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Citation: 58 Fed. Reg. 8451 1993

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# Part II



# Environmental Protection Agency

40 CFR Part 58 Ambient Air Quality Surveillance; Final Rule8452 Federal Register / Vol. 58, No. 28 / Friday, February 12, 1993 / Rules and Regulations

ENVIRONMENTAL PROTECTION

AGENCY

40 CFR Part 58
[AD-FRL-4099-61

RIN 2060-AD18

Ambient AirQualitySurveillance

AGENCY: Environmental Protection Agency (EPA). ACTION: Final rule.

SUMMARY: This final rule revises the ambient air quality surveillance regulations to include provisions forthe enhanced monitoring ofozone and its
precursors including oxides ofnitrogen, volatile organic compounds (including carbonyls) and meteorological parameters. These revisions satisfy the requirements oftitle I,section 182of the 1990 Clean Air Act Amendments. These revisions require States to establish photochemical assessment monitoring stations (PAMS) aspart oftheir State Implementation Plan (SIP) monitoring network in ozone nonattainment areas classified as serious, severe, or extreme. Included in these revisions are minimum criteria fornetwork design, monitor siting, monitoring methods, operating schedules, quality assurance, and data submittal.

EFFECTIVE DATE: These regulations take effect on February 12, 1993.
ADDRESSES: Docket Statement: All
comments received relative to this rule have been placed inDocket No. A-91- 22, located in the Central Docket Section, Room M1500 (FirstFloor, Waterside Mall), U.S. Environmental Protection Agency, 401 M Street SW., Washington, DC 20460. This docket is available forpublic inspection and copying from 8:30-12 a.m. and from 1:30-3:30 p.m., Monday through Friday. A reasonable fee may be charged for. copying.
FOR FURTHER INFORMATION CONTACT: Geri Dorosz-Stargardt, Technical Support Division (MD-14), Office ofAir Quality Planning and Standards, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711, phone: (919) 541-5492.

SUPPLEMENTARY INFORMATION: Background

Section 110(a)(2)(C) ofthe Clean Air Act requires ambient air quality monitoring forpurposes ofthe State Implementation Plan (SIP) and reporting ofthe data to EPA. Uniform criteria for measuring airquality and provisions for the reporting ofadaily air pollution index are required by section 319 ofthe Act.To satisfy these requirements, on May 10, 1979 (44FR 27571), EPA established 40 CFR part 58which provided detailed requirements for air quality surveillance and data reporting for all the pollutants except lead for which ambient air quality standards (criteria pollutants) had been established. On September 3, 1981 (46 FR44164) similar rules were promulgated for lead and on July 1, 1987 (52 FR 24740) forparticulate
matter (PMlo).

On March 4, 1992, these rules were proposed in the Federal Register as amendments to 40 CFRpart 58. These regulations address the minimum requirements for the monitoring of speciated volatile organic compounds (VOC), oxides ofnitrogen (NOx), and meteorological parameters aswell as additional ambient air monitoring for

ozone (03). Title I,section 182 ofthe 1990 Clean AirAct Amendments requires EPAto promulgate regulations forthe enhanced monitoring of03 and its precursors and forthe affected States
to incorporate the requirements as a part oftheir State Implementation Plans. Also, section 184(d) requires that the best available air quality monitoring and modeling techniques be used in making determinations concerning the contribution ofsources in one area to concentrations of03 in another area which is a nonattainment area for

ozone. Additionally, these enhanced

ozone and ozone precursor monitoring rules adhere to the fundamental recommendations, regarding ambient monitoring, ofthe National Academy of Sciences (NAS) in the report entitled, Rethinking the Ozone Problem in Urban and Regional AirPollution, which was prepared pursuant-to section 185B of the 1990 Clean Air Act Amendments. In that report, the NAS noted the need for additional feedback mechanisms for evaluating the effectiveness of ozone control strategies.

The intent ofthese enhanced ozone and ozone precursor monitoring regulations is to require air pollution control agencies to obtain an air quality database that will assist in evaluating, tracking the progress of, and,if
necessary, refining control strategies for attaining the ozone National Ambient Air Quality Standards (NAAQS). Photochemical assessment monitoring stations (PAMS)will be established to collect ambient concentrations ofozone (03), oxides ofnitrogen (NOx), nitrogen dioxide (NO2 ),nitrogen oxide (NO), and speciated VOC.including carbonyls, and meteorological data to better characterize the nature and extent ofthe 03problem, aid intracking VOC and NOx emission inventory reductions, assess air quality trends, and make attainment/nonattainment decisions. In addition, the PAMS will provide a more definitive database for evaluating photochemical model performance, especially for future control strategy mid-course corrections as part ofthe continuing air quality management process. The data will be particularly useful to States in ensuring the implementation ofthe mostcosteffective regulatory controls.

In the process ofdeveloping these regulations, EPA sought the assistance ofthe Standing Air Monitoring Work Group (SAMWG). SAMWG was established by EPA in 1975 to assist in developing air monitoring strategies, correcting identified monitoring problems, and improving overall national monitoring operations. SAMWG members represent State and local air pollution control agencies and EPA program and Regional Offices. SAMWG members were active partners in developing and reviewing the 1979 part 58rulemaking package which formally established the existing framework ofthe ambient air quality surveillance and data reporting regulations. The group also played a prominent role In all subsequent revisions to part 58.

Public Comments

The object ofFederal Register proposals is to allow comments on new regulations prior to theirpromulgation, thereby providing an opportunity for the public to participate in the rulemaking
process. On March 4, 1992, these rules

were proposed in the Federal Register with a 30-day comment period. In
response to requests from the public, especially from the regulated community ofState and local air pollution control agencies on April 3, 1992, EPA extended the public
comment period on the enhanced 03 and 03 precursor monitoring regulations until May 4, 1992.

EPA received 40 written comment letters on the proposal ofMarch 4, 1992. All ofthe written comments submitted
to EPA are contained in EPA's Docket No. A-91-22. Ofthe letters reviewed, 16

come from State agencies, 10 from industry, 2 from institutes and universities, 6 from State/local associations, 5 from local agencies, and 1from a federal agency. A list ofall
commenters writing to the public docket is provided inDocket A-91-22.

The following discussion covers the substantive comments. A detailed discussion ofthe basic concepts of the regulations can be found in the preamble to the March 4, 1992 proposal.Federal Register / Vol.- 58, No. 28 / Friday, February 12, 1993 / Rules and Regulations

A. GeneralComments

The comments discussed under this heading were not specific to any rule or appendix, butwere general comments

on some aspect ofthe proposed monitoring program.

One commenter noted that the Muskegon nonattainment area had been reclassified from a serious to a moderate classification and therefore should be withdrawn from consideration inthe final rules. Since this area and the Sheyboygan area have been reclassified and are no longer serious, severe, or extreme 03 nonattainment areas, EPA
agrees that these rules would not apply
to either Muskegon orSheyboygan. Accordingly, Muskegon and Sheyboygan are not included in EPA's estimated requirements forPAMS. Note that applicability ofthese enhanced 03 and 03 precursormonitoring rules is determined by the classification ofthe
03 nonattainment area and notby the fact that an area is listed specifically in

oromitted from this notice.

One commenter observed that Ventura County, California, was created

as a separate 03 nonattainment area fromthe Los Angeles Consolidated Metropolitan Statistical Area (CMSA) and requested clarification as to this area's status with regard to the enhanced 03 and 03 precursor monitoring requirements. EPA notes that since Ventura County was classified

as a severe 03 nonattainment area, the county is subject to these rules.

One commenter agreed with the basic concepts proposed on March 4, but suggested that the final promulgation
not add additional requirements. A second commenter expressed a similar opinion that EPA notkill the effort with additional mandates unless the Agency is willing to proceed slowly and absorb the costs.EPA evaluated the substantive
comments on their individual and collective merits and has incorporated a number of modifications to the original proposal. Only those additional activities addressed, inthe March 4 proposal, were added. Regarding

resources, EPA has demonstrated its willingness to participate in the funding
process; afurther discussion ofresource needs and funffling follows under Resources and Costs.

One commenter indicated that although the regulation is reasonably specific concerning network design, it lacks specificity forthe submittal ofSIP revisions. Given the complexity ofthe rules, EPA believed that it was necessary to provide extensive detail concerning the design ofthe new PAMS networks. The wide variability, inherent in SIPs, precludes such specificity when requiring SIP revisions. Each currentlyapproved SIP contains appropriate provisions for establishing and operating the network ofState and Local Air Monitoring Stations (SLAMS) including those stations identified as National AirMonitoring Stations (NAMS). The SIPs generally provide that SLAMS and NAMS will measure ambient concentrations ofthose criteria pollutants forwhich standards have been established in 40 CFRpart 50. The SIP revisions submitted to comply with these revisions to 40 CFR part 58.20 will additionally provide forthe monitoring ofambient concentrations ofnoncriteria pollutants such as speciated VOC including carbonyls, NO and NOx,

aswell as meteorological parameters in the same manner thatthe criteria pollutants were addressed. Note that the reference to aldehydes has been changed to carbonyls to more accurately reflect therequirements ofthe technical assistance document (Reference 2 of Appendix C). The guidance currently stipulates sampling and analysis forthe following carbonyls: Formaldehyde, acetaldehyde, and acetone.

The same commenter contends that the rules indicate virtually no need for

new 03 sites and amodest expansion of the NO2 monitoring effort and believes that these conclusions are based in great part on the assumption that PAMS monitors could be located at existing 03 and/orNO2 monitoring sites. The
commenter was concerned that ifthis assumption is in error, theexpansion needs ofthe networks may be underestimated. In fact, EPA did assume that some ofthePAMS stations could be located atexisting SLAMS orNAMS sites. For example, the PAMS type (3) site is located atthe downwind site where maximum 03 concentrations are expected to occur. This description corresponds to the category (a)NAMS 03 site specified in appendix D of40 CFR part 58. Such a site isrequired for all urban areas having a population of greater than 200,000. Because most of the nonattainment areas classified as severe, serious, orextreme for03 are located inurbanized areas which exceed thispopulation threshold, each area would currently be expected to be operating a category (a)NAMS 03 site. Assuming thatthese sites are properly located, it would therefore be common to find the PAMS type (3)site and the NAMS category (a) site coincident. In siting NAMS NO 2 sites in urban areas with populations greater than 1,000,000, the monitoring sites could potentially be collocated with one ofthe two PAMS type (2) sites. Generally, EPA believes that some collocation ofPAMS and SLAMS/NAMS sites is highly likely. In addition, in areas where a substantial number ofSLAMS 03 and NO2 sites currently exist, it is not unreasonable, forpurposes ofestimating costs,to

assume that the State air pollution control agency will relocate ambient monitors and appurtenances rather than purchase only new monitors to develop the PAMS network. For example, in one nonattainment area, 26 03 monitors and 15 NO2 monitors werein operation during the 1991 fiscal year compared to

aPAMS requirement ofonly 5 sites,

some ofwhich could obviously be located coincident with existing sites. In
response to the concerns expressed by the commenters, however, EPA has adjusted its cost estimates to reflect the collocation ofPAMS with existing monitors at only two sites in a five-site network.

One commenter was doubtful that the potential-benefits to be received from the program would bejustified given the estimated implementation costs and the unaddressed technical questions. A slower,more cautious schedule was recommended. In designing the requirements for the PAMS network, EPA considered the potential benefits of the data and weighed those against the projected costs and uncertainties. In

ight ofthe Agency's estimate forfuture 03 control costs of$8 to 12billion per year (Ozone Nonattainment AnalysisClean Air Amendments of1990. Office ofAir Quality Planning and Standards, U.S. Environmental Protection Agency, Research Triangle Park,NC 27711. DRAFT. September 1991), the potential
return in benefits for a cost of$5to 12 million per year provides an exceptionally prudent investment. Nevertheless, the Agency made every effort to craft aminimum requirement which would in great part satisfy a number ofimportant objectives, yetnot become a financial burden either upon the air pollution control agencies orthe States (notefurther discussions'of financial burden in thispreamble under Resources and Costs). Modifications to the proposed five-year transitional period address the commenter's concern and should provide ample flexibility.

This commenter also indicated that computer model sensitivity analyses should be conducted for all parameters to be measured and that the rule should acknowledge the need formeasuring pollutant concentrations aloft. EPA
notes that although the PAMS network design is not the direct result of sensitivity analyses foreach affected

area, it nevertheless reflects thecurrent expectations ofthe photochemical models. Heretofore, the national
program has nothad the benefit ofthe 84538454 Federal Register / Vol. 58, No. 28 / Friday, February 12, 1993 / Rules and Regulations

availability ofcomprehensive 03
precursor data as atool to evaluate, calibrate, or otherwise adjust and conduct reality checks on the operation ofthe Urban Airshed Model (UAM). EPA viewsthe PAMS networks as a vital step forward in complementing gridmodel applications and control strategy assessments and refinements.

Although the sampling ofpollutant concentrations aloft may also bea highly valuable activity, EPA does not agree that such activities should be included in the specifications for minimum routine measurements. These rules, however, donot preclude a State
agency from proposing such pollutant
measurements (made either on aroutine basis orat periodic intervals during

more Intensive sampling efforts), including them intheir EPA-approved comprehensive network description. and subsequently utilizing Clean Air Act Section 105 Grant monies, inpart,
to support these monitoring efforts. In fact, EPA has encouraged affected air pollution control agencies to view these rules as a base upon which to tailor and expand the precursormonitoring
program to meetthe States' individual needs.Monitoring pollutant concentrations aloft has therefore been assigned to the category ofdesirable, yet optional activities.

Two commenters suggested that EPA adjust its program to reflect information from previous field studies (i.e., base the rules on actual field-verified techniques rather than on good technical assumptions alone). EPA recognizes the value ofquality measurements and field-proven techniques. In fact, the fundamental tenets ofthe proposal were based on the demonstration ofemerging
measurement technology and data obtained during anumber of field studies, particularly the Atlanta O3 Precursor Study conducted during the

summer of 1990 (Reference 32 of Appendix D). Although technical assumptions were necessary to some extent due to the emerging nature and complexity ofthe measurement technology, EPA believes that these assumptions were warranted considering theneed formore definitive 03 precursor data to develop improved
03 control strategies. States are encouraged to take full advantage of experience and data obtained in past studies and routine monitoring efforts, and use that experience to refine and focus their individual PAMS network designs.

One commenter notedthat the requirements forintensive daily sampling will engender majordatabase management activities. EPA agrees that the measurement ofnumerous compounds during multiple hours of the day will create a very large database. Consequently, the Agency is proceeding
torevise the capabilities ofits computer-based Aerometric Information and Retrieval System (AIRS) to allow these data to be securely stored, retrieved, and adequately analyzed via the existing national system. The AIRS is currently utilized by all States for the storage and/or retrieval ofNAMS and SLAMS data. The data required to be submitted by § 58.45 will be deposited in this same data bank. Further information on AIRS and its capabilities
may be obtained by contacting any of the 10 EPA Regional Offices or the National AirData Branch, Technical Support Division (MD-14), Office ofAir Quality Planning and Standards, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina 27711. The Agency is also revising its technical assistance document (Reference 2 ofAppendix C) to include additional guidanceregarding the processing ofdata atthe State and local
agency level, i.e., generic procedures for data processing and validation.

In a related topic, another commenter estimated that the proposed rules will result in aworkload increase of60 percent, predominantly in data reporting burden. This commenter advocates the development by EPA of expert software foruse with the VOC analyzers. The Agency notes this

concern and has therefore undertaken the aforesaid modifications tothe AIRS system and to its technical assistance document.

One commenter was concerned that a bias in 03 measurements often occurs

on design-value days, in part due to differences in measurement techniques. While the Agency cannot substantiate a particular problem occurring on 03 design value days, the Agency notes that data which is gathered in accordance with 40 CFR part 58 and the quality

assurance procedures ofappendix A, are acceptable foruse in computing design values and for conducting attainment/ nonattainment determinations.

The same commenter believes that EPA should examine the following four

areas more carefully before finalizing the rule: (1)The linking ofmonitoring specifications with monitoring objectives, (2) the consequences foran urban area adhering to the minimum stipulated monitoring requirements, (3) the rationale forrecommended averaging times and frequencies for sampling ofVOC, and (4) the rationale for air quality and meteorological siting requirements. The Agency considered these suggestions, recognized their value, and subsequently incorporated these considerations intothe final rules. Specificrecommendations made by this
commenter are addressed elsewhere in this preamble.

Two commenters expressed concern that EPA had not adequately addressed critical issues relating tothe role ofNOx in the photochemical process. These
commenters assert that EPA must

ensure that the data gathered willbe appropriate for NOx sensitivity modeling and willfacilitate discrimination and impact ofvarious

sources ofNOx. EPA is concerned about the function ofnitrogenous compounds in 03 formation, particularly in the southeastern United States. Special studies are being initiated asjoint projects withEPA inthe Southeast employing research monitoring concepts to derive the most effective strategies forNOx monitoring and control. These integrated projects are expected tohave a significant impact on future 03 control actions. Modeling predictions ofvarious nitrogen species [e.g., total reactive oxides ofnitrogen (NOy), NOx, NO, NO 2,peroxyacetyl nitrate 

### (PAN), and nitric acid (HNO3}, etc.] can then be examined by the research community to determine the performance ofchemical mechanisms in predicting non-03 oxidants. This will help ensure that chemistry, leading to 03 formation inurban and rural areas, is properly characterized and may lead
to further modeling improvements. Note that the measurement ofmore highly oxidized forms ofnitrogen requires a high degree ofskill/training using nonstandard techniques to measure pollutants at very low concentrations. EPA has determined that it ispremature to require such efforts in a routinely operated network, but encourages and recommends that States consider the option ofdeploying more sensitive NOx instruments when establishing future PAMS sites. For the near term, the
current NOx monitoring methodology 

### (Federal Reference Method for NO 2) will be acceptable. The Agency will develop future guidance for more sensitive and definitive NOx methods and
measurements.

One commenter expressed concarn that many technical, logistical, and fiscal issues remain to be resolved to

ensure the success ofthe PAMS monitoring program. This respondent asserted that its comments, analyses and suggestions were, for the most part, ignored. On the contrary,however, the Agency has considered all comments and suggestions received by the Agency. This commenter's suggestions, being rather comprehensive, complicated, and unique, received careful scrutiny by EPA. In a number ofcases, these

### Federal Register / Vol. 58, No. 28 / Friday, February 12, 1993 / Rules and Regulations

suggestions were incorporated both in the previous draftproposals aswell as in thisfinal promulgation. In fact, the final regulation has been revised to allow alternative monitoring schemes and intermittent sampling frequencies in section 4 of appendix D, in part in direct response to this commenter. The factthat EPA did not radically change its approach to identically match the suggestions ofthis particular respondent in noway diminishes the importance of the suggestions, nor does it equate to ignoring the recommendations. Each specific recommendation has been addressed elsewhere in thispreamble.

B.PublicComments-Resourcesand Costs

Several commenters were concerned withthe statement in the proposal which says that the primary responsibility forImplementing the
program with its associated costs rests withthe States. The commenters feel strongly that EPA needsto make amuch larger financial commitment to the
program to ensure its success. EPA understands that thisunique program will require a strong federal presence both as a partner in system management and in providing appropriate technical and financial assistance. EPA has provided funds during FY-92 to initiate monitoring for air toxics in 10 areas. These sites, which are generally located consistent with the requirements for PAMS type (2) sites, willbe continued

aspart ofthe PAMS program in 1993. Additionally, the Agency has earmarked approximately $4,000,000 in § 105 Grant monies for distribution to the States in FY-93 and has provided technical support via contract and direct EPA involvement and participation. Overall, EPA will have home theburden of financing a significant portion ofthe

costs ofinitiating sampling during FY92 and FY-93. The Agency has plans for subsequent years which will ensure a major financial role inthis partnership for EPA.

Eighteen commenters submitted other observations related to funding and

resource needs to properly implement the PAMS program. Ten of those
commenters believed that the proposed levels offederal funding (discussed above) are generally inadequate to support the PAMS program. Three
commenters noted that the potential benefits ofthe program outweigh the projected costs, that serious consideration shouldbe given to utilizing permit fees collected under title V of the Clean AirAct Amendments forthis program, and/or 'that the monitoring costs are only a fraction ofthe costs incurred by society in attaining the air quality standards. Two commenters expressed strong objections to the use ofreprogramming ofexisting funds to support the PAMS

rogram. As previously discussed, EPA

as provided substantial section 105 Grant funds to support both FY-92 and FY-93 monitoring activities. The Agency expects to continue to provide significant support through section 105 grants in subsequent years. Reprogramming ofexisting monies is an action which historically has been used by the Agency to designate certain portions ofsection 105 Grant funds, provided annually to the States for support ofair pollution planning and control programs. EPAbelieves that this mechanism is a legitimate tool to focus its limited grant funds in part on particular air pollution problems having high national priorities. Rarely does the Agency suggest using this mechanism unless the priority of acompeting
program or projectis significantly greater than the currently-funded activity. EPA has determined thatthe potential benefits ofthePAMS program

are significant enough tojustify taking this unilateral action.

One commenter suggested that the distribution ofsection 105 Grant funds be based on the number ofsites and monitors operated regardless ofthe location ofthe nonattainment areas. Perennially, ithas been EPA's practice
to develop reasonable allocation schemes forthe available grant dollars based on defensible parameters such as activity levels, numbers ofsources, etc. In the case ofthe monies set aside for the photochemical assessment monitoring program, EPA concluded that an appropriate mechanism forthe distribution offunds was to consider the number ofrequired PAMS sites. Each affected Regional Office receives an allocation of fundsbased on anational prorata scheme; the final allocation to State or local grantees is computed by the Region. During FY-93, the primary allocation criteria was essentially the minimum number ofPAMS sites that would be required in each areaby the regulation. By FY-94, the Agency will have received more information on individual network designs from each affected State and willtherefore be able
to consider the actual number ofsites to be operated during the year as one ofthe criteria for the distribution ofgrant funds.

Another commenter suggested that if States are unable to hire additional personnel, theycould return grant monies in exchange forEPA contracted services or perhaps pool analytical support among agroup ofStates. Given the continuing nature ofmuch ofthe federal funding for photochemical
assessment monitoring, EPA asserts that it would notbe inappropriate for a State
agency to utilize the monies to hire new personnel. Further, due to economies of scale and within permissible limitations, States may take advantage ofEPA contracts which are designed to provide support to State agencies. Additionally, the EPA Regions may at the urging of agroup ofStates, reserve certain monies for aparticular State who would agree to,in turn, provide services to the others.

One commenter was concerned that the design ofthe enhanced 03 and 03
precursor monitoring program was influenced moreby financial constraints than by scientific constraints. EPA disagrees with this contention, and instead has attempted to provide a sensible balance between the costs of the program and degree to which the
program objectives are satisfied. In any
case, EPA has only provided the framework for aminimum required monitoring strategy. States are encouraged to implement larger, more comprehensive networks ifthose networks will provide a superior database for the fulfillment ofthe data objectives.

Five commenters expressed concern that EPA's estimates for the costs of implementing this monitoring program

were too low. EPA's costs estimates

were prepared from data gathered during 1990 and 1991, and therefore are generally expressed as 1990 and 1991 dollars. It is not surprising that estimates prepared in 1992 should be somewhat higher. In many cases it was difficult to compare estimates prepared by the commenters, since they often utilized different wage scales, different quoted equipment costs, and different operating scenarios. In mostcases, recognizing that these figures are only estimates ofthe true implementation costs, the Agency believes that its original estimatesreflected a reasonable appraisal ofthe resources needed to implement a minimally-acceptable
program at that time.EPA has, however, incorporated many ofthe suggestions of the commenters forcomputing costs and has compiled an updated version ofits
cost estimates. These estimates reflect the changes inthe boundaries ofseveral nonattainment areas, changes in classification of others, higher equipment and labor costs, revised sampling frequencies, additional allocations for data processing, upper air measurements, 03 and NOx monitors, security concerns, and larger monitoring shelters. For information, the Agency's updated cost estimates for each affected area may be found in Table 1. 8455

### 8456 Federal Register / Vol. 58, No. 28 / Friday, February 12, 1993 / Rules and Regulations

TABLE 1.-ESTIMATED REQUIREMENTS FOR PAMS

Aresname Po ion r Claslflcatlonof nonattailn- Number of re- Estimated liveManeayear cumulative

Beaumont-Port Arthur,TX

............................. Less Than Serious

................................ 2 $2,323,820 500,000. Porsmouth-Dover-Rochester NH-ME

........... ...... do................ Serious

............................. 2 2,227,130 Southeast Desert Modified AOMA, CA

................................. do.

..... Severe

............................... 2 2,280,860 Baton Rouge, LA

................................................................................. 500.000 to Serlous

...................... a 3,199,135 1,000,000. El

Paso,TX

........................................................................................... ......

do

.......... S........ serious

............................... 3 3,199,135 Springfield, MA

...................... ......... . ................................. O....................Serious

................................ 3 3,127,495 Ventura County CA

..................................................................................... do

... . .. Severe

............................ 3 3,199,135 Milwaukee-Racine, WI

.................................................................................... 100,000 to Severe......

.. 4 3,789,490 2,000,000. Provldence-Pawtucket-Fa River, RI-MA

..................................................... d

.................. se4ous

............................. 4 3,789,490 Sacramento, CA

.............................. ..................................................... ...... o

.................. Serious

............................... 4 3.873,070 Atlanta, GA

........................................................................................ More than Serious

........ .. ... 5 4,031,150 2,000,000. Baltimore, MD

. . ...-.

.... . . . do

................. d Severe

....................... 5 3,995,300 Boston-Lawrence-Worcester, MA-NH

. ..... .......... do......... Serious

................................ 5 3,995300 Chicago-Gary-Lake County (IL), IL-IN-Wi

....... .. do......... Severe

................................. 5 3,995.300 Greater Connecticut CT

............................................................................... ......do

................. Serlou

...................... 5 3,995,300 Houston-Galveto-Brzore. TX

................................................................ ......do

.................. Severe

................................ 5 4,084.850 Los Angeles-South Coast Air Basin, CA

........................................................ .... do

......... .... Extreme

............................... 5 4,084,850 NewYork-New Jersey-Long Island, NY-NJ-CT

..... ... ... do.. Severe

........................ 5 3,995,300 Philadelphla-Wilmlngton-Trenton. PA-NJ-DE-MD

................................. do............" .Severe

................................. 5 3,995,300 San Diego. CA

......................................................................................... . ...do

. Severe

................................. 5 4,0 4,850 San Joaquln Valley, CA

......... ..... ....... ............ ............ do

. . ......... Serious

. ............. ..... 5 4,084,850 Washington, DC-MD-VA

. ...... . . . ... .............. Serious

........................... 6 3,995,300

Totals

................................................................................................ ................... ...... ...................................... 90 79,.346410
'1992 Dollars.

Additionally, several commenters
were concerned that EPA only computed costs for the three-month period ofJune, July, andAugust, while the draft rule implies that monitoring should be conducted during the entire

03 season, which can be much longer. EPA indeed states that monitoring for
precursors should be conducted during the entire 03 season, butrecognizes that monitoring for only 3 months is an acceptable minimum.The preamble from the March 4, 1992 proposal clearly stated that because ofthe relatively large

resource requirements to conduct PAMS monitoring, 3months was proposed as the minimum annual precursor monitoring period forthe PAMS. EPA did encourage, however, the establishment ofa monitoring period for the entire 03 season in order toprovide

a morecomprehensive airquality database and increase the possibility of actually conducting monitoring during
mostof theWorst 03 episodes. EPA goes further,however, inthe revised section 4.3 ofappendix D, stating that alternate
precursor monitoring periods may be submitted for approval as apart ofthe PAMS network description. This action, therefore, allows a State to propose a monitoring season which willbest meet its particular needs as long asthe proposal will capture those worst 03
events. The length ofany particular PAMS monitoring season may therefore
vary from areato area. Two commenters asserted that the data collection requirements ofthe rule

were excessive for some ofthe stated
purposes and inadequate forothers. EPA has continually maintained that in formulating the data requirements for the PAMS program, it was necessary to achieve some compromises, (i.e., some

morecrucial objectives would bebetter satisfied than other less important objectives). Regardless, the Agency has reconsidered the requirements for data collection, and has modified the specifications to better reflect a balance ofthe needs ofthe data users.

One commenter alleged that EPA committed to provide full funding for all efforts required under the Photochemical Assessment Monitoring Program and further alleged that EPA committed that it would not require
state or local agencies to perform the specified monitoring iffull funding of all materials, equipment and labor is not provided by EPA. That commenter also requested that EPA clearly articulate this assertion in the rules promulgated today. Another commenter assertsthat EPA indicated this intent in the proposed regulation. It is common practice for State agencies to share substantially in the costs of implementing and operating all air pollution monitoring and control
programs. In fact, the Clean AirAct Amendments of1990, section 802, revise section 105 ofthe Act to require that States provide an overall minimum of40 percent ofthe costs of implementing programs forthe prevention and control ofairpollution

or implementation ofnational primary and secondary ambient air quality standards. EPA is therefore unable to commit that it would provide 100 percent ofthe funding for such a substantial program. Evidently, some confusion has resulted from EPA's attempts to provide maximum monetary support forthe implementation ofthe enhanced 03 

### and 03 precursor monitoring regulations.

One commenterbelieved that although the proposed funding for this
program maybe adequate to encompass capital expenses, provisions for skilled labor costs will be aproblem. EPA notes that provisions for the hiring ofhighly skilled chemists and statisticians were included in its cost estimates and planning for PAMS. Further, these estimates were reviewed by the Agency and revised upward to reflect changes in the national laborburden andthe expressed needs ofthe State and local air pollution control agencies.

One commenter believed thatthe comprehensive sampling and analysis schedule stipulatedby the proposed rules is the primary contributor to the high costs ofthe program. As previously stated, EPA is committed to only requiring a minimum program which will comprise thebest technical-fiscal balance to satisfy a variety ofdata objectives. Since the proposal wasFederal Register / Vol. 58, No. 28 / Friday, February 12, 19931 Rules and Regulations

published, EPA has refined its sampling and analysisrequirements to better reflect the data needs.

In an effort to focusresources and reduce thecosts ofimplementation, several commenters have recommended totally different strategies that they believe will also achieve the data objectives ofthe PAMS program. The Agency has reviewed these different proposals and believes that they donot constitute appropriate national minimum requirements, butmay be considered as alternative networks for particular nonattainment areas ifthey

are submitted pursuant to the requirements of§ 58.40 and appendix D

aspromulgated. EPA has determined that the suggestions were too closely tailored toparticular geographic areas to be applied nationally.

One commenter was concerned that the costs ofmeasuring air toxics was a substantial addition to the price ofthe PAMS program. EPA has noted thatthe PAMS stations would be available as platforms forthe additional monitoring ofairtoxics compounds ifnecessary. Specifically, it is noted by the Agency that by measuring the VOC targeted in reference 2 appendix C, a number of toxic air pollutants will also be measured. Although compliance with title I,section 182 ofthe Clean AirAct Amendments does.not require the
measurement and analysis ofadditional toxic air pollutants,the Agency believes that the PAMS stations can serve as cost-effective platforms foran enhanced air toxics monitoring program. The adjunct use ofPAMS for air toxics monitoring will allow the consideration ofair toxics impacts inthe development offuture 03 control strategies. The establishment ofa second PAMS type (2) site will prvide an even better data base for such uses. The Agency, however, takes note ofthe concerns of several respondents that the PAMS network is not ideal asa source of primary air toxics data and further, regards the collection ofair toxics data

as an incidental and secondary, though important, objective ofthe PAMS system.

In overall response to concerns over the estimates ofcosts previously provided by the Agency,EPA has recomputed its estimates including such additions noted previously as inflation factors, additional capital equipment, etc.; the new computations are summarized in Table 1.

C.PublicComments--Regulations

The following discussions address the Lomments received on specific provisions ofthe enhanced 03 and 03 precursor monitoring regulations: 1.Public Comments-Section 58.1- Definitions

Four commenters suggested adding definitions for the termNOy, a relatively

new term fortotal reactive oxides of nitrogen including NO, NO2,PAN, HNO3, and organic nitrite compounds which all participate in the photochemical process. Current research has revealed that these other compounds may indeed play a significant.role in 03 formation. EPA does notdisagree withthe commenters. Since noreadily-available monitoring method has been designated forthese species, however, and mostinformation

on the role ofNO, orother such compounds, still lieswithin the research community, EPA has determined that inclusion of any definition and/or regulatory requirements fQr monitoring forNOy is premature. Future revisions to 40 CFR part 58will reexamine the state of the research and reconsider this Issue. Nevertheless, EPA encourages the deployment ofthis emerging technology
atPAMS sites to further augment the value ofthe 03 and 03 precursor measurements.

Additionally, two commenters recommended that the definition of VOC be clarified and perhaps focused to indicate areference to reactive organic
gases. Further, one commenter suggested that an acronym be included fortoxic air pollutants. Inasmuch as EPA has specifically named the compounds (VOC) targeted for monitoring and analysisby this
program, see reference 2 appendix C, and expects that list to evolve asthe monitoring program matures, the Agency believes that amore focused regulatory definition is notneeded at this time. Such a move, made prematurely, might unnecessarily constrain development ofthe program in future years and inadvertently limit the data available to the States to craft the most effective 03 control strategies. Since the foci ofthis monitoring
program areclearly 03 precursors and 03, these rules are notthe most appropriate vehicle to define or name air toxics compounds. Such actions will be subsequently considered by the Agency's air toxics control programs.
2. Public Comments--Section 58.2- Purpose

Onecommenter felt that it is an oversight not to consider application of thisregulation tomoderate 03 nonattainment areas. EPA notes that enhanced information on 03, 03
precursors, and meteorology would be beneficial to any State government wrestling with the enigma ofany level of03nonattainment. Section 182(c)(1) ofthe Clean AirAct Amendments of 1990, however, authorized the Agency
to develop rules only for those areas classified as serious or above for 03 nonattainment. The fact that Stateswith moderate areaswill notbe required to institutethese specifications, should not impede those State agencies from configuring monitoring strategies which

are similar tothe photochemical
assessment monitoring program.
3. Public Comments--Section 58.13- Operating Schedule

One commenter recommended that this section be amended to restate the monitoring period requirements of section 4.3 ofappendix D. EPA notes that it would bebeneficial to include a reference to section 4.3 in §58.13, and has amended the final rule accordingly.,

4. Public Comments-Section 58.20- Air Quality Surveillance Plan Content

Yourcommenters expressed concern that the requirements forVOC and/or meteorological parameters were.too comprehensive and constituted excessive collection ofdata. Additionally, several commenters believed that the substitution of
measurements fortotal VOC, nonmethane organic compounds (NMOC),

or total non-methane hydrocarbons (NMHC) (note that these acronyms essentially represent the same group of species) wouldbe adequate to fulfill the PAMS data objectives, atleast at some ofthe designated sites. EPA has reexamined its position regarding requirements forthe speciation ofVOC analyses and has concluded that continuation ofthe speciated requirement isboth appropriate and
necessary. This conclusion isbased on the need formore definitive information regarding VOC at the specific geographic locations where 03 exceeds the National Ambient Air Quality Standard (NAAQS), in orderto address the multi-faceted PAMS objectives. The sampling for speciated VOC data allows the verification ofNMOC measurements and provides a better understanding of the biogenic contribution to the 03 problem. The corroboration ofprogress in the reduction of03 precursor emissions inventories would necessitate the quantification ofthe biogenic and. anthropogenic fractions for those areas where biogenics represent a significant component ofthe ambient air. Additionally, the Agency has modified t'e sampling and analysis requirements

to reflect the acceptance ofevent sampling at 3 ofthe 5 minimallyrequired sites. Such a modification has 84578458 Federal Register / Vol. 58, No. 28 / Friday, February 12, 1993 / Rules and Regulations

the potential to reduce the data handling requirements, costs, and level oftechnology needed. The amended sampling and analysis requirements are specified in section 4.4 ofappendix D. Alterations to therequirements for the
measurement ofmeteorological parameters are discussed in section 4.6 ofappendix D. Note, however, that the promulgated sampling requirements for speciated VOC donot preclude the submittal of alternative sampling schemes as a part ofthe network design reqirdby § 58.40. ecommenters felt that 6 months

is too short a time frame forSIP development, processing, and approval. Note the briefdiscussion ofSIPs under General Comments, EPA believes that the required SIPrevision to empower States to implement the enhanced 03 and 03 precursor monitoring regulationi will be arelatively uncomplicated procedure. Given the intrinsic need for the data required inthis promulgation, the Agency recommends that all States, including those which are not affected by these rules, develop such SIP revisions. Based on a review of common SIP procedures, EPA has subsequently modified § 58.20 to allow 9 months for the submittal ofarevision to the SIP for the establishment and maintenance of PAMS.

5. Public Comments--Section 58.40- PAMS Network Establishment

Seven commenters asserted that 6 months is insufficient time for a State to develop and submit a PAMS network description. Inter- and intra-State cooperation, data needs, and complexity issues were cited as reasons forthe demand for moretime. EPA Headquarters and the EPA Regional Offices have beenworking with affected State and local air pollution control agencies as well as cooperative bodies such as the Northeast States for Coordinated Air Use Management (NESCAUM) and the Mid-Atlantic Regional Air Management Association (MARAMA), to develop the basics of individual and regional PAMS network descriptions. Additionally, EPA has provided funding during FY-92 to begin the establishment ofmonitoring sites,
many ofwhich will eventually constitute the first PAMS type (2) sites. Given the extensive preparatory work conducted since 1990 byboth the Agency and the States,EPA believes that a 6-month requirement forthe submittal ofa network design is both achievable and appropriate. In response to the concerns ofthe commenters, however, EPA has clarified, in § 58.41, its need for detail in the initial network design submittal and has indicated that specific details on the first PAMS type (2) siteplus general information on other sites, would constitute a complete submittal for fulfillment ofthe requirements of §58.40. Note, however, thatsince the network design must receive the approval ofthe Administrator as stipulated by §58,42, EPA will require the submittal of subsequent phases ofdetailed network design byJanuary I ofeach year of implementation. In this way, a State
may focus its resources on an annual basis towardthe establishment ofone site perarea. For groupsof States planning to submit coordinated network designs,the process will also be simplified somewhat. Sections 58.40, 58.41, and 58.42 have been amended accordingly.

Four commenters felt that the language of §58.40, which allows the joint submittal of network descriptions and implementation schedules by disparate States (andfurther discussed in section 4.2 ofappendix D), should be strengthened to make such inter/intraState cooperation mandatory to ensure consistency and coordination, especially in 03 transport regions. In general, EPA believes that cooperation
among State and local air pollution control agencies should be encouraged, butnot required. The Agency has demonstrated its preference for cooperation by its technical, administrative, and financial support of such multi-State cooperative agencies as the State and Territorial Air Pollution Program Administrators and the Association of Local AirPollution Control Officials (STAPPA/ALAPCO), NESCAUM and permanent FederalState-local work groups such as the Standing AirMonitoring Work Group (SAMWG), the Standing AirEmissions Work Group (SAEWG), and the Standing Air Simulation Work Group (SASWG), affiliated with STAPPA/ ALAPCO. This particular provision of the rule is designed to enable the exercise ofcooperative efforts, but does
not serve as the tool to require States to plan and implement programs jointly. Note, however, that section 182(j) ofthe Clean Air ActAmendments of1990 does stipulate that each State in which there is located a portion ofa single 03 nonattainment area which covers more than one State should take all reasonable steps to coordinate, substantially and procedurally, the revisions and implementation ofState implementation plans applicable to the nonattainment area concerned. Also, interstate transport regions established pursuant to section 176A ofthe Clean AirAct Amendments should be guided in multi-State coordination and consistency via the establishment of transport commissions. Further, section 184 ofthe Actindicates that such procedures are requisite forthose northeastern States included in an 03 transport region. These premises have been articulated in an advance notice of how EPA generally intendsto take action on SIP submissions and to interpret various titleIprovisions inthe Federal Register on April 16, 1992, as amendments to 40 CFR part 52. It is therefore inappropriate for EPA to separately require such cooperation as a part ofthese enhanced 03 and 03 precursor monitoring rules. The Agency has,however, modified the rules to Indicate thispreference forcooperation andjoint network design submittal, where appropriate.

One commenter suggested that EPA supportjoint submittals, but not joint implementation schedules. In §58.40, EPA indicates a preference for coordination, but does not necessarily require identical designs and implementation schedules for cooperating States. Differences in designs and schedules would be evaluated on a case-by-case basis.

One commenter recommended that regional plans be given favorable ifnot at least equal attention as isgiven to State-by-State plans within the same regional area. EPA has previously expressed its preference for regionally coordinated network designs, but must provide equal consideration to both types ofdescriptions allowed by these rules.

Two commenters suggested that the approval ofthe PAMS program be relegated to the Regional Offices in lieu ofrequiring approval bythe Administrator. In considering this comment, EPA agrees with the contention ofthe commenter that the Regions are more familiar with the idiosyncrasies ofeach 03 nonattainment

area and, as aresult, Regional Office

concurrence on each network design is required. In several cases, however, the

areas subjectto theserules, cross both State and EPA Regional boundaries. The Agency is convinced that a program of this magnitude requires intensive national oversight and a high degree of consistency and coordination; final approval must therefore rest with a central reviewing authority.

Two commenters suggested that flexibility be included to allow each network to be designed on acase-bycase basis because each area has unique features such as irregular terrain or distinct meteorology, such as sea/lake breezes, which should be addressed separately. EPA alsobelieves that each

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ares's network design shouldbe specifically tailored to fit that particular

area orregion, The network design parameters promulgated today are those considered by the Agency as a minimum and/or a default network for those Stateagencies wishingto omit .comprehensive, area-specific planning exercises. Although EPA does not recommend minimizing planning, the Agency recognizes that State resources and technical-epertise often demand a

- fallbackposition in lieu ofextensive investments inthe planning process. Note that the Agency isrevisingthe sitingcriteria guidance document (Reference 19 ofAppendixD) toprovide guidance on siting and network design forareas with complex terrain or unique meteorology.

One commenter recommended that a working group be established todeal with the coordination ofmonitoring strategies and network designs inthe Northeast Ozone Transport Region. The
commenter recommended two specific
groups associated with electric utilities,

as technical resources for such a working group. EPA maintains that the responsibility forthe implementation, and therefore the coordination, ofSIP strategies lies-with the States. The Agency is therefore cooperating with NESCAUM, MARAMA, and the Regional Ozone Modeling for Northeast Transport (ROMNET) committees to form a working group of State, local, and EPA officials to provide guidance in the development ofacoordinated monitoring network for the Northeast.

Another commenter encouraged EPA
to perform quantitative statistical analyses to ensure that the minimumrequired network is sufficient to corroborate emission inventories and determine precursor trends. Due tothe emerging nature ofthe technology for corroborating emission inventories and procedures for determining precursor trends, it is not feasible at this time to perform quantitative statistical analyses forthis purpose. EPA believes, however, that these analyses can be performed effectively once the PAMS networks are in place and producing data. Adjustments based on these analyses will be appropriate when the procedures aremore mature and the data bases are morecomplete. To shed light on these comments, EPA has .prepareda Data Quality Objectives (DQO) document which was used to evaluate the original network proposal ofMarch 4, 1992, and this modified final rule. That document is identified as'reference 24 ofappendix D. Additionally, EPA supported and/or noted other analyses concerning data for emissions inventory applications and trends. Those studies are noted as references 26, 27, 28, 29, and 30 of appendix D.

Several commenters pointed outthe need forEPA tobetter articulate guidance onthe submittal of information fornetwork approval and
any criteria EPA would utilize for approval ofthese and any alternative network submittals. Furtherinformation concerning network design is included in section 4ofappendix D.EPA has also incorporated additional information and criteria regarding the approval of alternative networks in section 4 of appendix D asa part ofthis promulgation.

During the comment period, several agencies submitted proposals fortheir

areas which are considered tobe alternativenetwork descriptions. EPA will review those designs individually and respond directly totheparticular
agency. Those designs are not considered germane to therequirements oftheregulation and so are not specifically reviewed in thisnotice of rulemaking.

One commenter urged EPAto eliminate thepublic notice

rumirements ofalternative plans and subject them tothe sameprocess as other network designs. EPA realizes that although it istoday promulgating minimum criteria for PAMS networks,
many designs will have peculiarities which may qualify them as alternative networks and subject them tothe proposed public noticerequirements of §58.40 and further, sections 4.3 of appendix Cand 4.2ofappendix D.To facilitate the submittal ofnetwork descriptions and to expedite their processing by the Agency, EPA is today removing the proposed requirements for public notice for alternative network descriptions and will instead focus

resources on improvingthe quality of thenegotiation, review and approval

process.

One commenter noted that it may be necessary to site PAMS monitoring stations near major roadways and certain large stationary sources because ofthepossibility oftheir direct influence on local concentrations of03. The regulations promulgated today require the siting ofcertain monitors at the location ofthe maximum impact of emissions from sources of03
precursors. EPA recognizes that in some instances this site maybe substantially affected by one or more verylarge major stationary sources whichconstitute a principal source of 3precursors for the nonattainment area. Additionally, ifthe major impact on 03 in a particular area originates from mobile sources, It would be logical toplace aPAMS site

- downwind ofa major roadway. In any case, itiscrucial to consider and
account for localNOx sources including roadways which may act as local • depressors for 03 when designing a network as described in section 10of appendix E.

6. Public Comments-Section 5&42- PAMS Approval

Note that comments submitted recommending approval ofnetwork designs at the EPA Regional Office level

were previously addressed under §58.40.

One commenter invoicing support of the flexibility of allowing alternative plans noted that their agency doesnot feelthat national consistency and uniformity ofmethods are essential, given that different areas are at different levels oflearning withrespect to their area's 3precursor composition and concentrations. EPA notes that each air pollution control agency program is subjected to its own particular set of problems, strategies, limitations, and
coverage; in many cases some ofthese factors are quite unique. EPA, on the otherhand, must deal withnational databases and national problems under

an entirely dissimilarset oflimitations than any particular airpollution control
agency. To that end, EPA ischarged with ensuring some reasonable degree of national consistency so that national trends, comparisons, and strategies can be devised. Further, the Agencyis convinced that during the phase-in period specified in section 4.5 of appendix 1, most agencies willbe capable ofrisingtothechallenge of developing thenecessary expertise to 'operate PAMS.

Concerning the approval ofnetwork designs, one commenter recommended that this section (and specifically section 4.2 ofappendix D)be revised to require an EPA approval ordisapproval within 60 days ofthe receipt ofan alternative plan. Although EPA notes this commenter's sense ofurgency with regard tothe approval and 'implementation ofthe PAMS monitoring program, the Agency has determined that instituting artificial approval deadlines would notprove beneficial toimproving the quality of alternatives, nor would the public be served by imposing restrictions which could result in lowering the quality of the review and approval process. EPA has therefore not incorporated this 60- day deadline.

7. Public Comments-Section 58.43- PAMS Methodology

Onecommenter suggested that additional language be added tothe 

### 84598460 Federal Register / Vol. 58, No. 28 / Friday, February 12, 1993 / Rules and Regulations

rules to establish a process bywhich EPA could streamline the review and approval ofinnovative monitoring and analytical techniques. Further, this
commenter recommended the use at PAMS ofa particular new type of monitor which continuously tracks key photochemical oxidant components. The Agency believes that the new requirements provide sufficient flexibility for the incorporation of innovative monitoring and analytical techniques. The Atmospheric Research and Exposure Assessment Laboratory (AREAL) is currently responsible forthe development, evolution, review and testing ofnew methodology to ensure its applicability and appropriateness for emerging national air monitoring needs. Regarding the use ofthis new measurement technology for photochemical oxidant tracking, AREAL, in conjunction with other interested parties, is engaged in an evaluation study ofthe proposed instrumentation to determine its utility in depicting the photochemical process. Additionally, research isunderway to ascertain the usefulness ofthe data gathered by thisinstrument and others inmeeting necessary 03 control objectives such asthose described in thisrule. The results ofthese investigations will likely have a significant bearing on the future uses of the proposed instrumentation. In any case, neither the current research status ofthe procedures nor the innovative
nature ofthe methods preclude theiruse at PAMS stations. A State air pollution control agency may, at its own initiative, implement thismonitoring strategy as an adjunct to the minimum PAMS requirements; or, may submit a sampling scheme utilizingthis technology exclusively, for consideration by EPA as an alternative pursuant to §58.40 ofthisregulation.

8. Public Comments--Section 58.44- PAMS Network Completion

Ten commenters provided observations regarding the 5-year transition (phase-in)period further delineated in section 4.5 ofappendix D. Four ofthose respondents indicated that total implementation ofthe program

was not only possible, but also desirable in a 2- to 3-year period. One commenter, however, in supporting a 3-year transition, indicated that the reporting ofVOC data should be deferred for 5
years due in greatpart to the technical, financial,.and technology issues associated with VOC monitoring. Four ofthe ten commenters also characterized the urgency ofexpediting the implementation ofPAMS to provide data support to the 1994 SIP photochemical grid modeling process. Five commenters indicated that the 5-
year schedule isreasonable or atleast ambitious, although two ofthese respondents suggested that the initial phases ofthe transition be either deferred or prolonged, essentially to allow fortesting and evaluation ofthe

new monitoring technologies and for training ofprofessional staff.One
commenter suggested that due to technology issues, the implementation simply be delayed one year.Five ofthe
ten commenters reiterated their

concerns with funding and urged EPA

to provide substantial, adequate

resources to complete the PAMS transition. One additional commenter urged EPA to allow sufficient flexibility for States tophase-in the program over time in a manner consistent with the level ofavailable resources.

Due to expected near-term changes to the atmospheric mix of03 precursors and the needto begin monitoring as

soon aspracticable to provide ameasure of support to SIP strategy development and emission inventory corroboration efforts, EPA believes that deferral of implementation is not a preferred option. Accordingly, the Agency is continuing efforts to support FY-92 and FY-93 PAMS-type monitoring initiatives via the Section 105 Grant
process. Noting, however, the real

concerns ofState and local air pollution control agencies regarding the phase-in details, EPA is, inthis promulgation, reconfirming the transition requirements, previously proposed, of

one station per year and modifying the requirements to include provisions for flexibility.

9. Public Comments-Section 58.45- PAMS Data Submittal

Seven respondents expressed the opinion that the 6-month time period allowed by §58.45 isreasonable and adequate for the submittal ofVOC data. Three ofthese commenters indicated that allowing a reporting deadline of9 months to a year forthe first 2 years or

so ofthe program would be preferable. This data phase-in would then allow added time for training inthe implementation and interpretation of data and the data acquisition system. The final rules stipulate that the VOC data mustbe reported within 6 months following the end ofeach quarterly reporting period. Since the PAMS minimum monitoring season runs from June through August and encompasses two quarterly reporting periods, the June data would notbe due until January I ofthe following year, and the remainder ofJuly and August data would notbe due until the following April 1.The'Agency believes that when the systems ofdata analysis, handling, and reporting are routinized, these time periods willbe more than adequate for VOC data reporting. The Agency understands, however, as States begin to wrestle With new personnel and technology, that even such a reasonable reporting deadline maybe difficult to
meet during the initial years of implementation.

One commenter questioned the need
to delay submittal ofthe meteorological data past the time period.required for submittal ofthe NOx and 03 data. EPA
agrees that the measurement and data handling technology for meteorological parameters iscurrently sufficient for States to be capable of submitting such information on amore expedited schedule.The Agency recognizes, however, that the uses for such data in photochemical modeling, receptor analysis, and emissions inventory functions, generally requires integration with the VOC data. Since the utility of expediting this data submittal would be only marginal, EPA has required that the meteorological measurements be submitted on the same time schedule as the VOC data.

Concurrent with the development of the photochemical assessment monitoring proposal ofMarch 4, 1992, EPA was considering a modification to the data reporting requirements for SLAMS and NAMS monitoring as iterated in §§58.26 and 58.35. The stipulation for 60-day reporting for 03, NO, NO2,and NOx, outlined in § 58.45(c), was patterned after the changes to the draft requirements for NAMS, since atthat time it was expected that these otherrevisions would be complete. Since the revisions
to NAMS and SLAMS requirements have not yetbeen proposed and subjected to public comment, EPA today ispromulgating a modification to §58.45(c) which would cause these pollutants to be reported on an identical schedule to that stipulated in §58.35 for NAMS. Changes to the reporting schedule for all monitors will thus be considered in a separate Federal Register notice at a later date. This modification would alsobe consistent with the comments from two ofthe respondents.

Two commenters expressed the belief that EPA should make agreater commitment to assist the States in developing and implementing VOC data acquisition andprocessing systems to

ensure timely compliance withthe 6- month requirement for VOC data submittal.An additional commenter expressed a similar concern, that given the large data handling requirements,Federal Register / Vol. 58, No. 28 / Friday, February 12, 1993 / Rules and Regulations 

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the 6-month limitation would be difficult to meet. EPA has sponsored parallel projects involving the acquisition, processing, analysis, and interpretation ofVOC data which may provide needed assistance to States in the handling ofthe massive VOC data base. Further, theAgency has revised'its PAMS cost estimates upwards to consider the necessary costs ofVOC data acquisition and processing and is considering the inclusion ofadditional guidance in the technical assistance document (Reference 2 ofAppendix C).

One respondent suggested that a target list ofVOC species should be developed and augmented with a shorter priority list forreporting. EPA
notes that such a target listhas been published by the Agency in reference 2 of appendix C,but believes that placing limits on reporting via a priority list is premature and would in nocase be universally applicable.

Two commenters pointed out the immediate need tomake appropriate changes to the Aerometric Information Retrieval System tAIRS), the national ambient air monitoring database, to accommodate the new PAMS data elements. EPA has incorporated such changes to AIRS.

One commenter suggested that §58.45(d) be reworded to allow the monitoring and reporting ofNMHC (non-methane hydrocarbons) in lieu of VOC. Note that this issuehas been previously addressed in comments pertaining to §58.20'.

10. Public Comments--Section 58.46- System Modification

One commenter stated that they believe that changes in attainment status should not reduce the requirements of the PAMS and that monitoring should continue to be funded by EPA. A second
commenter suggested that once an area demonstrates attainment ofthe 03 NAAQS, EPA should either reduce the PAMS monitoring requirements or

assume responsibility forthe PAMS funding in that area. EPAbelieves that continued PAMS monitoring, even after

a demonstration of attainment is performed, will be crucial to maintaining the 03 NAAQS overtime. Nevertheless, ifa State can demonstrate that itcan properly track unexpected changes in the ambient VOC mix and emission inventories, while maintaining the NAAQS, it may propose changes,

even reductions, in its PAMS monitoring network as stipulated by §58.46(b). EPA-is not authorized to accept a cessation ofPAMS monitoring, however, until an area is redesignated to attainment. EPA has demonstrated its willingness
to provide substantial funding to States for ambient air monitoring activities via the section 105 Grant process. Although the Agency is predisposed to continue
to contribute to ambient air monitoring
programs such as PAMS, it is ofcourse subject to the limitations ofsection 105, in part described in the Resources and Costs section ofthis Preamble.

One commenter felt that the annual network review should be conducted and approved by the Regional Administrator. EPA notes that the network review for ambient air monitoring systems described in §58.20 is currently conducted and approved annually by the appropriate EPA Regional Office. Section 58.46 articulates anational approval process forchanges to PAMS networks similar
to that required for NAMS and referenced in §§ 58.32 and 58.36. National data needs and consistency dictate Headquarters EPA approval for changes inboth cases.
11. Public Comments-Appendix AQuality Assurance

All five commenters on this section p'ointed outthe explicit need for a specific, uniform, improved system of quality assurance (QA) for the VOC sampling and analysis requirements (especially) mandated by PAMS. One respondent added the following three recommendations for anational QA
program: (1)The establishment of uniform QA criteria including calibration schedules, duplicates schedules, blanks schedules, (2)the establishment ofstandardized audit procedures, and (3)theestablishment of laboratory audit samples and an interlaboratory exchange program between States and EPA laboratories.

EPA is aware thatthe PAMS sites will require aQA program similar to the one

nowused for SLAMS criteria pollutants. EPA is currently developing the audit materials and QA guidance required to establish such a system for the pollutant monitoring systems that will be located
at the PAMS sites.These materials for the VOC measurement systems are being developed in conjunction with the evaluation study EPA is now conducting on the candidate VOC instrumentation foruse at PAMS sites. This study is briefly described in the public comments on 858.43-PAMS Methodology. Additionally, EPA plans
to provide VOC samples to the State and local agencies operating PAMS sites to assist them in validating their VOC monitoring systems and the performance ofthe personnel operating these systems. 12. Public Comments-Appendix CMonitoring Methodology

Five commenters recommended that equivalency ofmethodology mustbe established at least on a regional level and perhaps even nationally. Several
commenters went so far as to recommend that EPA develop federal reference and equivalent methods for VOC. Further, several commenters reiterated their perception ofthe need for routine inter-State, inter-area quality

assurance procedures. Given that the complexity ofthe technology for VOC sampling and analysis and its rapid rate ofdevelopment and change, EPA has chosen topublish specific guidance for monitoring methodology in lieu of publishing federal reference or equivalent methods. Such guidance has been published and is available as reference 2 ofappendix C.The Agency will track the progress ofthe development ofnew methods and will reconsider the specificity ofmethods in the future. EPA agrees that common and continuing, orat least comparable, methodologies are desirable on a regionwide basis. Comparability ofdata will be one factor used by the Agency in approving coordinated, region-wide network designs.

One commenter pointed outthat the rules should not preclude the expansion ofthe monitoring period to longer than 3 months, noting also that the length of the monitoring season is not necessarily proportional to the total network operational costs. EPA notes that provisions for changing the monitoring period are promulgated today In section 4.3 ofappendix D. EPAagrees withthis respondent that monitoring periods should be consistent across aregional network. This factor would also be scrutinized when approvingjoint networks. EPA recognizes the role that the length ofthe monitoring period plays in the computations oftotal costs and has weighted that role accordingly.

Onecommenter felt that EPA should specify a particular chromatographic column foruse on gas chromatographs (GCs) analyzing forthe various VOC. Reference 2 ofappendix C specifies those column characteristics which AREAL believes are necessary to produce meaningful data on the target VOC compounds. The laboratory even goes so far as to provide specifications

on several acceptable columns, but falls short ofrequiring achromatographer to choose any one particular design. EPA reiterates its position that the technology forVOC sampling is simply evolving too quickly to allow such specificity at this time. 8461,8462 Federal Register / Vol. 58, No. 28 / Friday, February 12, 1993 / Rules and Regulations

Onecommenter believed that the VOC monitoring technology is not yet advanced enough for State and local agencies to economically operate a speciated VOC monitoring program. As previously stated, the Agency believes that States are capable ofcompetency in utilizing new monitoring methods, and in fact a number ofState agencies are currently employing such emerging techniques with success. Per this commenter's suggestion, EPA is providing significant financial and technical assistance for implementation ofthis technologi.

In a related issue, acommenter suggested that the rules should tighten the equipment design and performance standards for VOC in order to drive the technology. Noting the progress made to date by theresearchers, designers, and fabricators ofVOC sampling equipment, EPA believes that the existing technical specificity and market pressures are sufficient to spark development in new and emerging sampling and analysis methods. One other respondent
encourages the development of less labor-intensive methodologies to counter the specter offuture resource constraints. AREAL has continued to articulate its support for such efforts and will continue to exercise flexibility in investigating new, more economical, and uncomplicated procedures as recommended by yet another

commenter.

Onecommenter felt that EPA should append the provisions ofthe rules (and particularly appendix C)to facilitate and encourage the use ofinnovative analytical technologies which are useful for 03control strategies. Although EPA is investigating the use ofsuch innovative monitoring technology, and specifically the technology recommended by thiscommenter the Agency hasnot yet determined howthe

use ofthese sampling methods will fit into thecurrent SIP process. Nevertheless, EPA does not wish to preclude the use nor discourage the development ofnew monitoring technologies and so has amended the language ofappendix C accordingly. In

a related issue, a second commenter was concerned that the stipulations of section 4.2 ofappendix C required the

use ofreference orequivalent methods for the monitoring ofNO and NOx at PAMS. This respondent recommends the use ofmore advanced and sensitive methods for such monitoring. EPA notes that in great part, the use ofthe NOx data measured atPAMS is dictated by the need forprecursor information rather than for comparison with the NO2 NAAQS. Since the Agency does not wish to preclude the use ofpotential innovations or more sensitive monitoring devices for eitherVOC or NOx, It has therefore added additional language to sections 4.2 and 4.3 of appendix Cto indicate that such other methodology may be proposed by the State asalternatives. Further,although the Agency has determined that such

new technologies may be proposed and

even encourages and recommends their

use, It is premature to make their use a requirement.

One commenter specifically raised a number oftechnical questions for consideration by EPA. In response, EPA has determined that pressurized and nonpressurized canister samples are equivalent and that drying ofsamples prior to analysis to reduce water content is an acceptable procedure. Additionally, the Agency notes that an 03 scrubber isrequired on the carbonyl samplers, and C-18 cartridges are equivalent to silica gel cartridges for such analyses. Guidance on standardization protocols (whatgas, how many points, what concentrations?) will be addressed in future revisions to the Technical Assistance Document for Sampling and Analysis of 03 Precursors (EPA 600/8-91-215). Further detail concerning such information may be found inreference 2 ofappendix C.

13. Public Comments-Appendix DNetwork Design for SLAMS, NAMS, and PAMS

The following discussions address the
comments received on specific provisions to appendix D:

14. Public Comments-Section 4.1 of Appendix D-PAMS Data Uses

Five commenters expressed concern that the PAMS program mightbe insufficient for thepurpose ofverifying emissions inventories. One suggested that further flexibility be built into the regulation since techniques for inventory verification are still inthe developmental stages. Further, two
commenters expressed conflicting views in the use ofair quality data and/or emissions inventory data for the tracking of emissions reductions over time. The use ofair quality data, and especially that ofphotochemically reactive species, isadmittedly an evolving science. EPA does believe, however, that such data have been demonstrated to be a constructive adjunct tool to emissions inventories in qualitatively verifying their accuracy and serving as a corroborative instrument to calculations ofreasonable further progress (RFP)in reductions of emissions (See References 26-30 of Appendix D). Note that the Clean Air Act clearly stipulates that RFP is defined viareductions ofemissions rather than progress in air quality
measurements for precursors or fox 03. Emissions inventory reduction calculations musttherefore persist as the primary tool forevaluating both
progress andreductions. These facts do

notlessen the importance, however, of ensuring that those calculated values are corroborated by actual air quality
measurements. EPA would be remiss if it allowed the disregard ofair quality information injudging the adequacy of State Implementation Plan performance. The Agencynotes that since the inventory corroboration techniques are not specified or limited by this section, adequate flexibility is incorporated in the rule.

In a related matter, one commenter suggested thatEPA has not shown the correlation oftarget listcompounds to actual emissions inventories and
proposes that continuous NMOC monitoring in conjunction with integrated canister samples would be a better indicator ofemissions inventories. As previously iterated, EPA is promulgating rules which can be applied nationally as a minimum requirement. The Agency recognizes and clearly articulates that the PAMS network requirements are designed to provide information which can be used in maximizing the utility of anumber of data objectives. Were a commenter to demonstrate that their particular method ofmonitoring is superior to PAMS for one data use, it is possible that further scrutiny would reveal that it is not ideal for the remainder. Air pollution agencies are not precluded by the rule from instituting monitoring strategies additional to the PAMS minimums or proposing alternatives

more tailored totheir particular geographic area. Similarly, one commenter was concerned that the
program may not fulfill the needs for SIP control strategy evaluation and suggests that modeling is the preferable tool forthis purpose. The Agency agrees that modeling is the more appropriate tool to determine the potential forthe

success of aproposed SP strategy; however, the Agency asserts that knowing what changes actually occurred in the ambient air is an extremely useful measure ofthe true effectiveness ofany control program.

Two commenters indicated the need for the Agency to publish a data uses guidance document. They imply that such a document should expound on the details ofhow the data generated by PAMS can be used to meet the data objectives. One respondent complained thatIt currently does nothave a program that can use the data providedFederal Register / Vol. 58, No. 28 / Friday, February 12, 1993 / Rules and Regulations

by the PAMS. EPAhas prepared documents dealing with the data quality objectives (DQOs) for the PAMS
program. Additionally, other demonstrations ofthe continuing use of such data are noted as references 26-31 ofappendix D. Further, in response to these comments, minor revisions have been made to clarify section 4.1 of appendix D. Those State agencies which have recognized their lack ofability to

use these important data may employ the additional section 105 Grantmonies made available forPAMS toward enhancing their data processing and analysis capabilities.

Fourrespondents noted that although

some ofthe stated objectives forPAMS support application ofphotochemical grid modeling techniques, the network design does not seem to effectively accomplish this feat. Further, three
commenters protest that the network specifically does notmeet the data requirements oftheir State's photochemical modeling protocol. EPA has reexamined the overall data needs ofthe photochemical modeling -community and has modified the network to be more responsive. Since the Agency is attempting to ensure that PAMS is compatible with national needs, particular States may find that the requirements provide better data than needed to execute a minimal modeling run or thattheir particular model application demands other information notmeasured by PAMS. In the latter case oras one commenter noted, when more intensive data is needed, the State is free to measure those additional parameters which they feel are necessary to drive and/or evaluate future model applications.

. One commenter questioned why the methodology to determine air quality trends is not specified in the rules. This respondent joined with another to point
out the need to address and eliminate the variability ofair quality data due to meteorology. EPA maintains that a rule which specifies monitoring requirements and network design, is not

an appropriate vehicle to promulgate particular statistical techniques for calculating or presenting trends analyses. Given the variety ofsuch techniques available to the State and local air pollution agencies today, it would be nearly presumptuous or EPA
to attempt to limittheir ability to analyze their own data via rulemaking. The absence ofspecific trends requirements allows the States to retain the maximum flexibility and employ the
most appropriate state-of-the-art analysis techniques. Clearly, there are two basic concepts which may be employed in preparing trends analyses: (1)Displaying unadjusted
measurements which portray the quality ofthe air actually breathed by the public, or (2) calculating adjusted trends
to infer progress towards attainment of standards due to the influences of pollutant control programs. In either

case, the cornerstone ofthe analyses are the actual air quality and meteorological
measurements such as those required by PAMS. Particularly, for evaluating the effectiveness ofcontrol programs, it may be appropriate to integrate such factors

as meteorology and emissions inventory data. EPA simply disagrees thatthis rule is the correct forum to expound on specific procedures for the analysis of pollutant trends. Trends techniques utilized by EPA for criteria pollutants have appeared perennially inthe Agency's National Air Quality and Emissions Trends Report. Frther,EPA is currently evaluating techniques for improving the effectiveness of 03 control strategies including indicators for assessing progress. This work will address techniques forintegrating meteorology, emissions, and ambient data.

The second commenter concerning trends went further to question whether

ornotthe 5-site PAMS network is sufficientto conduct 03 and 03
precursor trends analyses. Since PAMS sites are located to detect particular characteristics ofthe air quality, such as maximum 03 or upwind transport, the 5 sites have been determined by EPA to be the minimum network necessary for larger areas to encompass specific situations ofinterest. Experience with the NAMS network requirements has shown that some areas may choose to supplement this minimum network to meet their own objectives. EPAhas decided that the 5-site network represents aminimum core requirement which will provide a consistent and stable database to be used fortrends. Additionally, the Agency notes that for

areas which submit coordinated, joint network designs, it is expected that

more than 5 sites will be established and become available fortrends analyses.

One commenter noted that sampling sites located to measure either VOC or air toxics impacts may notbe an optimal location for the other. EPA has previously articulated its view on this matterin this preamble's discussion of Resources and Costs.

One commenter vociferously criticized the basic tenets ofthe PAMS
program and professes that a successful PAMS program can be cultivated via a program ofless-frequent focused sampling for generalized precursor data (e.g., NMOC) with a minimum of speciation information. Theybelieve that their experience with thistype of
program has been largely ignored in designing the PAMS program. EPA again observes that a program which has been simplified ormerely focused to meet the specific data needs ofa particular locale, may not be approiiate to fulfill the data uses for a national program which is generally routine 03 precursor data-poor. Nevertheless, the opportunity is provided by section 4 ofappendix C and section 4 ofappendix D for the approval ofsuch focused alternative networks in accordance with §58.40, especially where significant historical precursor monitoring data are available. The adoption ofdifferent or more comprehensive requirements, as discussed further in the Agency's
response to comments on §58.42, does
not imply deficiencies in an existing monitoring program. EPA's program simply highlights that national needs

are often different and more inclusive than local needs.

15. Public Comments--Section 4.2 of Appendix D-PAMS Monitoring Objectives

Fourrespondents revived the issue that the sites chosen for PAMS would
notnecessarily constitute appropriate locations forthe monitoring ofair toxics. Further,these commenters seem to support a separate and expanded air toxics monitoring effort. As noted by EPA in the discussion ofresources and
costs in thispreamble, the Clean AirAct Amendments call for a network which is geared towardthe monitoring of photochemical parameters. The Agency
agrees that PAMS may notbe the ideal platform for monitoring air toxics, but eels thatthe establishment of additional air toxics monitoring at these sites is a valuable adjunct to the PAMS
program. Separate national air toxics monitoring networks are not currently a highly-ranked, nationally mandated priority.

Two additional commenters requested that the Agency continue its efforts to define and monitorNO,. EPA previously expressed, in addressing
comments to §58.1, its reluctance to rush the regulatory and monitoring
program forNOy. EPA will continue its investigations ofthis concept and will
propose future revisions to 40 CFRpart 58 ifappropriate.

One commenter espoused the importance ofmeasuring VOC aloft. EPA has previously indicated its reluctance to require this monitoring in the discussions ofthe general
comments. 8463

### 8464 Federal Register / Vol. 58, No. 28 / Friday, February 12, 1993 / Rules and Regulations

The same commenter felt that rural sites for thecollection ofboundary condition carbon monoxide (CO)and NOx datashould be added to the PAMS program. EPA also has recognized the importance of including sites thatwill better define boundary conditions. Consequently, section 4.2 ofappendix D and its associated Figures have been modified to betterreflect the
measurement ofboundary conditions. Note that since CO was not addressed in section 182 ofthe Clean AirAct Amendments as a required pollutant for PAMS, no monitoring requirements for CO were included. This omission does
notpreclude a State from adding CO monitoring to its network design.'

One commenter believes that due to the effects ofcomplex meteorology, the placement ofPAMS sites should be

ased more on studies ofpast 03 episodes rather than the generic model proposed by EPA. The Agency agrees in principal with thiscomment and has alteredthe location ofthe PAMS sites to correspond more closely with the wind conditions associated with 03 events.

One commenter requested that EPA provide more specificity forlocating PAMS type (2) sites, the sites where maximum emissions are expected to impact. Inresponse, EPA has clarified and added additional detail forthis site'slocation.

One commenter was concerned that
many oftheir current NAMS and SLAMS monitors are not located at potential PAMS sites. EPA notes this

concern and considered that some, but
not allPAMS sitesmight be coincident with SLAMS orNAMS in its recomputation ofcost estimates. Reference is made to a similar discussion under General Comments and Resources and Costs in this preamble.

One commenter also requested that existing data be allowed to be used as

a partofalternative PAMS monitoring schemes. Note as discussed in §58.40 that EPA has amended section 4.2 of appendix D to include broad criteria for the approval ofalternative networks. The use ofexisting information and existing monitoring networks is not precluded bythese changes to the rule.

16. Public Comments--Section 4.3 of Appendix D-Monitoring Period

Ten commenters expressed opinions regarding the length and specificity of the monitoring period forthe PAMS. Three of thoserespondents supported the proposed requirement of 3 months, especially June,July. and August, although they indicated that more sampling would obviously be better, that consistency across regions is crucial, and that more specificity would beuseful. Three others indicated that they felt that the 3 month period was too short and would create staffing problems for affected State governments with a minimal cost savings over sampling for longer periods such as the entire 03 season. One ofthese
commenters asserted that 5 months would be abetter choice, especially in the State ofCalifornia. Five commenters believed that employing 03 level forecasting and episode monitoring wouldbe a more efficient use of

resources andprovide amore intensive database forthe critical periods and could make better use ofmanual sampling methods. One commenter felt that the length ofthe sampling period shouldbest be specified on a regional basis and that while a 3-month period would likely capture the majority of episodes inthe Northeast, such aperiod would be insufficient forthe South and West.

EPA agrees that more than 3-months would be preferable and has articulated this opinion in section 4.3. The Agency has recognized, however, that other particular months rather than June, July, and August may, on a case-by-case basis be more appropriate. Accordingly, EPA has expressed its intent to allow other monitoring periods ifsubmitted and approved as a part ofthe network description required by §58.40. inthe discussion concerning comments to § 58.40 inthis preamble, EPA has clearly espoused its support for coordination and consistency among States and across regions and noted that other requirements ofthe Clean Air Act Amendments mayrequire such coordination, in this case in establishing 'the monitoring period forPAMS. The Agency's goal in choosing the 3-month period was to attempt to capture the highest03 evetts for the year.The Agency has established only a minimum sampling period; any affected State or region may expand thisperiod to a" longertime to meet its particular needs. Flexibility has been included in the rule
to allow the use ofeither manual or continuous sampling technologies. Given that the Agency recognizes the utility and efficiency offocussing its efforts on 03 events, section 4.4 sampling requirements have been amended inthis promulgation to allow the sampling for such events and as an option make theuse ofmanual methods

more feasible. A discussion ofthose changes follow under section 4.4. EPA has included astipulation in section 4.3 that intermittent sampling must follow the previously-established national schedule forintermittent sampling such as the one-in-six-day schedule used for particulate matter.

17. Public Comments--Section 4.4 of Appendix D--Minimum Network Requirements

Twenty-four commenters responded
tothis section ofthe proposed rule concerning the details ofPAMS network sampling and design. Eleven ofthose respondents specifically indicated their

concern that theproposed requirements for VOC sampling were excessive and the rule should be amended to allow less intensive sampling. Many suggested that such a less-intensive sampling
program would save funds which could bebetter allocated for other purposes, upper atmospheric monitoring for example. Several commenters included suggested sampling plans for implementation in lieu ofthe proposed schedule. Six commenters believed that

abetter use oflimited resources would be to focus VOC monitoring on days when high 03 levels would be expected

orforecast. EPA has examined the proposed optional sampling schedules, considered the economic impact ofthe schedule, revisited the current state of the monitoring technology and has concluded that it is appropriate to make

a number ofchanges to the minimum sampling schedule forVOC. To respond
to the data needs of the Agency and the State and local air pollution control agencies, EPA has decided the following: Sampling schedules forNO, NO2,NOx, 03 and surface meteorological parameters remain unchanged. EPA has determined that the minimum requirements forpollutant sampling will continue to mirror those for gaseous criteria pollutants, (i.e., continuous measurements). The minimum sampling period for
precursors is designated as three months, specifically June, July, and August unless a different 3-month period is proposed by the State and approved by EPA. The minimum sampling period forozone remains for the entire ozone season. The Agency has added an option forVOC monitoring at sites otherthan PAMS type (2) sites. In lieu ofone in 3-day sampling (as stipulated by Frequency A-in section 4.4 ofappendix D), a State may substitute monitoring before and during03 events

asspecified by section 4.4 ofappendix D plus one in 6-day sampling. Since the Agency is not promulgating a preferred
event forecasting method, each State choosing this option (identified as sampling Frequency C by section 4.4 of appendix D), must submit an 03 event forecasting scheme as apart ofthe PAMS network description as delineated in § 58.41. States or areas

### Federal Register / Vol. 58, No. 28 / Friday, February 12, 1993 / Rules and Regulations -8465

proposing thejoint submittal ofnetwork descriptions and choosing this option should include a strategy forensuring a coordinated, network-wide -esponse to O3 event monitoring. Such achange in focus to event monitoring will also increase the feasibility ofutilizing manual sampling methods as requested by several commenters.

Also inresponse to these concerns and in order to ensure the collection of data sufficient to conduct emission inventory verification and reconciliation exercises, establish source-receptor relationships, corroborate reasonable further progress (RFP) calculations, and produce meaningful precursor trends analyses, the proposed PAMS type (3) site has been changed to an additional PAMS type (2) site. To respond to other photochemical modeling concerns, the proposed PAMS type (5) sitehas been moved downwind of thenew type (3) site andrenumbered PAMS type (4). Responding to observations by six
commenters that sampling schedules shouldbe standardized to promote data comparability among parameters, carbonyl sampling requirements have been amended tomore closely coincide with the required frequencies forVOC.

Eleven respondents suggested alternative locations or numbers of PAMS sampling stations.There was considerable variation among the suggested options, with several commenting that more sites were needed, others notingthat specific local terrain and meteorological effects require different station placement. Five respondents in particular recommended that the collected data should be more responsive to theneeds ofthe photochemical grid modeling process. EPA hasclosely surveyed the specific data needs engendered by the program objectives, especially the necessity to provide a measure ofsupport for photochemical gridmodeling, and has concluded that further clarification on the location ofthe PAMS sitesis requisite. Accordingly, EPA has provided detail regarding the use of particular high 03 daywind data,rather than general seasonally-predominant winds, forthe location ofpotential PAMS monitoring sites.Further the Agency has provided guidance in reference 19 ofappendix D to aid in specifying the location ofsites, particularly sites type (2), when there

are no predominant high 03 day winds which can be accurately identified. Also, the Agency has relocated the upwind and downwind sitesto correspond more appropriately to the data needs forphotochemical grid models and has added guidance on the location ofmonitors, especially site types (3) or (4). in areas ofcomplex terrain, e.g., mountain-valley, coastal,
etc., to reference 19.

One-commenter inquired why there Is

no requirement for a site in thearea of greatest 03 concentration given thatthe rule's objectives include making attainment/nonattainment decisions and characterizing the nature and extent of the 03 problem. EPA notesthat the siting requirements for PAMS type (3) sites and its monitoring objectives as articulated in section 4.2 and secdon 4.4 ofappendix D clearly require its location tobe the maximum 03 monitoring site forthe area.

. Several respondents suggested that the requirement for eachPAMS site to monitor all parameters was not necessary, i.e., that some PAMS sites should be allowed to operate with monitoring conducted for only some of the specified pollutants. EPAhas revisited its PAMS data objectives and has determined this monitoring I requirement should remain unchanged. Elimination ofparameters at individual sites would weaken an otherwise comprehensive database and decrease its utility forfulfillment ofthe PAMS data objectives and future undiscovered data needs.

One commenter, while recommending alternate monitoring technologies for the PAMS, stated that in lieu of monitoring 1-hour averages forVOC monitoring, the sampling of10-minute
average forVOC equivalents or surrogates should be allowed. The technology recommended by this
commenter is currently being scrutinized by the AREAL laboratory to determine its utility in the SIP process

as noted in the discussion of§58.43. EPA has otherwise determined thatVOC monitoring at increments of10 minutes is not practical atthis time.

Several other commenters suggested the use of24-hour and/or continuous NMOC monitoring (with periodic speciation) as an adjunct to oreven as

areplacement for the PAMS speciated VOC monitoring. They assert that the technology for NMOC monitoring is
proven and that the subsequent data are sufficient forthe development and tracking ofcontrol strategies. EPA has considered these arguments and has determined that although some ofthe PAMS objectives may be fulfilled via total NMOC data, the remainder require the gathering ofspeciated VOC
measurements. The Agency has therefore not adopted the use ofNMOC instead ofspeciated VOC as anational requirement as discussed previously under the public comments to 

### §58.20. The PAMS requirements, however, do
not preclude the collection ofadditional NMOC data as an adjunct or forthe submittal ofalternative networks which
propose elements ofNMOC monitoring.

Two commenters questioned the utility ofgathering a 24-hour integrated and speciated VOC sample to supplement the 1-hour speciated VOC samples. EPA notes that given the variations inherent in continuous/IhourVOC measurement technology, the addition ofa periodic 24-hour sample forpurposes ofquality assurance is a prudent and necessary reality check. Additionally, theyear-round 24-hour periodic samplewill provide information on emissions inventories, RFP, and long-term VOC trends and data forexposure assessments.

One State commenter felt that the guidance for regional network design. provided by figure 2 ofappendix D, is
too generic. This respondent suggests specifically that EPA should develop PAMS monitoring network description for the Northeast 03 Transport Region. EPA recognizes the unique nature ofthe 03 problem occurring in the northeastern United States.Further, the Agency agrees with the principle that a strong federal contribution to the development ofa region-wide monitoring network is critical to develop the needed consistency, cohesiveness, and comparability ofthe PAMS inthe Northeast. Accordingly, the Agency has offered and is supplying both technical and financial assistance to coordinated region-wide State and local efforts. EPA doesnot agree, however, that the Agency should, by rule, usurp the State Implementation Plan process established by section 110 ofthe Clean Air Act, nor shortcut the requirements forthe submittal of anetwork description forPAMS. Failure ofa State
to comply with the requirements for submittal ofa SIP could,however, ultimately require EPA to promulgate and implement a Federal "

. Implementation Plan for that State pursuant to section 110.

Several agencies submitted a PAMS monitoring plan which was fundamentally different from the proposed rule and requested that EPA substitute those requirements as the national requirements forPAMS monitoring. EPAobserves that these agencies, being proximate to one another, would benefit greatly by submitting and implementing similar monitoring strategies. In thisrespect, EPA applauds those agencies' efforts toward consistency across a geographical region. On the contrary, however, for the same reasons that the requirements are specifically tailored to the characteristics ofthat particular8466 Federal Register / Vol. 58, No. 28 / Friday, February 12, 1993 / Rules and Regulations

region, the Agency does notbelieve that it would suffice asa national minimum
program.
18. Public Comments-Section 4.5 of Appendix D-Transition Period

Sixcommenters responded to this section, with varying points ofview, although mostwere discussed as part of the debate outlined in §58.44. Additionally, however, two commenters suggested that the early years ofthe program requirements should not be overly prescriptive and that areasbe allowed to build up their programs over 'time, intimating that technology changes and resource needs could be * phased in along with the monitoring
program. In response, EPA has incorporated additional transition period flexibility as iterated in the discussion of§ 58.44.

19. Public Comments---Section 4.6 of Appendix D-Meteorological Monitoring

Sixteen commenters provided observations regarding the meteorological monitoring requirements proposed by section 4.6 ofappendix D and further stipulated by reference 2 of appendix C.Eleven of these respondents indicated support for the collection of
upper air meteorological data in each
area, especially ifhigh quality upper air data are not currently available. Several supported this suggestion with notations that the photochemical grid models demand such data. One commenter, although recognizing the need forupper air monitoring, advised caution and deferral ofsuch requirements due tothe current state of atmospheric sounding technology. EPA has investigated the merits and projected costs ofupper air meteorological monitoring and has concluded that the benefits of incorporating arequirement forupper air measurements are substantial. In response, therefore, the Agency has amended section 4.6 to reflect these requirements and has further indicated its predisposition to allow adequate time for securing data from this network. EPA also believes that States should take advantage ofexisting upper air monitoring programs and where possible, substitute these data for the PAMSrequirements. EPA will provide guidance forthe collection ofthese data.

Several respondents provided specific recommendations concerning the particular meteorological parameters which should be monitored and those forwhich they believed monitoring shouldbe limited. EPA notes that with the exception ofdew point measurements, the recommendations for particular parameters are incorporated into reference 2 ofappendix C. Concerning dew point, one commenter stated that theirmeteorological stafffind dew point temperature measurements to be much more useful than relative humidity tothe study and forecasting of 0 episodes.The measurement technique fordewpoint is straightforward; States are encouraged
to include such measurements at PAMS, ifthey find them useful. The Agency has not required the measurement of this parameter since it may not be essential for all locations and may be derived fromtemperature and relative humidity measurements. As observed by one commenter, barometric pressure generally doesnot vary widely within a large area, except in areaswith complex terrain features. EPAtherefore indicates its predisposition to allow approved network designs which offer limited
measurements ofbarometric pressure (or other parameters) ifthe State can demonstrate that the area's topography is not conducive to significant pressure (or other) variations.

One respondent indicated thatthe rule should allow measurements ata minimum height, or a range, above ground rather than specify 10 meters. For consistency, EPA has retained the 10-meter requirement. The Agency has determined that the lackof flexibility in thisrequirement should not constitute
any hardship inasmuch as measurements at 10 meters are traditional as well as practical. States.
may institute additional monitoring at other heights, at their own volition.

In the preamble to the March 4, 1992 proposal, EPA recognized the potential difficulty in siting a 10-meter meteorological monitoring tower at a particular PAMS site.The Agency therefore requested comments on criteria to determine how such data collected at a nearby site could be used
to represent the meteorology ata PAMS site where the tower and air monitoring equipment could not becollocated. One respondent agreed withthe premise that nearby data (such ascollected at airports or National Weather Service stations) shouldbe accepted, but provided no suggestions for criteria to judge the representativeness ofthose data. EPA has consequently decided to consider requests to use nearby existing meteorological data,both surface and
upper air, on a case-by-case basis.

- 20. Public Comments-Appendix EProbe Siting Criteria forAmbient Air Quality Monitoring

Fourrespondents provided specific
comments regarding the placement of the probe and siting criteria forPAMS. One was particularly concerned over the description forthe PAMS site tobe located downwind in the second-most prevalent wind direction noting that the probe siting criteria werebased on the primary wind direction. EPA recognizes this deficiency, andnotes that the rules have been amended to eliminate this PAMS type (5) site. Additional language has been added to sections 10.2 and 12 ofappendix E to correct this anomaly forthe other sites.

One commenter, based on experience, recommends that VOC samplers should be located further from sources than criteria pollutant monitors ifthey are to

measure area-emitted and regionallytransported VOC. EPA notes that the minimum'network detailed in section 4 ofappendix D, stipulates 3 sitetypes which are located to adequately

measure incoming transported emissions [type (1)], maximum 03 measurements [type (3)], and downwind outgoing conditions [type (4)], all sited

as urban scale monitors.

Two agencies recommend the use of

a vertical manifold for the measurement of ambient 03 precursor data rather than

a horizontal manifold. They further recommend that a heated line from the manifold to the GCbe employed to

ensure the transmission ofheavy hydrocarbons through the line. EPA
notes no compelling reason to specify the orientation ofthe sampling manifold. The requirements published in the technical assistance document (Reference 2 ofAppendix C) do not preclude the use ofa vertical sampling manifold. Likewise, the Agency has not specified nor prohibited the heating of the manifold which maybe necessary in high humidity areas.

One commenter believes that the specifications for separation distance between PAMS androadways, trees and obstacles appear to be lenient and should be more stringent. EPA believes that the specifications are adequate based on current bestjudgement. As

more information becomes available, the Agency will revisit this issue.

D. PublicComments Concerning Impact

on SmallEntities

The U.S. Small Business Administration (SBA) requested further detail regarding the impact ofthese regulations on small entities which are defined to include small businesses, small organizations, and small governmental jurisdictions (5 U.S.C. 601
et seq.). Since EPA is utilizing the State Implementation Plan process as outlined in section 110 ofthe Clean Air Act, the provisions ofthese regulations promulgated today, apply directly only
to State Governments, and particularly,

### Federal Register / Vol. 58, No. 28 / Friday, February 12, 1993 / Rules and Regulations

to the State air pollution control agencies havingjurisdiction over 03 nonattainment areas classified as severe, serious, orextreme. EPA therefore has concluded that no small entities would be affected by the proposal. At the request ofthe SBA's ChiefCounsel for Advocacy, this certification hasbeen clarified. Therefore, pursuant to 5 U.S.C. 605(b), the Administrator certifies that

. these amendments would not-have a

significant economic impact on a substantial number ofsmall entities.

Classification

Since this revision Is classified as minor, no additional reviews are required. The ruleswere submitted to the Office ofManagement and Budget*. (OMB) for review (underExecutive Order 12291). Thisis not amajor

### rule under E.O. 12291 because itdoes not'
meet any ofthe criteria defined Inthe Executive Order.

ListofSubjects in40CFR Part 58

Airpollution control, air quality surveillance and data reporting, ambient airquality monitoring network design and siting, intergovernmental relations, pollutant standard index, quality

assurance program.

Effective Date ofRegulation

These revisions to 40 CFR Part58 incorporate a flexible, reasonable, transition schedule forefficient phase-in ofthe rules in lieu of a waiting period for a rule effective date. This schedule
accounts forthe anticipated delays encountered by States inhiring qualified personnel, obtaining equipment, and providingtraining. Given that States will need to begin as

soon as possible to prepare for03

season sampling, a 30-day waiting period is not appropriate and an effective date ofimmediately upon promulgation is deemed necessary. This explanation isprovided pursuant to the requirements of5 U.S.C. 553.

Dated: January 19, 1993.
William K. Reilly,
' Administrator.

For the reasons set forthin the preamble, part 58 ofchapter I oftitle40 ofthe Code ofFederal Regulations is amended as follows:

PART58-AMBIENT AIR QUALITY SURVEILLANCE

1.The authority citation forpart 58 is revised to read as follows:

Authority: 42 US.C. 7410, 7601(a)..7613, and 7619. 2. Section 58.1 Is amended byrevising paragraph (f)and byaddingparagraphs (w), (x), and (y) to read as follows:



### 158.1 DefinitI.

(f) NO 2 means nitrogen dioxide.NO

means nitrogen oxide. NOx means. oxides ofnitrogen and is defined as the

sum ofthe concentrations ofN0 2and NO.

{w) PAMS means Photochemical Assessment Monitoring Stations. (x) VOC means volatile organic compounds.

(y)Meteorological measurements

means measurements ofwind speed, wind direction, barometric pressure, temperature, relative humidity, and solarradiation.

3.Section 58.2 is amended by redesignating paragraph (d)as paragraph (e) and by adding anew paragraph (d)toread as follows:



### 58.2 Purpos.

(d)This section also actsto establish

a Photochemical Assessment Monitoring Stations (PAMS) network as

a subset ofthe State's SLAMS network forthe purpose ofenhanced monitoring in 03nonattainment areas listed as serious, severe, or extreme. The PAMS network will be subject tothe data reporting and monitoring methodology requirements ascontained in subpart E ofthis part.

4. Section 58.13 is amended by revising paragraph (b), redesignating paragraph (c) asparagraph (d), and adding a newparagraph (c)to read as follows:

558.13 Operating schedul.

Cb) For manual methods (excluding PM10 samplers and PAMS VOC samplers), at least one 24-hour sample
mustbe obtained every sixth day except during periods orseasons exempted by the Regional Administrator.

Cc) For PAMS VOC samplers, samples
mustbe obtained as specified in sections 4.3 and 4.4 ofappendix D to thispart. Area-specific PAMS operating schedules must be,included as part of the network description required by §58.40 and mustbe approved by the Administrator.

5. Section 58.20 is amended by revising paragraphs (a) and (c) and adding paragraph (f)to read asfollows: 

### 158.20 Airqualityaurveillanwe: Plan content.

(a)Provide forthe establishment ofan air quality surveillance system that consists ofanetwork ofmonitoring stations designated as State and Local Air Monitoring Stations (SLAMS) which

measure ambient concentrations of those pollutants for which standards have been established in part 50 ofthis chapter. SLAMS (including NAMS) designated asPAMS will also obtain ambient concentrations ofspeciated VOC and NOx, and meteorological

measurements. PAMS maytherefore be located at existing SLAMS orNAMS sites when appropriate.

(c)Provide forthe operation ofat least

one SLAMS per criteria pollutant except Pb during any stage ofan air pollution episode as defined in the plan.

(f)Within 9 months after; (1)February 12,1993; or (2)Date ofredesignation or reclassification ofany existing 03 nonattainment area to serious, severe, or extreme; or (3) The designation ofa new area and classification to serious, severe, or extreme, affected States shall adopt and submit aplan revision to the Administrator.
The plan revision will provide for the establishment and maintenance of PAMS. Each PAMS site willprovide for the monitoring ofambient concentrations ofcriteria pollutants (Os, NO2),and non-criteria pollutants (NOx, NO, and speciated VOC) as stipulated in section 4.2 pfappendix D, and meteorological measurements. The PAMS network ispart ofthe SLAMS network, and the plan provisions in paragraphs (a) through (f)ofthis section will apply to the revision. Since NAMS sites are also part ofthe SLAMS network, some PAMS sites maybe coincident with NAMS sites and maybe designated asboth PAMS and NAMS.
Subparts E and F-[Redesgnated as Subparts Fand G]

6. Subparts E (S58.40) and F (§§58.50 and 58.51) are redesignated as subparts F (§ 58.50) and G (§§58.60 and 58.61). respectively. Subpart E is added toread

as follows:

Subpart E-Photochemical Assesament MonitoringStations (PAMS)

Sec. 58.40 PAMS network establishment 58.41 PAMS network description. 58.42 PAMS approval. 58.43 PAMS methodology 

### 84678468 Federal Register / Vol. 58, No. 28 / Friday, February 12, 1993 / Rules and Regulations

*Sec.

58.44 PAMS network completion. 58.45 PAMSdata submittal. 58.46 System modification.
Subpart E--Photochemlcal Assessment MonitoringStations (PAMS)

§ 58.40 PAMS network establishmenL

(a) In addition to the plan revision, the State shall submit a photochemical
assessment monitoring network description including a schedule for implementation to the Administrator
within 6 months after,

(1) February 12, 1993; or (2) Date ofredesignation or reclassification ofany existing 03 nonattainment area to serious, severe, or extreme; or

(3)The designation of anew area and classification to serious, severe, or extreme 03 nonattainment. The network description will apply to all serious, severe, and extreme 03 nonattainment areas within the State. Some 03 nonattainment areas may extend beyond State or Regional boundaries. In instances where PAMS network design criteria as defined in appendix D to this partrequire monitoring stations located in different States and/or Regions, the network description and implementation schedule should be submitted jointlyby the States involved. When appropriate, such cooperation and joint network design submittals are preferred. Network descriptions shall be submitted through the appropriate Regional Office(s). Alternative networks, including different monitoring schedules, periods, ormethods, may be submitted, butthey must include a demonstration that they satisfy the monitoring data uses and fulfill the PAMS monitoring objectives described in sections 4.1 and 4.2 ofappendix D to thispart.

(b) Forpurposes ofplan development and approval, the stations established or designated as PAMS mustbe stations from the SLAMS network or become part ofthe SLAMS network required by §58.20.

(c)The requirements of appendix D to this part applicable to PAMS mustbe
met when designing the PAMS network.

§58.41 PAMS network description.

The PAMS network description required by §58.40 must contain the following:

(a) Identification ofthe monitoring

area represented.

(b)The AIRS site identification form for existing stations.

(c)The proposed location for scheduled stations. (d)Identification ofthe site type and location within the PAMS network design foreach station as defined in appendix D to this part except that during any year, a State may choose to submit detailed information for the site scheduled tobegin operation during that year'sPAMS monitoring season, and defer submittal ofdetailed information on theremaining sites until succeeding years. Such deferred network design phases should be submitted to EPA for approval no later than January I ofthe first year of scheduled operation. As a minimum, general information on each deferred site should be submitted each yearuntil final approval ofthe complete network is obtained from the Administrator. (e)The sampling and analysis method for each ofthe measurements.

(f)The operating schedule for each of the measurements. (g)An 03 event forecasting scheme, if appropriate.

(h)A schedule forimplementation. This schedule should include the following:

(1)A timetable for locating and submitting the AIRS site identification form for each scheduled PAMS that is
not located atthe time ofsubmittal of the network description; (2) A timetable forphasing-in operation oftherequired number and type of.sites as defined in appendix D
to thispart; and (3)A schedule for implementing the quality assurance procedures of appendix A to this part for each PAMS.

958.42 PAMS approval.

The PAMS network required by §58.40 is subject tothe approval ofthe Administrator. Such approval will be contingent upon completion ofeach phase ofthe network description as outlined in §58.41 and upon conformance to the PAMS network design criteria contained in appendix D
to this part.
§58.43 PAMS methodology.

PAMS monitors must meet the monitoring methodology requirements ofappendix Cto this part applicable to PAMS.

I58.44 PAMS network completion.

- (a)The complete, operational PAMS network will be phased in asdescribed in appendix D to this part over a period of 5years after;

(1)February 12, 1993; or (2) Date of redesignation or reclassification ofany existing 03 nonattainment area to serious, severe, or extreme; or (3)The designation of anew area and classification to serious, severe, or extreme 03 nonattainment.

(b)The quality assurance criteria of appendix A to this part mustbe implemented for allPAMS.

958.45 PAMS data submittal.

(a) The requirements ofthis section apply only to those stations designated

as PAMS by the network description requiredby §58.40.

(b)All data shall be submitted tothe Administrator in accordance with the format,reporting periods, reporting * deadlines, and other requirements as specified forNAMS in § 58.35.

(c) The State shall reportNO and NOx data consistent with the requirements of §58.35 for criteria pollutants.

(d) The State shall report VOC data and meteorological data within 6 months following the end ofeach quarterly reporting period.

§58.46 System modification.

(a) Anyproposed changes to the PAMS network description will be evaluated during the annual SLAMS Network Review specified in §58.20. Changes proposed by the State must be approved by the Administrator. The State will be allowed I year (until the

next annual evaluation) to implement -theappropriate changes to the PAMS network.

(b) PAMS network requirements are mandatory only for serious, severe, and
extreme 03nonattainment areas. When
any such area is redesignated to attainment, the State may revise its PAMS monitoring program subject to approval by the Administrator.

7. Two new sentences are added before the last sentence in the first paragraph of section 2.2 ofappendix A
to read as follows: Appendix A to Part 58--Quality Assurance Requirements for State and Local AirMonitoring Stations (SLAMS)

* * * * *

2.2 * * * Quality assurance guidance for meteorological systems at PAMS is contained in reference 3. Qualityassurance procedures forVOC, NOx (including NO and NO 2 ),03, and carbonyl measurements atPAMS must be consistent with EPA guidance. * * *

* *€ * * *

8. In the References section of appendix A redesignate references 5, 6, and 7 asreferences 6, 7, and 8, respectively, and a new reference 5 is added to read as follows:

References

* * *€ * *

5. Technical Assistance Document for Sampling and Analysis of Ozone Precursors.Federal Register / Vol. 58, No. 28 / Friday, February 12, 1993 / Rules and Regulations

Atmospheric Research and Exposure Assessment Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711. EPA 600/8-91-215. October 1991.

9. Sections 4.0, 5.0 and 5.1 of appendix C

are redesignated as sections 5.0, 6.0, and 6.1, respectively (reference 5.1 willbecome reference 6.1 ofsection 6.0), sections 4.0, 4.2, and 4.3 are added, and newly redesignated section 6.0 is revised to read as follows:

Appendix C-Ambient AirQuality Methodology

4.0 Photochemical AssessmentMonitoring Stations(PAMS)

4.1 Methods used for 03 monitoring at PAMS must be automated reference or equivalent methods as defined in §50.1 of this chapter.

4.2 Methods used for NO, N02 and NOx monitoring at PAMS should be automated reference or equivalent methods as defined for NO 2 in §50.1 ofthis chapter. Ifalternative NO, N02 orNOx monitoring methodologies

are proposed, such techniques must be detailed in the network description required by §58.40 and subsequently approved by the Administrator.

4.3 Methods for meteorological

measurements and speciated VOC monitoring are included in the guidance provided In references 2and 3.Ifalternative VOC monitoring methodology (including the

use ofnew orinnovative technologies), which is not included in the guidance, is proposed, it must be detailed In the network description required by § 58.40 and subsequently approved by the Administrator.

6.0 References

1.Pelton, D.J..Guideline for Particulate Episode Monitoring Methods, GEOMET Technologies, Inc., Rockville, MD. Prepared for U.S. Environmental Protection Agency, Research Triangle Park, NC. EPA Contract No. 68-02-3584. EPA 450/4-83-005. February 1983.

2.Technical Assistance Document For Sampling and Analysis ofOzone Precursors. Atmospheric Research and Exposure Assessment Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711. EPA 600/8-91-215. October 1991.

3.Quality Assurance Handbook forAir Pollution Measurement Systems: Volume IV. Meteorological Measurements. Atmospheric Research and Exposure Assessment Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711. EPA 600/4-90-0003. August 1989.

10. The heading of appendix D is revised to read as follows: Appendix D-Network Designfor State and LocalAir Monitoring Stations (SLAMS), National Air Monitoring Stations (NAMS), and Photochemical Assessment MonitoringStations (PAMS)

11. The second sentence ofthe first paragraph ofsection I ofappendix DIs revised to read asfollows:

1. * " * It also describes criteria for determining the number and location of National Air Monitoring Stations (NAMS) and Photochemical Assessment Monitoring Stations (PAMS). These criteria will also be used byEPA in evaluating the adequacy of the SLAMS/NAMS/PAMS networks.' ' "

Sections 4 and5 of Appendix D [Redesignated asSections5 and6)
12. Section 4 and section 5 of appendix D are redesignated as section 5 and section 6, respectively, and a new section 4 is added to read as follows:

4. NetworkDesign forPhotochemical AssessmentMonitoringStations(PAMS)

In order to obtain more comprehensive and representative data on 03 air pollution, the 1990 Clean Air Act Amendments require enhanced monitoring for ozone (03), oxides ofnitrogen (NO, NO 2,and NOx), and monitoring for VOC in 03 nonattainment

areas classified as serious, severe, orextreme. This will be accomplished through the establishment ofa network ofPhotochemical Assessment Monitoring Stations (PAMS).

4.1 PAMS Data Uses.Data from the PAMS are intended to satisfy several coincident needsrelated to attainment ofthe National Ambient Air Quality Standards (NAAQS), SIP control strategy development and evaluation, corroboration ofemissions tracking, preparation oftrends appraisals, and exposure assessment.

(a)NAAQS attainmentandcontrolstrategy development.Like SLAMS and NAMS data, PAMS data will be used formonitoring 03 exceedances and providing input for attainment/nonattainment decisions; In addition, PAMS data will help resolve the roles oftransported and locallyemitted 03 precursors in producing an observed exceedance and may be utilized to identify specific sources emitting excessive concentrations of 03 precursors and potentially contributing to observed exceedances ofthe 03 NAAQS. The PAMS data will enhance the characterization of 03 concentrations and provide critical information on the precursors which cause 03, therefore extending the database available for future attainment demonstrations. These demonstrations will bebased on photochemical grid modeling and other approved analytical methods and will provide a basis for prospective mid-course control strategy corrections. PAMS data will provide information concerning (1)which

areas and episodes to model to develop appropriate control strategies; (2)boundary conditions required by the rnodels to produce quantifiable estimates of needed emissions reductions; and (3) the evaluation ofthe predictive capability ofthe models used.

(b) SIPcontrolstrategyevaluation.The PAMS will provide data for SIP control strategy evaluation. Long-term PAMS data willbe used to evaluate the effectiveness of these control strategies. Data may be used to evaluate the impact of VOC and NOx emission reductions on airquality levels for 03 Ifdata is reviewed following thetime period during which control measures were implemented. Speciation ofmeasured VOC data will allow determination ofwhich organic species are mostaffected bythe emissionsreductions and assistin developing cost-effective, selective VOC reductions and control strategies. A Stateor local air pollution control agency can therefore ensure that strategies which are implemented in their particular nonattainment area are those which are best suited for that area and achieve themost effective emissions reductions (andtherefore largest impact) at the least cost.

(c) Emissionstracking. PAMS data will be used to corroborate the quality ofVOC and NOx emission inventories. Although a perfect mathematical relationship between emission inventories and ambient
measurements does not yet exist, a qualitative assessment ofthe relative contributions ofvarious compounds to the ambient aircan be roughly compared to current emission inventory estimates to evaluate the accuracy ofthe emission inventories. In addition, PAMS data which

aregathered year roundwill allow tracking ofVOC and NOx emission reductions, provide additional information necessary to supportReasonable Further Progress (RFP) calculations, and corroborate emissions trends analyses. While the regulatory
assessments ofprogress will be made in
terms ofemission inventory estimates, the ambient data can provide independent trends analyses and corroboration of these
assessments which either verify or highlight possible errors in emissions trends indicated by inventories. The ambient assessments, using speciated data, can gauge the accuracy ofestimated changes in emissions. The speciated data can also beused to assess the quality of the VOC speciated and NOx emission inventories for input during photochemical grid modeling exercises and identify potential urban airtoxic pollutant problems which deserve closer scrutiny.

The speciated VOC data will be used to determine changes in the species profile, resulting from the emission controlprogram, particularly those resultingfrom the reformulation offuels.

(d) Trends. Long-term PAMS data will be used to establish speciated VOC. NOx, and limited toxic air pollutant trends, and supplement the 03 trends database. Multiple statistical indicatorswill be tracked, including 03 and its precursors during the
events encompassing the days during each
year with thehighest 03 concentrations, the seasonal means for these pollutants, and the annual means at representative locations.

The more PAMS that are established in and

near nonattainment areas, the more effective the trends data will become. As the spatial 8469.470 Federal Register / Vol. 58. No. 28 / Friday, February 12, 1993 / Rules and Regulations

distribution and number of03 and 03 precursor monitors improves, trends analyses will be lessinfluenced by instrument or site location anomalies. The requirement that surface meteorological monitoring'be established at eachPAMS will help maximize theutility ofthese trends analyses by comparisons with metedrological trends, and transport influences. Themeteorological data can also help interpret the ambient air pollution trends by taking meteorological factors into account

(a) Exposureassessment. PAMS data will be used to better characterize 03 and toxicair pollutant exposure to populations living in serious, severe, orextreme areas. Annual

mean toxic airpollutant concentrations will be calculated tohelp estimate the average risk to the population associated with individual VOC species, which are considered toxic, in urban environments.

4.2 PAMS MonitoringObjectives.Unlike the SLAMS and NAMS design criteria which

are pollutant specific, PAMS design criteria

are site specific.Concurrent measurements of 0,. NOx, speciated VOC, and meteorology

are obtained at PAMS. Design criteria for the PAMS network are based on selection ofan array ofsite locations relative to 03 precursor

source areas and predominant wind directions associated with high 03 events. Specific monitoring objectives are associated with each location. The overall design should enable characterization ofprecursor emission

sources within the area, transport of03 and its precursors into and out ofthe area. and the photochemical processes related to03 nonattainment, as well as developing an initial,though limited, urban air toxic pollutant database. Specific objectives that
mustbe addressed include assessing ambient trends in 03, NO, NO, NOx. VOC (including carbonyls), and VOC species, determining spatial and diurnal variability of03. NO, NO 2,NOx. and VOC species and assessing changes in the VOC species profiles that

occurover time, particularly those occurring due to the reformulation offuels. A maximum offive PAMS sites are required in

an affected nonattainment area depending on the population ofthe Metropolitan Statistical Area/Consolidated Metropolitan Statistical Area (MSA/CMSA) or nonattainment area, whichever is larger. Specific monitoring objectives associated with each ofthese sites result in fourdistinct site types. Note that detailed guidance for the locating of these sitesmay be found in reference 19.

Type (1)sites are established to characterize upwind background and transported 03 and its precursor concentrations entering the area and will identify those areas which are subjected to overwhelming transport.Type 11) sites are located in the predominant morning upwind direction from the local area ofmaximum
precursoremissions during the 03 season and at a distance sufficient toobtain urban scale measurements as defined in section 1 ofthis appendix. Typically, type (1)sites will be located near the edge ofthe photochemical grid model domain in the predominant morning upwind direction from the city limits or fringe ofthe urbanized area. Depending on the boundaries and size ofthe nonattainment area andthe orientation of the grid, this site may be located outsideof the nonattainment area. The appropriate predominant morning wind direction should be determined from historical wind data occurring during theperiod 7 a.m. to 10a.m.

on high %3 days oron those days which exhibit thepotential for producinghigh 03 levels, i.e., %-conducive days as described in reference 25. Alternate schemes for specifying this morningwind direction may be submitted as a part ofthe network description required by 6§ 58.40 and 58.41. Data measured at type (1)sites will be used principally for the following purposes:
.

* Future development and evaluation of control strategies,

" Identification ofincoming pollutants, * Corroboration ofNOx and VOC emission inventories,

* Establishment ofboundary conditions for future photochemical grid modeling and mid-course control strategy changes,and

* Development of incoming pollutant trends.

Type (2)sites are established to monitor the magnitude and type ofprecursor emissions in the area where maximum
precursor emissions are expected to impact and are suited for the monitoring ofurban air toxic pollutants. Type (2)sites are located immediately downwind ofthe area of maximum precursor emissions and are typically placed near the downwind boundary of thecentral business district to obtain neighborhood scale measurements. The appropriate downwind direction should be obtained similarly to that for type (1)sites. Additionally, a second type (2) sitemaybe required depending on the size ofthe area, and should beplaced in the second-most predominant morning wind direction as noted previously. Data measured at type (2) sites will be used principally for the following purposes:

* Development and evaluation of imiminent and future control strategies,

* Corroboration of NOx and VOC emission inventories,

" Augmentation ofRFP tracking. * Verification ofphotochemical grid model performance,

* Characterization of 03 andtoxic air pollutant exposures (appropriate site for measuring toxic emissions impact),

e Development of pollutant trends, particularly toxic air pollutants and annual ambient speciated VOC trends tocompare with trends in annual VOC emission estimates, and

* Determination ofattainment withthe NAAQS for NO 2and 03. Type (3)sites areIntended to monitor maximum 03 concentrations occurring downwind from the area ofmaximum
precursor emissions. Locations for type (3) sites should be chosen so that urban scale
measurements are obtained. Typically, type (3)sites wiil be located 10to 30 miles downwind from the fringe ofthe urban area. The downwind direction should also be determined from historical wind data. but should be Identified as those afternbon winds occurring during the period I p.m. to 4p.m.

on high 03 days or on those days which exhibit thepotential for producing high 03 levels. Alternate schemes for specifying this afternoon wind direction may also be submitted asa part ofthe network description required by S§ 58.40 and 58.41. Data measured at type (3)sites willbe used principally for the following purposes:

* Determination ofattainment with the NAAQS for O (thissite maycoincide with

anexisting maximum concentration 0, monitoring site),

* Evaluation offuture photochemical grid modeling applications,

* Future development and evaluation of control strategies,

" Development ofpollutant trends, and " Characterization of 03 pollutant exposures.

Type (4)sites are established to characterize the extreme downwind transported 03 and itsprecursor concentrations exiting the area and will identify those areas which are potentially contributing to overwhelming transport in other areas. Type (4) sites are located inthe predominant afternoon downwind direction,

as determined for the type (3)site, from the local area ofmaximum precursor emissions during the 03 season and at a distance sufficient to obtainurban scale
measurements as defined elsewhere in this appendix. Typically, type (4) sites will be located near the downwind edge ofthe photochemical grid model domain. Alternate schemes for specifying the location ofthis site may be submitted as a part ofthe network description required by §§ 58.40 and 58.41. Data measured at type (4)sites will be used principally for the following purposes:

e Development and evaluation of 03 control strategies,

• Identification ofemissions and photochemical products leaving the area,

* Establishment ofboundary conditions for photochemical gridmodeling,

" Development ofpollutant trends, " Background and upwind information for other downwind areas, and

* Evaluation ofphotochemical grid model performance.

States choosing to submit an individual network description for each affected nonattainment area, irrespective ofits proximity to other affected areas, must fulfill the requirements for isolated areas as described in section 4 ofappendix D,as an example, and illustrated by Figure 1.States containing areas which experience significant impact from long-range transport'

or are proximate to other nonattainment areas (even in other States) should collectively submit a network description which contains alternative sites tothose that would be required for an isolated area. Such a submittal should, as a guide, bebased on the example provided in Figure 2, but must include ademonstration that the design satisfies the monitoring data uses and fulfills the PAMS monitoring objectives described in sections 4.1 and 4.2 ofappendix D. EPA recognizes that specific monitoring sites identified for one area may serve to fulfill the monitoring objectives for a different site in another area; for example, a downwind site for one areamay suffice as an upwind site for another. These alternative network designs mustalso be reviewed and approved by the Administrator.

9ILUN0 CODE se-

.Federal Register / Vol. 58, No. 28 / Friday, February 12, 1993. / Rules and Regulations 

# FIGURE 1- ISOLA TED AREA NETWORK DESIGN 

# 0

U2


# 0

4 

# Ul URBANIZED FRINGE



# U3

NOTE: U1 AND U2 REPRESENT THE FIRSTAND SECOND MOST PREDOMINANT HIGH OZONE DA YMORNING WIND DIRECTION. U3 REPRESENTS THE HIGH OZONE DAYAFTERNOON WIND DIRECTION. 84718472 Federal Register / Vol. 58, No. 28 / Friday., February 12, 1993 

### 1 Rules and Regulations 

# FIGURE2

- MUL TI-AREA AND TRANSPORT AREA NETWORK DESIGN 

# 0

~>'- 

# CITY Z 

# CITY Y 

# (3

BUSINESS DI



# CITY X

U2

FRINGE



# U3 NOM-" LI? Ad U2 REPRESENT T FIRST SD SECOND MOST
PREDOMINANT tiNGH OZONECA YMOJWN WAJlD .IREC ffO
U3 REPRESENTS THE HIGH OZONE DAYAFTERNOON WIND DIREC77ON



### 113

BILUNG CODE 560-Co-- 

# 4

Ul



# AlsopFederal Register/ Vol. 58, No. 28 / Friday, February 12, 1993 / Rules and Regulations 8473

Alternative PAMS network designs should,

on a site-by-site basis,provide those data
necessary to enhance the attainment/ nonattainment database for criteria pollutants end explain theorigins ofoverwhelming 03 transport. The alternative PAMS data should be usableforthecorroboration and verification of03precursor emissions inventories and should comprisee qualitative lfmnatquantitative) measure of theaccuracyofRFP calculations.The data should be sufficient to evaluatethe effectiveness ofthe implemented 03 control strategies and shouldprovide datanecessary toestablishphotochemical gridmodeling boundary conditions and necessary inputs Including appropriate meteorological parameters, and provide measurements whichcan serve asmodelevaluation tools. lFuther,utilizing its PAMS database (alternative or not), a State shouldbe able to draw conclusions regarding population
exposure and conduct trends analyses for both criteria and non-criteria pollutants. Overall, the PAMS network should serve as

one ofseveral complementary means, together with modeling and analysisofother databases (e.g., Inventories) and availability oflcontrol technology, etc., for Statesto justify the modification ofexisting control
programs, design new programs, and evaluate future courses ofactions for 03 control.

4.3 Monitoring Period. PAMS precursor monitoring willbe conducted annually throughout the months ofJune,July and August fasa-iminmum) when peak 03values

are expected in each area; however,'precursor monitoring during the entire 03 season for the area ispreferred.Alternate precursor monitoringperiods maybe submittedfor approval as apartofthe PAMS network description Tequired by §58.40. Changes to thePAMS monitoring periodmust be identified during theannual SLAMS " NetworkReview specified in § 58.20. PAMS

03 onitors mustadhere to the 03 monitoring season specified insection 2.5 of appendixD. Toensures degreeofnational consistenc,, monitoring for the 1993 season 'shouldcimence asfollows:

One in 3-day sarpling-me 3, 1993. One in 6-daysampling-June 6, 1993. These monitoring dates will therebybe coincident with the previousty-established, intermittent schedule forparticulate matter. States initiatingsamplingearlier (orlater) than June'3,1993 should adjust their schedules tocoincide with this national schedule.

4.4 MinimumMonitoring Network Requiments. The minimumrequired number and typeofmonitoring sites and sampling requirements arebased onthe population of the affectedMSA/CMSA or nonattainment area (whicheveris larger). The MSAICMSA basis for monitoring network requirements was chosen because ittypically is the most representative ofthe areawhich
encompasses the emissions sources contributing to assathlmament. The MSAI CMSA emissions densitycan also be effectively and conveniently portrayed by the surrogate ofpopulation. Additionally, a network which is adequate to characterize the ambient air ofan MSA/CMSA often must extend beyond the boundaries ofsuch an area (especiallyfor 03 and ItsprecursorsLtherefore, theuse ofsmaller geographical units Israch ascounties or nonattainment

areaswhich resmallerthanthe MSA/ CMSA) for monltoringnetworkdesign purposes is inappropriate.'Various sampln requirements re imposedaccordingtothe size ofthe areatoaccommodate the impact oftransporton the smaller MSAs/CMSAs, to account for the spatial variations Inherent in large areas, tosatisfythediffering dataneeds oflarge versus smallareas due tothe intractability ofthe 03 nonattainment problem, endtorecognize the potential economic impact-ofimplementation on State andlocalgovernment. Population figures
must reflect the mostrecent decennial U.S.

census population report. Specific guidance

on determining network requirements is provided inreference 19.Minimum network requirements areoutlined in'Table 2.

TA&E 2.--PAMS MINNIUM MONITORING NETWORK REORREMENTS 1

mum Minispec- -mu P lalon of USN Re- ated =atbony

or nonattain- qulred VOC sam- sam- pling -meritareae Sbp 3 frr "ape pling fe fre- quency'4 cy

Less than500,000.. (1) AorC

(2) AorC OorF s 500,000 to () AorC

1,000,000. 

### (2) 13) Aor C

I1000 00to (t AorC

2,00,000. (a) S E

12) 

### 18 E (' AorC More ftantOO900 () AorC (2) 

## B E (3) AorC (4) AorC

1O and NOx (including NO and NO 2 ) monitoring should be oontlkni measurements.

tWhichever area Is larger. 3Soe Figure 1. 4Ffequsrc1 Requiremlts are as follows: A-Eig,t 3-ho"W sautles every third day aid one additional 24-hour sample evefy sixth day during the monitoring i Bo- , 3-bour samples, every day during monklt§ perid and one additional 24-hoar sample every sbeth dat yearround; GE %m samples on the 5 pea 03 days u eacn previous day, eight 3-hour samples every sixth day, and one additonal 244=r sample every sixth day, dung the fmitoring peiod; D-EWIAh3-hotr e every third day during the monitoring period; E-9gh 3- hour samples evey dayduring the monitoring period; F-Eight 341our samples onthe 5peak 03 days plus each previousday and *ight 34*or samles every ,clh day during the inatorig gerod. (NOTE: multiple samples taken on adally basis must begn at mridt and consist of sequent, on- oveplng sampn peiods.)

6Carbonyl .9sln frequency must meatch the

wosenspecisted VOC Irequency. Note that ft use of Frequencies C or F requires the submittal of an ozone event forecasting scheme.

Forpurposes ofnetwork implementation and transition, EPA recommends the following priority order forthe establishment of sites:

9 The type (2) site which provides the

most comprehensive data concerning 03

precursor emissions and toxic airpollutants, a The type (3) sitewhich provides a maximum 0. measurement and total conversion of03 precursors,

* The type (1) sitewhich delineates the effect ofincoming precursor emissions and

ncenrations ofOa and provides upwind boundary conditions,

o The type (4) site which provides extreme downwind boundary conditions, and

* The second type 12) site which provides comprehensive data concerning 03 precursor emissions and toxic air pollutantsin the second-most predominantmorning wind direction on high 03 days.

Note also that 03event (peak day) monitoring will require the development of

a scheme for forecasting suchbigh 03 days

or will necessitate the stipulation ofwhat meteorological conditions constitute a potential high03 day; monitoringcould then be triggered only via meteorological projections.The 03 event forecasting and monitoring scheme shouldbe submitted as a part ofthe network description required by § 58.40 and 58.41 and should be reviewed during eachannual SLAMS Network Review .specifiedin § 58.20.

4.5 "bnsion Period.A variable period of time is proposed for phasing in the operation ofal requiredPAMS. Within i

year after (1) February 12.1993, (2) or date ofredesignation orreclassification ofany existing 03 nonattainment area to serious,

severe, or extreme, or 13) thedesignation of

a new area and classification to serious.

severe, orextreme 03 nonattainment, a minimum ofone type J2) site must be operating

,Operation of theremaining sites
must, at aminimum,be phased inatthe rate ofone site'per year during subsequent years

as outlined in the approved PAMS network description provided by the State.

4.6 Meteoraloical Monitoring.In orderto support monitoringobjectives associated with theneed forvarious air quality analyses, model inputs and performance'valuations, meteorological monitoringincluding wind

measurements at 10 meters above groundis required at eachPAiS site. Monitoring should begin with site establishment. in addition, upperairmeteorological monitoring is required for each FAMS area. Upper airmonitoring should be Initiated as

soon as possible.butnolater than 2 years after (1) February 12. 1993. (2) ordate of redesignatloa or eclassification ofany existing 0 nonattalnment area to serious.

severe, or extreme, or13) the designation of

a new area and classification to serious.

severe, or extreme 03 nonattainment. The

upper air monitoringalte may be located separately from the type (1) through [4) sites, but the location should be representative of the upper air data inthenonattainment area. Upper airmeteorological data mustbe collected duringthose days specified for monitoring by the sampling frequencies in Table 2. of'section4.4 ofthis appendixD In accordance with current EPAguidance.

Section 6 of AppendixD [Amended]

13. References 19 through 32 are added to section 6 ofappendix D to read as follows:

6.References

* *8474 Federal Register / Vol. 58, No. 28 / Friday, February i2, 1993 / Rules and Regulations

19. Enhanced Ozone Monitoring Network Design and Siting Criteria Guideline Document. Office ofAir Quality Planning and Standards, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711. EPA 45/4-91-033. November 1991.

20. Technical Assistance Document For Sampling and Analysis of Ozone Precursors. Atmospheric Research and Exposure Assessment Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711. EPA 600/8-91-215. October 1991.

21. Quality Assurance Handbook for Air Pollution Measurement Systems: Volume IV. Meteorological Measurements. Atmospheric Research and Exposure Assessment Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711. EPA 600/4-90-0003. August 1989.

22. Criteria for Assessing the Role of Transported Ozone/Precursors in Ozone Non-attainment Areas. Office ofAir Quality 'Planningand Standards, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711. EPA-450/4-91-015. May 1991.

23. Guideline for Regulatory Application of the Urban Airshed Model. Office ofAir Quality Planning and Standards, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711. EPA-450/4-91- 013. July 1991.

24. Ambient Air Monitoring Data Quality Objectives (DQOs) for the Photochemical Assessment Monitoring Stations (PAMS) Program. Guideline Document. Office ofAir Quality Planning and Standards, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711. Draft Report. July 1992.

25. Shao-Hung Chu, "Using Windrose Data
to Site Monitors ofOzone and Its Precursors", Office ofAir Quality Planning and Standards, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711. DraftReport. June 1992.

26. Lewis, Charles W., and Teri L Conner, "Source Reconciliation of Ambient Volatile Organic Compounds Measured in theAtlanta 1990 Summer Study: The Mobile Source Component", Atmospheric Research and Exposure Assessment Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711. September 1991.

27. Fujita, Eric M., BartE. Croes, Charles L.Bennett, Douglas R. Lawson, Frederick W. Lurmann, and Hilary H. Main, "Comparison ofEmission Inventory and Ambient Concentration Ratios ofCO, NMOG, and NOx in California's South CoastAir Basin", J.Air andWaste Management Association 42:264- 276. March 1992.

28. Nelson, P. F., S. M. Quigley and M. Y. Smith, "Sources ofAtmospheric Hydrocarbons in Sydney: A quantitative Determination Usinga Source Reconciliation Technique", Atmospheric Environment Vol 17, No. 3. 1983.

29. Mayrsohn, H. and J.H. Crabtree, "Source Reconciliation ofAtmospheric Hydrocarbons", Atmospheric Environment Vol 10. 1976. 30. Mayrsohn, Henry,James H. Crabtree, Mutsuo Kuramoto, Ray D. Sothern, and Henry Mano, "Source Reconciliation of Atmospheric Hydrocarbons 1974", Atmospheric Environment Vol 11. 1977.

31. Analysis ofthe Ambient VOC Data Collected in the Southern California Air Quality Study, State ofCalifornia Air Resources Board--Research Division, 1800 15th Street, Sacramento, CA 95814, Final Report, Contract No. A832-130. February, 1992.

32. Purdue, LarryJ., "Summer 1990 Atlanta Ozone Precursor Study", presented at the 84th Annual Meetingand Exhibition of the Air and Waste Management Association, Vancouver, British Columbia, Canada.June 1991.

14. Appendix E is amended by adding a

new paragraph after the first paragraph in section 9, redeslgnating sections 10, 11, and 12 as sections 11, 12, and 13, and adding a

new section 10, redesignating Table 5 as Table 6 in newly redesignated section 12, and adding a new Table 5 in new section 10, amending the last sentence in newly redesignated section 11 to add reference to PAMS, and amending newly redesignated section 12 by adding an entry to the bottom ofTable 6 for VOC to read as follows:

Appendix E-Probe SitingCriteria for Ambient AirQuality Monitoring

9. * * *

For VOC monitoring atthose SLAMS designated as PAMS, FEP teflon is unacceptable as the probe material because of VOC adsorption and desorption reactions on the FEP teflon.Borosilicate glass, stainless ,steel, or its equivalent are the acceptable probe materials for VOC and carbonyl sampling. Care must be taken to ensure that the sample residence time Is 20 seconds or less.

10. Photochemical AssessmentMonitoring Stations(PAMS)

10.1 Horizontaland VerticalProbe Placement.The height ofthe probe inlet

must be located 3 to 15 meters above ground level. This range provides a practical compromise for finding suitable sites for the multipollutant PAMS. The probe inlet must also be located more than 1metervertically

or horizontally away from any supporting

structure.

10.2 SpacingfromObstructions.The probe mustbe located away fromobstacles and buildings such thatthe distance between the obstacles and the robe inlet is at least twice the height that te obstacle protrudes above the sampler.There must be unrestricted airflow in an arc ofat least 2700 around the probe inlet.Additionally, the predominant wind direction for the period of greatest pollutant concentration (as described for each site in section 4.2 ofappendix D) must be included in the 270* arc. Ifthe probe is located on the side ofthe building, 180°

clearance is required.

10.3 Spacing from Roads.It is Important in the probe siting process to minimize destructive interferences from sources of nitrogen oxide.(NO) since NO readilyreacts with 03. Table 5 below provides the required minimum separation distances between roadways andPAMS (excludingupperair measuring stations):

TABLE 5.-SEPARATION DISTANCE BETWEEN PAMS AND ROADWAYS (Edge ofNearest Traffic Lane]

Minimum separa- dion distance beRoadway average dailytraffic tweenroadwa vehicles perday and station meters'

<10,000

..................................... >10 15,000

............................. ...... 20 20,000

.............................. ...... 30 40,000

....................................... 50 70,000

....................................... 100 >110,000

................................... >250

IDistances should be Interpolated based on traffic flow.I Type (1), (3)and (4) sites are intended to be regionally representative and should notbe unduly influenced by nearby roadways. Similarly, a nearby roadway should not act

as a local depressor of03 concentrations for type (2)and (3)sites.

10.4 Spacing from Trees.Trees can provide surfaces for adsorption and/or reactions to occur and can obstruct normal wind flow patterns. To minimize these effects atPAMS, the probe inlet shouldbe placed at least 20meters from the drip line oftrees. Since the scavenging effect of trees is greater for 03 than for the other criteria pollutants, strong consideration of this effect

must be given in locating the PAMS probe inlet to avoid this problem. Therefore, the samplers must be at least 10 meters from the drip line oftrees that are located between the urban city core area andthe sampler along the appropriate wind direction.

10.5 Meteorological Measurements.The 10-meter meteorological tower at each PAMS site should be located so that measurements

can be obtained that are not immediately influenced by surrounding structures and
trees. It is importantthat the meteorological data reflect the origins of, and the conditions within, the air mass containing thepollutants collected at the probe. Specific guidance on siting ofmeteorological towers is provided in references 31 and 32.

11. WaiverProvisions

For those SLAMS also designated as NAMS or PAMS, the request willbe forwarded to the Administrator.

12. DiscussionandSummary

### Federal Register / Vol. 58, No. 28 / Friday, February 12, 1993 / Rules and Regulations 8475

TABLE 6.-SUMMARY OF PROBE SITNG CRITERIA

Distance from supporting stnucPollutant ale Height above ture, motos Otterspacing citera ground, meters Vertical Horizontal

VOC 3-15 >1 >1 1.Should be >20 meters from the dripline and must be 10 meters from the driline when the tree(s) act as an obstruction.
2. Distance from probe Inlet to obstacle must be at least twice the height the obstacle protniles above the Inlet probe. 3. Must hsve unrestricted sir flow Inan arc of at least 270* around the probe Inlet and the prodominant wind direction for the period of greatest pollutant concentration (as described for each site Insection 4.2 of appendix D) must be Included Inthe 270r arc.'f probe located on the side ofa building unrestricted airflow must be 1800. 4. Spacing from roadways (seeTable 5).

,When probe Islocated on rooftop, this separation distance IsInreference to walls, parapets, or penthouses located on the roof.

0t .it * * d

Section 13 ofAppendix [ Amended]
15. References 31- 32, and 33 are added to section 13 of appendix E to read as follows:

13. References

31. Technical Assistance Document For Sampling and Analysis ofOzone Precursors. Atmospheric Research and Exposure Assessment Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711. EPA 600/8-91-215. October 1991.

32. Quality Assurance Handbook for Air Pollution Measurement Systems: Volume IV. Meteorological Measurements. Atmospheric Research and Exposure Assessment Laboratory, U.S: Environmental Protection Agency, ResearchTriangle Park, NC 27711. EPA 600/4-90-0003. August 1989.

33. On-Site Meteorological Program Guidance for Regulatory Modeling Applications. Ofce ofAir QualityPlanning and Standards, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711. EPA 450/4-87-013. June 1987.
[FR Doc. 93-3072 Filed 2-11-93; 8:45 am]

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