8 hour NAAQS.

Finally, EPA noted that such a SIP revision must also be consistent with sections 110( l) and 193 of the CAA.

b. Summary of final rule We are adopting the approach we set forth in our proposed rule and providing clarification regarding the penalty obligations under sections 181( b)( 4) and 185A of the CAA that apply in severe areas that do not attain the 1 hour NAAQS by the applicable attainment date. The final rule provides that as of the effective date of revocation of the 1 hour NAAQS:

We will no longer make findings of failure to attain the 1 hour NAAQS and, therefore, ( a) we will not reclassify areas to a higher classification for the 1

hour NAAQS based on such a finding, and ( b) areas that were classified as severe for the 1 hour NAAQS are not obligated to impose fees as provided under sections 183 181( b)( 4) and 185A of the CAA.

Areas will not be obligated to continue to demonstrate conformity for the 1 hour NAAQS as of the effective date of the revocation of the 1 hour NAAQS.

An area with an approved 1 hour maintenance plan under section 175A of the CAA may modify its maintenance plan to: ( 1) remove the planning obligation to develop the second 10 year maintenance plan for the 1 hour NAAQS;

and, ( 2) replace the existing 1 hour contingency measure trigger with an 8 hour value. However, before the EPA can consider approving such a revision, certain conditions must be met. If the area is designated nonattainment for the 8 hour ozone NAAQS, it must first have an approved 8 hour attainment demonstration in place. If the area has been designated as attainment for the 8 hour ozone NAAQS, it must first have an approved section 110( a)( 1) maintenance plan in place for the 8 hour NAAQS.

NSR under the 1 hour NAAQS will no longer apply in areas that are 8 Hour NAAQS nonattainment/ 1 Hour NAAQS nonattainment.

Each of these provisions is discussed further below.

( i) Findings of Failure to Attain the 1 hour NAAQS.

We continue to believe, as stated in the preamble to the proposed rule, that areas should focus their resources on 184 attainment of the 8 hour NAAQS and that it would be counterproductive to establish new obligations for States with respect to the 1 hour NAAQS after they have begun planning for the 8 hour NAAQS. Moreover, we do not believe there is a basis to determine whether an area has met the 1

hour NAAQS once that NAAQS no longer applies; once the 1

hour NAAQS is revoked, there will not be an applicable attainment date with which to make a determination as to whether an area has met its attainment date or not. Since the obligations to reclassify areas and impose fees are based on a determination that an area has failed to meet the NAAQS by the appropriate attainment date, those obligations also would no longer apply for the 1 hour NAAQS once the 1

hour NAAQS has been revoked.

While we did not specifically state in our proposal that severe areas would no longer be obligated to impose fees under sections 181( b)( 4) and 185A based on a failure to attain the 1 hour NAAQS after the effective date of the revocation of the 1 hour NAAQS, it is a logical extension of our proposal as that obligation is triggered by a finding of failure to attain. In addition, this is consistent with Appendix B of the June 2, 2003 proposal, which did not identify the section 185A fee provision as an applicable requirement.

( ii) Conformity under the 1 hour NAAQS. Regarding 185 conformity, we are adopting the approach we set forth in our proposed rule( 68 FR 32823). The final rule provides that,

upon revocation of the 1 hour NAAQS for an area, conformity determinations will no longer be required for the 1 hour NAAQS. At that time, any provisions of applicable SIPs that require conformity determinations for the 1 hour NAAQS in such areas will no longer be enforceable pursuant to section 176( c)( 5) of the CAA.