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Approval and Promulgation of Maintenance Plan and Designation of Area for Air Quality Planning Purposes for Carbon Monoxide; State of Arizona


Final Rule.


EPA is taking final action to redesignate the Tucson Air Planning Area (TAPA) to attainment for the carbon monoxide (CO) National Ambient Air Quality Standard (NAAQS) and to approve a maintenance plan that will insure that the area remains in attainment.


Table of Contents Back to Top

Tables Back to Top


This action is effective on July 10, 2000.

ADDRESSES: Back to Top

Copies of the state submittal and other information are available for public inspection at EPA's Region IX office during normal business hours, 75 Hawthorne Street, San Francisco, CA 94105-3901.

The technical support document (TSD) and copies of other documents relevant to this action can be found in the docket for this proposal. The docket can be reviewed or copied during normal business hours at the following locations between 8:00 a.m. and 4:30 p.m. on weekdays. You may need to pay a fee for copying. Copies of the SIP submittal are also available for inspection at the following address: Pima County Department of Environmental Quality, 130 West Congress, Tucson, Arizona 85701, (520) 740-3340.

Electronic Availability Back to Top

This document is also available as an electronic file on EPA's Region 9 Web Page at


Eleanor Kaplan, Air Planning Office (AIR-2), Air Division, U.S. Environmental Protection Agency, Region IX, 75 Hawthorne Street, San Francisco, CA 94105-3901, (415) 744-1159, email:


I. Background Back to Top

On October 6, 1997 Arizona submitted a request to redesignate the CO Tucson Air Planning Area (TAPA) nonattainment area to attainment for the NAAQS and for approval of a maintenance plan. EPA found that the TAPA met all the redesignation requirements specified in section 107(d)(3)(E) of the Clean Air Act (CAA) and also that the TAPA was eligible to use the Limited Maintenance Plan (LMP) option provided for in EPA guidance. [1] EPA therefore proposed approval of the request and the maintenance plan on July 22, 1998 (see 63 FR 39258) and provided for a 30-day public comment period.

For a full discussion of EPA's evaluation of the TAPA redesignation request and the maintenance plan, the reader is referred to the original EPA proposal (63 FR 39258, July 22, 1998) and to the Technical Support Document (TSD) accompanying that proposal notice which may be found in the docket on file at the addresses noted above.

EPA received one set of comments during the 30-day comment period provided under the original proposal. Those comments came from the Arizona Center for Law in the Public Interest (ACLPI) in a letter dated August 21, 1998. To respond to the public comments, EPA requested supplementary information from the Pima Association of Governments (PAG) relating to CO emissions projections for the area for the 10-year maintenance period extending through 2010. EPA received the information in a letter from PAG dated June 18, 1999. EPA is responding to ACLPI's comments in section II below. On December 17, 1999 (see 64 FR 70660) EPA reproposed to approve the TAPA redesignation request in order to provide the public with the opportunity to comment on the additional information provided by PAG and on additional issues that had arisen since the original proposal. EPA received no public comments during the 30-day public comment period provided under the reproposal.

II. Public Comment and EPA Responses Back to Top

EPA has considered all of the comments received from ACLPI on the original proposal and is providing the following responses.

Comment: ACLPI expressed concern that one of the CAA's requirements for redesignation, namely that the improvement in air quality is due to permanent and enforceable reductions, would not be met by the TAPA following redesignation because several Arizona statutes, including the state's auto emission inspection and maintenance program, the oxygenated fuels program and other control measures defined Tucson as “Area B”, a carbon monoxide nonattainment area. ACLPI expressed concern that the area, following redesignation, would no longer be subject to these control measures and said that under the circumstances EPA cannot conclude that the emission reductions from these programs are permanent and enforceable.

Response: The Arizona legislature has acted to amend various Arizona Statutes to expand the definition of Area B to include CO maintenance areas. On May 18, 1999 Arizona Governor Hull signed into law House Bill 2189 which amended Arizona statutes 41-796.01, 41-2121, 49-401.01, 49-402, 49-404, 49-454, 49-541 and 49-571 to ensure continued implementation of committed SIP control measures in maintenance areas.

All of these statutory amendments have been submitted as SIP revisions and EPA in this notice is approving those SIP revisions. On the basis of these statutory amendments, EPA believes that this comment has been adequately addressed.

Comment: ACLPI questioned whether the assumption in the LMP option that an area beginning the maintenance period at or below 85% of exceedance levels will continue to meet the standard for another ten years is applicable to the TAPA, given the growth that is projected for the area.

ACLPI also questioned the LMP guidance waiver of the CAA's requirement for a 10 year maintenance demonstration and also the fact that under a LMP an emissions budget may be treated as essentially not constraining for the length of the maintenance period. ACLPI made the following arguments:

  • With regard to the LMP's waiver of the maintenance demonstration, the mere fact that air quality and CO emissions are at or below 85% of exceedance levels does not assure that they will not increase to above exceedance levels in less than 10 years.
  • The fact that under the LMP there is no emissions budget test for conformity purposes flagrantly violates EPA's own conformity rules which explicitly apply the emission budget test to all maintenance areas. There is no exception for areas that are at or below 85% of exceedance levels and EPA cannot amend or repeal rules with a guidance document.
  • There is no factual or scientific basis for presuming that a motor vehicle emissions budget will not be constraining in a limited maintenance area. The potential for emissions growth has nothing to do with existing CO levels, but is driven by factors such as growth in vehicle miles traveled (VMT), increases in vehicle trips and increased congestion. In the Tucson area, VMT is almost doubling every 20 years, and congestion is expected to significantly worsen. Continued application of conformity rules is vital to ensuring that transportation plans, programs and projects, and federal activities, are consistent with maintenance of CO standards.

Response: The additional information provided by PAG included projections extending to 2010 and 2020 for CO mobile source emissions, vehicle miles traveled (VMT) and population growth, as well as information on ambient air CO concentrations for the years 1990 through 1998. That information is contained in Tables 1 and 2 below. The full text of the PAG letter and details on the sources used for these projections are in the TSD accompanying the reproposal notice, which may be found in the docket for this document.

TABLE 1.—PAG Projections for CO Mobile Emissions and VMT Back to Top
Year (Population) CO Mobile Emissions (tpd) VMT Population
1990 444.8 15,491,995 666,880
1995 17,915,850 766,172
1999 (2000) 325.8 20,243,419 854,329
2003 (2005) 325.1 22,873,378 943,795
2010 367.2 27,286,950 1,031,623
2020 428.7 32,760,981 1,206,244
TABLE 2.—Ambient Air Concentrations—1990-1998 Back to Top
Year Ambient air concentration
1990 6.5
1991 5.7
1992 5.8
1993 6.0
1994 5.5
1995 5.9
1996 5.1
1997 4.4
1998 4.0

EPA has reviewed the additional information provided by PAG and, based on that data, has come to the following conclusions:

  • Although there are projected increases in population and vehicle miles traveled (VMT), the data indicates that CO emissions will drop from 444.8 tons per day in 1990 to 367.2 in 2010, rising again to a projected 428.7 tons per day in 2020 which is still below 1990 levels. In summary, despite the projected growth in population and VMT, CO mobile source emissions in the TAPA will continue to decrease. The decrease in projected CO emissions can be attributed to existing control measures and the impacts of other programs that were not included in the Mobile model used by PAG in preparing these projections including the Pima Travel Reduction, Rideshare and Traffic Signal Coordination programs. In addition it may be anticipated that national mobile source control programs that will take effect in the future will play a role in reducing CO emissions from mobile sources.
  • According to data contained in Table 2, the design value for the Tucson area for 1993-1995 was 6.0 or 67% of the NAAQs standard for CO. The design value is the second highest eight-hour concentration observed at any site in the area. The data also indicated that the design value for the years 1996 through 1998 dropped to 5.1 or 57% of CO NAAQS. EPA believes that these design values provide an ample margin of safety and time to take action in the event of a possible violation of the CO NAAQS in the future.
  • EPA reviewed the projected CO mobile source emissions, VMT and population values and the corresponding design values for the years 1990 through 1999 and concluded that it would be reasonable to assume that the future relationship of these four elements would be comparable through 2010.
  • The control measures contained in the TAPA maintenance plan are currently mandated by federal and state statutes and are permanent and enforceable. They include the Federal Motor Vehicle Control program, the State Inspection and Maintenance program and the State Oxyfuels program. The Arizona legislature has amended the statutes that had defined Tucson as a nonattainment area to ensure continued implementation of SIP control measures following redesignation to attainment. In addition, the Arizona legislature has amended the statutes pertaining to the State's Vehicle Emission and Inspection Program (VEIP) to assure continuation of the program through December 31, 2008. With regard to the VEIP sunset date of 2008, which is two years short of the ten-year maintenance period, in a letter to EPA dated August 23, 1998, the Arizona Department of Environmental Quality (ADEQ) states that Arizona Revised Statutes 41-2955 limits to ten years the existence of a program before it undergoes a sunset review and therefore the VEIP has been extended for the maximum time allowed under this statute, i.e., ten years. The letter supplies a recent history of legislative changes to the VEIP, concluding that “The VEIP has consistently received support for necessary program updates from the Legislature.” EPA therefore believes that on the basis of this legislative history, it is reasonable to assume that the program will be extended when it expires in 2008. The full text of the letter from ADEQ is attached to the TSD accompanying the reproposal.
  • The maintenance plan for the TAPA contains a pre-violation action level trigger which would set in motion a process designed to forestall a future violation of the CO NAAQS. Under the plan, a pre-violation action level would be reached when two verified 8-hour average concentrations in excess of 85% of the CO NAAQS occurred at any one monitor site in any CO season. When this criterion is reached, it would trigger field studies and technical evaluations and recommendations for implementation of contingency measures.
  • With regard to the ACLPI's comments that: (1) The LMP policy flagrantly violates EPA's own conformity rules which explicitly apply the emission budget test to all maintenance areas; and (2) that the rule does not provide an exception for areas that are at or below 85% of exceedance levels, EPA's conformity policy has clearly provided for opportunities for a SIP to demonstrate that no budget is needed (see Transportation Conformity Rule, 61 FR 36118, July 9, 1996, paragraph B, finalized on August 15, 1997, 62 FR 43780). This section addresses this question and mentions limited maintenance plans specifically. The policy states that areas must meet budgets that the SIP identifies, but if the SIP adequately justifies that no budget is necessary, then no regional emissions test is necessary.

Comment: ACLPI contends that under section 175(A)(a) of the CAA a maintenance plan must “provide for” and “ensure” maintenance for at least 10 years. ACLPI said that EPA's LMP is based on mere speculation and neither provides for, nor ensures, maintenance for ten years and is therefore contrary to the CAA.

Response: The LMP guidance provides the rationale for the policy. It states that “EPA believes it is justifiable and appropriate to apply a different set of maintenance plan requirements to nonclassifiable CO nonattainment areas whose monitored air quality is equal to or less than 85% of exceedance levels of the CO NAAQs. The EPA does not believe that the full maintenance plan requirements need be applied to these areas because they have achieved air quality levels well below the standard without the application of control measures required by the Act for moderate and serious nonattainment areas. Also, these areas do not have either a recent history of monitored violations of the CO NAAQS or a long prior history of monitored air quality problems. EPA believes that the continued applicability of prevention of significant deterioration (PSD) requirements, any control measures already in the SIP, and Federal measures (such as the Federal motor vehicle control program) should provide adequate assurance of maintenance for these areas.”

EPA therefore believes that the LMP guidance considered the requirements of 175(A)(a) of the CAA, and interpreted those requirements in a manner consistent with the Act.

Comment: ACLPI expressed concern over the lack of clear commitments to address actual violations of the CO standards. According to ACLPI, the plan notes that state law gives ADEQ the option of reducing fuel volatility levels and raising fuel oxygen content, but there is no clear commitment from the state to take either of these steps if a violation occurs. The plan also lists various potential control measures that might be adopted to address future CO violations, but does not commit to any of them.

ACLPI asked EPA to seek clarification from the state and PAG that they are committed to adopt whatever additional controls are necessary to correct an actual violation, and to implement such controls by the start of the next CO season after the violation occurs. ACLPI claimed that without such clarification the plan will not satisfy the requirements of section 175A(d) to assure that any CO violation will be promptly corrected.

Response: As requested, EPA sought clarification from PAG as to whether they are committed to adopt whatever additional controls are necessary to correct an actual violation of the CO NAAQS, and to implement such controls by the start of the next CO season after the violation occurs. The following is a summary of the points made in the PAG response, dated November 19, 1998. The full text is contained in the TSD accompanying the reproposal notice.

  • The TAPA CO LMP was designed to set evaluation triggers at a point where any violation of the CO NAAQS could be anticipated at least 5 years ahead of time. This would give enough time to fully evaluate the risk of violation and the best control measures to address any projected violations of the standard.
  • The TAPA CO LMP provides that in the event of an exceedance (which must always precede a violation) the evaluation and implementation process described in the Plan will be triggered. The most likely control measure for immediate response is high oxygen requirement in the oxyfuels program that can be implemented no later than the following CO season.
  • The TAPA plan provides that if the PAG finding indicates a probable violation of the CO NAAQS within 5 years, the recommended control measures to fully mitigate the projected violation must be initiated by the start of the next CO season after the violation occurs. EPA believes that the clarification of this issue provided by PAG is an adequate response to the ACLPI comment.

In summary, EPA considered the population growth and CO emissions projections provided by the PAG and the summary of the area's design values over the past few years and believes that the data, in conjunction with the pre-violation action triggers and the contingency measures provided for in the TAPA maintenance plan, provide reasonable assurance that the area will not violate the CO NAAQS during the maintenance period. EPA is therefore taking final action to approve the redesignation of the TAPA to attainment for the CO NAAQS and for approval of the maintenance plan on the grounds that the area meets the requirements for redesignation specified under the Clean Air Act, and that the TAPA is qualified to utilize the LMP option.

III. Summary of Final Actions Back to Top

In this action EPA is approving the following SIP revisions relating to changes that were made in various Arizona statutes:

Amendments to A.R.S. 41-2083, 41-2122 and 41-2125 relating to the State's oxyfuels program in the Tucson area both as SIP revisions and as control measures in the maintenance plan to be implemented in the event of a probable or actual violation of the CO NAAQS in the TAPA. The SIP revision for these statutory amendments were submitted to EPA as part of the TAPA maintenance plan on October 6, 1997 and were found complete by operation of law on April 6, 1998.

Amendments to A.R.S. 49-401 and 49-406 which expand the authority of State and local certified metropolitan planning organizations to develop plans and to implement and enforce control measures for attainment as well as maintenance areas as required by section 110(a)(2)(E) of the CAA. Previous to those statutory amendments, those statutes referred only to nonattainment areas. These amendments were signed into law on May 29, 1998. They were submitted as a SIP revision on August 20, 1998 and were found complete by operation of law on February 20, 1999.

Amendments to A.R.S. 41-796.01, 41-2121, 49-401.01, 49-402, 49-404, 49-454, 49-541 and 49-571 revised the definition of the TAPA nonattainment area” to reflect continued application of all pertinent control measures in the TAPA following redesignation to attainment. Prior to these amendments, these statutes referred to the TAPA as Area B, a “carbon monoxide nonattainment area”. These amendments were signed into law on May 18, 1999. SIP revisions containing these statutory amendments were submitted to EPA on September 1, 1999 and were found to be complete on October 20, 1999.

Amendments to A.R.S. 41-3009.01, 49-541.01, 49-542, 49-545, 49-557, 49-573, 41-803, and 41-401.01 which were signed into law on May 18, 1999 relate to the continued implementation of the State's Vehicle Emissions Inspection Program (VEIP) through December 31, 2008. The SIP revisions containing these statutory amendments were submitted to EPA on September 1, 1999 and were found to be complete on October 20, 1999.

EPA is approving the Emissions Inventory for the base year 1994 contained in the LMP as meeting the requirements of section 172(c)(3) of the CAA.

EPA is approving the TAPA CO maintenance plan because it meets the requirements set forth in section 175A of the CAA and the requirements of the LMP option contained in EPA guidance of October 6, 1995.

EPA is taking final action to remove the Agency's disapprovals (56 FR 5459, February 11, 1991) of the attainment demonstration and contingency measures that were contained in the 1988 Arizona CO SIP revision for Pima County. Those disapprovals were based on the finding of the Ninth Circuit Court of Appeals on March 1, 1990 in Delaney vs. EPA, 898 F.2d 687, that the Arizona CO plans for Maricopa and Pima Counties did not fully comply with the Clean Air Act as amended in 1977, and with EPA guidance issued pursuant to that law. (See 46 FR 7182, January 21, 1981). In vacating EPA's 1988 approval of the Arizona plans, the court determined that they did not contain sufficient control measures to attain the CO ambient air quality standard as soon as possible. The Court did not say that the measures submitted by the State were unworthy of approval for their effect in strengthening the SIP.

EPA is taking final action to remove the attainment demonstration disapproval because the TAPA has not had an exceedance of the CO NAAQS from 1988 to the present, and, therefore, the original reason for the disapproval, namely that the plan did not contain sufficient control measures to attain the CO ambient air quality standard as soon as possible, is no longer applicable.

EPA is also taking final action to remove the disapproval of the 1988 CO plan contingency measures. That disapproval was based on non-compliance with the EPA guidance of January 21, 1981. (46 FR 7182, January 21, 1981) That guidance has since been superseded by new guidance, specifically the section on the contingency provisions for not-classified CO nonattainment areas contained in the General Preamble (See 57 FR 13535, April 16, 1992). The contingency provisions contained in the TAPA Limited Maintenance Plan are in compliance with the guidance provided both in the General Preamble and in the Limited Maintenance Plan Policy Guidance.

Finally, EPA is approving Arizona's request for the redesignation to attainment of the CO NAAQS for the Tucson Air Planning Area.

IV. Administrative Requirements Back to Top

Under Executive Order 12866 (58 FR 51735, October 4, 1993), this action is not a “significant regulatory action” and therefore is not subject to review by the Office of Management and Budget. This action merely approves state law as meeting federal requirements and imposes no additional requirements beyond those imposed by state law. Accordingly, the Administrator certifies that this rule will not have a significant economic impact on a substantial number of small entities under the Regulatory Flexibility Act (5 U.S.C. 601 et seq.). Because this rule approves pre-existing requirements under state law and does not impose any additional enforceable duty beyond that required by state law, it does not contain any unfunded mandate or significantly or uniquely affect small governments, as described in the Unfunded Mandates Reform Act of 1995 (Public Law 104-4). For the same reason, this rule also does not significantly or uniquely affect the communities of tribal governments, as specified by Executive Order 13084 (63 FR 27655, May 10, 1998). This rule will not have substantial direct effects on the States, on the relationship between the national government and the States, or on the distribution of power and responsibilities among the various levels of government, as specified in Executive Order 13132 (64 FR 43255, August 10, 1999), because it merely approves a state rule implementing a federal standard, and does not alter the relationship or the distribution of power and responsibilities established in the Clean Air Act. This rule also is not subject to Executive Order 13045 (62 FR 19885, April 23, 1997), because it is not economically significant.

In reviewing SIP submissions, EPA's role is to approve state choices, provided that they meet the criteria of the Clean Air Act. In this context, in the absence of a prior existing requirement for the State to use voluntary consensus standards (VCS), EPA has no authority to disapprove a SIP submission for failure to use VCS. It would thus be inconsistent with applicable law for EPA, when it reviews a SIP submission, to use VCS in place of a SIP submission that otherwise satisfies the provisions of the Clean Air Act. Thus, the requirements of section 12(d) of the National Technology Transfer and Advancement Act of 1995 (15 U.S.C. 272 note) do not apply. As required by section 3 of Executive Order 12988 (61 FR 4729, February 7, 1996), in issuing this rule, EPA has taken the necessary steps to eliminate drafting errors and ambiguity, minimize potential litigation, and provide a clear legal standard for affected conduct. EPA has complied with Executive Order 12630 (53 FR 8859, March 15, 1988) by examining the takings implications of the rule in accordance with the “Attorney General's Supplemental Guidelines for the Evaluation of Risk and Avoidance of Unanticipated Takings” issued under the executive order. This rule does not impose an information collection burden under the provisions of the Paperwork Reduction Act of 1995 (44 U.S.C. 3501 et seq.).

The Congressional Review Act, 5 U.S.C. 801 et seq., as added by the Small Business Regulatory Enforcement Fairness Act of 1996, generally provides that before a rule may take effect, the agency promulgating the rule must submit a rule report, which includes a copy of the rule, to each House of the Congress and to the Comptroller General of the United States. EPA will submit a report containing this rule and other required information to the U.S. Senate, the U.S. House of Representatives, and the Comptroller General of the United States prior to publication of the rule in the Federal Register. A major rule cannot take effect until 60 days after it is published in the Federal Register. This action is not a “major rule” as defined by 5 U.S.C. 804(2).

Under section 307(b)(1) of the Clean Air Act, petitions for judicial review of this action must be filed in the United States Court of Appeals for the appropriate circuit by August 7, 2000. Filing a petition for reconsideration by the Administrator of this final rule does not affect the finality of this rule for the purposes of judicial review nor does it extend the time within which a petition for judicial review may be filed, and shall not postpone the effectiveness of such rule or action. This action may not be challenged later in proceedings to enforce its requirements. (See section 307(b)(2).)

List of Subjects Back to Top

Authority: Back to Top

42 U.S.C. 7401 et seq.

Dated: April 24, 2000.

Felicia Marcus,

Regional Administrator, Region IX.

begin regulatory text

Parts 52 and 81, Chapter I, Title 40 of the Code of Federal Regulations are amended as follows:

PART 52—[AMENDED] Back to Top

1.The authority citation for part 52 continues to read as follows:


42 U.S.C. 7401 et seq.

Subpart D—Arizona Back to Top

2.Section 52.120 is amended by adding paragraphs (c)(91), (c)(95), and (c)(96) to read as follows:

§ 52.120 Identification of plan.

* * * * *

(c) * * *

(91) The following amendments to the plan were submitted on October 6, 1997 by the Governor's designee.

(A) Arizona Revised Statutes.

(i) Incorporation by reference.

(1) Senate Bill 1002, Sections 26, 27 and 28: ARS 41-2083 (amended), 41-2122 (amended), 41-2125 (amended), adopted on July 18, 1996.

* * * * *

(95) The following amendments to the plan were submitted on August 11, 1998 by the Governor's designee.

(i) Incorporation by reference.

(A) Arizona Revised Statutes.

(1) Senate Bill 1427, Section 14: ARS 49-401.01 (amended) and Section 15: 49-406 (amended), approved on May 29, 1998.

* * * * *

(96) The following amendments to the plan were submitted on September 1, 1999 by the Governor's designee.

(i) Incorporation by reference.

(A) Arizona Revised Statutes.

(1) House Bill 2254, Section 1: ARS 41-3009.01 (amended); Section 2: 49-541.01 (amended); Section 3: 49-542 (amended); Section 4: 49-545 (amended); Section 5: 49-557 (amended); Section 6: 49-573 (amended), approved by the Governor on May 18, 1999.

(2) House Bill 2189, Section 3: ARS 41-796.01 (amended); Section 9: 41-2121 (amended); Section 40: 49-401.01 (amended), Section 41: 49-402 (amended); Section 42: 49-404 (amended): Section 43:49-454 (amended); Section 44: 49-541 (amended); and Section 46: 49-571 (amended), adopted on May 18, 1999

* * * * *

3.Section 52.123 is amended by removing and reserving paragraph (e)(2) and by adding paragraph (i) to read as follows:

§ 52.123 Approval Status.

* * * * *

(i) The Administrator approves the Maintenance Plan for the Tucson Air Planning Area submitted by the Arizona Department of Environmental Quality on October 6, 1997 as meeting the requirements of section 175(A) of the Clean Air Act and the requirements of EPA's Limited Maintenance Plan option. The Administrator approves the Emissions Inventory contained in the Maintenance Plan as meeting the requirements of section 172(c)(3) of the Clean Air Act.

§ 52.124 [Amended]

4.Section 52.124 is amended by removing and reserving paragraph(a)(2).

PART 81—[AMENDED] Back to Top

1.The authority citation for part 81 continues to read as follows:


42 U.S.C. 7401-7671 et seq.

2.In § 81.303, the table for Arizona-Carbon Monoxide is amended by revising the entry for “Tucson Area” to read as follows:

§ 81.303 Arizona.

* * * * *

end regulatory text
Arizona—Carbon Monoxide Back to Top
Designated area Designation Classification
Date1 Type Date1 Type
1This date is November 15, 1990, unless otherwise noted.
Tucson Area:        
Pima County (part) July 10, 2000 Attainment    
Township and Ranges as follows: T-11-12S, R12-14E; Salt River Baseline and Meridian excluding portions of the Saguaro National Monument and the Coronado National Forest        

[FR Doc. 00-13978 Filed 6-7-00; 8:45 am]


Footnotes Back to Top

1. Memorandum entitled “Limited Maintenance Plan Option for Nonclassifiable CO Nonattainment Areas”, from Joseph W. Paisie, Group Leader, Integrated Policy and Strategies Group, Office of Air Quality Planning and Standards, U.S. EPA, Research Triangle Park, North Carolina, October 6, 1995.

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