Skip to Content

Notice

Official Release of the MOVES2010a and EMFAC2007 Motor Vehicle Emissions Models for Transportation Conformity Hot-Spot Analyses and Availability of Modeling Guidance

Document Details

Information about this document as published in the Federal Register.

Published Document

This document has been published in the Federal Register. Use the PDF linked in the document sidebar for the official electronic format.

Start Preamble

AGENCY:

Environmental Protection Agency (EPA).

ACTION:

Notice of Availability.

SUMMARY:

This Notice announces the availability of two new EPA guidance documents for: completing quantitative particulate matter (PM2.5 and PM10) hot-spot analyses using EPA's Motor Vehicle Emissions Simulator model (MOVES), California's EMission FACtor model (EMFAC), and other models, and completing project-level carbon monoxide (CO) analyses using MOVES. These guidance documents will assist practitioners with implementing MOVES, EMFAC, air quality models, and applicable requirements.

EPA is approving the latest version of the MOVES model (MOVES2010a) for official use for quantitative CO, PM2.5, and PM10 hot-spot analyses outside of California. This notice also announces a two-year grace period before the MOVES2010a emissions model is required to be used in quantitative CO and PM hot-spot analyses for project-level conformity determinations outside California.

EPA is also approving the latest version of the EMFAC model (EMFAC2007) for quantitative PM hot-spot analyses for transportation conformity purposes within California.[1] This notice announces a two-year grace period before EMFAC2007 is required to be used for quantitative PM hot-spot analyses for project-level conformity determinations in California. While EPA is approving the MOVES2010a and EMFAC2007 models today for project-level transportation conformity purposes, this notice is applicable to current and future versions of the MOVES and EMFAC models, unless EPA notes otherwise when approving the models for conformity purposes.

DATES:

EPA's approval of the MOVES2010a and EMFAC2007 emissions models is effective December 20, 2010. Today's approval also starts a two-year transportation conformity grace period that ends on December 20, 2012, after which:

  • MOVES2010a (outside of California) is required to be used for new quantitative CO, PM10, and PM2.5 hot-spot analyses for transportation conformity purposes; and
  • EMFAC2007 (within California) is required to be used for new PM10 and PM2.5 hot-spot analyses for transportation conformity purposes.

These models can also be used during the grace period, as described further in this notice.

Start Further Info

FOR FURTHER INFORMATION CONTACT:

For questions regarding the official release of MOVES2010a for quantitative CO, PM2.5, and PM10 hot-spot analyses, contact Meg Patulski at patulski.meg@epa.gov, (734) 214-4842, Transportation and Regional Programs Division, Office of Transportation and Air Quality, EPA, 2000 Traverwood Road, Ann Arbor, MI 48105. For questions regarding the official release of EMFAC2007 for quantitative PM2.5 and PM10 hot-spot analyses in California, contact Karina O'Connor at oconnor.karina@epa.gov, (775) 833-1276, Air Planning Office (AIR-2), Air Division, EPA, Region 9, 75 Hawthorne Street, San Francisco, CA, 94105-3901. Technical questions about completing emissions and air quality modeling for CO and PM hot-spot analyses can also be sent to conformity-hotspot@epa.gov.

End Further Info End Preamble Start Supplemental Information

SUPPLEMENTARY INFORMATION:

The contents of this notice are as follows:

I. Background

II. Using MOVES at the Project Level

III. Using EMFAC at the Project Level

IV. Availability of Modeling Guidance

I. Background

A. What is transportation conformity?

Transportation conformity is a Clean Air Act (CAA) requirement to ensure that Federally supported highway and transit activities are consistent with (“conform to”) the State air quality implementation plan (SIP). Conformity to a SIP means that a transportation activity will not cause or contribute to new air quality violations, worsen existing violations, or delay timely attainment of the national ambient air quality standards (NAAQS) or any interim milestone. EPA's transportation conformity regulations (40 CFR Parts 51.390 and 93) describe how Federally funded and approved highway and transit projects meet these statutory requirements.

B. Hot-Spot Analyses

A hot-spot analysis in the context of transportation conformity is defined at 40 CFR 93.101 as an estimation of likely future localized pollutant concentrations and a comparison of those concentrations to the relevant Start Printed Page 79371NAAQS. A hot-spot analysis assesses the air quality impacts on a scale smaller than an entire nonattainment or maintenance area, including, for example, congested highways or transit terminals. Such an analysis of the area substantially affected by the project is a means of demonstrating that statutory requirements are met for the relevant NAAQS in the project area. When a hot-spot analysis is required, it is included within a project-level conformity determination.

Sections 93.116 and 93.123 of the conformity rule contain the requirements for when a CO, PM10, or PM2.5 hot-spot analysis is required for a project-level conformity determination. In CO nonattainment and maintenance areas, a hot-spot analysis is required for all Federal non-exempt projects, with quantitative hot-spot analyses being required for congested and high volume intersections and other projects (40 CFR 93.123(a)(1)).

The conformity rule requires a hot-spot analysis for only a subset of all Federal non-exempt highway and transit projects in PM nonattainment and maintenance areas (40 CFR 93.123(b)(1)), such as new or expanded highway or transit projects with significant increases in diesel traffic. However, unlike CO hot-spot analyses, to date only qualitative PM hot-spot analyses have been required.[2] Section 93.123(b) states that the requirement to conduct quantitative analyses for PM does not take effect until EPA releases modeling guidance on the subject and announces in the Federal Register that these requirements are in effect.

Today's notice announces the availability of such final modeling guidance: “Transportation Conformity Guidance for Quantitative Hot-Spot Analyses in PM2.5 and PM10 Nonattainment and Maintenance Areas” (EPA-420-B-10-040). This guidance describes conformity requirements for quantitative PM hot-spot analyses; provides technical guidance on estimating project emissions using EPA's MOVES model, California's EMFAC model, and other methods; outlines how to apply air quality dispersion models for quantitative PM hot-spot analyses; and includes other resources and examples to assist in conducting quantitative PM hot-spot modeling analyses. EPA has coordinated with the Department of Transportation (DOT) in developing this final guidance.

In addition, EPA stated in the preamble to the March 10, 2006 final conformity rule that finalizing the MOVES emissions model was critical before quantitative PM hot-spot analyses could be required, due to the limitations of applying MOBILE6.2 for PM at the project level.[3] With today's notice approving MOVES2010a and EMFAC2007 for quantitative PM hot-spot analyses (see Sections II and III) and the release of associated modeling guidance (see Section IV.A), the requirement to conduct quantitative PM hot-spot analyses as required by 40 CFR 93.123(b)(4) is now in effect, subject to the conformity grace period for using new emissions models for such analyses.

C. Latest Emissions Models and Hot-Spot Analyses

CAA section 176(c)(1) states that “* * * [t]he determination of conformity shall be based on the most recent estimates of emissions, and such estimates shall be determined from the most recent population, employment, travel, and congestion estimates. * * *” The transportation conformity rule (40 CFR 93.111) requires that conformity analyses be based on the latest motor vehicle emissions model approved by EPA.

The conformity rule states that EPA will consult with the DOT to establish a grace period following the specification of any new emissions model. The rule further provides for a grace period for new emissions models of between 3-24 months, to be established by notification in the Federal Register (40 CFR 93.111(b)).

In consultation with DOT, EPA must consider various factors when establishing a grace period for conformity determinations, including the degree of change in emissions models and the effects of the new model on the transportation planning process (40 CFR 93.111(b)(2)).

The conformity rule provides some flexibility for hot-spot analyses that are started before the end of a grace period. A conformity determination for a transportation project may be based on a previous model if the analysis was begun before or during the grace period, and if the final environmental document for the project is issued no more than three years after the issuance of the draft environmental document (40 CFR 93.111(c)).

II. Using MOVES at the Project Level

A. What is MOVES?

MOVES is EPA's state-of-the-art, upgraded model for estimating emissions from cars, trucks, motorcycles, and buses. MOVES is based on an analysis of millions of emission test results and considerable advances in the Agency's understanding of vehicle emissions. EPA released MOVES2010 in December 2009, and then released minor updates to the model in the MOVES2010a version in August 2010.[4]

On March 2, 2010, EPA approved the use of MOVES2010 in official SIP submissions to EPA and for certain transportation conformity analyses outside of California (75 FR 9411). The March 2010 approval also applies to the MOVES2010a version for SIPs and regional conformity analyses.[5] However, until today, EPA has not approved any version of MOVES for project-level CO and PM analyses, since project-level MOVES guidance documents were not yet available.[6]

B. Using MOVES2010a for Quantitative CO, PM2.5 and PM10 Hot-Spot Analyses

In today's notice, EPA is approving MOVES2010a as EPA's official motor vehicle emissions factor model for project-level CO and PM analyses outside of California. EPA is also establishing a two-year grace period for using MOVES2010a for quantitative CO and PM hot-spot analyses for project-level conformity determinations, as described further below. This conformity grace period begins today and ends December 20, 2012. Future updates to the MOVES2010a model will not start a new conformity grace period for quantitative CO and PM hot-spot analyses unless EPA notes otherwise.[7]

In deciding the length of the MOVES2010a conformity grace period, EPA consulted with DOT and considered the degree of change in the model and the scope of re-planning likely to be necessary for project development, pursuant to 40 CFR 93.111(b). EPA understands that Start Printed Page 79372numerous areas will be required to conduct quantitative hot-spot analyses using MOVES, and sufficient time must be allowed for State and local agencies to obtain the necessary training and otherwise prepare to use MOVES for these analyses. The following paragraphs elaborate further on the factors that were considered in establishing the maximum two-year conformity grace period for hot-spot analyses with MOVES.

First, EPA considered the time it will take State and local transportation and air quality agencies to conduct and provide technical support for quantitative hot-spot analyses. As described in EPA's new modeling guidance documents (see Section IV), there are several steps involved in a quantitative PM hot-spot analysis and for applying MOVES for CO hot-spot analyses, and a significant amount of instruction will be necessary for these agencies to understand the context for applying MOVES for these analyses.

Second, State and local agencies will need to become familiar with the MOVES emissions model. Agencies need to understand how to configure and run MOVES at the project level for a variety of different types of projects. The MOVES generation of models is not merely an upgrade of the previous MOBILE model using more recent emissions data; it involves brand-new software, designed from the ground up to estimate emissions at a more detailed level. MOVES output will also need to be prepared for use in recommended air quality models. This will require many project sponsors to obtain training in the use of these air quality models, which are being applied for the first time for localized PM analyses of transportation projects.

EPA will work with DOT to develop and provide training to address these concerns, including:

  • General and detailed overviews of the project-level guidance documents described in Section IV of this notice.
  • Technical training for applying MOVES at the project level consistent with the guidance documents being released today.
  • Technical training for using recommended air quality models in accordance with EPA's guidance and regulations.

All of these courses are anticipated to be provided in the form of webinars, other Web-based courses, conference seminars, or in-person training. Courses will be developed to address different levels of State and local expertise as well as different roles and responsibilities for agencies involved.[8]

EPA and DOT intend to maximize training opportunities given available resources and allow sufficient time so that State and local agencies become trained. Following training, additional time will also be needed to gain experience applying guidance and models for real-world situations.

EPA also considered the need to collect and prepare data required to run MOVES at the project level. To take advantage of the full modeling capabilities of MOVES, those conducting hot-spot analyses will generally need to be collecting or generating data specific to individual projects, and some project-level data may not readily be available. Also, the data will need to be entered on the basis of individual “links” to capture vehicle activity occurring on a specific project.

Finally, EPA considered the general time and monetary resource constraints in which State and local agencies currently operate. These agencies need to participate in EPA and DOT training and possibly provide training to other individuals in their offices. Many agencies will be implementing the transition to PM and CO hot-spot analyses with MOVES for projects in several nonattainment and maintenance areas, with each analysis involving multiple State and local agencies.

C. Implementation of the Conformity Grace Period

EPA has previously described how the conformity grace period for CO and PM hot-spot analyses will be implemented in the policy guidance for applying MOVES2010a for these purposes.[9] For CO hot-spot analyses outside California that are started during the two-year grace period, project sponsors can choose to use either MOBILE6.2 or MOVES2010a. EPA encourages sponsors to use the interagency consultation process to determine which option may be most appropriate for a given situation. Any new quantitative CO hot-spot analyses for conformity purposes begun after the end of the grace period must use MOVES2010a.

For PM hot-spot analyses, project sponsors can continue to conduct qualitative PM hot-spot analyses for analyses that are started during the grace period (40 CFR 93.111(c)).[10] Quantitative PM hot-spot analyses can also be completed for conformity purposes during the grace period, if desired. However, any quantitative PM hot-spot analyses conducted during the grace period must use MOVES2010a, since MOBILE6.2 does not have the capabilities to produce viable results for project-level PM emissions analyses and is therefore not appropriate for this purpose.[11] Any quantitative PM hot-spot analysis for conformity purposes begun after the end of the grace period must use MOVES2010a. The interagency consultation process should be used if it is unclear if a previous analysis was begun before the end of the grace period. If you have questions about which model should be used in your conformity determination, you can also consult with your EPA Regional Office.

D. Availability of MOVES2010a and Support Materials

Copies of the official version of the MOVES2010a model, along with user guides and supporting documentation, are available on EPA's MOVES Web site: http://www.epa.gov/​otaq/​models/​moves/​index.htm.

Guidance on how to apply the MOVES model for transportation conformity purposes can be found on EPA's transportation conformity Web site at: http://www.epa.gov/​otaq/​stateresources/​transconf/​policy.htm. EPA will continue to update this Web site as other MOVES support materials and guidance are developed. See Section IV for further information on the availability of new guidance about using MOVES to estimate project-level emissions. This guidance applies for MOVES2010a and future versions of the MOVES model unless EPA notes otherwise.

Individuals who wish to receive EPA announcements related to the MOVES model can subscribe to the EPA-MOBILENEWS e-mail listserver. For more information about subscribing to the EPA-MOBILENEWS listserver, visit EPA's Web site at http://www.epa.gov/​otaq/​models/​mobilelist.htm. Start Printed Page 79373

III. Using EMFAC at the Project Level

A. What is EMFAC?

The EMFAC model is a computer model developed by the California Air Resources Board (CARB) to estimate emission rates for on-road mobile sources operating in California for calendar years 1970 to 2040. The latest version of this model is EMFAC2007, and EPA approved this version of the model for SIP development in California and for most transportation conformity analyses (i.e., all regional emissions analyses and CO hot-spot analyses) on January 18, 2008 (73 FR 3464). However, EMFAC2007 was not approved for quantitative PM2.5 and PM10 hot-spot analyses at that time.

As stated in the January 2008 notice, EPA believed that modeling guidance would be necessary before quantitative PM hot-spot analyses could be required.[12] With the release of EPA's PM hot-spot guidance, we can approve EMFAC2007 for quantitative PM hot-spot analyses.

B. Using EMFAC2007 for Quantitative PM 2.5 and PM 10 Hot-Spot Analyses

Today's notice approves EMFAC2007 for project-level PM2.5 and PM10 analyses in California. This notice also establishes a two-year grace period for using EMFAC2007 for quantitative PM hot-spot analyses for project-level conformity determinations. This grace period begins today and ends December 20, 2012. Future updates to the EMFAC2007 model will not start a new conformity grace period for quantitative PM hot-spot analyses unless EPA notes otherwise.

EPA consulted with DOT on the appropriate length of the conformity grace period for EMFAC2007 and considered the start-up factors described in 40 CFR 93.111(b). EPA considered how many PM areas are affected by this transition to quantitative PM hot-spot analyses and that sufficient time must be allowed for State and local agencies for all areas subject to this new requirement to obtain the necessary training and planning to apply EMFAC in California. More details on the factors considered are included below, and many are similar to those discussed in Section II for establishing the MOVES grace period.

EPA considered the time it will take State and local agencies in California to conduct and provide technical support for quantitative PM hot-spot analyses. These agencies will also need to become familiar with applying EMFAC2007 at the project level for PM, since the model is currently not applied in the “project-level mode” when developing inventories for PM SIPs or regional conformity analyses. These agencies will also need to learn how to prepare EMFAC outputs for recommended air quality models that are currently not used for transportation projects.

As described in Section II.B, EPA is working with DOT to develop and provide new training courses on EPA's quantitative PM hot-spot guidance, as well as technical training for air quality modeling. EPA and DOT will be working with California agencies on State and local agency training for using EMFAC for quantitative PM hot-spot analyses. Training opportunities will be based on available resources and consider budgetary and other constraints.

In addition to training needs, EPA also considered the data collection and preparation for using EMFAC for quantitative PM hot-spot analyses. For example, project sponsors will need to obtain project-specific fleet data (as opposed to using EMFAC fleet data for regional inventories). EMFAC contains fleet data for each nonattainment and maintenance area in California which are used in the model as “defaults” for fleet characteristics used in SIPs and regional conformity analyses. However, these defaults will not be appropriate for use as-is in PM hot-spot analyses; project sponsors will need to make additional effort to obtain fleet information for the specific project area covered by the PM hot-spot analysis.

Finally, as with the transition to using MOVES, EPA considered the time required for individuals to participate in future training courses, the time to learn to apply the guidance and models after training, and other constraints affecting California agencies. For example, State agencies will be charged with preparing and supporting quantitative PM hot-spot analyses for many projects across the State, which has eleven PM10 and seven PM2.5 metropolitan nonattainment and maintenance areas, as well as isolated rural PM areas.

C. Implementation of the Conformity Grace Period

EPA has previously described how the conformity grace period for PM hot-spot analyses will be implemented.[13] For PM hot-spot analyses, project sponsors can continue to conduct qualitative PM hot-spot analyses for analyses that are started during the grace period (40 CFR 93.111(c)).[14] Quantitative PM hot-spot analyses can also be completed for conformity purposes during the grace period, if desired. However, any quantitative PM hot-spot analyses conducted for conformity purposes during the grace period, or begun after the end of the grace period, must use EMFAC2007. The interagency consultation process should be used if it is unclear if a previous analysis was begun before the end of the grace period. If you have questions, you can consult the EPA Region 9 person listed in For Further Information Contact, above.

D. Availability of EMFAC and Support Materials

Copies of the official version of the EMFAC2007 model are available on CARB's Web site: http://www.arb.ca.gov/​msei/​onroad/​latest_​version.htm. This Web site also contains technical support documentation for the development of EMFAC2007 as well as other related documents.

Policy guidance on how to apply the EMFAC model for transportation conformity purposes can be found on EPA's transportation conformity Web site at: http://www.epa.gov/​otaq/​stateresources/​transconf/​policy.htm. See Section IV.A for further information on the availability of new guidance which articulates how to estimate PM project-level emissions using EMFAC. This guidance applies for EMFAC2007 and future versions of the EMFAC model unless EPA notes otherwise.

IV. Availability of Modeling Guidance

A. Guidance for Quantitative PM Hot-Spot Analyses

Today's notice also announces the availability of the final guidance document: “Transportation Conformity Guidance for Quantitative Hot-Spot Analyses in PM2.5 and PM10 Nonattainment and Maintenance Areas” (EPA-420-B-10-040). This guidance, a fact sheet, and other documentation are available online at the EPA Web site: http:/www.epa.gov/​otaq/​stateresources/​transconf/​policy.htm. As described in Sections II and III, EPA and DOT will provide outreach and training for using this guidance.

This guidance describes conformity requirements for quantitative PM hot-spot analyses; provides technical Start Printed Page 79374guidance on estimating project emissions using EPA's MOVES model, California's EMFAC model, and other methods; and outlines how to apply air quality dispersion models for quantitative PM hot-spot analyses. The guidance also discusses how to calculate design values for comparison to each PM NAAQS, as well as how to determine which air quality modeling receptors may or may not be appropriate for PM hot-spot analyses.[15] The guidance also describes how the interagency consultation process should be used to develop quantitative hot-spot analyses in PM nonattainment and maintenance areas. In addition, the guidance includes other resources and examples to assist in conducting quantitative PM hot-spot modeling analyses. However, the guidance does not change transportation conformity rule requirements for PM hot-spot analyses, such as what types of projects are subject to these analyses. EPA notes that this guidance helps implement existing CAA and transportation conformity requirements and is not a regulation. In addition, certain sections of this guidance may be applicable when completing air quality analyses for transportation projects for purposes other than transportation conformity. EPA has coordinated with the DOT in developing this final guidance.

A draft of this guidance was made available for public comment on May 26, 2010, with a closing date of July 19, 2010 (75 FR 29537-29538). EPA received 15 sets of comments on the draft guidance and considered these comments when developing the final document.

As discussed in Section I, the conformity rule requires EPA to release guidance on how to conduct quantitative PM hot-spot analyses prior to announcing that the requirement to conduct such analyses is in effect (40 CFR 93.123(b)(4)). This regulatory requirement is met with today's release of this final quantitative PM hot-spot modeling guidance, as described in this notice. The qualitative PM hot-spot requirements under 40 CFR 93.123(b)(2) will no longer apply in any PM2.5 and PM10 nonattainment and maintenance areas once the grace period is over and quantitative requirements are in effect. At that time, the 2006 EPA/FHWA qualitative PM hot-spot guidance will be superseded by EPA's quantitative PM hot-spot guidance for these analyses.

B. Guidance for Using MOVES in Project-Level CO Analyses

EPA is also releasing today the final guidance document: “Using MOVES in Project-Level Carbon Monoxide Analyses” (EPA-420-B-10-041). The purpose of this guidance is to describe how to use MOVES to estimate CO emissions from highway and transit projects in States other than California. This guidance is available online at the EPA Web site: http://www.epa.gov/​otaq/​stateresources/​transconf/​policy.htm. EPA coordinated with DOT in developing this guidance.

This guidance can be applied when using MOVES to complete any quantitative CO project-level analysis, including: CO hot-spot analyses for transportation conformity determinations, localized SIP modeling, and CO project-level analyses completed pursuant to the National Environmental Policy Act. EPA and DOT will provide outreach and training for using this guidance.

Start Signature

Dated: December 14, 2010.

Margo Tsirigotis Oge,

Director, Office of Transportation and Air Quality.

End Signature End Supplemental Information

Footnotes

1.  EPA previously approved EMFAC2007 for quantitative CO hot-spot analyses in California.

Back to Citation

2.  For more information on qualitative PM hot-spot analyses, see EPA and FHWA's joint “Transportation Conformity Guidance for Qualitative Hot-spot Analyses in PM2.5 and PM10 Nonattainment and Maintenance Areas” (EPA-420-B-06-902, March 2006).

Back to Citation

3.  See EPA's March 2006 final conformity rule for further information (71 FR 12498-12502).

Back to Citation

4.  See the EPA document: “EPA Releases MOVES2010a Mobile Source Emissions Model Update: Questions and Answers” (EPA-420-F-10-050, August 2010) at: http://www.epa.gov/​otaq/​models/​moves/​index.htm#generalinfo.

Back to Citation

5.  EPA has said that it is not considering MOVES2010a a new emissions model for SIPs and regional conformity analyses under 40 CFR 93.111. The MOVES2010 grace period for regional conformity analyses (which began on March 2, 2010) applies to the use of MOVES2010a as well.

Back to Citation

6.  Also see the March 2, 2010 Federal Register notice (75 FR 9413-9414).

Back to Citation

7.  EPA may provide minor, periodic updates to the MOVES model in order to improve its functionality and performance.

Back to Citation

8.  For example, Section 2.9 of the final quantitative PM hot-spot guidance describes the different roles and responsibilities for Federal, State, and local agencies for these analyses.

Back to Citation

9.  See Questions 10 and 13 in EPA's “Policy Guidance on the Use of MOVES2010 for State Implementation Plan Development, and Other Purposes,” (EPA-420-B-09-046, December 2009) at: http://www.epa.gov/​otaq/​models/​moves/​420b09046.pdf. Areas outside of California should refer to Section III on using EMFAC for PM hot-spot analyses.

Back to Citation

10.  Since previous emissions models have not been approved in the past for quantitative PM hot-spot analyses, a qualitative PM analysis is considered “the previous version of the model” for the purposes of 40 CFR 93.111(c).

Back to Citation

11.  See EPA's March 2006 final rule for further information (71 FR 12498-12502).

Back to Citation

12.  See Section II.C of the January 2008 notice for further information (73 FR 3466).

Back to Citation

13.  See Question 15 in EPA's “Policy Guidance on the Use of MOVES2010 for State Implementation Plan Development, and Other Purposes,” (EPA-420-B-09-046, December 2009) at: http://www.epa.gov/​otaq/​models/​moves/​420b09046.pdf.

Back to Citation

14.  Since previous emissions models have not been approved in the past for quantitative PM hot-spot analyses, a qualitative PM analysis is considered “the previous version of the model” for the purposes of 40 CFR 93.111(c).

Back to Citation

15.  EPA stated in the March 2006 final rule that the PM hot-spot modeling guidance would “consider how projects of air quality concern are predicted to impact air quality at existing and potential PM2.5 monitor locations which are appropriate to allow the comparison of predicted PM2.5 concentrations to the current PM2.5 standards, based on PM2.5 monitor siting requirements (40 CFR Part 58).” (71 FR 12471)

Back to Citation

[FR Doc. 2010-31909 Filed 12-17-10; 8:45 am]

BILLING CODE 6560-50-P