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### ENVIRONMENTAL PROTECTION AGENCY 40 CFR Part52 [EPA-R08-0AR-2006-0952; FRL- ] Air Quality Implementation Plans; Montana; AttainmentPlan for Libby, MT PM2.5 Nonattainment Area and PM IO 

### State Implementation Plan Revisions AGENCY: Environmental Protection Agency (EPA). 

### ACTION: Proposed rule 

### SUMMARY: EPA is proposing to approve the State Implementation Plan (SIP)revision submitted by the State ofMontana on March 26, 2008. Montana submitted this SIP revision to meet Clean Air Act requirements for attaining the 15.0 micrograms per cubic meter**(~g/m3)** annual fine Particulate Matter (PM2.

### s ) national ambient air quality standard (NAAQS) for the Libby nonattainment area. The plan, herein called an "attainment plan," includes an attainment demonstration, an analysis ofReasonably Available Control Technology and Reasonably Available Control Measures (RACT/RACM), base-year and projection year emission inventories, and contingency measures. The requirement for a Reasonable Further Progress (RFP) plan is satisfied because Montanaprojects that attainment with the 1997 PM25 NAAQS will occur in the Libby nonattainment area by April 2010. In addition, we are proposing to approve the PM JO SIP revisions to the Lincoln County Air Pollution Control Program submitted by Montana on June 26, 2006 for inclusion into Libby's attainment plan. This submittal contains provisions, including contingency measures, for controlling both PM]o and PM25emissions from woodstoves, road dust, and outdoor burning. Finally, EPA is proposing to find on-road directly emitted PM25 and oxides ofnitrogen (NOx) in the Libby, Montana nonattainment area insignificant for regional transportation conformity purposes. Ifthis insignificance finding is20f53 finalized as proposed, the Libby, Montana nonattainment area will not have to perform a regional emissions analysis for either direct PM2.5 or NOx as part offuture conformity determinations for the annual 1997 PM2.5NAAQS.



### DATES: Written comments must be received on orbefore 

### [Insert date 30 days after publication in 

### the Federal Register].

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R08-0AR-2006­ 0952, by one ofthe following methods:
• www.regulations.gov
. Follow the on-line instructions for submitting comments.
• E-mail: freeman.crystal@epa.gov
• Fax: (303) 312-6064 (please alert the individual listed in 

### FORFURTHER INFORMATION CONTACT ifyou are faxing comments).
• Mail: Callie Videtich, Director, Air Program, Environmental Protection Agency (EPA), Region 8, Mailcode 8P-AR, 1595 Wynkoop St., Denver, Colorado 80202­ 1129.
• Hand Delivery: Callie Videtich, Director, Air Program, Environmental Protection Agency (EPA), Region 8, Mail Code 8P-AR, 1595 Wynkoop St., Denver, Colorado 80202-1129. Such deliveries are only accepted Monday through Friday, 8:00 a.m. to 4:30 p.m., excluding Federal holidays. Special arrangements should be made for deliveries ofboxed information. Instructions: Direct your comments to Docket ID No. EPA-R08-0AR-2006-0952. EPA's policy is that all comments received will be included in the public docket without change30f53 and may be made available online at www.regulations.gov, including any personal information provided, unless the comment includes information claimed to be Confidential Business Information (CBI) orother information whose disclosure is restricted by statute. Do not submit information that you considerto be CBI orotherwise protected through www.regulations.gov or e-mail. The www.regulations.gov web site is an anonymous access system, which means EPA will not know your identity or contact information unless you provide it in the body ofyour comment. Ifyou send an e-mail comment directly to EPA, without going through www.regulations.gov, your e-mail address will be automatically captured and included as part of the comment that is placed in the public docket and made available on the Internet. Ifyou submit an electronic comment, EPA recommends that you include your name and other contact information in the body ofyour comment and with any disk or CD-ROM you submit. IfEPA cannot read your comment due to technical difficulties and cannot contact you for clarification, EPA may not be able to consider your comment. Electronic files should avoid the use ofspecial characters, any form ofencryption, and be free ofany defects orviruses. For additional information about EPA's public docket, visit the EPA Docket Centerhomepage at http://www.epa.gov/epahome/dockets.htm
. For additional instructions on submitting comments, go to Section I, "General Information," ofthe SUPPLEMENTARY INFORMATION section ofthis document. 

### Docket: All documents in the docket are listed in the www.regulations.gov index. Although listed in the index, some information is not publicly available, e.g., CBI or other information whose disclosure is restricted by statute. Certain other material, such as c-opyrighted material, will be publicly available only in hard copy. Publicly available docket materials are available either electronically in www.regulations.gov or in hard copy at the Air Program, Environmental40f53 Protection Agency (EPA), Region 8,1595 Wynkoop St., Denver, Colorado 80202-1129. EPA requests that, ifat all possible, you contact the individual listed in FORFURTHER INFORMATION CONTACT to viewthe hard copy ofthe docket. You may view the hard copy ofthe docket Monday through Friday, 8:00 a.m. to 4:00 p.m., excluding Federal holidays.

FOR FURTHERINFORMATION CONTACT: Crystal Freeman, Air Program, Environmental Protection Agency (EPA), Region 8, Mailcode 8P-AR, 1595 Wynkoop Street, Denver, Colorado 80202-1129, Phone: (303) 312-6602, Fax: (303) 312-6064, freeman.crystal@epa.gov
.
SUPPLEMENTARY INFORMATION: Definitions Forthe purpose ofthis document, we are giving meaning to certain words or initials as follows: (i) The words orinitialsActor CAA mean orrefer to the Clean Air Act, unless the context indicates otherwise. 

### (ii) The words 

### EPA. we. us orour mean orrefer to the United States Environmental Protection Agency. 

### (iii) The initials

### SIP mean orrefer to State Implementation Plan. (iv) The initials 

### PM 2.5 mean orrefer to particulate matter with an aerodynamic diameterofless than 2.5 micrometers. (v) The initials

### PM IO mean orrefer to particulate matter with an aerodynamic diameterofless than 10 micrometers. (vi) The word State orMontana refers to the State ofMontanaunless the context indicates otherwise.50f53 (vii) The initials NAAQS mean or refer to National Ambient Air Quality Standards.

Table ofContents I. General Information II. What Action Is EPA Proposing? III. What Is the Background for EPA's Proposed Action? A. Designation History B. Clean Air Fine Particle Implementation Rule IV. What Is Included in Montana's Submittal? A. Background B. PM IO SIP Revisions to the Lincoln County Air Pollution Control Program C. Libby and Vicinity PM25 Control Plan V. EPA's Analysis ofMontana's Submittal A. PM IO SIP Revisions to Lincoln County Air Pollution Control Program B. Attaimnent Demonstration C. Analysis ofMontana's Submittal 1. Pollutants Addressed and Attainment Date 2. Monitoring Data 3. Emission Inventory 4. Modeling 5. RACT/RACM 6. Contingency Measures 7. Transportation Conformity Requirements60f53 VI. Proposed Action VII. Statutory and Executive OrderReviews

I. General Information A. What Should I Consider as I Prepare My Comments for EPA? 

### 1. Submitting CBI Do not submitthis information to EPA through www.regulations.gov
or e-mail. Clearly mark the part or all ofthe information that you claim to be CBI. For CBI information in a disk or CD ROM that you mail to EPA, mark the outside ofthe disk or CD ROM as CBI and then identify electronically within the disk or CD ROM the specific information that is claimed as CBI. In addition to one complete version ofthe commentthat includes information claimed as CBI, a copy ofthe commentthat does not contain the information claimed as CBI mustbe submitted for inclusion in the public docket. Information so marked will not be disclosed except in accordance with procedures set forth in 40 CFR part 2. 

### 2. Tips/or Preparing Your Comments. When submitting comments, remember to:
a. Identify the rulemaking by docket number and other identifying information (subject heading, Federal Register date and page number). b. Follow directions

- The agency may ask you to respond to specific questions or organize comments by referencing a Code ofFederal Regulations (CFR) part or section number.
c. Explain why you agree or disagree; suggest alternatives and substitute language for your requested changes. d. Describe any assumptions and provide any technical information and/or datathat you used.70f53

e. Ifyou estimate potential costs or burdens, explain howyou arrived at your estimate in sufficient detail to allow for it to be reproduced. f. Provide specific examples to illustrate your concerns, and suggest alternatives. g. Explain your views as clearly as possible, avoiding the use ofprofanity or personal threats. h. Make sure to submit your comments by the comment period deadline identified.



### II. What Action 

### Is EPA Proposing? EPA is proposing to approve two Montana SIP submittals for the Libby nonattainment
area: (1) PM1 0 SIP revisions to the Lincoln County Air Pollution Control Program submitted by Montana on June 26, 2006; and (2) the Libby PM2 .5 attainment plan submitted by Montanaon March 26, 2008. EPA has determined that the PMlO SIP revisions and the PM2.5 attainment plan meet applicable requirements ofthe Clean Air Act, including the Clean Air Fine Particle Implementation Rule (herein referred to as the implementation rule) issued byEPA on April 25, 2007 (72 FR 20586). Furthermore, EPA has determined that Montana's PM2.5 SIP submittal for the Libby area includes an attainment demonstration, an analysis ofRACTIRACM, base-year and projection-year emission inventories and contingency measures. The attainment plan supports a determination that the Libby PM2 .5 nonattainment areawill attain the 1997 PM2 .5 NAAQS by the April 2010 deadline for attainment. Finally, EPA is proposing to find on-road directly emitted PM2.5 and NOx in the Libby, Montana nonattainment area insignificant for regional transportation conformitypurposes.80f53 EPA's analysis and findings are discussed in this proposed rulemaking. Additional technical support documents are available at www.regulations.gov, DocketNo. EPA-R08-0AR-2006­ 0952.


### III. WhatIs the Background for EPA's Proposed Action? A. Designation History On July 18, 1997 (62 FR 38652), EPA established PM2 .5 NAAQS, including anannual standard of 15.0 ).tg/m3 based on a 3-year average ofannual mean PM2 .5concentrations, and a 24­ hour (or daily) standard of65 ).tg/m3 based ona 3-year average ofthe 98thpercentile of24-hour concentrations. EPA established the standards based on significant evidence and numerous health studies demonstrating that serious health effects are associated with exposures to PM2.5.
Following promulgation ofa new orrevised NAAQS, EPA is required by the CAA to designate areas throughoutthe United States as attaining or not attaining the NAAQS; this designation process is described in section 1 07(d)(l) ofthe CAA. In 1999, EPA and state air quality agencies initiated the monitoring process for the 1997 PM25 NAAQS, and, by January 2001, established a complete set ofair quality monitors. On January 5,2005, EPA published initial air quality designations for the 1997 PM25 NAAQS (70 FR 944), based on air quality monitoring data for calendar years 2001-2003. On April 14,2005, EPA published a final supplemental rule amending the agency's initial designations (70 FR 19844). EPA did not consider modifications made inthis rule to be "re-designations"because the changes were made before April 5, 2005, the effective date ofthe initial designations. As a result ofthe final supplemental rule, PM2.5 nonattainment designations are in effect for 39 areas, comprising 20890f53 counties within 20 states (and the District ofColumbia) nationwide, with a combined population ofabout 88 million people. The Libby nonattainment area which is the subject ofthis rulemaking is included in the list ofareas not attaining the 1997 PM2.S NAAQS.

OnOctober 17,2006, EPA strengthened the 24-hour PM25 NAAQS to 35 f-lg/m3 and retained the level ofthe annual PM25 standard at 15.0 f-lg/m3(71 FR 61144). OnNovember 13, 2009 EPA designated areas as either attainment/unclassified ornonattainment with respect to the revised 24-hourNAAQS (74 FR 58688). In the November 2009 designation action, EPA established a deadline ofDecember 14,2012 for states to submit attainment plans for areas designated as nonattainment for the revised 24-hourPM2 .5 NAAQS.

Ofrelevance to the proposed rulemaking herein, the notice for the November 2009 action clarified designations for the 1997 PM2 .5NAAQS by relabeling the existing designationtables to identify designations for the annual NAAQS, and by providing a separate table identifying designations for the 1997 24-hourNAAQS (i.e. 65 f-lg/m\ In that table, the Libby nonattainment areais designated as attaining the 1997 24-hour PM2.5 NAAQS.



### B. Clean Air Fine Particle Implementation Rule On April 25, 2007, EPA issued the Clean Air Fine Particle Implementation Rule for the 1997 PM2.5 NAAQS (72 FR 20586). The implementationrule describes the CAA framework and requirements for developing state PM2.5 attainment plans. An attainmentplan must include a demonstration that a nonattainment area will meet applicable NAAQS withinthe timeframe provided in the statute. This demonstration must include modeling (40 CFR 51.1007) that is10 of53 perfonned in accordance with EPA modeling guidance (EPA-4541B-07-002, April 2007). It must also include supporting technical analyses and descriptions ofall relevant adopted federal, state, and local regulations and control measures that have been implemented by the proposed attainment date.

Forthe 1997 PM2.5 NAAQS, an attainment plan must showthat a nonattainment areawill attain the standard by 2010. Alternatively, ifthe area is not expected to meet the NAAQS by 2010, a state may propose an attainment-date extension for up to five years based onthe severity ofthe nonattainment problem and onthe availability and feasibility ofpollution control measures (CAA section 172(a)(2».

For each nonattainment area, the state must demonstrate that it has adopted all RACT/RACM needed to show thatthe area will attain the PM2 .5 standards "asexpeditiously as practicable." The implementation rule provided guidance for making these RACM and RACT detenninations (72 FR 20616-21). Any measures that are necessary to meet these requirements which are not already either federally promulgated orpart ofthe state's SIP mustbe submitted in enforceable fonn as part ofa state's attainment plan.

The implementation rule also included policies on pollutants that comprise total PM2 .5

. Fivemain types ofpollutants contribute to fine particle concentrations: direct PM2.5, sulfur dioxide (S02), nitrogen oxides (NOx), ammonia, and volatile organic compounds (VOCs). All but direct PM2 .5is considered to be "precursors"to PM2.5 fonnation. The effect ofreducing emissions ofeach ofthese five types ofpollutants varies by area, depending on PM2.511 of53 

### composition, emission levels, and other area-specific factors. Forthis reason, the implementation rule established policiesregarding what states should include in their PM2.5 

### attainment plans for evaluating these pollutants.

Under these policies, sources ofdirect PM2 .5

### emissions (including organic particles, elemental carbon and inorganic particles) and S02 must be evaluated for emission reduction
measures in all PM2 .5

### nonattainment areas. Sources ofNOx 

### must be evaluated for emission reduction measures in each area unless the state and EPA demonstrate thatNOx 

### is not a significant contributorto PM2 .5 

### concentrations in a specific area. Neither VOC nor ammonia
sources are required to be evaluated for emission reduction measures in an area unless the state
or EPA demonstrates that either ofthese pollutant types significantly contributes to PM2 .5 

### concentrations. To reverse any ofthe presumptive precursor policies, the implementation rule provided guidance onthe types ofanalyses that may be included in a technical demonstration.

The implementation rule also provided guidance on other elements ofa state's attainment plan, including but not limited to, consideration of emission inventories, contingency measures, and motor vehicle emissions budgets used for transportation conformity purposes.


### IV. What Is Included in Montana's Submittal? A. 

### Background Libby, Montana, a small rural community, is located in Lincoln County in the northwestern part ofthe State. Libby sits in the narrow, triangular Kootenai valley at an elevation of2,1 00 feet. The nonattainment area is dominated by three majormountain ranges120f53 

### that limitthe air-shed: (1) the Rocky Mountain and Flathead Ranges on the eastern boundary; (2) the Purcell Range, which roughly bisects the area from north to south; and (3) the Selkirk and Cabinet Ranges on the western boundary. The vast majority ofthe area surrounding Libby is National Forest managed by the U.S. Forest Service. Based on the 2000 census and a growth rate through 2005 of3.71

### %, Libby'spopulation is estimated at 2,674.

The highest PM25

### concentrations in Libby generally occur during the winter months of Novemberthrough February. The winter concentrations are related to stagnant weather conditions dominated by light winds and strong temperature inversions. These meteorological conditions can trap emissions within the valley for many days or weeks.

Airquality datarecorded during 2001-2003 at the PM2.5

### monitor at the Libby Courthouse Annex showed violations ofthe annual PM2 5 

### standard. Libby was designated nonattainment for PM25 

### under section 107(d)(3) ofthe CAA, on AprilS, 2005 (40 CFR part 81). The air quality planning requirements for PM25 

### nonattainment areas are set out in Title I subpart 1ofthe Act.!
Historically, Libby was designated nonattainment for PMIO by operation oflawon November 15, 1990 (56 FR 56694,56794, November 6, 1991), under CAA section 107(d)(4)(B) and was classified as 'Moderate.' The PM!oattainment plan was approved by EPA on August 30, 1994 (59 FR44627). Montana has submitted revisions to the Lincoln County Air Pollution Control Program (herein referred to as the Program) and the Libby and Vicinity PM25

### Control Plan (herein referred to as the Libby attainment plan) for the purpose ofdemonstrating

1 Subpart 1applies to nonattainment areas generally.13 of53 attainment ofthe annual PM25 NAAQS. Afterpublic notice, public hearings regarding these two submittals were held on February 27, 2006 for the Lincoln County Air Pollution Control Program and on March 25, 2008 for the Libby and Vicinity PM25 Control Plan. The Montana Board ofEnvironmental Review approved the revised Lincoln County Air Pollution Control Program onMarch 23, 2006 and the Libby attainment plan on March 25, 2008. Montanahas met the requirements ofSection 110(a)(2) for reasonable notice and public hearings.

B. PMJO SIP Revisions to the Lincoln County Air Pollution Control Program Montana submitted revisions to the'PMJO SIP for the Lincoln CountyAirPollution Control Program for the Libby nonattainment areato improve and strengthen the PMJO attainmentplan. The revisions include several provisions to regulate solid fuel burning devices and require owners and operators to obtain operating permits. Operatingpermits may onlybe issued for EPA-certified woodstoves orfor pellet stoves. Furthermore, only specified materials can be burned in these devices, and visible emissions ofgreaterthan 20% opacity from them are prohibited. Additionally, these provisions allow for air pollution alerts ifPMJO orPM2 ,5 concentrations averaged over a 4-hourperiod exceed a level 20percent below any federal or state particulate matter standard. Provisions are also included for penalties for non-compliance and contingency measures.
Additionally, revisions were made for open and outdoorburning regarding prohibited materials, major open burning and managementburning, minor open burning orresidential open burning, and special burning. These revisions generally included significant limits onthe time periods for open burning activities as comparedto the existing PMJO SIP. Furtherrestrictionsl40f53 also include prohibitions on burning from November 1to March 31, which is the winter-time period when exceedances ofPM2 .5typically occur. Lincoln County's Programprohibits burning the same materials as the State but is more restrictive because the burning oftrade waste, Christmas tree waste, leaves, grass clippings and stumps is prohibited within the Air Pollution Control District2(herein referred to as the District). The June 26, 2006 submittal also included a stringency analysis for the Program showing thatthe revisions are more stringentthan comparable State law.

C. Libby and Vicinity PM25 Control Plan The Libby attainment plan provides a demonstration that the annual PM2 .5NAAQS will be met byApril 2010 through the implementation ofthe Lincoln County Program described in section B above. The Libby attainment plan includes an emissions inventory (EI), a woodstove air pollution control calculation, and a technical analysis showing that the emissions ofPM2.5 will be reduced sufficiently to meet the NAAQS. The key components ofthe Libby attainment plan
are described as follows:

1. Ambient air quality monitoring in the Libby area began in 1999 and is conducted using Federal Reference Method (FRM) PM2 .5samplers at the Courthouse Annex site in downtown Libby. Based onmonitoring data from the years 2001 to 2003, the 3-year annual design value
was 15.9**~g/m3,** which is a violation ofthe annual PM2.5 NAAQS. In February 2002, speciation monitoring was conducted to determine possible PM2.5 emission sources. The results identified organic carbon as the main component ofwintertime PM25 emissions. Further ambient

2 The boundaries ofthe District are identical to those for the nonattainment area.150f53 monitoring was conducted from November 2003 to February 2004 to determine the geographic distribution ofPM25 concentrations. Afteradditional monitoring from various locations beyond Libby city limits and meteorological data from Libby Courthouse Annex site, it was determined that the Libby Courthouse Annex site represented the worst-case ambient PM2.5 levels inthe
area. 2. A chemical mass balance study (CMB) was conducted during the winter of2003-2004 bythe University ofMontana, Centerfor Environmental Health Sciences (UM-CEHS). The goal ofthe CMB study was to identifythose emission sources in the Libby areathat contributedto elevated PM2.5 concentrations. The CMB model runs indicated that emissions from residential wood combustion were the major source ofthe fine particles on the PM2.5 filters, averaging 82% during the CMB study period (i.e. winter months). Othercontributing PM2.5 sources identified bythe CMB model were automobile exhaust (7%), ammonium nitrate (5%), diesel exhaust (4%), and sulfate (2%).3

3. Carbon 14 (14C) analysis, as a part ofthe CMB study completed by UM-CEHS, was conducted bythe University ofArizona's AcceleratorMass Spectrometry Laboratory Facility to provide further evidence that wood combustion was the major source ofPM25emissions in Libby.4

4. The Libby base year PM2.5 EI included a quantification ofactual PM25 emissions and apportioned the emissions on a seasonal and annual basis for point and area sources. The State

3 Ward, TJ., Rinehart, L.R., Lange, T. The 2003/2004 Libby, MontanaPM2.5 Source Apportionment Research Study. Aerosol Science and Technology. Vol. 40:166-177. 2006. 4Ibid.160f53 used calendar year 2005 as the base year for the development ofan EI for the Libby area. The EI
was used to support a proportional rollback model for the emission control plan. The State developed infonnation for 2005 that allowed for the calculation ofresidential wood combustion and commercial fuel use.

5. The Libby PM IO SIP as revised also serves as the control plan for emissions ofPM25. Controls exist for reducing emissions from re-entrained road dust through aggressive street sweeping and flushing, and traction sand durability requirements. Emissions oforganic carbon
are controlled through residential woodstove regulations and outdoor burning restrictions.

6. A significantpart ofthe PM2,5 control strategies has been the completion ofa woodstove changeoutprogram. Approximately 1,130 uncertified woodstoves were replaced with EPAcertified woodstoves orpellet fuel burning devices. After the changeout, PM25 emissionshave been reduced from approximately 138.78 tons/yearto 57.21 tons/year, a decrease of59%. PM25 control strategies are primarily focused on residential wood combustion. The control strategies also include: air pollution alerts maybe declared during the winter months; solid fuel burning devices must have an operatingpennit; only EPA-certified woodstoves andpellet fuel burning devices can obtain pennits; and only permitted pellet fuel devices can operate during air pollution alerts. Othercontrol strategies for PM2,5 have included an expanded area for the prescribed burning control program and the continuing federal tailpipe standards.

7. Analysis for RACT/RACM was conducted for the Libby area. EPA's RACT/RACM guidance covers three general source categories: stationary, mobile and area (79 FR 20586). The170f53 Libby PM25 CMB study did not identify any emissions from local stationary sources, only a minor amount from mobile sources, and a significant amount from an area source category residential wood combustion. EPA's area source RACM guidance covers four source categories: (1) reduced solvent usage or solvent substitution; (2) controls on charbroiling orother commercial cooking operations; (3) controls on woodstoves and fireplaces; and (4) new or improved regulations on open burning (79 FR 20586 and 20621). The Libby attainment plan concluded that wood combustion control strategies and more stringent rules onopen burning constituted RACM for area sources. The analysis further noted that the othertwo categories of
area sources, commercial users ofsolvent and commercial cooking, were infrequent in the Libby
area. The analysis also considered mobile sources, but determined that in light oftheir small contribution to PM25 nonattainment, existing federal tailpipe standards and natural turnoverrates ofthe local vehicle fleet made additional measures for mobile sources unnecessary.

8. The Lincoln County Air Pollution Control Program is**l~gally** enforceable by Lincoln County, and by the State should Lincoln County fail to administerthe program. The Libby attainment plan also provides for contingency measures ifthe NAAQS are exceeded after implementation. There is one contingency measure for wood burning for space heating purposes ifit is determinedthat wood burning emissions contribute to an exceedance ofthe PM2.5 NAAQS, then only biomass pellet fuel burners may operate within the District. Othercontingency measures
are included for re-entrained dust and industrial facilities. There is also a review process to consider permanent adoption ofa contingency measure.



### V. EPA's Analysis ofMontana's Submittal18 of53 A. PMIO SIP Revisions to Lincoln County Air Pollution Control Program EPA's summary ofthe PMIO SIPrevisions is addressed in detail under section IV. B. These revisions were made for two purposes: (1) to address PM2.5 attainment plan requirements; and (2) to improve and strengthen requirements for continued attainment ofPMIO. The revisions
are a significant improvementto a plan that was approved by EPA 16 years ago. The Libby area has not had an exceedance ofthe PMIO NAAQS since 1993. Furthermore, clarifications were made to the language to better explain to the public the requirements ofthe air quality program. The revisions removed exemptions and replaced them with requirements for obtainingpermits for wood burning appliances. These revisions also added enforcement provisions where previously none had existed.

Section 1100) ofthe Clean AirAct states that a SIP revision cannot be approved ifthe revision would interfere with any applicable requirement concerning attainment and reasonable further progress toward attainment ofthe NAAQS orany other applicable requirement ofthe Act. The Libby area is currently meeting the NAAQS for all criteriapollutants and has nothad any violations ofthe PM10 standard for over a decade. Furthermore, the revisions do not relax the stringency ofany SIP provision; in fact, the revisions generally strengthenthe SIP. As a result, the PM IO SIP revisions do not interfere with attainment ofthe NAAQS orany other applicable requirement ofthe Act. Therefore, section 1100)requirements are satisfied.

B. Attainment Demonstration In accordance with section 172(c) ofthe CAA and the implementationrule, the attainment plan submitted by Montana for the Libby area included: (1) emission inventories for19 of53 the plan's base year (2005) and projection year (2009); and (2) an attainment demonstration consisting of: (a) technical analyses that locate, identify, and quantify sources ofemissions contributingto violations ofthe annual PM25 NAAQS; (b) analyses offuture-year emission reductions and air quality improvements expected to result from national and local programs, and from newmeasures to meet RACT/ RACM requirements; (c) adopted emission reduction measures; and (d) contingency measures.

C. Analysis ofMontana's submittals 1. Pollutants Addressed and Attainment Date In accordance with policies described in the implementation rule, Montana's PM2.5 attainmentplan evaluates emissions ofdirect PM25, S02 and NOx in the Libby area. Montana provided documentation ofexpeditious attainment ofthe annual PM25 NAAQS inthe Libby area by April 201 O. Areas that demonstrate attainment by 2010 are considered to have satisfiedthe requirement to showreasonable further progress toward attainment and need not submit a separate RFP plan. For similarreasons such areas are also not subjectto a requirement for a mid-course review.

Montana's evaluation ofemissions is based onthe work conducted by UM-CEHS for the CMB model runs indicating that emissions from residential wood combustion were the major
source (82%) ofthe fine particles on the PM2.5 filters. Other PM2.5 sources identified by the CMB model were automobile exhaust (7%), ammonium nitrate (5%), diesel exhaust (4%), and sulfate (2%). In addition, a Carbon 14 analysis confirmed that wood combustion is the major
source ofPM2.5 emissions inthe Libby area and that emissions ofboth S02 and NOx are very20 of53 minor compared to PM2.5 emissions from residential wood combustion. As described in the emissions inventory, the sources ofS02 are from home heating oil and sources ofNOx are from on-road and off-road mobile sources (see further discussion in section V.C.7. on NOxemissions from mobile sources).

2. Monitoring Data As shown in the table below, the annual weighted average for 2009 shows that the Libby
areahas met the April 2010 deadline for the 1997 PM2 ·.5NAAQS. The trend in annual average concentrations is downward and coincides with the implementation ofthe woodstove changeout program. This is based on quality-controlled and quality-assured monitoring data from 2005­ 2009 that is available in the EPA Air Quality System (AQS). Table V.2.-1

!

! Year Annual Weighted Average (lJ.g/m3) 2005 15.8
I 2006 15.2
i 2007 13.0 2008 12.9 2009 10.7 I 3. Emission Inventory CAA section 172(c)(3) states that for nonattainment areas, the State shall prepare a statewide emission inventory no later than three years after designation. The baseline emission inventory for calendar year 2005 oranother suitable year shall be used for attainment planning (40 CFR 51.1008(b». EPApromulgated the Air Emissions Reporting Rule (AERR) (40 CFR part 51, subpart A) in order to consolidate the various reporting requirements that already exist, including those requirements outlined in the PM2.5 implementationrule. The AERR requires21 of53


### states to report state-wide emissions every three years. Montanaprepared a statewide emission inventory for 2005. 

### This inventory included annual totals ofemissions ofcriteriapollutants and theirprecursors. The State used data from this statewide inventory to create an emission inventory specific to the Libby area. Monitoring data for 2005 

### showed an exceedance ofthe PM2 .5 

### annual standard. The year 2005 

### is a suitable year for attainment planning because an emission inventory for this year is representative ofambient emission levels that led to the exceedance ofthe annual standard. The 2005 

### emission inventory showed that residential wood burning comprised 82% 

### ofthe direct PM2 .5

### emissions during the winter. The next largest direct source, road dust, was 11

### %, followed by locomotive emissions at 3.4%. The remaining criteriapollutant emissions were very minor, including the precursors ofPM2 .5 ( 

### i.e. NOx 

### and SOz). 

### Background values ofPM2.5 were accounted for by the State using monitored datacollected at remote stations far away from emissions sources in the Libby area. EPA notes thatthe State used a conservative emission inventory approach for projecting future growth for the 2010 

### attainment year which involved increasing the vehicle emissions by 2.1% 

### (the population growth rate) from the 2005 

### base year inventory, and not taking any credit for potential emissionreductions that may have been available from fleet turnover and the Federal tailpipe standards for vehicles. Condensable particulate matter was not considered in the emission inventory because ofa lack ofsources in the Libby area.

4. Modeling22ofS3 CAA Section 172(c) requires states with nonattainment areas to submit an attainment demonstration. A PM25 attainment demonstration consists of(l) analyses which estimate whether selected emissions reductions will result in ambient concentrations that meet the NAAQS and (2) a set ofcontrol measures which will result in the required emissions reductions.

Montana's analysis of**future~year** emissions reductions and air quality improvements was based on a proportional rollback model for showing attainment ofthe standard and a roll forward model demonstrating attainment in the future. The proportional models were applied in conjunction with the findings from chemical mass balance and Carbon 14 studies conducted by the University ofMontana.

In the particularcase ofLibby, a proportional model is more appropriate than dispersion models. The great majority ofperiods with elevated PM2 .5 concentrations in Libby occur during wintertime stagnation conditions. Furthermore, dispersion in Libby is constrained by steep terrain. The most suitable approach for stagnation conditions shouldbe determined on a**case~ by~case**  basis, (see sections 7.2.8 and 8.3.4.2(b) ofthe Guideline on Air Quality Models, 40 CFR part 51, appendix W), and an alternative model should be selected by the EPA Regional Office when a preferred model is less appropriate (see section 3.2.2 ofthe Guideline).

The proportional model used the emission inventory for 2005 when there was an exceedance ofthe standard. The decrease in PM2 .5emissions for the Libby area resulting from the woodstove changeoutprogram was calculated based on the amount ofwood burned bythe EPA-certified woodstoves and then compared to the amount ofemissions resulting from burning23 of53 the same amount ofwood from the uncertified woodstoves that were still in use. The decrease in emissions would be an indication ofthe effectiveness ofthe control strategy. Montana estimated that PM2 .Semissions would be reduced by 81.57 tons as a result ofthe new EPA-certified woodstoves installed in Libby households.

The State projected future annual average PM2 .Sconcentrations for Libby at 9.5 /lg/m3

. This projection was based onthe installation ofthe new stoves and a 100 percent compliance with the wood burning restrictions for Libby_ EPA's guidance is based on emission sources complying with state and local restrictions on emission sources (Emissions Inventory Guidance for Implementation ofOzone and Particulate Matter National Ambient Air Quality Standards (NAAQS) and Regional Haze Regulations, appendix B, EPA-454/R-05-001, August 2005.) The guidance defines rule effectiveness (RE) as a method to account for the realitythat not all emission sources are in compliance 100% ofthe time.

The guidance provides a listing ofthe factors that are most likely to affect RE. EPA used a conservative 70% RE instead ofa 100 percent compliance to determine ifLibby would still reach attainment ofthe PM2.5 standard. EPA estimated that using the more conservative compliance percentage for wood burning restrictions, the future value for Libby would still be belowthe PM2.5 standard of 15 /lg/m3• As stated above in Table V.2.-1 the Libby area 2009 annual average is currently 10.7 /lg/m3.

5. RACTIRACM Determination ofRACTIRACM is a three-step process: (1) identifying potential24 of53

measuresthat are reasonable; 

### (2) modeling to identify the attainment date that is as expeditious
as practicable; and (3) selecting RACTIRACM. Identification ofpotential measures should ordinarilybe supported by an inventory ofemissions ofdirectly emitted PM2.5 and ofprecursors from the relevant sources and source categories; the technologically feasible control measures for each source or source category; and, for each measure, the control efficiency, possible emission reductions by pollutant, estimated cost perton, and the date by which the measure was orcould 

### be implemented; and otherrelevant information.

Forthe first step, identification ofpotential measures that are reasonable, Montana supported its RACTIRACM analysis with the emissions inventory and the CMB study. The RACTIRACM analysis first noted that there are no major stationary sources ofPM2.5 in the Libby area. 

### It also noted that minor stationary sources are currently regulated under Montana's minor source program, which requires permits and a Best Available Control Technology (BACT) review. As discussed in the implementationrule, ifstate or federal rules already regulate a given sector, it is reasonable for a state to look to unregulated sectors for RACTIRACM measures. Furthermore, the implementation rule permits the state to use reason in the extent ofits effort to identify potential control measures. For example, the rigor ofthe analysis may depend on the relative contribution ofa particular pollutant to the PM25 nonattainment problem (72 FR 20613). As shownby the CMB study, stationary sources are a very minor contributorto PM2 .5 nonattainmentin Libby. Similarly, the RACT/RACM analysis reasoned that mobile sources are currently regulated, make only a minor contributionto the nonattainment problem, and the overall emissions will continue to be reduced through fleet turnover. Thus, the first step focused onmeasures for area sources.25 of53

The analysis further noted thattwo types ofarea sources (commercial users ofsolvents and commercial charbroilers orothercommercial cooking operations) were infrequent in the Libby area. The analysis also discussed re-entrained road dust, which the CMB study did not identify as a contributorto PM2.5 nonattainment, and notedthat there were existing SIP provisions to control road dust. Asto homeheating oil, a source ofS02, the CMB study found only a 2% contributionto PM2.5 nonattainment for all sulfates combined. Thus, the RACM analyses focused on the remaining area sources ofwood burning devices and openburning and identified several control measures to be included in the attainment plan.

Forthe second step, as discussed in more detail in section V.C.4, Montana modeled attainmentby 

### 20I

### 0based on adoption ofthese reasonable control measures. Finally, for the third step, based on the analysis, Montana selected and adopted RACM for woodburning devices and openburning. Forwood burning devices, the State developed and implemented a woodstove changeout control strategy. The woodstove changeoutpermanently removed 1,130 old, uncertified woodstoves and replaced them with EPA-certified woodstoves orpellet stoves. Additionally, the State adopted measures that require permits for solid fuel burning devices (including woodstoves) and restrict installation and operation ofthese devices to three categories: pellet stoves, devices with a catalytic emissions control system, and devices with a non-catalytic emissions control system. Forthe lattertwo, emission limits are imposed.

RACM measures were also included for major open burning, managementburning, residential burning, and special burning. The PM2.5attainmentplan includes BACT and permits26 of53 for an expanded area, which is the entire Air Pollution Control District, for all ofthese different types ofburning activities. Additionally, these burning activities were restricted to shortertime periods.

In summary, the State evaluated, by source category, sources ofdirect PM25, S02 and NOxfor RACT/RACMcontrol measures. The State's evaluation ofsources ofS02 and NOx resulted intheirdecision that no additional controls are necessary to attainthe NAAQS based on the absence ofmajor sources or area sources that can be cost effectively or reasonably controlled. The State therefore adopted RACM for direct PM2.5. In accordance with Section 172(c) ofthe CAA, Montanahas adopted all RACT/RACM needed to attain the standards as expeditiously as practicable. EPA has reviewed Montana's RACT/RACM analysis and has determined that the state reasonably identified potential control measures, modeled the attainment date that is as expeditious as practicable and reasonably selected RACTIRACM for the Libby area.

6. Contingency Measures In conformance with Section 172(c)(9) ofthe CAA, the implementation rule requires that PM2 .5attainment area plans include contingency measures. These measures must be fully adopted or otherwise ready for quick implementation, should contain triggermechanisms and an implementation schedule, should be measures not included in the SIP control strategy, and should provide the equivalent ofone year ofRFP. Once triggered, a contingency measure should take effect without further action by the State orEPA.27 of53 The Libby SIP contains contingency measures for residential wood burning, re-entrained dust, and industrial facilities. Ifit is determined thatresidential woodburning contributes to an exceedance ofthe PM2.5 NAAQS, then only biomass pellet fuel burners may operate within the District. Ifre-entrained dust contributes to noncompliance, thenthe existing regulations (which currently only apply in a limited area) are made applicable to the entire Air Pollution Control District. Finally, ifan industrial facility contributes to noncompliance, the MontanaDepartment ofEnvironmental Quality (MTDEQ) will initiate contingency measures to reduce emissions. Once a contingency measure is initiated, it must remain active until the Libby SIP demonstration is revised and resubmitted to EPA for approvaL

The contingency measures for residential wood burning and re-entrained dust meetthe requirements ofthe implementationrule. The contingency measure for majorpoint sources would require further action by MTDEQ to determine whether additional controls are necessary. However, the contingency measures for residential wood burning andre-entrained dust are sufficientto meet the requirements ofthe CAA, including equivalence to one year ofRFP.

7. Transportation Conformity Requirements Transportation conformity is required under CAA section 1 76(c) (42 U.S.C. 7506(c)) to
ensure that transportation plans, transportation improvementprograms (TIPs) and federally supported highway and transit projects are consistent with ("conform to") the state airquality implementationplan. Transportation conformity applies to areas that are designated nonattainment, and to those areas redesignated to attainment after 1990 with a CAA section28 of53 175A maintenance plan ("maintenance areas"), for transportation-related criteriapollutants: carbon monoxide (CO), NOx and particulate matter (PM25 and PMlO).

EPA'stransportation conformityrule (40 CFRparts 51 and 93) establishes the criteria and procedures for determining whethertransportation activities conform to the SIP. One requirement ofthe rule is that transportation plans, TIPs, and projects must satisfy a regional emissions analysis for the relevant pollutants and precursors (40 CFR 93.118, 119). However, section 93.109(m) ofthis rule states that an area is notrequired to satisfy a regional emissions analysis for a pollutant or precursor ifthe SIP demonstrates that motor vehicle emissions ofthat pollutant orprecursor are an insignificant contributor to the area's air quality problem. In today's notice, EPA is proposing to find that motor vehicle emissions ofPM2.5 and NOxare insignificant contributors to Libby's PM2 ,5 nonattainment problem. Ifthis proposal is finalized, PM2 .5 and NOx motor vehicle emissions budgets (MVEB) would not be established and a regional emissions analysis would not be required for either PM2,5 orNOx in any future conformity determination in Libby. Please note, however, that this proposed action would not apply to PM2,5 hot-spot analyses for individual projects, ifsuch an analysis is required in the future for transportation conformity purposes.

There are specific transportation conformityprovisions that EPA proposes to determine
as applicable to the Libby PM25 nonattainment area. As provided in more detail belowand in 40 CFR93.109(m), these specific conformity provisions are addressed when EPA finds that emissions from motor vehicles in the Libby PM25 nonattainment area are an insignificant290f53 

### contributorto the areas' nonattainmentproblem for a relevant NAAQS and/orprecursor. 40 CFR 93.109(m) states: "(m) Areas with insignificant motor vehicle emissions. Notwithstanding the other paragraphs in this section, an area is not required to satisfy a regional emissions analysis for §93.118 and/or §93.119 for a given pollutant/precursor and NAAQS, if EPA finds through the adequacy or approval process that a SIP demonstrates that regional motor vehicle emissions are an insignificant contributor to the airquality problem for that pollutant/precursor and NAAQS. The SIP would have to demonstrate that it would be unreasonable to expect that such anarea would experience enough motor vehicle emissions growth inthat pollutant/precursor for a NAAQS violation to
occur. Such a finding would be based on a number offactors, including the percentage ofmotor vehicle emissions in the context ofthe total SIP inventory, the current state of airquality as determined by monitoring data for that NAAQS, the absence ofSIP motor vehicle control measures, and historical trends and future projections ofthe growth of motor vehicle emissions. A conformity determinationthat meets otherapplicable criteria in Table 1ofparagraph (b) ofthis section is still required, including regional emissions analyses for §93.l18 and/or §93.119 for otherpollutants/precursors and NAAQS that apply. Hot-spot requirements for projects in CO, PMIO, and PM2.5 areas in §93.116 must also be satisfied, unless EPA determines that the SIP also demonstrates that projects will not create new localized violations and/or increase the severity or number ofexisting violations ofsuch NAAQS. IfEPA subsequently finds that motor vehicle emissions ofa given pollutant/precursor are significant, this paragraph would30 of53

no longer apply for future conformity determinations for that pollutant/precursor and NAAQS."

To consider making such an insignificance finding, EPA evaluated the provisions of40 CFR 93.109(m) against therelevant information contained in the SIP attainment plan, the SIP revision's associated technical support document (TSD), and additional information as developed by EPA. We evaluated the following factors in determining whetheron-road direct PM2 .5 and NO" emissions are insignificant contributors to the area's PM2 .5 airquality problem; (1) the percentage ofmotorvehicle emissions in the context ofthe total SIP inventory; (2) the current state ofairquality as determined by monitoring data for that NAAQS; (3) the absence of SIP motorvehicle control measures; and (4) historical trends and future projections ofthe growth ofmotorvehicle emissions. Ourevaluation and conclusions are as follows:

A. The percentage ofPM2 .5 motor vehicle emissions in the context ofthe total SIP inventory. This factor, with regard to PM2.5 emissions, is addressed in two areas ofthe SIP revision documentation. Table 27.12.11.4B (HPM25 Annual Demonstration ofCompliance") ofthe Libby attainment plan provides relevant information with regard to 2003-2004 CMB percentages by source category, percentreduction in emissions due to control strategies, estimated growth in emissions overthe 2005 to 2010 time period, and 2010 compliance year contributions. The dominant CMB source was residential woodstoves at 82% with motor vehicle tailpipe emissions at 7% oftotal PM2 .5 mass and diesel exhaust at 4% ofthe total PM2.5
mass.3 I of53

The contribution ofmotorvehicle PM2.5 emissions is also documented in Table S.IA ("Seasonal PM 2.5 Emissions in Libby by Source Category") ofthe SIP's TSD. Table S.IA presents estimated emissions based on metric tons and percentage ofthe inventory for 2005, by season; we have provided these motor vehicle tailpipe PM2.5 emissions, as percent oftotal PM2.5 emissions, in Table V.7-1 below. We note that inTable 5.IA ofthe SIP's TSD, the inventory is dominated bywoodstove emissions in all four seasons.

Table V.7.-1 Motor Vehicle PM2 .5Emissions Percentage ofTotal Inventory for 2005 

### (Ilfi . . ) a 19ures are Inmetnc tons Season Motor Vehicle PM25 Emissions Total Inventory PM2.5 Emissions Motor Vehicle Emissions % ofTotal Winter 0.48 80.63 0.59 Spring 0.55 46.43 1.18 Summer 0.66 13.66 4.83 Fall 0.51 97.67 0.52 Total Year 2.2 238.38 0.92

As shown in Table V.7.-1 above, motor vehicle tailpipe PM25 emissions represent an annual average ofonly 0.92 

### % ofthe total PM2.5 inventory. That is, motor vehicle emissions are less than one percent ofthe inventory over the course ofa year. During the summer, motor vehicle emissions make up close to five percent ofthe inventory, butmotor vehicle emissions are only slightly higher during the summerthan during other seasons. The motor vehicle emissions percentage is much greater during the summercompared with other seasons primarily because total PM25 emissions are significantlyreduced during the summer compared to other seasons;
summeris the season with the fewest emissions from woodstoves. The information provided in the State's submittal supports a conclusion that regional PM2.5 on-road mobile source emissions32 of53

are a minimal percentage in the context ofthe total PM25 emissions inventory. Therefore, this factor supports the proposed finding that on-road PM2 .5 emissions are insignificant for the Libby PM2.5 nonattainment area.

B. The current state ofair quality as determined by monitoring data for the PM25 NAAQS. This factor is addressed as shown in the table below. From the State's SIP revision and section V.B.2 above, from 2007 to 2009 the Libby areacontinues to demonstrate attainment of the 1997 annual PM2.5 NAAQS. Furthermore, the trend in annual average concentrations is downward and coincides with the implementation ofthe woodstove changeout program. This data is based onquality-controlled and quality-assured monitoring data from 2005-2009 that are available in the EPAAQS. This factor supports the proposed finding that on-road PM2.5 emissions are insignificant for the Libby PM25 nonattainment area.

Table V.2.-1

I

I '--' PM2.5 Annual Weighted Year Average (l-lg/m3) 2005 15.8 2006 15.2 2007 13.0 2008 12.9 2009 10.733 of53 C. The absence ofSIP motor vehicle control measures for PM2.5. The Libby PM2.5 attainment plan relies on a 59% reduction in residential woodstove emissions to reach attainment ofthe annual PM25 NAAQS and took no credit for any emission reductions in the motor vehicle tailpipe and diesel exhaust categories (e.g. Federal tailpipe emission standards and fleet turnover). The State further described these assumptions in sections 27.12.7.3 (HFederal Tailpipe Standards Control Program") and 27.12.11.4 (HPM25 2010 Demonstration ofCompliance") ofthe Libby attainment plan. EPA also notes there is no State
orlocal mandated motor vehicle emission control requirements (e.g., inspection and maintenance program, fuels, ortransportation control measures) for the Libby PM2 .5 nonattainment area. Therefore, this factor supports the proposedfinding that on-road PM2.5 emissions are insignificant for the Libby PM25 nonattainment area.

D. Historical trends and future projections ofthe growth ofmotor vehicle PM2 .5 emissions. Libby's annual PM2.5 2001-2003 design value was 15.9 f,lgim3

. In November 2003 through February 2004 air quality data was collected in Libby to support CMB modeling. This CMB modeling showed that residential wood smoke was the primary source ofPM2 .5in Libby. Table 27.12.l1.4B in the Libby attainment plan shows that, when the results ofthe CMB modeling are appliedto the air quality data from 2001-2003, residential wood smoke contributed 13.0 f,lgim3 (82%) ofthe 2001-2003 annual PM25 design value, motor vehicle tailpipe emissions contributed 1.1 f,lg/m3 (7%), and diesel exhaust emissions contributed 0.7 f,lgim3 f,lgim3 (4%). Based on the results ofthis modeling Montanabased its attainment strategy for the area on a woodstove change-out program.34 of53

The SIP assumes that the woodstove change-out program will reduce those emissions by 59% in 2010. The SIP also assumes that motor vehicle tailpipe emissions and diesel exhaust emissions would grow by 2.1% between 2005 and 2010, which is equal to the expected population growth rate during thatperiod. The SIP does not account for any reductions in motor vehicle emissions ordiesel exhaust that would occur due to fleet turnoverto new lower emission motorvehicles, on-road diesel vehicles or off-road equipment. Table 27.12.11.4B in the Libby attainmentplan shows that in 2010 the predicted annual average PM2.5 concentration would be 

### 8.37 J.lg/m3• The table also shows that residential wood smoke is expected to contribute 5.44 J.lg/m3 (65%) in 2010, motor vehicle tailpipe emissions would contribute 1.12 J.lg/m3 (13%), and diesel exhaust emissions would contribute 0.71 J.lg/m3 (8%). As can be seen, on a percentage basis the contribution ofmotorvehicle emissions and diesel exhaust increases; however, overall PM2.5 concentrations are expected to decrease by 53% to 8.37 J.lg/m3
, the contribution ofwood smoke emissions is expected to decrease by 59%, and the total contribution ofemissions from motor vehicles and diesel exhaust to PM2.5 mass in 2010 is expected to increase by only 0.03 J.lg/m3 between 2005 and 2010. This increase in mass is due to the assumptions that emissions from these sources increase atthe same rate as population growth and that no emissions reductions from fleet turnover are included in the calculations. Both ofthese are conservative assumptions.

EPAnotes that the contribution ofmotor vehicle emissions of 13% to PM2.5 mass in 2010 represents the projected chemical mass balance ofPM25 and not an emission inventory projection. The SIP includes a base year PM2.5 inventory (Table 5.lA) for 2005. That inventory35 of53



### soows that motor vehicle emissions ofPM2 ,5 

### are 2.20 tpy and that total PM2.5 emissions in the base year are 238.39 tpy. Therefore, the motor vehicle emissions in the base year are slightly less than I% 

### ofthe total direct PM2.5 emissions. On the surface this may seem to be in conflict with the results ofthe CMB modeling, which shows that motor vehicle exhaust contributed about 7% ofthe PM2 .5 

### mass in the base year. However, it should be noted that the chemical mass balance data and the PM2 ,5 data collected at the Libby Courthouse Annex represents only one receptor within the City ofLibby, and only for the period oflate 2003 through early 2004. While this location is believed to be representative ofLibby's air quality, numerous factors influence the local particulate matter concentrations and air quality. Local scale meteorology (wind speed, wind direction, temperature, relative humidity, barometric pressure, and solar radiation at a minimum), traffic patterns, and precipitation are a few examples ofthese factors which vary throughout the city. Accepting that variable conditions exist throughout Libby, as well as the inherent uncertainty associated with ambient air monitoring, the difference that exists between PM2.5 monitoring data at one receptor and a city-wide emission inventory appears to be plausible.

We also note that the actual location ofthe monitor may have exposed it to additional influence from motor vehicle emissions. We have not performed an in-depth analysis, but we do note that the monitor is located directly adjacent to U.S. Highway 2, the main north/south highway through Libby. Although motor vehicle PM25 emissions are shown to be minimal in the State's emissions inventory (ref. Table S.IA: "Seasonal PM25 Emissions in Libby by Source Category" and Table V.7.-1 above), motor vehicle emissions may have shown a greater than36 of53 anticipated contribution on the chemical mass balance analysis due to the monitor's close proximity to Highway 2.
Overall, this factor supports the proposed finding that on-road PM2.5 emissions are insignificant for the Libby PM25 nonattainment area. In summary, all four factors support the proposed finding. After weighing these four factors described in 40 CFR 93.109(m) and evaluated above, EPAproposes to find that on-road PM2.5 emissions are insignificant for the Libby PM2.5 nonattainment area. We tum to applying the four factors to on-roadNOx emissions.

E. The percentage ofNOx motor vehicle emissions in the context ofthe total SIP inventory. The Libby attainment plan focuses on directly emitted PM2.5 and controls ofPM25 emissions from woodstoves and does not address any motor vehicleNOx emissions otherthan to indicate in Table 27.12.11.4B "PM2.5 Annual Demonstration ofCompliance" that the CMB data showthat ammonium nitrate was only 5% ofthe mass found on the filters. EPA, therefore, drew upon otherrelevant, available datato evaluate whetherNOxmotor vehicle emissions in the Libby PM2 .5nonattainment area are significant andrequire that a NOx motor vehicle emissions budget be established for transportation conformity purposes or whether on-road NOx emissions could be found insignificant based onthe criteria in 40 CFR 93.109(m).

EPA reviewed relevant information from EPA's National Emissions Inventory (NEI) data for 2005 that were used for the 2009 final designations for the 24-hour 2006 PM2.5 NAAQS (7437 of53 FR 58688, November 13,2009).5 However, since the NEI data were for Lincoln County as a whole, we needed to assess how much ofthe Lincoln County on-road NOx inventory could be apportioned to the Libby PM2.5 nonattainment area. Ourmethodology was to calculate how many vehicle miles traveled (VMT) the Libby PM25 nonattainment area contributes to Lincoln County'stotal VMT and to assign that same proportion ofthe total Lincoln County on-roadNOx emissions to the Libby PM2.5 nonattainment area, as explained further below. We then needed to determine what percentage this was oftotal NOx from the Libby PM2.5 nonattainment area.
Specific emissions data for Lincoln County, MT, which includes the Libby PM2.5 nonattainment area, are presented in Table V.7.-2 below and are from EPA's PM25 24-hour 2006 NAAQS final designations information.

. t a e V 7 2 (All emISSIOn fi 19ures are In ons peryear ) T bl 

# ­ I County Major VOC NOx S02 NH3 PM2.5 OC EC S04 N03 PMFine Category •Lincoln Fires 6106 310 277 425 2199 1286 219 20 10 664 

## I Lincoln Non­ 338 2403 169 1 76 16 55 0 0 4 Road
i Lincoln On-Road 366 545 15 23 11 3 6 0 0 2

Lincoln Other­ 871 138 74 57 453 108 16 5 1 323 Stationary 296TI:L Total 7681 3395 535 506 2738 1412 

### 11 I 994 I

The "On-Road" ormotorvehicle, 2005 NEI emissions were calculatedby EPA for Lincoln County based ona county annual total ofVMT of231 ,246,800. This VMT figure,

5 The 2005 NEI data from EPA's PM2.5 24-hour 2006 NAAQS final designations information are available at: http://www.epa.gov/ttnlnaags/pm/pm25 2006 techinfo.html.380f53 which represents data for the entire county, is also referenced in our 2006 PM25 24-hour NAAQS final designations information.6

Based on the 2005 NEI datareferenced above in Table V.7.-2, Lincoln County's total annual VMT of231,246,800results in approximately 545 tpy ofon-road NOx• To calculate the estimated on-road NOxemissions for the Libby PM2.5nonattainment area, we first needed to determine what percentage ofLincoln County'stotal VMT is attributed to the Libby PM2,5 nonattainment area. We then applied that VMT percentage to the total Lincoln County on-road NOxemissions to getthe estimated on-roadNOxemissions for the Libby PM2,5 nonattainment
area. The total VMT for the Libby PM2,5 nonattainment area, 54,877,360, came from the MTDEQ.7 This is 23.73% ofLincoln County's total VMT (i.e., 54,877,360 VMT from Libby divided by 231,246,800 VMT from Lincoln County as a whole). Itis reasonable to assume that the Libby PM25 nonattainment area contributes this same percentage ofon-road NOxemissions to the total Lincoln County on-roadNOxemissions. Therefore, we applied this 23.73% to the Lincoln County total of545 tpy ofon-road motor vehicle NOxemissions, which results in approximately 129.33 tpy ofon-road NOxemissions for the Libby PM2 .5 nonattainment area. In lieu ofother specific data, EPA considers this approach a reasonable estimate ofthe on-roadNOx emissions for the Libby PM2,5 nonattainment area.

Once we had a figure for the number oftons ofon-road NOxemissions from Libby, the next step in our analysis was to determine what percentage ofthe total anthropogenic NOxthis
6 See http://www.epa.gov/ttnfnaaqs/pm/pm25_2006_techinfo.html; Factor4.B "Vehicle Miles Traveled".390f53 represents. Again, since the NEI data available were for Lincoln County as a whole, we needed to assess howmuch ofthe Lincoln Countytotal anthropogenic NOxcould be apportioned to the Libby PM2.5 nonattainment area. To do so, we needed to establish what NOx emissions were from anthropogenic sources in the Libby PM2.5 nonattainment area otherthan from on-road motor vehicle tailpipes. To develop these particularemissions figures, we assumed that the percentage ofLincoln County's anthropogenic NOx coming from Libby would be the same as the percentage ofLincoln County's anthropogenic PM2.5 emissions coming from Libby, as described below.
First, we determined the anthropogenic NOxemissions for Lincoln County from the "Non-Road" and "Other Stationary" source categories. We used the data from Table V.7.-2 above and eliminatedthe "Firest!8 and "On-Road" emissions categories from the Lincoln County 2005 NEI data (see Table V.7.-3 below):

T bl

a e V 7 

## ..

# - 3 (All emISSIons are In tons peryear) County Major Category VOC NOx S02 NH3 PM2.5 OC EC S04 N03 PM Fine Lincoln NonRoad 338 2403 169 1 76 16 55 0 0 4 Lincoln OtherStationary 871 138 74 57 453 108 16 5 1 323 Total 1209 2541 243 58 529 124 71 5 1 327 The total anthropogenic NOx in Lincoln County from sources otherthan on-road is 2541 tpy.

7 VMTdata was communicated in a February 26,2010, email from Jim Carlin ofMTDEQto Tim Russ ofEPA Region 8.40 of53 Next, we summed-up the PM25 emissions from the Libby PM2 .5 nonattainment area from the State's SIP emission inventory Table S.lA, but did not include emissions from fires (i.e., PM2 .5 emissions from "Large Prescribed Burning" and "General Burning" were not included from the State's Table S.lA); see Table V.7.-4 below.
Table V.7.-4: Libby Anthropogenic PM2.5 Emissions (As adapted from Table S.IA "Seasonal PM25 Emissions in Libby by Source Category" ofthe L'bb )y A' SIP E . . I ) I ttalnment miSSIOn**nventory~**

• Sources Winter Spring Summer Fall Woodstoves Residential/Com. 66.65 20.74 5.08 58.76

Paved Roads Fugitive Dust 8.92 2.57 3.23 9.61 Large Prescribed Burning 

## --­ --­ - - -

## - General Burning 

## --­ --­ --­ -

## -­

Locomotives 2.72 2.72 2.72 2.72 Unpaved Roads

Fugitive Dust 1.22 1.34 1.53 1.2 i Propane Heating

Residential/Com. 0.13 0.04 0.01 0.11 Oil Heating Residential/Com. 0.48 0.15 0.04 0.42 Aircraft 0.0 0.03 0.03 0.0 Road & Building Construction Dust 0.02 0.36 0.36 0.36

Motor Vehicle Tailpipe 0.48 0.55 0.66 0.5\ Total (Metric Tons) 80.62 28.50 13.66 73.69 Total Short Tons (2000 Ibs. perton) 88.88 31.42 15.06 81.24 Total Annual AnthropogenIc Short Tons ofPM2.5 EmIssIons = 216.60 tons.

Based on the data in Table V.7.-4 above, the total annual anthropogenic shorttons of PM2 . 5 emissions (without including emissions from the "MotorVehicle Tailpipe" category) from

8 The "Fires" category ofthe 200S NEI relates to wildfires, prescribed bums and such. This correlates to the "Large Prescribed Burning" and "General Burning" categories in the State's Table S.IA.41 of53 "Non-Road" and "Other Stationary" sources in the Libby PM2 .5nonattainment area are estimated
as 214.17 tons per year.

The Libby PM25 nonattainment area's annual emissions ofPM25 from "Non-Road" and "Other Stationary" anthropogenic sources is 214.17 tpy, whereas these sources emit 529 tpy for Lincoln County as a whole (see Table V.7.-3 above). Therefore, Libby's share ofLincoln County's PM25 emissions from "Non-Road" and "Other Stationary" anthropogenic sources is approximately 40.48%.

We then added Lincoln CountyNOx emissions from the "Non-Road" and "Other Stationary" sources categories, 2541 tpy (see Table V.7-3 above), and attributed 40.48% ofthose emissions to the Libby PM2 .5nonattainment area's NOx "Non-Road" and "Other Stationary"
sources categories, whichresults in 1028.6 tpy. To summarize, EPA estimated the Libby PM2.5 nonattainment area's on-road NOx motorvehicle emissions as 129.33 tpy, and the non-road and other stationary sources' NOxemissions as 1028.6 tpy. Therefore, the total estimated annual anthropogenic NOxemissions from all ofthese source categories are estimated to be 1157.93 tpy for the Libby PM2 .5nonattainment area. The approximate contribution ofannual on-road NOx motorvehicle emissions (129.33 tpy) to the total estimated NOx annual anthropogenic emissions from all sources (1157.93 tpy) in the Libby PM2.5 nonattainment area is 11.17% ofthe total inventory.

EPA indicated in its July 1,2004Transportation Conformity final rule (69 FR 40004) that mobile source emissions ofapproximately 10% may be considered insignificant, but did not42 of53 make 10% a specific threshold. While the 11.7% figure calculated for on-road NOx in the Libby PM2 .5nonattainment area is slightly greater than this, in this same rulemaking EPA explained: "This example also illustrates the reason EPA believes it is important to have flexibility in implementing this provision. Although the commenter specifically mentions 10% as the threshold for finding motor vehicle emissions insignificant, EPA clarifies that this figure is a general guideline only. Depending on the circumstances, we may find that motor vehicle emissions that make up less than 10% ofan area's total inventory are still significant. Conversely, we may also find that motor vehicle emissions in excess of 10%
are still insignificant, under certain circumstances relating to the overall composition of the air quality situation. In general, the percentage ofmotor vehicle emissions in the area's total inventory is an important criterion for determining whether motor vehicles are
a significant or insignificant contributor to an area's air quality problem, yet there are other criteria that EPA will examine when making this finding, as described in the regulatory text for 

### § 93.109(k)." (69 FR 40062)9
As stated in the 2004 preamble, 10 percent is a guideline only. As described below, EPA considered other factors that lead EPA to propose that motor vehicle emissions ofNOx are an insignificant regional contributor to the PM25 nonattainment problem.

F. The current state ofair quality as determined by monitoring data for PM2 .5NAAQS. This factor is addressed with the ambient PM25 air quality data presented in section V.7.B above which demonstrate the Libby PM2.5 nonattainment area is attaining the PM2.5 annual43 of53

Area/County/State PM2.5 Composition Data Sulfate (Ilmg/m3) Nitrate (Ilmg/ m3) Carbon (Ilm g/

m3) Crustal (Ilmg/ m3) Total (Ilmg/m3) Nitrate Percent Carbon Percent UbbyfLincolnlMT Total Concentration (Cold) 1.4 0.8 41.9 0.3 44.4 2 94 Regional Concentration (Cold) 0.9 0.4 2.4 0.2 3.9 10 62 Urban Concentration (Cold) 05 0.4 395 0.1 40.5 1 98

I Total Concentration (Warm) 1.2 0.0 6.7 0.8 8.7 0 77 Regional Concentration (Warm) 1.0 0.0 2.5 Ll 4.6 0 54
Urban Concentration (Warm) 0.2 0.0 4.2 0.0 4.4 0 95

Total Concentration (Annual Average) 1.0 0.1 12.8 0.4

i 14.3 1 90 NAAQS. Additional data, relevantto NOx or in this case nitrates derived from NOx emissions, 10
were provided by EPA with the 2009 final designations for the 24-hour 2006 PM2.5 NAAQS. This information, as provided in Table V.7-5 below, is from EPA's PM2.5 24-hour 2006 NAAQS final designations and is located at: http://www.epa.gov/ttnlnaaqs/pmlpm25 2006 techinfo.html

Table V 75 

### - PM2.5 ComposltlOn Data fIorL'bb 1 'y, MT



### I

I

As can be seen in Table V.7-5 above, nitrates (as derived from NOx) are a very small component ofthe PM2,5 composition found inthe Libby PM2,5 nonattainment area. Therefore, NOx as derived from motor vehicle tailpipe emissions also is a very small component. This
9 EPA redesignated the insignificance provision ofthe transportation conformity rule from 40 CFR 93.l09(k) to 40 CFR 93.109(m) in its March 24,2010 "PM Amendments" final rule (75 FR 14260).44 of53 factor thus supports the proposed finding that on-road NO" emissions are insignificant for the Libby PM25 nonattainment area.

G. The absence ofSIP motor vehicle control measures for NO". As discussed in section V.7.C above, the Libby PM2.5 attainment plan took no credit for any emissionreductions in the motor vehicle tailpipe and diesel exhaust categories (e.g. Federal tailpipe emission standards and fleet turnover). The State further described these assumptions in sections 27.12.7.3 ("Federal Tailpipe Standards Control Program") and 27.12.11.4 ("PM25 2010 Demonstration ofCompliance") ofthe Libby attainment plan. EPA also notes there is no State
or local mandated motor vehicle emission control requirements (e.g., inspection and maintenance program, fuels, ortransportation control measures) for the Libby PM25 nonattainment area. Therefore this factor supports the proposed finding that on-roadNO" emissions are insignificant for the Libby PM25 nonattainment area.

H. Historical trends and future projections ofthe growth ofNO" motor vehicle emissions. As noted in our discussion in section V.7.D above, the Libby attainment plan uses a 59% reduction in residential woodstove emissions to reach attainment ofthe annual PM2.5 NAAQS and took no credit for any emission reductions in the motor vehicle tailpipe and diesel exhaust categories. The State further described these assumptions in sections 27.12.7.3 ("Federal Tailpipe Standards Control Program") and 27.12.11.4 ("PM2.5 2010 Demonstration of Compliance") ofthe Libby attainment plan. EPA notes that the State used a conservative
10 Nitrogen oxides react in the atmosphere to form nitrates. Forourpurposes, the impact of45 of53 emission inventory approach for projecting the 2010 attainment year future growth which involved merely increasing the vehicle emissions by 2.1

### % (the population growth rate) from the 2005 base year inventory, and not taking any credit for potential emissionreductions that may have been available from fleet turnover and the Federal tailpipe standards for vehicles. In addition, as we noted above, there are no State or local mandated motor vehicle emission control requirements (e.g., inspection and maintenance program) for the Libby PM25 nonattainment
area.

This factor supports the proposed finding that on-road NOxemissions are insignificant for the Libby PM25 nonattainment area. After weighing these four factors described in 40 CFR 93. 1 09(m) and evaluated above, EPA proposes to find that on-roadNOxemissions are insignificant for the Libby PM25 nonattainment area.

I. Conclusion. In view ofourevaluation presented above per40 CFR93.109(m), EPA is proposing to find that direct PM25 andNOxmotorvehicle emissions are an insignificant contributor to the air quality issues associated with the PM2 .5annual NAAQS in the Libby PM2 .5 nonattainment area; thus, motor vehicle emission budgets for on-road direct PM2S andNOx would not be established by this rulemaking. Based on our evaluation ofthe four factors described in 93. 1 09(m), EPA proposes to conclude that it would be unreasonable to expect that the Libby PM2.5 nonattainment
area would experience enough motor vehicle emissions growth such that a PM25 annual NAAQS violation would occur.

NOx emissions is measured as the amount ofnitrates found at the PM2 .5monitor.46 of53



### VI. Proposed Action The EPA has reviewed Montana's SIP revision for attaining the 15f,lg/m3 annual PM2.5 NAAQS for the Libby PM2 .5nonattainment area. EPA is proposing to approve the State of Montana's revisions to the Lincoln County Air Pollution Control Programto be included in Montana's SIP, submitted on June 26, 2006, and the Libby PM2.5 attainment plan, submitted on March 26, 2008. Action was not taken earlier on the June 26, 2006, submittal atthe request of the State ofMontana to delay action until the submittal ofthe Libby PM2 .5attainment plan at a later date. EPA has determined thatthe SIP meets applicable requirements ofthe CAA, as described in the Clean Air Fine Particle Implementation Rule. Specifically, EPAhas determined thatMontana's SIP includes an attainment demonstration and adopted state regulations and programs needed to support the determination that the Libby PM2 .5nonattainment area will continue attaining the annual PM25 NAAQS. Finally, EPA is proposing to find on-road, directly emitted PM2 . 5 and NOx in the Libby, Montananonattainment area insignificant for regional transportation conformity purposes.


### VII. Statutory and Executive OrderReviews A. Executive Order 12866, Regulatory Planning and Review Under Executive Order 12866, (58 Federal Register 51735 (October4, 1993)) the Agency must determine whetherthe regulatory action is "significant" and therefore subjectto the Office ofManagement and Budget (OMB) review and the requirements ofthe Executive Order. The Orderdefines "significant regulatory action" as one that is likely to result in a rule that may: (1) have an annual effect on the economy of$100 million or more or adversely affect in a material way the economy, a sector ofthe economy, productivity, competition,jobs, the47 of53 environment, public health or safety, or state, local, ortribal governments orcommunities; (2) create a serious inconsistency orotherwise interfere with an action taken orplanned by another agency; (3) materially alterthe budgetary impact ofentitlements, grants, user fees, or loan programs orthe rights and obligations ofrecipients thereof; or (4) raise novel legal orpolicy issues arising out oflegal mandates, the President's priorities, orthe principles set forth in the Executive Order." The OMB has exempted this regulatory action from Executive Order 12866 review.



### B. Paperwork Reduction 

### Act This action does not impose an information collection burden under the provisions ofthe Paperwork Reduction Act, 44 U.S.C. 3501 ET seq. This action proposes to approve the SIP revisions submittedby the State ofMontana.



### C. Regulatory Flexibility 

### Act The Regulatory Flexibility Act (RFA) generally requires an agency to prepare a regulatory flexibility analysis ofany rule subject to notice and commentrulemaking requirements underthe Administrative Procedure Act or any other statute unless the agency certifies that the rule will nothave a significant economic impact on a substantial numberof small entities. Small entities include small businesses, small organizations, and small governmentaljurisdictions.

This proposed rule will not have a significant impact on a substantial number ofsmall entities because SIP approvals and disapprovals under section 110 and subchapter I, part D ofthe48 of53 Clean Air Act do not create any new requirements, but simply approve or disapprove requirements that the state is already imposing. Therefore because the Federal SIP approval does not create any newrequirements, I certify that this action will not have a significant economic impact on a substantial number ofsmall entities. Moreover, due to the nature ofthe Federal-state relationship under the Clean Air Act, preparation offlexibility analysis would constitute Federal inquiry into the economic reasonableness ofstate action. The Clean Air Act forbids EPA to base its actions concerning SIPs on such grounds. Union Electric Co., v. U.S. EPA, 427 U.S. 246, 255-66 (1976); 42 U.S.C. 7410(a)(2).



### D. Unfunded Mandates Reform Act Title II ofthe Unfunded Mandates Reform Act of 1995 (UMRA), P.L. 104-4, establishes requirements for Federal agencies to assess the effects oftheirregulatory actions on state, local, and tribal governments and the private sector. Under section 202 ofthe UMRA, EPA generally mustprepare a written statement, including a cost-benefit analysis, for proposed and final rules with "Federal mandates" that may result in expenditures to state, local, and tribal governments, in the aggregate, or to the private sector, of$100 million ormore in anyone year. Before promulgating an EPA rule for which a written statement is needed, section 205 ofthe UMRA generally requires EPA to identify and consider a reasonable number ofregulatory alternatives and adopt the least costly, most cost-effective or leastburdensome alternative that achieves the objectives ofthe rule. The provisions ofsection 205 do not apply when they are inconsistent with applicable law. Moreover, section 205 allows EPA to adopt an alternative other than the least costly, most cost-effective or least burdensome alternative ifthe Administrator publishes with the final rule an explanation why that alternative was not adopted. Before EPA establishes49 of53 

### any regulatory requirements that may significantly oruniquely affect small governments, including tribal governments, it must have developed under section 203 ofthe UMRA a small government agency plan. The plan must provide for notifying potentially affected small governments, enabling officials ofaffected small governments to have meaningful and timely input in the development ofEPA regulatory proposals with significant Federal intergovernmental mandates, and informing, educating, and advising small governments oncompliance with the regulatory requirements.

EPA has determined that this rule does not contain a Federal mandate that may result in expenditures of$100 million ormore for state, local, and tribal governments, in the aggregate, or the private sector in anyone year. This Federal action proposes to partially approve and partially disapprove**pre~existing** 

### requirements under state or local law, and to disapprove a redesignation request, and imposes no newrequirements. Accordingly, no additional costs to state, local, or tribal governments, or to the private sector, result from this action. Thus, today's rule is not subjectto the requirements ofsections 202 and 205 ofthe UMRA.



### E. Executive Order 13132, Federalism Executive Order 13132, entitled "Federalism" (64 FR43255, August 10,1999), requires EPA to develop an accountable process to ensure "meaningful and timely input by state and local officials in the development ofregulatory policies that have federalism implications." "Policies thathave federalism implications" is defined in the Executive Orderto include regulations that have "substantial direct effects on the states, on the relationship between the national government50 of53 and the states, oronthe distribution ofpower and responsibilities among the various levels of government."

This proposed rule does not have federalism implications. Itwill not have substantial direct effects on the states, on the relationship between the national government and the states, or
onthe distribution ofpowerand responsibilities among the various levels ofgovernment, as specified in Executive Order 13132. This rule merely proposes to partially approve and partially disapprove state rules implementing a Federal standard, and to disapprove a redesignation request, and does not alter the relationship or the distribution ofpower andresponsibilities established in the Clean Air Act. Thus, Executive Order 13132 does not apply to this rule.



### F. Executive Order 13175, Coordination with Indian Tribal Governments Executive Order 13175, entitled Consultation and Coordination with Indian Tribal Governments (65 FR 67249, November 9, 2000), requires EPA to develop an accountable process to ensure meaningful and timely input by tribal officials in the development ofregulatory policies that have tribal implications. This proposed rule does not have tribal implications, as specified in Executive Order 13175. 

### It will not have substantial direct effects on tribal governments, on the relationship between the Federal government and Indian tribes, oronthe distribution ofpower and responsibilities between the Federal government and Indian tribes. This action does not involve orimpose any requirements that affect Indian Tribes. Thus, Executive Order 13175 does not apply to this rule.51 of53 

### G. Executive Order 13045, Protection ofChildren from Environmental Health Risks and Safety Risks Protection o/Children/romEnvironmentalHealth Risks andSafety Risks (62 FR 19885, April 23, 1997), applies to any rule that: (1) is determined to be economically significant as defined under Executive Order 12866, and (2) concerns an environmental health or safety risk that EPA has reasonto believe may have a disproportionate effect onchildren. Ifthe regulatory action meets both criteria, the Agency must evaluate the environmental health or safety effects of the planned rule on children, and explain why the planned regulation is preferable to other potentially effective and reasonably feasible alternatives considered by the Agency.

EPA interprets Executive Order 13045 as applying only to those regulatory actions that
are based on health or safety risks, such that the analysis required under section 5-501 ofthe Order has the potential to influence the regulation. This proposed rule is not subjectto Executive Order 13045 because it proposes approve a state rule implementing a Federal program.



### H. Executive Order 13211, Actions that Significantly Affect Energy Supply, Distribution, orUse This rule is not subject to Executive Order 13211, Actions Concerning Regulations That Significantly Affect Energy Supply, Distribution, orUse (66 FR28355, May 22, 2001) because it is not a significant regulatory action under Executive Order 12866.52 of53



### I. National Technology Transfer and Advancement Act 

### Section 12(d) of the National Technology Transfer and Advancement Act of 1995 ("NTTAA"), Public Law No. 104-113, 12(d) (15 U.S.C. 272 note) directs EPA to use voluntary
consensus standards in its regulatory activities unless to do so would be inconsistent with applicable law or otherwise impractical. Voluntary consensus standards are technical standards (e.g., materials specifications, test methods, sampling procedures, and business practices) that are developed or adopted by voluntary consensus standards bodies. The NTTAA directs EPA to provide Congress, through OMB, explanations when the Agency decides not to use available and applicable voluntary consensus standards.

This proposed rulemaking does not involve technical standards. Therefore, EPA is not considering the use ofany voluntary consensus standards.

List ofSubjects in 40 CFRPart 52 

### Environmental protection, Air pollution control, Intergovernmental relations, Oxides of nitrogen, Particulate matter, Reporting and recordkeeping requirements.
Authority: 

### 42 U.S.C. 7401 et seq53 of53

Air Quality Implementation Plans; Montana; Attainment Plan for 

### Libby, MT 

### PM2.5 Nonattainment Area and PMlO State Implementation Plan Revisions

Dated: Acting Regional Administrator Region 8