FEDERAL REGISTER
Vol. 61, No. 156
Proposed Rules

ENVIRONMENTAL PROTECTION AGENCY (EPA)
40 CFR Part 81
[NV-029-0001; FRL-5549-5]

Clean Air Act Reclassification; Nevada-Clark County Nonattainment Area; Carbon Monoxide

61 FR 41759

DATE: Monday, August 12, 1996
ACTION: Proposed rule.

SUMMARY: EPA proposes to find that the Clark County, Nevada carbon monoxide (CO) nonattainment area has met the criteria in section 186(b)(4) of the Clean Air Act (CAA): it exceeded the CO National Ambient Air Quality Standard (NAAQS) once in 1995; it has adopted and implemented the CAA required moderate nonattainment area control measures; and, it has demonstrated progress towards attaining the CO NAAQS. As a result of this finding, EPA proposes to grant a one-year extension of Clark County's moderate area attainment date from December 31, 1995 to December 31, 1996. EPA's proposed finding is based on a review of monitored air quality data for compliance with the CO NAAQS, as well as the air quality planning progress of Clark County. If EPA takes final action on this proposed finding, the Clark County CO nonattainment area will remain classified as a moderate CO nonattainment area as a result of extending the CAA mandated attainment date for one year. The intended effect of extending the attainment date is to allow Nevada and Clark County either to fully implement and strengthen current CO control measures, or to adopt additional control measures prior to the 1996-97 winter CO season in an effort to attain the CO NAAQS.

DATES: Written comments on this proposal must be received by September 11, 1996.

ADDRESSES: Written comments should be sent to:

Wallace Woo, Chief, Plans Development Section, A-2-2, U.S. Environmental Protection Agency, Region 9, 75 Hawthorne Street, San Francisco, California 94105.

The rulemaking docket for this proposal, Docket No. 96-NV-PL-001, may be inspected and copied at the following location between 8 a.m. and 4:30 p.m. on weekdays. A reasonable fee may be charged for copying parts of the docket.

U.S. Environmental Protection Agency, Region 9, Air and Toxics Division, Plans Development Section, A-2-2, 75 Hawthorne Street, San Francisco, California 94105.

Copies of the docket are also available at the State and local offices listed below:

Nevada Division of Environmental Protection, 333 West Nye Lane, Carson City, Nevada, 89710; and,

Clark County Department of Comprehensive Planning, 500 South Grand Central Parkway, Suite 3012, Las Vegas, Nevada, 89155-1741.

FOR FURTHER INFORMATION CONTACT: Jerry Wamsley, A-2-2, Air and Toxics Division, U.S. Environmental Protection Agency, Region 9, 75 Hawthorne Street, San Francisco, California 94105, (415) 744-1226.

SUPPLEMENTARY INFORMATION:

I. Background

A. CAA Requirements and EPA Actions Concerning Designation and Classifications

With enactment of the Clean Air Act Amendments of 1990, under section 107(d)(1)(C) of the Clean Air Act (CAA), each carbon monoxide (CO) area designated nonattainment prior to enactment of the 1990 Amendments was designated nonattainment by operation of law. Under section 186(a) of the CAA, each CO area designated nonattainment under section 107(d) was also classified by operation of law as either "moderate" or "serious" depending on the severity of the area's air quality problem. CO areas with design values between 9.1 and 16.4 parts per million (ppm) were classified as moderate. States containing areas that were classified as moderate nonattainment by operation of law under section 107(d) were required to submit State implementation plans (SIPs) designed to attain the CO national ambient air quality standard (NAAQS) as expeditiously as practicable but no later than December 31, 1995.

On November 6, 1991, Clark County was designated nonattainment for CO and was classified as a "high" moderate area given its design value of 14.4 ppm (See 56 FR 56694). Clark County's nonattainment designation and classification is codified at 40 CFR part 81.329. The moderate area SIP requirements are set forth in section 187(a) of the CAA and differ depending on whether the area's design value is below or above 12.7 parts per million (ppm). With its design value of 14.4 ppm, Clark County is required to meet the "high" moderate nonattainment area requirements and attain the CO NAAQS by December 31, 1995.

B. Reclassification to a Serious Nonattainment Area

EPA has the responsibility, pursuant to sections 179(c) and 186(b)(2) of the CAA, of determining within six months of the applicable attainment date, December 31, 1995, whether a moderate area has attained the CO NAAQS. Under section 186(b)(2)(A), if EPA finds that a moderate area has not attained the CO NAAQS, it is reclassified as serious by operation of law. Pursuant to section 186(b)(2)(B) of the Act, EPA must publish a notice in the Federal Register identifying areas which failed to attain the standard and therefore must be reclassified as serious by operation of law.

EPA makes attainment determinations for CO nonattainment areas based upon whether an area has two years (or eight consecutive quarters) of clean air quality data. n1 Section 179(c)(1) of the Act states that the attainment determination must be based upon an area's "air quality as of the attainment date." Consequently, EPA will determine whether an area's air quality has met the CO NAAQS by December 31, 1995 based upon the most recent two years of air quality data entered into the Aerometric Information Retrieval System (AIRS) data base.

n1 See memorandum from Sally L. Shaver, Director, Air Quality Strategies and Standards Division, EPA, to Regional Air Office Directors, entitled "Criteria for Granting Attainment Date Extensions, Making Attainment Determinations, and Determinations of Failure to Attain the NAAQS for Moderate CO Nonattainment Areas," October 23, 1995 (Shaver memorandum).

EPA determines a CO nonattainment area's air quality status in accordance with 40 CFR 50.8 and EPA policy. n2 EPA has promulgated two NAAQS for CO: an eight-hour average concentration and a one-hour average concentration. Because there were no violations of the one-hour standard in the Clark County area in 1994 and 1995, this notice addresses only the air quality status of the Clark County area with respect to the eight-hour standard. The eight-hour CO NAAQS requires that not more than one non-overlapping eight-hour average per year per monitoring site can exceed 9.0 ppm (values below 9.5 are rounded down to 9.0 and they are not considered exceedances). The second exceedance of the eight-hour CO NAAQS at a given monitoring site within the same year constitutes a violation of the CO NAAQS.

n2 See memorandum from William G. Laxton, Director, Technical Support Division, entitled "Ozone and Carbon Monoxide Design Value Calculations", June 18, 1990. See also Shaver memorandum.

C. Attainment Date Extensions

If a state does not have the two consecutive years of clean data necessary to show attainment of the NAAQS, it may apply, under section 186(a)(4) of the CAA, for a one year attainment date extension. At its discretion, EPA may grant an extension if the area has: (1) measured no more than one exceedance of the CO NAAQS at any monitoring site in the nonattainment area in the year preceding the extension year, and (2) complied with the requirements and commitments pertaining to the applicable implementation plan for the area. Under section 186(a)(4), EPA may grant up to two one year extensions if these conditions have been met.

The Administrator's authority to extend attainment dates for moderate areas is discretionary. Section 186(a)(4) of the Act provides that the Administrator "may" extend the attainment date for areas meeting the minimum requirements specified above. The provision does not dictate or compel EPA to grant extensions to such areas. Therefore, EPA will examine the moderate area's air quality planning progress and will be disinclined to grant an attainment date extension unless a State has, in substantial part, addressed its moderate area CO planning obligations. To determine if the State has substantially met these planning requirements, EPA will review the State's attainment date extension application to assess whether the State has: (1) adopted and substantially implemented control measures to satisfy the requirements for a moderate CO nonattainment area; and, (2) that reasonable further progress is being met for the area.

If the State cannot make a sufficient demonstration that the area has met the extension criteria described above and EPA determines that the area has not demonstrated attainment of the CO NAAQS, then the area will be reclassified as serious by operation of law pursuant to section 186(b)(2) of the Act. If an extension is granted, then, at the end of the extension year, EPA will review the area's air quality data to determine if the area has attained the CO NAAQS. Recall that CO areas must have two consecutive years of clean air quality data to demonstrate attainment. Consequently, if the area measures a violation of the CO NAAQS during the extension year, the area will be unable to qualify for a second one year extension. Then, once EPA makes a finding of failure to attain the CO NAAQS, the moderate area will be reclassified as serious by operation of law.

II. Today's Action

In today's action, EPA proposes to find that the Clark County CO nonattainment area has met the criteria in section 186(b)(4) of the CAA, thereby qualifying for a one year attainment date extension. As a result of this finding, EPA proposes to grant a one-year extension of Clark County's moderate area attainment date from December 31, 1995 to December 31, 1996. This proposed finding is based on both EPA's review of 1994 and 1995 monitored air quality data for compliance with the CO NAAQS and EPA's review of Clark County's application for an attainment date extension.

A. Ambient Air Monitoring Data

The following table lists the location and dates that the eight-hour CO NAAQS of 9 ppm has been exceeded in Clark County during 1994, 1995, and 1996. Although the attainment and extension criteria address the 1994 and 1995 data, the 1996 data is relevant to later discussion in this section.

Exceedances of 8-hour Carbon Monoxide National Ambient Air Quality 
 Standard fn1 in the Clark County, Nevada Nonattainment Area 

                 1994            1995            1996 

Monitoring Site        Conc.    Date   Conc.    Date   Conc.  Date 
2850 East Charleston  10.6 ppm   1/4  10.2 ppm  11/23 10.1 ppm  1/6 
Blvd. 
                      9.5 ppm   1/21  10.3 ppm  1/14 
                      9.6 ppm   1/22  10.2 ppm  3/10 
                      9.6 ppm   12/1 
                     10.9 ppm  12/17 


fn1 The eight-hour carbon monoxide NAAQS is 9 parts per million. 

fn2 Concen. = monitored carbon monoxide concentration in parts per million.

1. 1994 Data

During calendar year 1994, Clark County exceeded the eight-hour CO NAAQS five times. All of these exceedances occurred at the East Charleston monitoring site. These exceedances total four violations of the CO NAAQS.

2. 1995 Data

During calendar year 1995, Clark County exceeded the eight-hour CO NAAQS once at the East Charleston monitoring site. Consequently, there were no violations of the CO NAAQS in 1995.

3. 1996 Data

During the first quarter of 1996, Clark County exceeded the eight-hour CO NAAQS three times; all at the East Charleston monitoring site. These exceedances total two violations of the CO NAAQS.

4. Discussion of CO NAAQS Exceedances During the 1995-96 Winter CO Season

Clark County meets the first statutory criterion for an attainment date extension by having no more than one exceedance of the CO NAAQS in the nonattainment area in 1995. However, this achievement is clouded by three exceedances of the CO NAAQS during January and March 1996. Furthermore, Clark County raised several concerns with the East Charleston monitoring site suggesting that siting problems biased the data collected there.

a. Clark County Concerns with East Charleston Monitoring Site

In recent correspondence from Clark County to EPA, Clark County raised several concerns with the siting of the East Charleston monitor and proposed several changes to the Clark County monitoring network. n3 Clark County asserted that the configuration of the East Charleston monitoring site is inconsistent with the requirements for National Air Monitoring Station (NAMS) given in the Code of Federal Regulations (see 40 CFR Part 58.) Clark County's specific concerns were as follows: (a) several trees located less than ten meters from the station and adjacent block walls, north and west of the station, impede the air flow around the monitor; (b) the current probe height is less than two meters above the top of the block wall, Clark County suggests it should be three meters or more; and, (c) vehicle emissions from a nearby apartment complex parking lot may be causing a bias of approximately 1.0 ppm during high CO episodes. In sum, Clark County asserts that air flow obstructions reducing windspeed in and around the sampling probe along with a potential source of nearby vehicle emissions both contribute to bias the East Charleston data. Clark County suggests that this total bias may contribute 1.4 ppm or approximately 10% to the 1995 high CO value of 10.3 ppm.

n3 See correspondence from Michael Naylor, Clark Co. Health District to John Kennedy, U.S. Environmental Protection Agency, February 7, 1996.

Because of these concerns, Clark County asked EPA to delay a finding of attainment or nonattainment for the CO NAAQS until new CO data is collected during October to December of 1996 at new monitoring sites. Towards this end, Clark County proposed the following actions: (a) to relocate the East Charleston monitoring station within the same neighborhood; (b) to increase the number of EPA recognized neighborhood sites by adding monitoring sites at East Sahara and East Flamingo Boulevards; (c) to identify and add a suitable microscale monitoring station with high pedestrian traffic; and, (d) to request designation of the Paul Meyer Park monitor in Spring Valley as a background CO monitoring site.

In response to Clark County's concerns and proposal, EPA and Clark County have agreed to revise the CO monitoring network in Clark County. The present East Charleston monitoring site will continue to operate according to all applicable protocols until its lease expires in 1997. Three new monitoring sites will be added to the Clark County air quality monitoring system before the 1996-97 winter CO season: two neighborhood scale sites, one at Sunrise Acres Elementary School and the other at Crestwood Elementary School in the East Charleston area; and, a microscale site on Las Vegas Boulevard at Tropicana. Both the neighborhood scale site at Sunrise Acres Elementary School and the microscale site on Las Vegas Boulevard will be potential National Air Monitoring Stations. As such, they must meet federal monitoring requirements and their siting and operating protocols are subject to EPA approval. To determine accurately and scientifically the air quality status of Clark County in 1996, it is essential that Clark County install these three new monitoring sites before October 1, 1996 and operate them correctly during the 1996-97 winter CO season.

b. EPA Review of Other CO Data Collected in East Charleston Area During 1995-96 Winter CO Season

During the 1995-96 winter CO season, two special purpose CO monitoring sites were operated within a city block of the East Charleston monitoring station: the "Proximity" site (2850 East Charleston Boulevard) and the "Microscale" (2801 East Charleston Boulevard) site. The data collected at these monitoring sites are not used for regulatory purposes and these monitors may have siting issues independent of those at the East Charleston station.

However, EPA staff examined the data collected at these two sites and compared them to the data obtained at the East Charleston station over the 1995-96 winter CO season on the days where exceedances of the CO NAAQS were observed at any of the three monitors. For these days, EPA compared the eight-hour maximum average value at the three sites to determine qualitatively the extent of the CO problem in the East Charleston area and the extent of any inconsistencies between East Charleston data and data collected at other CO monitors in the area.

The comparison shows that data from the three sites were very similar. On the exceedance days, the daily maximum eight-hour average values almost always occurred during the same time period at all three sites. Also, on the nine days where an exceedance of the CO NAAQS was observed at any of the three monitors, East Charleston recorded three exceedances, Proximity recorded five exceedances, and Microscale recorded seven exceedances. This suggests that exceedances at East Charleston did not appear to be anomalies solely derived from siting problems. Ambient CO values near or above the CO NAAQS appear to occur consistently in the East Charleston area.

The exception was the period between November 30, 1995 and December 21, 1995 when the East Charleston monitoring site was operated under a different protocol. The sampling probe height at East Charleston was raised from 3.7 meters to 14.2 meters while the sampling probes at the Proximity and Microscale sites remained at 10 and 3.5 meters respectively. Data collected in January 1996 suggest that CO values observed at the East Charleston monitor during this November/December timeframe were lower than they otherwise might have been due to the difference in probe height. Parallel monitoring at the two different probe heights during the January 1996 exceedances show CO values were 11-13% lower at 14.2 meters than when measured at 3.7 meters n4. Also, in contrast, where the East Charleston site measured no exceedances of the CO NAAQS during this timeframe, the Proximity site measured CO values greater than the CO NAAQS once and the Microscale site measured CO values greater than the NAAQS three times. After December 21, 1995, Clark County returned the East Charleston sampling probe to 3.7 meters at EPA's request. n5 EPA's request was consistent with the National Air Monitoring Station operating protocols used at the East Charleston site since its inception fifteen years ago.

n4 See February 7, 1996 Michael Naylor to John Kennedy correspondence at page 6. January 1996 exceedances were approximately 10.3 ppm, measured at 3.7 meters, while CO values measured at 14.2 meters were approximately 9.0 ppm.

n5 See correspondence from David P. Howekamp, U.S. Environmental Protection Agency to Michael Naylor, dated December 15, 1995.

In summary, data exists in addition to the data collected at East Charleston to suggest that frequency and severity of exceedances of the CO NAAQS at the East Charleston site do not appear to be anomalies solely derived from site problems. Under predictable weather patterns and meteorology, ambient CO values near or above the CO NAAQS occur consistently in the East Charleston area.

5. Conclusion

Clark County meets the first statutory criterion for an attainment date extension by having no more than one exceedance of the CO NAAQS in the nonattainment area in 1995. However, this achievement is clouded by 3 exceedances of the CO NAAQS in January and March of 1996.

EPA will not disqualify the January to March winter 1996 CO season monitoring data from the East Charleston station without further review and conclusive evidence that it is inaccurate. Clark County should operate the East Charleston monitor according to proper protocols through the coming 1996-97 winter CO season in parallel with the new monitors at Sunrise Acres Elementary School, Crestwood Elementary School, and on Las Vegas Boulevard & Tropicana. Then, in collaboration with Nevada Division of Environmental Protection and the Clark County Health District, EPA will compare the East Charleston data to data from the replacement site at Sunrise Acres Elementary School to determine what bias, if any, exists in the East Charleston data. In early 1997, EPA will use the data from Crestwood Elementary School and Las Vegas Boulevard, along with data from the rest of the Clark County air quality monitoring network, to determine Clark County's air quality status.

B. Review of Clark County's Attainment Date Extension Request

On March 28, 1996, Nevada submitted Clark County's application for a one-year extension of the moderate CO attainment date from December 31, 1995 to December 31, 1996. n6 Clark County does not have two consecutive years of clean data needed to show attainment of the CO NAAQS. So, as discussed earlier, EPA may grant a one year attainment date extension if Clark County meets the following two criteria: (1) no more than one exceedance of the CO NAAQS at any monitoring site in the nonattainment area in 1995, and (2) compliance with the requirements and commitments pertaining to the applicable implementation plan for the area. Having reviewed Clark County's ambient air quality data for exceedances of the CO NAAQS, the remainder of this proposal will review whether or not Clark County meets the second criterion.

n6 See "1996 Extension Year Application for the Las Vegas Valley Carbon Monoxide Nonattainment Area," Clark County Department of Comprehensive Planning, March 1996.

1. Review of SIP Implementation and Compliance

To determine whether or not Nevada and Clark County have complied with the applicable SIP, EPA will examine the air quality planning progress made in Clark County. In this assessment, EPA will review recent State implementation plan submittals and the extension application to determine if Nevada and Clark County have: (a) adopted and implemented the control measures needed to satisfy the CAA requirements for a moderate CO nonattainment area; and (b) made reasonable further progress towards meeting the CO NAAQS. These criteria are used as part of determining compliance with the applicable SIP because Nevada and Clark County have recently submitted amendments to several of these moderate area control measures. EPA has yet to review, approve, and include these recent amendments in the applicable SIP.

a. Compliance With Moderate Area Planning Requirements

The CAA requires moderate CO nonattainment areas, such as Clark County, to implement the following control measures and planning requirements: (a) enhanced inspection and maintenance of motor vehicles (enhanced I/M) for CO; (b) an oxygenated fuels program requiring gasoline to be sold with 2.7% oxygenate by weight; (c) areawide vehicle miles traveled (VMT) forecasts and linked contingency measures; (d) a demonstration of attainment for the CO NAAQS; and, (e) any additional control measures needed to attain the CO NAAQS. n7

n7 For more information on air quality planning requirements, see section 187(a) of the CAA, the "General Preamble to Title I of the CAA" (57 FR 13498-13570, April 16, 1992 and 57 FR 18070-18077, April 28, 1992), and the "Technical Support Document to Aid States with the Development of Carbon Monoxide State Implementation Plans" (EPA-452/R-92-003, July 1992)

Nevada has submitted two enhanced I/M programs for Clark County. Nevada submitted its first enhanced I/M program on July 28, 1994. It was intended to comply with EPA regulations extant at the time (see 57 FR 52950, November 5, 1992). Since then, Nevada redesigned its enhanced I/M program to take advantage of increased flexibility offered by EPA's revised enhanced I/M program regulations (see 60 FR 48029, September 18, 1995). Thus, Clark County's present enhanced I/M program is designed to meet EPA's "low" enhanced I/M performance standard. Nevada submitted this program to EPA on March 20, 1996. This low enhanced I/M program was not fully implemented in Clark County during the 1995-96 winter CO season. In September 1995, Nevada began implementing its low enhanced I/M program. Program improvements included connecting test analyzers to a common network over approximately 290 inspection stations. However, on road testing of the in-use registered motor vehicle population (remote sensing) was not implemented during the 1995-96 winter CO season. Nevada is scheduled to begin remote sensing in July 1996.

Requiring a minimum 2.5% oxygenate by weight, Clark County first implemented its oxygenated fuels program in November of 1989. By November 1991, the oxygenated fuels regulation, Health District Regulation-Section 53, was revised to meet the minimum 2.7% oxygenate by weight requirement of the CAA. Clark County submitted this regulation to EPA on July 6, 1992. Since this submittal, Clark County has revised its oxygenated fuels regulation several times within the 2.7% oxygenate content requirement. Clark County's latest submittal of the oxygenated fuels regulation (revised and adopted July 27, 1995) to EPA was on October 4, 1995.

Clark County provided vehicle miles traveled forecasts, contingency measures, and an attainment demonstration in three CO plan submittals. Clark County submitted its first CO plan on November 17, 1992 to comply with the CO plan submittal requirements of the CAA. Then, Clark County provided a second revised plan submittal on October 4, 1995. The second revision was required due to changes in the enhanced I/M program and resulting changes in Clark County's CO control strategy. Clark County submitted the third revised CO plan on November 8, 1995 including State and local commitments to control measures in 2000 and 2010. Assuming implementation of these enforceable commitments allowed transportation planning agencies to demonstrate that current transportation plans and programs will conform to the CO plan's emissions budget in 2000 and 2010.

Also, in the October 4, 1995 CO plan submittal, Clark County included a wintertime Reid vapor pressure (RVP) fuel requirement, a control measure not required by the CAA. However, Clark County determined that this added measure was needed to attain the CO NAAQS. The Nevada Board of Agriculture subsequently amended the Nevada Administrative Code to require a wintertime RVP of 9 pounds per square inch (psi).

In conclusion, Clark County has adopted and submitted items addressing the planning requirements of the CAA for moderate CO areas. Clark County's adopted CO control strategy for the 1995-96 winter CO season included the following elements: a low program standard enhanced vehicle I/M program, a 2.7% oxygenated fuels program, and a wintertime RVP requirement. However, the low enhanced I/M program was not fully implemented during the 1995-96 winter CO season. EPA expects Clark County's enhanced I/M program to be fully implemented before the 1996-97 winter CO season. Furthermore, Clark County submitted to EPA all CAA required plan elements such as VMT forecasts, contingency measures, and an attainment demonstration for the CO NAAQS.

b. Reasonable Further Progress Towards Meeting the CO NAAQS

Both the number and severity of violations of the CO NAAQS have decreased since 1990. n8 In 1990, Clark County violated the CO NAAQS thirteen times with a 14.2 ppm design value. In comparison, during 1995, Clark County exceeded the CO NAAQS once with a 9.2 ppm design value. The frequency and severity of CO NAAQS violations have decreased. Furthermore, these improvements in air quality coincide with implementation of the control measures described above, especially the oxygenated fuels program.

n8 See Attachments 1-4 to "1996 Extension Year Application for the Las Vegas Valley Carbon Monoxide Nonattainment Area," Clark County Department of Comprehensive Planning, March 1996.

2. Conclusion

Given the planning actions and reasonable further progress by Clark County, EPA proposes that Clark County meets the second statutory criterion required for a one year attainment date extension: it has adopted, submitted, and, for the most part, implemented, the control measures needed to satisfy the requirements for a moderate CO nonattainment area; it has adopted and submitted the planning requirements for a moderate CO area; and, it has made reasonable further progress towards meeting the CO NAAQS.

III. Consequences of Today's Action

If EPA takes final action on this proposed finding that Clark County has met the criteria for an attainment date extension, then Clark County will be granted a one year attainment date extension and will remain classified as a moderate CO nonattainment area. After December 31, 1996, EPA will again review the air quality data for Clark County to determine if it has attained the CO NAAQS.

If Clark County measures violations of the CO NAAQS during 1996, the area will be unable to qualify for a second one year extension. Then, after an EPA finding of failure to attain the CO NAAQS, Clark County would be reclassified as a serious carbon monoxide nonattainment area by operation of law.

IV. Executive Order (EO) 12866

Under E.O. 12866, 58 FR 51735 (October 4, 1993), EPA is required to determine whether regulatory actions are significant and therefore should be subject to OMB review, economic analysis, and the requirements of the Executive Order. The Executive Order defines a "significant regulatory action" as one that is likely to result in a rule that may meet at least one of the four criteria identified in section 3(f), including, under paragraph (1), that the rule may "have an annual effect on the economy of $100 million or more or adversely affect, in a material way, the economy, a sector of the economy, productivity, competition, jobs, the environment, public health or safety, or State, local, or tribal governments or communities."

The Agency has determined that extending attainment dates, as proposed today, would not result in the effects identified in section 3(f). Under section 186(a)(4) of the CAA, attainment date extensions are based upon air quality conditions and planning considerations and are either administrative in nature, or must occur by operation of law in light of certain air quality conditions. They do not, in-and-of-themselves, impose any new requirements on any sectors of the economy.

V. Regulatory Flexibility

Under the Regulatory Flexibility Act, 5 U.S.C. 601 et seq., EPA must prepare a regulatory flexibility analysis assessing the impact of any proposed or final rule on small entities. 5 U.S.C 603 and 604. Alternatively, EPA may certify that the rule will not have a significant economic impact on a substantial number of small entities. Small entities include small businesses, small not-for-profit enterprises, and government entities with jurisdiction over populations of less than 50,000.

As discussed in section IV. of this notice, attainment date extensions under section 186(a)(4) of the CAA do not create any new requirements. Therefore, I certify that today's proposed action does not have a significant impact on small entities.

VI. Unfunded Mandates

Under sections 202, 203 and 205 of the Unfunded Mandates Reform Act of 1995 (Unfunded Mandates Act), signed into law on March 22, 1995, EPA must assess whether various actions undertaken in association with proposed or final regulations include a Federal mandate that may result in estimated costs of $100 million or more to the private sector, or to State, local or tribal governments in the aggregate. EPA believes, as discussed above, that the proposed finding that Clark County nonattainment area meets the criteria in section 186(a)(4) and thereby qualifies for an attainment date extension is a factual determination based upon air quality considerations and must occur by operation of law and, hence, does not impose any Federal intergovernmental mandate, as defined in section 101 of the Unfunded Mandates Act.

List of Subjects in 40 CFR Part 81

Environmental protection, Air pollution control, Intergovernmental relations, Carbon monoxide.

Authority: 42 U.S.C. 7401-7671q.

Dated: July 22, 1996.

Felicia Marcus, Regional Administrator.

[FR Doc. 96-20370 Filed 8-9-96; 8:45 am]

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