55494 Federal Register / Vol. 75, No. 176 / Monday, September 13, 2010 / Proposed Rules 

(or their delegated agent). You are required 

to assure the product is airworthy before it 

is returned to service. 

(3) Reporting Requirements: For any 

reporting requirement in this AD, under the 

provisions of the Paperwork Reduction Act 

(44 U.S.C. 3501 et seq.), the Office of 

Management and Budget (OMB) has 

approved the information collection 

requirements and has assigned OMB Control 

Number 2120–0056. 

Related Information 

(h) Refer to MCAI European Aviation 

Safety Agency (EASA) Emergency AD No.: 

2009–0172–E, dated August 5, 2009; and 

EUROCOPTER Emergency Alert Service 

Bulletin No. 67.18, dated August 3, 2009, for 

related information. 

Issued in Fort Worth, Texas, on August 25, 

2010. 

Kimberly K. Smith, 

Manager, Rotorcraft Directorate, Aircraft 

Certification Service. 

[FR Doc. 2010–22775 Filed 9–10–10; 8:45 am] 

BILLING CODE 4910–13–P 

ENVIRONMENTAL PROTECTION 

AGENCY 

40 CFR Part 52 

[EPA–R10–OAR–2010–0669; FRL–9200–5] 

Approval and Promulgation of 

Implementation Plans; Idaho; 

Interstate Transport of Pollution 

AGENCY: Environmental Protection 

Agency (EPA). 

ACTION: Proposed rule. 

SUMMARY: EPA is proposing to approve 

a State Implementation Plan (SIP) 

revision submitted by the State of Idaho 

for the purpose of addressing the ‘‘good 

neighbor’’ provisions of the Clean Air 

Act (CAA) section 110(a)(2)(D)(i) for the 

1997 8-hour ozone National Ambient 

Air Quality Standards (NAAQS or 

standards) and the 1997 PM2.5 NAAQS. 

This SIP revision addresses the 

requirement that the State of Idaho’s SIP 

have adequate provisions to prohibit air 

emissions from adversely affecting 

another state’s air quality through 

interstate transport. In this action, EPA 

is proposing to approve the Idaho 

Interstate Transport SIP provisions that 

address the requirement of section 

110(a)(2)(D)(i) that emissions from Idaho 

sources do not significantly contribute 

to nonattainment of the 1997 8-hour 

ozone NAAQS and the 1997 PM2.5

NAAQS in any other state, interfere 

with maintenance of the 1997 8-hour 

ozone NAAQS and the 1997 PM2.5

NAAQS in any other state, and interfere 

with measures required in the SIP of 

any other state under part C of 

subchapter I of the CAA to prevent 

significant deterioration of air quality. 

This action is being taken under section 

110 and part C of subchapter I of the 

Clean Air Act (the Act or CAA). 

DATES: Written comments must be 

received on or before October 13, 2010. 

ADDRESSES: Submit your comments, 

identified by Docket ID No. EPA–R10– 

OAR–2008–0391, by one of the 

following methods: 

A. http://www.regulations.gov. Follow 

the online instructions for submitting 

comments. 

B. E-Mail: R10- 

Public_Comments@epa.gov. 

C. Mail: Donna Deneen, U.S. 

Environmental Protection Agency, 

Region 10, 1200 Sixth Avenue, Suite 

900, Mail Stop: AWT–107, Seattle, WA 

98101. 

D. Hand Delivery: U.S. Environmental 

Protection Agency, Region 10, Attn: 

Donna Deneen (AWT–107), 1200 Sixth 

Avenue, Suite 900, Seattle, Washington 

98101, 9th Floor. Such deliveries are 

only accepted during normal hours of 

operation, and special arrangements 

should be made for deliveries of boxed 

information. 

Instructions: Direct your comments to 

Docket ID No. EPA–R10–OAR–2010– 

0669. EPA’s policy is that all comments 

received will be included in the public 

docket without change and may be 

made available online at http:// 

www.regulations.gov, including any 

personal information provided, unless 

the comment includes information 

claimed to be Confidential Business 

Information (CBI) or other information 

whose disclosure is restricted by statute. 

Do not submit information that you 

consider to be CBI or otherwise 

protected through http:// 

www.regulations.gov or email. The 

http://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 of your comment. 

If you send an email comment directly 

to EPA without going through http:// 

www.regulations.gov, your email 

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. If you 

submit an electronic comment, EPA 

recommends that you include your 

name and other contact information in 

the body of you comment and with any 

disk or CD–ROM you submit. If EPA 

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 of 

special characters, any form of 

encryption, and be free of any defects or 

viruses. 

Docket: All documents in the 

electronic docket are listed in the 

www.regulations.gov index. Although 

listed in the index, some information, 

i.e., CBI or other information whose 

disclosure is restricted by statute, is not 

publicly available. Certain other 

material, such as copyrighted material, 

is not placed on the Internet and will be 

publicly available only in hard copy 

form. Publicly available docket 

materials are available either 

electronically in http:// 

www.regulations.gov or in hard copy 

during normal business hours at the 

Office of Air, Waste and Toxics, U.S. 

Environmental Protection Agency, 

Region 10, 1200 Sixth Avenue, Suite 

900, Seattle, Washington 98101. 

FOR FURTHER INFORMATION CONTACT: 

Donna Deneen, (206) 553–6706 or 

deneen.donna@epa.gov. 

SUPPLEMENTARY INFORMATION: 

Throughout this notice, the words ‘‘we’’, 

‘‘us’’, or ‘‘our’’ means the Environmental 

Protection Agency (EPA). 

Table of Contents 

I. What proposed action is EPA taking? 

II. What is a SIP? 

III. What is the background for this proposed 

action? 

IV. What is EPA’s evaluation of the State’s 

submission? 

A. EPA’s Evaluation of Significant 

Contribution to Nonattainment 

1. 1997 PM2.5 Nonattainment Areas and 

Monitoring Data in States Surrounding 

Idaho 

2. 1997 8-Hour Ozone Nonattainment 

Areas and Monitoring Data in States 

Surrounding Idaho 

3. State Regulatory Provisions 

4. Conclusion Regarding Significant 

Contribution to Nonattainment 

B. EPA’s Evaluation of Interference With 

Maintenance 

1. Background 

2. Idaho’s Interference With Maintenance 

Demonstration 

3. EPA’s Supplemental Analysis 

4. Conclusion Regarding Interference With 

Maintenance 

C. EPA’s Evaluation of Interference With 

PSD Measures in Other States 

V. Proposed Action 

VI. Statutory and Executive Order Reviews 

I. What proposed action is EPA taking? 

EPA is proposing to approve a portion 

of Idaho’s Interstate Transport State 

Implementation Plan (SIP) revision for 

the 1997 8-hour ozone and 1997 PM2.5

NAAQS submitted by the Idaho 

Department of Quality (IDEQ) on June 

28, 2010. Specifically, we are proposing 

to approve the portion of the plan that 

addresses the following elements of 

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1The PM2.5 standard was revised in 2006. See 

‘‘National Ambient Air Quality Standards for 

Particulate Matter,’’ at 71 FR 61144, (October 17, 

2006). 

2See ‘‘Rule to Reduce Interstate Transport of Fine 

Particulate Matter and Ozone (Clean Air Interstate 

Rule); Revisions to Acid Rain Program; Revisions to 

Continued 

CAA section 110(a)(2)(D)(i): (1) 

Significant contribution to 

nonattainment of these NAAQS in any 

other state, (2) interference with 

maintenance of these NAAQS by any 

other state, and (3) interference with any 

other state’s required measures to 

prevent significant deterioration (PSD) 

of its air quality with respect to these 

NAAQS. IDEQ addressed element (4), 

interference with any other state’s 

required measures to protect visibility, 

by referring to its Regional Haze SIP, 

which will be submitted separately. 

EPA will take action on the visibility 

element in a separate action. EPA will 

also take action on the portion of 

Idaho’s SIP that addresses the 2006 

PM2.5 NAAQS 1 in a separate action. 

Idaho’s June 28, 2010, SIP revision 

replaces a previously submitted section 

110(a)(2)(D)(i) SIP revision submitted by 

IDEQ on January 30, 2007, for the 1997 

PM2.5 standards. EPA proposed 

approval of that SIP revision on June 26, 

2007 (72 FR 35022), but did not take 

final action. When Idaho submitted its 

June 28, 2010, SIP revision, Idaho 

requested that EPA replace the SIP 

submitted on January 30, 2007, with the 

revised SIP submitted on June 28, 2010. 

In light of Idaho’s resubmittal of its 

Interstate Transport SIP, EPA is 

withdrawing its June 26, 2007, proposal 

and is issuing this proposal to approve 

Idaho’s June 28, 2010, SIP revision in its 

place. Accordingly, EPA will not be 

responding to comments on the June 26, 

2007, proposal. Any person who wishes 

to comment on EPA’s proposed 

approval of Idaho’s SIP revision 

addressing section 110(a)(2)(D)(i) for the 

1997 8-hour ozone and 1997 PM2.5

standards should do so at this time. 

II. What is a SIP? 

Section 110(a) of the CAA requires 

each state to develop a plan that 

provides for the implementation, 

maintenance, and enforcement of the 

NAAQS. EPA establishes NAAQS under 

section 109 of the CAA. Currently, the 

NAAQS address six criteria pollutants: 

Carbon monoxide, nitrogen dioxide, 

ozone, lead, particulate matter, and 

sulfur dioxide. 

The plan developed by a state is 

referred to as the SIP. The content of the 

SIP is specified in section 110 of the 

CAA, other provisions of the CAA, and 

applicable regulations. SIPs can be 

extensive, containing state regulations 

or other enforceable measures and 

various types of supporting information, 

such as emissions inventories, 

monitoring networks, and modeling 

demonstrations. 

A primary purpose of the SIP is to 

provide the air pollution regulations, 

control strategies, and other means or 

techniques developed by the state to 

ensure that the ambient air within that 

state meets the NAAQS. However, 

another important aspect of the SIP is to 

ensure that emissions from within the 

state do not have certain prohibited 

impacts upon the ambient air in other 

states through interstate transport of 

pollutants. This SIP requirement is 

specified in section 110(a)(2)(D). 

Pursuant to that provision, each state’s 

SIP must contain provisions adequate to 

prevent emissions that significantly 

contribute to violations of the NAAQS 

in any other state, interfere with 

maintenance in any other state, interfere 

with any other state’s required measures 

to prevent significant deterioration of its 

air quality, and interfere with any other 

state’s required measures to protect 

visibility. 

States are required to update or revise 

SIPs under certain circumstances. One 

such circumstance is EPA’s 

promulgation of a new or revised 

NAAQS. Each state must submit these 

revisions to EPA for approval and 

incorporation into the federallyenforceable SIP. 

III. What is the background for this 

proposed action? 

On July 18, 1997, EPA promulgated 

new standards for 8-hour ozone and fine 

particulate matter (PM2.5). This action is 

being taken in response to the 

promulgation of the 1997 8-hour ozone 

NAAQS and 1997 PM2.5 NAAQS. This 

action does not address the 

requirements of the 2006 PM2.5 NAAQS 

or the 2008 8-hour ozone NAAQS; those 

standards will be addressed in a future 

action. 

Section 110(a)(1) of the CAA requires 

states to submit SIPs to address a new 

or revised NAAQS within three years 

after promulgation of such standards, or 

within such shorter period as EPA may 

prescribe. Section 110(a)(2) lists the 

elements that such new SIPs must 

address, as applicable, including section 

110(a)(2)(D)(i) which pertains to 

interstate transport of certain emissions. 

On August 15, 2006, EPA issued its 

‘‘Guidance for State Implementation 

Plan (SIP) Submission to Meet Current 

Outstanding Obligations Under Section 

110(a)(2)(D)(i) for the 8-hour ozone and 

PM2.5 National Ambient Air Quality 

Standards’’ (2006 Guidance) for SIP 

submissions that states should use to 

address the requirements of section 

110(a)(2)(D)(i). EPA developed this 

guidance to make recommendations to 

states for making submissions to meet 

the requirements of section 110(a)(2)(D) 

for the 1997 8-hour ozone standards and 

1997 PM2.5 standards. 

On June 28, 2010, we received a SIP 

revision from the State of Idaho to 

address the requirements of section 

110(a)(2)(D)(i) for the 1997 8-hour ozone 

NAAQS and 1997 PM2.5 NAAQS. The 

‘‘good neighbor’’ provisions in section 

110(a)(2)(D)(i) require each state to 

submit a SIP that prohibits emissions 

that adversely affect another state in the 

ways contemplated in the statute. 

Section 110(a)(2)(D)(i) identifies four 

distinct elements related to the 

evaluation of impacts of interstate 

transport of air pollutants. In this 

rulemaking EPA is addressing the first 

three elements: (1) Significant 

contribution to nonattainment of these 

NAAQS in any other state, (2) 

interference with maintenance of these 

NAAQS by any other state, and (3) 

interference with any other state’s 

required measures to prevent significant 

deterioration (PSD) of its air quality 

with respect to these NAAQS. Idaho 

asserts in its SIP submission that its 

current SIP is adequate to prevent such 

contribution and interference, and thus 

no additional controls or revisions are 

needed with respect to the 1997 8-hour 

ozone NAAQS and 1997 PM2.5 NAAQS. 

EPA is proposing to find that Idaho’s 

Interstate Transport SIP provisions 

addressing elements (1), (2), and (3) of 

section 110(a)(2)(D)(i) are consistent 

with the requirements of the CAA. 

IV. What is EPA’s evaluation of the 

State’s submission? 

A. EPA’s Evaluation of Significant 

Contribution to Nonattainment 

Section 110(a)(2)(D)(i) provides that 

EPA cannot approve a state’s SIP for a 

new or revised NAAQS unless it 

contains adequate measures to prohibit 

emissions from sources within the state 

from contributing significantly to 

nonattainment of the NAAQS in another 

state. EPA’s August 2006 Guidance 

concerning section 110(a)(2)(D)(i) 

recommended various methods by 

which states might evaluate whether or 

not their emissions significantly 

contribute to nonattainment of the 1997 

8-hour ozone or the 1997 PM2.5 NAAQS 

in another state. Among other methods, 

EPA recommended consideration of 

available EPA modeling conducted in 

conjunction with the Clean Air 

Interstate Rule (CAIR),2 or in the 

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the NOX SIP Call; Final Rule,’’ at 70 FR 25162 at 

25263–69 (May 12, 2005). 3See Section B(1) of this notice for more history 

on CAIR and the Transport Rule Proposal. EPA has 

taken a similar approach in the recent Transport 

Rule Proposal discussed below. 

4Libby is in a narrow valley surrounded by 

mountains 4,000 feet higher than the town. The 

Rocky Mountain Range to the west of Libby (and 

east of the Idaho border) reaches summit elevations 

of 12,000 feet with most summit elevations between 

6000 and 7000 feet that act as a barrier to air 

movement between Idaho and Montana. 

5 ‘‘Technical Support for State and Tribal Air 

Quality Fine Particle (PM2.5) Designations,’’ (for 

Montana) Chapter 6, pp. 347–352, December 2004. 

6 ‘‘Technical Support for State and Tribal Air 

Quality Fine Particle (PM2.5) Designations,’’ (for 

Montana) Chapter 4.8.1, pp. 1–15, December 2008. 

7 ‘‘Technical Support for State and Tribal Air 

Quality Fine Particle (PM2.5) Designations,’’ Chapter 

6, pp. 347–352, December 2004. 

absence of such EPA modeling, 

consideration of other information such 

as the amount of emissions, the 

geographic location of violating areas, 

meteorological data, or various other 

forms of information that would be 

relevant to assessing the likelihood of 

significant contribution to violations of 

the NAAQS in another state. The 

assessment of significant contribution to 

nonattainment is not restricted to 

impacts upon areas that are formally 

designated nonattainment. Consistent 

with EPA’s approach in CAIR and in the 

Transport Rule Proposal, this impact 

must be evaluated with respect to 

monitors showing a violation of the 

NAAQS (70 FR 25172, May 12, 2005, 

and 63 FR 57371, October 27, 1998).3

Furthermore, although relevant 

information other than modeling may be 

considered in assessing the likelihood of 

significant contribution to 

nonattainment of the 8-hour ozone or 

PM2.5 NAAQS in another state, EPA 

notes that no single piece of information 

is by itself dispositive of the issue. 

Instead, the total weight of all the 

evidence taken together is used to 

evaluate significant contributions to 

violations of the 1997 8-hour ozone or 

1997 PM2.5 NAAQS in another state. 

This proposed approval addresses the 

significant contribution element for the 

1997 8-hour ozone and 1997 PM2.5

NAAQS in several ways. It takes into 

account Idaho’s SIP submission that 

addressed the significant contribution 

element for the 1997 8-hour ozone and 

1997 PM2.5 NAAQS by evaluating 

potential impacts from Idaho sources on 

1997 8-hour ozone and 1997 PM2.5

nonattainment areas in surrounding 

states based on a review of 

meteorological and other characteristics 

of those areas. The State’s SIP 

submission also relied on provisions in 

its air quality regulations that address 

Idaho’s authority to address 

nonattainment issues. In addition to the 

arguments presented by Idaho to 

support its demonstration that its SIP 

satisfies the significant contribution 

element of the CAA, EPA has 

supplemented its analysis with 

monitoring data and other information 

related to the 1997 PM2.5 nonattainment 

areas identified by Idaho, and has also 

provided monitoring data and other 

information for the surrounding states 

generally. Our evaluation below 

regarding how Idaho’s SIP satisfies the 

significant contribution element of the 

CAA is organized as follows. Section 1 

addresses the 1997 PM2.5 nonattainment 

areas in surrounding states (including 

PM2.5 monitoring data for those 

nonattainment areas) and PM2.5

monitoring data generally for 

surrounding states. Section 2 addresses 

the 1997 8-hour ozone nonattainment 

areas in surrounding states (including 

ozone monitoring data for those 

nonattainment areas) and ozone 

monitoring data generally for 

surrounding states. Section 3 addresses 

Idaho’s air quality regulations for both 

the 1997 8-hour ozone and 1997 PM2.5

NAAQS which pertain to Idaho’s 

authority to address nonattainment 

issues. 

1. 1997 PM2.5 Nonattainment Areas and 

Monitoring Data in States Surrounding 

Idaho 

1997 PM2.5 Nonattainment Areas 

To address whether Idaho sources 

significantly contribute to 

nonattainment of the 1997 PM2.5

NAAQS in another state, Idaho 

reviewed meteorological and other 

characteristics of any areas designated 

nonattainment for the 1997 PM2.5

NAAQS in surrounding states to 

determine whether transport of 

emissions from Idaho significantly 

contribute to nonattainment in those 

areas. Relying primarily on technical 

support documents (TSDs) prepared for 

EPA’s 8-hour ozone and PM2.5 NAAQS 

nonattainment designations, Idaho 

noted that air stagnation is cited as a 

major contributing factor to 

nonattainment in those areas and that 

under air stagnation conditions there is 

little to no transport of pollutants over 

long distances. Idaho also noted that 

none of the TSDs identified Idaho 

sources as significant contributors to 

any 1997 PM2.5 nonattainment areas. 

As a part of EPA’s analysis of whether 

or not PM2.5 emissions from Idaho 

significantly contribute to 

nonattainment in another state, EPA 

reviewed and analyzed information 

available for the 1997 PM2.5

nonattainment areas in states 

surrounding Idaho. Although significant 

contribution must be measured not just 

against nonattainment areas, but also 

against areas with monitors showing 

violations of the NAAQS, 

nonattainment areas are a convenient 

starting point for the analysis. For the 

1997 PM2.5 NAAQS, Libby, in Lincoln 

County, Montana is the only designated 

nonattainment area in any state 

bordering Idaho.4 In 2005, EPA 

designated this area nonattainment for 

the 1997 annual PM2.5 NAAQS. 70 FR 

944 (January 5, 2005) and 40 CFR 

81.327. 

A number of factors provide evidence 

that Idaho emissions do not 

significantly contribute to past 

violations of the 1997 annual PM2.5

standards in Libby, Montana. First, in 

the process of designating Libby 

nonattainment for both the 1997 PM2.5

NAAQS and the 2006 PM2.5 NAAQS, 

EPA noted the predominantly local 

origins of PM2.5 nonattainment in 

Libby.5 6 Residential wood-burning 

stoves during the winter-time, when 

frequent and persistent temperature 

inversions occurred, were specifically 

identified as a key source of PM 

emissions. 

Although local sources were believed 

to predominate in the Libby 

nonattainment area, EPA specifically 

considered in the 1997 PM2.5

designation process whether Idaho 

sources contributed to PM2.5

nonattainment in Libby. While a 

nonattainment designation analysis is 

not the same inquiry that is required 

under CAA section 110(a)(2)(D), some of 

the factual findings from that effort are 

helpful in understanding the potential 

for interstate transport of pollutants in 

the Libby area. If there were an area in 

Idaho from which significant 

contribution would be most likely, it 

would arguably be from Bonner and 

Boundary counties in Idaho. These 

counties are located in Idaho’s 

panhandle and are the only Idaho 

counties located to the west of the Libby 

nonattainment area. Transport winds 

generally flow across Idaho from west to 

east, and Libby is directly east of Bonner 

and Boundary counties. In the process 

of designating Libby nonattainment for 

the 1997 PM2.5 NAAQS, EPA concluded 

that there was insufficient data to justify 

including those two Idaho counties (or 

any portion thereof) in the Libby 

nonattainment area.7 Monitoring data 

from 1999 through 2009 show that PM2.5

design value levels for both Idaho 

counties have remained below 30 μg/m3

or 85 percent of the 1997 PM2.5 NAAQS. 

This is consistent with a conclusion that 

local sources in Libby were a key 

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8 In 2001, 2002 and 2006, design values for two 

monitors in Missoula County were 11.1, 11.4 and 

11.8 μg/m3. Computed from AQS monitoring data. 

75 FR 16028 (March 31, 2010). 

9State of Montana, Department of Environmental 

Quality, ‘‘State Implementation Plan-Libby Annual 

PM2.5 Control Plan,’’ submitted to EPA April 1, 

2008. 

10See Section B of this notice for a more complete 

discussion of the Transport Rule Proposal and 

EPA’s modeling analysis of the western states. 

11 In 2005, EPA designated this area 

nonattainment for violations of the 1997 and annual 

PM2.5 NAAQS. 70 FR 944 (January 5, 2005), and 40 

CFR 81.305. 

contributor to the area’s past 

nonattainment. Although the 

predominance of local sources does not 

rule out the possibility of impacts from 

interstate transport, this fact taken in 

conjunction with the mountainous 

topography of the area, supports a 

conclusion that Idaho emissions do not 

contribute significantly to the past 

NAAQS violations in Libby. 

Second, monitoring data from 1999 

through 2009 from areas outside of 

Libby in Montana support a 

determination that Idaho does not 

significantly contribute to 

nonattainment in Libby. At all other 

sites in Montana, annual PM2.5 design 

value levels have remained below the 15 

μg/m3 nonattainment threshold. Annual 

PM2.5 design values for this period for 

most of these monitors remained at 

levels equal to, or less than, two-thirds 

of the 1997 NAAQS. Even the three 

highest design values at these monitors 

were 20 percent below the level of the 

annual standard.8 The lower PM2.5

levels elsewhere in Montana are 

evidence that local sources, and not 

interstate transport, are key contributors 

to past nonattainment in Libby. 

Monitoring data from Idaho likewise 

supports a finding that Idaho does not 

significantly contribute to 

nonattainment elsewhere. In Idaho, 

annual PM2.5 design values from 1999 

through 2009 have remained below the 

1997 NAAQS. The comparatively lower 

levels of PM2.5 monitored throughout 

Idaho and elsewhere in Montana are 

consistent with a conclusion that local 

sources, and not sources in another 

state, are the predominant source of 

PM2.5 levels in Libby. The fact that 

monitors located in Idaho have not 

registered violations of the 1997 PM2.5

NAAQS does not conclusively establish 

that emissions from Idaho could not 

contribute in the aggregate to violations 

in Libby, but this fact combined with 

the localized nature of the violations in 

Libby supports the conclusion that 

sources in Idaho do not significantly 

contribute to PM2.5 levels in Libby. By 

2007–2008, the annual PM2.5 design 

values for the Libby nonattainment area 

itself fell below the levels of the 

NAAQS. This reduction has been 

attributed to an effective wood stove 

replacement program that decreased 

PM2.5 emissions by approximately 59 

percent.9 In other words, even if 

emissions from Idaho sources were 

reaching Libby, they would not 

significantly contribute to violations of 

the 1997 PM2.5 NAAQS because 

monitoring data demonstrate that Libby 

is not violating the 1997 PM2.5 NAAQS. 

Finally, EPA’s conclusion that 

emissions from Idaho do not 

significantly contribute to 

nonattainment in Libby, Montana, is 

further supported by a modeling 

analysis for monitors in the western 

United States.10 This modeling 

concludes that in 2012 the average 

design values in Lincoln County, 

Montana for PM2.5 will be below the 

threshold for consideration as a 

nonattainment receptor. 

The next closest 1997 PM2.5

nonattainment area to the state of Idaho 

is the San Joaquin Valley in California.11

This nonattainment area is over 300 

miles southwest of the closest point on 

the Idaho border and is on the other side 

of the Sierra Nevada Mountains. This 

400 mile long north-south range of 

mountains has peaks of more than 

14,000 feet which act as a natural barrier 

to air movement between Idaho and 

California. In addition, San Joaquin 

Valley, California, is not in the 

predominant direction of winds from 

Idaho. Transport winds across Idaho 

generally flow from west to east, and not 

toward the southwest. Given the 

relatively long distance between Idaho 

and the San Joaquin Valley, the 

intervening mountainous topography, 

and the general west-to-east direction of 

transport winds across Idaho, EPA 

believes it is reasonable to conclude that 

Idaho sources do not significantly 

contribute to nonattainment of the 1997 

PM2.5 NAAQS in the San Joaquin 

Valley. 

PM2.5 Monitoring Data in Other Areas of 

Surrounding States 

As mentioned above, EPA considers 

not only significant contribution to 

designated nonattainment areas, but 

also significant contribution to areas 

with monitors showing violations of the 

NAAQS. A review of the most recent 

three years of monitoring data in EPA’s 

Air Quality System (AQS) for the 

bordering states of Washington, Oregon, 

Nevada, Utah, Wyoming and Montana 

shows there are no monitors violating 

the 1997 PM2.5 NAAQS. Between 1999 

and 2009, just two monitors in any of 

these bordering states violated the 1997 

PM2.5 NAAQS. Both violations were for 

the annual NAAQS. The first such 

monitor is in Libby, Montana, which 

has not violated the 1997 PM2.5 NAAQS 

since 2005. As discussed previously, 

EPA believes that existing information 

supports the conclusion that there is not 

significant contribution to 

nonattainment from Idaho sources to 

this area in Montana. The second is a 

monitor in Salt Lake City, Utah, which 

violated the 1997 PM2.5 NAAQS at a 

single monitor in 2004. Since 2004 it 

has not violated the NAAQS. Taking 

into account the total weight of all of the 

factors discussed above, EPA concludes 

that Idaho does not significantly 

contribute to 1997 PM2.5 NAAQS 

nonattainment in another state. 

2. 1997 Ozone Nonattainment Areas and 

Monitoring Data in States Surrounding 

Idaho 

1997 8-Hour Ozone Nonattainment 

Areas 

To address whether Idaho sources 

significantly contribute to 

nonattainment of the 1997 8-hour ozone 

standard in another state, Idaho’s SIP 

uses the same approach as it used for 

the 1997 PM2.5 NAAQS. Relying 

primarily on TSDs prepared for EPA’s 

8-hour ozone and PM2.5 nonattainment 

designations, Idaho noted that air 

stagnation is cited as a major 

contributing factor to nonattainment in 

those areas and that under stagnant air 

conditions there is little to no transport 

of pollutants over long distances. Idaho 

also noted that none of the TSDs 

identified Idaho sources as significant 

contributors to any 1997 8-hour ozone 

nonattainment area. 

EPA also reviewed and analyzed 

information available for the designated 

1997 8-hour ozone nonattainment areas 

in states surrounding Idaho. Although 

significant contribution must be 

measured not just against nonattainment 

areas, but against areas with monitors 

showing violations of the NAAQS, 

nonattainment areas are a convenient 

starting point for the analysis. For the 

1997 8-hour ozone NAAQS, the only 

nonattainment area in states bordering 

Idaho is Clark County in southern 

Nevada (Las Vegas area). In 2005, EPA 

designated this area nonattainment for 

violations of the 1997 8-hour ozone 

standard. 69 FR 23858 (April 30, 2004) 

and 40 CFR 81.329. EPA has evaluated 

whether emissions from Idaho 

contribute significantly to the 

nonattainment of the 8-hour ozone 

standard in Clark County. Clark County 

is about 350 miles south of the closest 

point on the Idaho border. Distance per 

se is not an obstacle to long range 

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12Approval and Promulgation of State 

Implementation Plans; State of Utah; Interstate 

Transport of Pollution and Other Revisions (73 FR 

16543, March 28, 2008). 

transport of ozone and/or its precursors, 

as discussed in the January 30, 2004, 

notice proposing CAIR (69 FR 4599); 

NOX (the primary ozone precursor that 

was the object of the CAIR transport 

study) may be transported for long 

distances, contributing significantly to 

high ozone concentrations in other 

states. However, with increasing 

distance there are greater opportunities 

for ozone and/or NOX dispersion and/or 

removal from the atmosphere due to the 

effects of winds and chemical sink 

processes. In this context, one may 

conclude that the 350 mile distance 

between Idaho and the Clark County 

nonattainment area decreases, but does 

not exclude, the possibility of 

significant contribution to this area’s 

nonattainment. Another transport factor 

is wind direction. Clark County, Nevada 

is south of Idaho and, therefore, is not 

in the predominant direction of winds 

from Idaho. Transport winds across 

Idaho generally flow from west to east, 

and not toward the south. Given the 

relatively long distance between Idaho 

and Clark County, Nevada and the 

general west-to-east direction of 

transport winds across Idaho, EPA 

believes it is reasonable to conclude that 

Idaho sources do not significantly 

contribute to nonattainment of the 1997 

8-hour ozone NAAQS in Clark County, 

Nevada. 

Ozone Monitoring Data in Other Areas 

of Surrounding States 

As mentioned above, EPA considers 

not only significant contribution to 

designated nonattainment areas, but 

also to areas with monitor readings 

showing violations of the NAAQS. A 

review of the most recent monitoring 

data from EPA’s Air Quality System 

(AQS) for the bordering states of 

Washington, Oregon, Nevada, Utah, 

Wyoming and Montana shows no 

monitors violating for the 1997 8-hour 

ozone NAAQS. A review of past 

monitoring data from 1999 through 2008 

shows that the only area in any of these 

border states that violated the 1997 

8-hour ozone NAAQS was Salt Lake 

City, Utah. This area, however, is not 

currently violating and has not violated 

the 1997 8-hour ozone NAAQS since a 

violation occurred at a single monitor in 

2007. Observed days of high ozone 

levels in the Salt Lake City metropolitan 

area are usually associated with a ‘bowl 

effect’ resulting from an inversion that 

has a stagnant air pollution mass 

surrounded by the Oquirrh Mountains 

to the west, the Great Salt Lake to the 

north, and the Wasatch Range on the 

east.12 In light of these considerations, 

it is unlikely that Idaho makes a 

significant contribution of ozone and/or 

ozone precursors in the Salt Lake City 

area. 

In addition, none of the ozone 

monitors in Idaho have themselves 

indicated a violation of the 1997 8-hour 

ozone NAAQS, and Boise, Idaho, the 

area of Idaho with the highest 

concentrations of ozone, is almost 300 

miles from Salt Lake City. The absence 

of violations in Idaho itself do not rule 

out the possibility of transport, but 

taken in conjunction with other relevant 

information, this fact helps to support 

the conclusion that there is no such 

transport from Idaho to Salt Lake City. 

Distance per se is also not an obstacle 

to long range transport of ozone and/or 

its precursors, as discussed above. 

However, with increasing distance there 

are greater opportunities for ozone and/ 

or NOX dispersion and/or removal from 

the atmosphere due to the effects of 

winds and chemical sink processes. In 

this context, the 300 mile distance 

between Idaho and the Salt Lake City 

area reduces but does not exclude the 

possibility of significant contribution to 

this area’s nonattainment. Taking into 

account the total weight of all of the 

factors discussed above, EPA concludes 

that Idaho does not significantly 

contribute to 1997 8-hour ozone 

NAAQS nonattainment in another state. 

3. State Regulatory Provisions 

In addition to monitoring data 

providing evidence that Idaho sources 

do not contribute to nonattainment in 

any other state, Idaho points to air 

quality provisions in its regulations that 

prohibit emissions that contribute 

significantly to nonattainment. 

Specifically, the State points to its air 

quality provisions at IDAPA 

58.01.01.203.02 that require that a 

proposed source’s projected emissions 

will not cause or significantly contribute 

to a violation of any ambient air quality 

standard. The state explains that this 

provision applies to both major and 

minor sources and that the owner or 

operator of such a source must 

demonstrate that the source’s projected 

emissions will not cause or significantly 

contribute to a violation of any ambient 

air quality standard. In addition, they 

point out that the demonstration is not 

constrained to evaluating impacts solely 

in Idaho and that all estimates of 

ambient concentrations must be based 

on the requirements specified in 40 CFR 

51, Appendix W, which look to the 

point of maximum concentration, not a 

jurisdictional boundary. 

The state also relies on its rules for 

existing sources at IDAPA 

58.01.01.401.03, which provide IDEQ 

with the authority to require a permit 

(called a ‘‘Tier II permit’’) if emission 

rate reductions are necessary to attain 

any ambient air quality standard. As 

part of the Tier II permitting process, the 

facility operator (or responsible official) 

must demonstrate the source does not 

cause or significantly contribute to a 

violation of any ambient air quality 

standards. The state asserts that it has 

used this authority in the past as part of 

a suite of control measures implemented 

to address nonattainment and other air 

quality issues and this authority could 

be used if the state’s emissions were 

significantly contributing to 

nonattainment in another state. For 

example, between 2000 and 2003 the 

state issued fifteen Tier II permits to 

sources in two PM10 nonattainment 

areas to establish federally-enforceable 

emission limits on PM10 emissions in 

order to ensure that the PM10 NAAQS 

would be attained and maintained. A 

summary of these 15 permits, including 

links to the permits on the Idaho 

website, is included in the docket for 

this rulemaking. 

Idaho incorporates by reference 

annually any updates to the NAAQS 

ensuring that implementation of the 

regulatory provisions at IDAPA 

58.01.01.203.02 and IDAPA 

58.01.01.40.03 are implementing the 

most recently revised NAAQS. 

In light of these air quality provisions 

in Idaho’s regulations and evidence that 

Idaho has used these air quality 

provisions to address nonattainment 

and other air quality issues in the past, 

EPA believes that in this case these 

regulatory provisions provide additional 

support for our conclusion that 

emissions from Idaho sources do not 

significantly contribute to 

nonattainment in any other state and 

that Idaho has the ability to address 

nonattainment if, in the future, the 

state’s emissions significantly contribute 

to nonattainment of the 1997 8-hour 

ozone and 1997 PM2.5 NAAQS in 

another state. 

4. Conclusion Regarding Significant 

Contribution to Nonattainment 

The data and weight of the evidence 

analysis presented above support EPA’s 

conclusion that the Idaho Interstate 

Transport SIP (submitted on June 28, 

2010) is adequate to ensure that 

emissions from Idaho do not 

significantly contribute to 

nonattainment in any other state for the 

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13See, 63 FR 57356 (October 27, 1998). EPA’s 

general approach to section 110(a)(2)(D) was upheld 

in Michigan v. EPA, 213 F.3d 663 (D.C. Cir. 2000), 

cert denied, 532 U.S. 904 (2001). However, EPA’s 

approach to interference with maintenance in the 

NOX SIP Call was not explicitly reviewed by the 

court. See, North Carolina v. EPA, 531 F.3d 896, 

907–09 (D.C. Cir. 2008). 

14See, 70 FR 25162 (May 12, 2005). 

15 2006 Guidance at page 5. 

16See, North Carolina v. EPA, 531 F.3d 896 (D.C. 

Circuit 2008). 

17 Id. 531, F.3d at 909. 

18 Id. 

19See ‘‘Federal Implementation Plans to Reduce 

Interstate Transport of Fine Particulate Matter and 

Ozone,’’ 75 FR 45210 (August 2, 2010). 

1997 8-hour ozone or 1997 PM2.5

NAAQS, consistent with the 

requirements of element (1) of CAA 

section 110(a)(2)(D)(i) 

B. EPA’s Evaluation of Interference With 

Maintenance 

1. Background 

The second element of CAA section 

110(a)(2)(D)(i) requires that a state’s SIP 

must prohibit any source or other type 

of emissions activity in the state from 

emitting pollutants that would ‘‘interfere 

with maintenance’’ of the applicable 

NAAQS in any other state. The CAA 

does not specifically mandate how 

interference with maintenance is to be 

determined. Therefore, EPA has 

interpreted this term in past regulatory 

actions, such as the 1998 NOX SIP Call, 

in which EPA took action to remediate 

emissions of NOX that significantly 

contributed to nonattainment, or 

interfered with maintenance of, the then 

applicable ozone NAAQS through 

interstate transport of NOX and the 

resulting ozone.13 The NOX SIP Call was 

the mechanism through which EPA 

evaluated whether or not the NOX

emissions from sources in certain states 

had such prohibited interstate impacts, 

and if they had such impacts, required 

the states to adopt substantive SIP 

revisions to eliminate the NOX

emissions, whether through 

participation in a regional cap and trade 

program or by other means. 

After promulgation of the 1997 8-hour 

ozone NAAQS and the 1997 PM2.5

NAAQS, EPA again recognized that 

regional transport was a serious concern 

throughout the eastern United States 

and therefore developed the 2005 CAIR 

to address emissions of SO2 and NOX

that exacerbate ambient ozone and PM2.5

levels in many downwind areas through 

interstate transport.14 Within CAIR, EPA 

likewise interpreted the term ‘‘interfere 

with maintenance’’ as part of the 

evaluation of whether or not the 

emissions of sources in certain states 

had such impacts on areas that EPA 

determined would either be in violation 

of the NAAQS, or would be in jeopardy 

of violating the NAAQS, in a modeled 

future year unless action were taken by 

upwind states to reduce SO2 and NOX

emissions. Through CAIR, EPA again 

required states that had such interstate 

impacts to adopt substantive SIP 

revisions to eliminate the SO2 and NOX

emissions, whether through 

participation in a regional cap and trade 

program or by other means. 

EPA’s 2006 Guidance addressed CAA 

section 110(a)(2)(D) requirements for the 

1997 8-hour ozone NAAQS and 1997 

PM2.5 NAAQS. For those states subject 

to CAIR, EPA indicated that compliance 

with CAIR would meet the two 

requirements of section 110(a)(2)(D)(i)(I) 

for these NAAQS. For states not within 

the CAIR region, EPA recommended 

that states evaluate whether or not 

emissions from their sources would 

‘‘interfere with maintenance’’ in other 

states, following the conceptual 

approach adopted by EPA in CAIR. 

After recommending various types of 

information that could be relevant for 

the technical analysis to support the SIP 

submission, such as the amount of 

emissions and meteorological 

conditions in the state, EPA further 

indicated that it would be appropriate 

for the state to assess impacts of its 

emissions on other states using 

considerations comparable to those used 

by EPA ‘‘in evaluating significant 

contribution to nonattainment in the 

CAIR.’’15 EPA did not make specific 

recommendations for how states should 

assess ‘‘interfere with maintenance’’ 

separately, and discussed the first two 

elements of section 110(a)(2)(D) together 

without explicitly differentiating 

between them. 

In 2008, however, the U.S. Court of 

Appeals for the DC Circuit found that 

CAIR and the related CAIR federal 

implementation plan were unlawful.16

Among other issues, the court held that 

EPA had not correctly addressed the 

second element of section 

110(a)(2)(D)(i)(I) in CAIR. The court 

noted that ‘‘EPA gave no independent 

significance to the ‘interfere with 

maintenance’ prong of section 

110(a)(2)(D)(i)(I) to separately identify 

upwind sources interfering with 

downwind maintenance.’’ 17 EPA’s 

approach, the court reasoned, would 

leave areas that are ‘‘barely meeting 

attainment’’ with ‘‘no recourse’’ to 

address upwind emissions sources.18

The court therefore concluded that a 

plain language reading of the statute 

requires EPA to give independent 

meaning to the interfere with 

maintenance requirement of section 

110(a)(2)(D) and that the approach used 

by EPA in CAIR failed to do so. 

In addition to affecting CAIR directly, 

the court’s decision in the North 

Carolina case indirectly affects EPA’s 

recommendations to states in the 2006 

Guidance with respect to the interfere 

with maintenance element of section 

110(a)(2)(D) because the agency’s 

guidance suggested that states use an 

approach comparable to that used by 

EPA in CAIR. States such as Idaho have 

made SIP submissions that rely upon 

the recommendations in EPA’s 2006 

Guidance. Given the court decision on 

CAIR in the interim, however, EPA 

believes that it is necessary to evaluate 

these state submissions for section 

110(a)(2)(D) in such a way as to assure 

that the interfere with maintenance 

element of the statute is given 

independent meaning and is 

appropriately evaluated using the types 

of information that EPA recommended 

in the 2006 Guidance. To accomplish 

this, EPA believes it may be necessary 

to supplement the technical analysis 

provided the state in order to adequately 

evaluate the submissions with the 

respect to the interfere with 

maintenance element of section 

110(a)(2)(D). 

EPA has recently proposed a new rule 

to address interstate transport pursuant 

to section 110(a)(2)(D), the ‘‘Federal 

Implementation Plans to Reduce 

Interstate Transport of Fine Particulate 

Matter and Ozone’’ (Transport Rule 

Proposal), in order to address the 

judicial remand of CAIR.19 As part of 

the Transport Rule Proposal, EPA 

specifically reexamined the section 

110(a)(2)(D) requirement that emissions 

from sources in a state must not 

‘‘interfere with maintenance’’ of the 1997 

8-hour ozone NAAQS and 1997 PM2.5

NAAQS in other states. In the proposal, 

EPA developed an approach to identify 

areas that it predicts to be close to the 

level of the 1997 8-hour ozone NAAQS 

and 1997 PM2.5 NAAQS, and therefore 

at risk to become nonattainment for 

these NAAQS unless emissions from 

sources in other states are appropriately 

controlled. This approach starts by 

identifying those specific geographic 

areas for which further evaluation is 

appropriate, and differentiates between 

areas where the concern is with 

interference with maintenance, rather 

than with significant contribution to 

nonattainment. 

As described in more detail below, 

EPA’s analysis evaluates data from 

existing monitors over three overlapping 

three year periods (i.e., 2003–2005, 

2004–2006, and 2005–2007), as well as 

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20A memorandum in the docket for this action 

provides the information EPA used in order to 

identify monitors that are receptors for evaluation 

of interference with maintenance for certain states 

in the western United States. See, Memorandum 

from Brian Timin of EPA’s Office of Air Quality 

Planning and Standards, Air Quality Modeling 

Group entitled ‘‘Documentation of Future Year 

Ozone and Annual PM2.5 Design Values for 

Western States’’ (August 2010) (Timin Memo). 

21To begin this analysis, EPA first identifies all 

monitors projected to be in nonattainment or, based 

on historic variability in air quality, projected to 

have maintenance problems in 2012. The ‘‘problem’’ 

is that these maintenance areas are at risk not to 

stay in attainment because they are so close to the 

level of the 1997 ozone and PM2.5 NAAQS that 

minor variations in weather or emissions could 

result in violations of the NAAQS in 2012. 

22 2006 Guidance at 4. 

23 Id. at 5. 

24See, Transport Rule Proposal, 75 FR 45210 

(August 2, 2010) at page 45227. 

air quality modeling data, in order to 

determine which areas are predicted as 

likely to be violating the 1997 8-hour 

ozone and PM2.5 NAAQS in 2012, and 

which areas are predicted to potentially 

have a difficulty with maintaining 

attainment as of that date. In essence, if 

an area’s projected data for 2012 

indicates that it would be violating the 

NAAQS based on the average of these 

three overlapping periods, then this 

monitor location is appropriate for 

comparison for purposes of the 

significant contribution to 

nonattainment element of section 

110(a)(2)(D). If, however, an area’s 

projected data indicate that it would be 

violating the NAAQS based on the 

highest single period, but not over the 

average of the three periods, then this 

monitor location is appropriate for 

comparison for purposes of the interfere 

with maintenance element of the 

statute.20

By this method, EPA has identified 

those areas with monitors that are 

appropriate ‘‘maintenance sites’’ or 

maintenance ‘‘receptors’’ for evaluating 

whether the emissions from sources in 

another state could interfere with 

maintenance in that particular area. EPA 

then uses other analytical tools to 

examine the potential impacts of 

emissions from upwind states on these 

maintenance sites in downwind states. 

EPA believes that this new approach for 

identifying those areas that are 

predicted to have maintenance 

problems is appropriate to evaluate the 

section 110(a)(2)(D) SIP submission of a 

state for the interfere with maintenance 

element.21 EPA’s 2006 Guidance did not 

provide this specific recommendation to 

states, but in light of the court’s decision 

on CAIR, EPA will itself follow this 

approach in acting upon the Idaho 

submission. 

As explained in the 2006 Guidance, 

EPA does not believe that section 

110(a)(2)(D) SIP submissions from all 

states necessarily need to follow 

precisely the same analytical approach 

of CAIR or the Transport Rule Proposal. 

In the 2006 Guidance, EPA stated that: 

‘‘EPA believes that the contents of the 

SIP submission required by section 

110(a)(2)(D) may vary, depending upon 

the facts and circumstances related to 

the specific NAAQS. In particular, the 

data and analytical tools available at the 

time the State develops and submits a 

SIP for a new or revised NAAQS 

necessarily affects the contents of the 

required submission.’’ 22 EPA also 

indicated in the 2006 Guidance that it 

did not anticipate that sources in states 

outside the geographic area covered by 

CAIR were significantly contributing to 

nonattainment, or interfering with 

maintenance, in other states.23 As noted 

in the Transport Rule Proposal, EPA 

continues to believe that the more 

widespread and serious transport 

problems in the eastern United States 

are analytically distinct.24 For the 1997 

8-hour ozone NAAQS and the 1997 

PM2.5 NAAQS, EPA believes that 

nonattainment and maintenance 

problems in the western United States 

are relatively local in nature with only 

limited impacts from interstate 

transport. In the Transport Rule 

Proposal, EPA did not calculate 

interstate ozone or PM2.5 contributions 

to or from western states. 

Accordingly, EPA believes that 

section 110(a)(2)(D) SIP submissions for 

states outside the geographic area of the 

Transport Rule Proposal may be 

evaluated using a ‘‘weight of the 

evidence’’ approach that takes into 

account available relevant information, 

such as that recommended by EPA in 

the 2006 Guidance for states outside the 

area affected by CAIR. Such information 

may include, but is not limited to, the 

amount of emissions in the state 

relevant to the NAAQS in question, the 

meteorological conditions in the area, 

the distance from the state to the nearest 

monitors in other states that are 

appropriate receptors, or such other 

information as may be probative to 

consider whether sources in the state 

may interfere with maintenance of the 

1997 8-hour ozone NAAQS and 1997 

PM2.5 NAAQS in other states. These 

submissions can rely on modeling when 

acceptable modeling technical analyses 

are available, but EPA does not believe 

that modeling is necessarily required if 

other available information is sufficient 

to evaluate the presence or degree of 

interstate transport in a given situation. 

2. Idaho’s Interference With 

Maintenance Demonstration 

To show that Idaho emissions, as 

controlled under its SIP, do not interfere 

with maintenance of the 1997 8-hour 

ozone NAAQS and 1997 PM2.5 NAAQS 

in another state, Idaho’s submittal 

analyzed several types of factors to 

support its assertion. First, for its PM2.5

analysis, Idaho relied on information 

from the Western Regional Air 

Partnership (WRAP) Technical Support 

System (TSS). The WRAP TSS is a 

system developed in a collaborative 

effort by state and tribal governments 

and federal agencies to provide the tools 

needed to comply with the federal 

Regional Haze Rule. Idaho used it to 

provide general insight on how Idaho 

sources influence PM2.5 concentrations 

in Class I areas in surrounding states. 

For the 8-hour ozone NAAQS, Idaho 

evaluated NOX and VOC emissions data 

from Idaho sources. These emissions 

data were evaluated to understand how 

Idaho’s emissions sources may 

contribute to ozone impacts in 

surrounding states. The WRAP TSS 

results provided in Idaho’s submittal to 

address the 1997 PM2.5 standard and 

Idaho’s evaluation of NOX and VOC 

emissions data from Idaho sources to 

address the 1997 8-hour ozone NAAQS 

are discussed later. 

Idaho also relied on information about 

air stagnation conditions in other states 

to show that Idaho sources do not 

interfere with maintenance of the 1997 

8-hour ozone NAAQS and 1997 PM2.5

NAAQS. Idaho argued that stagnant air 

conditions are associated with weak 

transport and were cited in technical 

support documents for the 8-hour ozone 

and PM2.5 designations as a major 

contributing factor to poor air quality in 

surrounding states. Idaho also identified 

its state air quality regulations to 

demonstrate both that Idaho can, and 

does, work with other states and tribes 

to ensure that an Idaho activity would 

not interfere with maintenance by any 

other State with respect to the NAAQS. 

Idaho also relies on its permitting 

rules discussed earlier that not only 

require for new sources a demonstration 

that the proposed source’s emissions 

will not cause or significantly contribute 

to a violation of any ambient air quality 

standard, but also specifically require 

for existing sources an operating permit 

if emission rate reductions are necessary 

to attain or maintain any ambient air 

quality standard. It also points out that 

neither of these required demonstrations 

is limited to an analysis of impacts 

solely in Idaho. In light of these 

provisions and evidence that Idaho has 

used these air quality provisions in the 

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25See, the Transport Rule Proposal at 75 FR 

45210 (August 2, 2010). 

26Additional information concerning these 

weighted averages is provided in the docket in the 

Timin Memo. 

27 Data undergoing review from EPA’s Air Quality 

System which is EPA’s repository of ambient air 

quality data. (http://www.epa.gov/ttn/airs/airsaqs/). 

28Transport Rule Proposal, 75 FR 45210, (August 

2, 2010), pages 45253–45270, and Timin Memo. 

29The Transport Rule Proposal identifies 

nonattainment and maintenance receptors in the 

Eastern U.S. It does not include modeling results for 

the West. The Timin Memo documents further 

evaluation of the 2012 modeling to identify 

nonattainment and maintenance receptors in the 

West. 

past, as discussed in the section on 

significant contribution (section IV.A), 

EPA believes that in this case these 

regulatory provisions support our 

conclusion that Idaho does not interfere 

with maintenance in any other state and 

that Idaho has the ability to address 

interference with maintenance if in the 

future the state’s emissions interfere 

with maintenance of the 1997 8-hour 

ozone and 1997 PM2.5 NAAQS in 

another state. 

3. EPA Supplemental Analysis 

On July 6, 2010, the EPA proposed a 

rulemaking proposal (the Transport 

Rule Proposal) in response to the 

judicial remand of CAIR. The Transport 

Rule Proposal includes a new approach 

to determine whether emissions from a 

state interfere with maintenance of the 

1997 8-hour ozone NAAQS and the 

1997 PM2.5 NAAQS in other states. EPA 

is using a comparable approach to that 

of the Transport Rule Proposal in this 

action in order to evaluate whether 

emissions from Idaho sources interfere 

with maintenance of these NAAQS in 

other states. 

In the Transport Rule Proposal, EPA 

projected future concentrations of ozone 

and PM2.5 to identify areas that are 

expected to be out of attainment with 

the NAAQS or to have difficulty 

maintaining compliance with the 

NAAQS in 2012. These areas are 

referred to as nonattainment and 

maintenance receptors, respectively. 

These nonattainment and maintenance 

receptors are based on projections of 

future air quality at existing ozone and 

PM2.5 monitoring sites in those 

locations. EPA then used these sites as 

the receptors for examining the 

contributions of emissions from sources 

located in upwind states to 

nonattainment and maintenance 

problems at these monitoring locations. 

Monitoring data was obtained from 

AQS. 

For the PM2.5 NAAQS EPA evaluated 

concentrations of both the annual PM2.5

NAAQS and the 24-hour PM2.5 NAAQS. 

The 1997 annual PM2.5 NAAQS is met 

when the 3-year average of the annual 

mean concentration is 15.0 micrograms 

per cubic meter (μg/m3) or less. The 3- 

year average annual mean concentration 

is computed at each site by averaging 

the daily Federal Reference Method 

(FRM) samples by quarter, averaging 

these quarterly averages to obtain an 

annual average, and then averaging the 

three annual averages to get the design 

value. The 2006 24-hour PM2.5 NAAQS 

is met when the 3-year average of the 

annual 98th percentile PM2.5

concentrations is 35 μg/m3 or less. The 

1997 24-hour PM2.5 NAAQS is met 

when the 3-year average of the annual 

98th percentiles is 65 μg/m3 or less. The 

3-year average mean 98th percentile 

concentration is computed at each site 

by averaging the 3 individual annual 

98th percentile values at each site. The 

3-year average 98th percentile 

concentration is referred to as the 

24-hour average design value. In this 

action, EPA is only evaluating whether 

Idaho’s emissions impact other states’ 

ability to maintain the 1997 annual and 

24-hour PM2.5 NAAQS and the 1997 

8-hour ozone NAAQS, because those are 

the NAAQS at issue in this section 

110(a)(2)(D) SIP submission. In later 

actions, the state and EPA will evaluate 

the impacts of interstate transport from 

emissions from Idaho sources with 

respect to other NAAQS. 

For the ozone NAAQS, EPA evaluated 

concentrations relevant to the 1997 8- 

hour ozone NAAQS. The level of the 

1997 8-hour ozone NAAQS is 0.08 parts 

per million (ppm). The 8-hour ozone 

standard is met if the 3-year average of 

the annual 4th highest daily maximum 

8-hour ozone concentration is less than 

or equal to 0.08 ppm (i.e., less than 

0.085 ppm based on the rounding 

convention in 40 CFR part 50 Appendix 

I). This 3-year average is referred to as 

the ‘‘design value.’’ 

To project future ozone and annual 

PM2.5 design values, EPA projected 

future ozone values based on an average 

of three design value periods which 

include the years 2003–2007 (i.e., 

design values for 2003–2005, 2004– 

2006, and 2005–2007). The average of 

the three design values creates a ‘‘5-year 

weighted average’’ value. The 5-year 

weighted average values were then 

projected to the future years that were 

analyzed for the Transport Rule 

Proposal.25 26 EPA used the 5-year 

weighted average concentrations to 

project concentrations anticipated in 

2012 to determine which monitoring 

sites are expected to be nonattainment 

in this future year. EPA also projected 

2012 design values based on each of the 

three year periods (i.e., 2003–2005, 

2004–2006, and 2005–2007). The 

highest projection is referred to as the 

‘‘maximum design value’’ and gives an 

indication of potential variability in 

future projections due to differences in 

actual meteorology and emissions from 

what was modeled. 

EPA identified those sites that are 

projected to be attainment based on the 

5-year weighted average design value, 

but that have a maximum design value 

(based on a single three year period) that 

exceeds the NAAQS, as maintenance 

sites because EPA anticipates that there 

will be more difficulty in maintaining 

attainment of the NAAQS at these 

locations if there are adverse variations 

in meteorology or emissions. These 

projected maintenance sites are the ones 

that EPA has used to determine if 

emissions from Idaho sources 

potentially interfere with maintenance 

of the 1997 8-hour ozone NAAQS and 

1997 annual PM2.5 NAAQS in other 

states in this action. 

For the annual PM2.5 NAAQS, EPA 

identified from the modeling analyses 

conducted for the Transport Rule 

Proposal the following sites as 

maintenance receptors: A site in Cook 

County, Illinois in the Chicago area; a 

site in Harris County, Texas, in the 

Houston/Galveston/Brazoria area. From 

the modeling analysis conducted for 

states not included in the Transport 

Rule Proposal, EPA identified only sites 

in southern California. Based on recent 

monitoring data (2007–2009 design 

values that are under final EPA review), 

the highest 24-hour PM2.5 design value 

in the 47 states of the continental U.S. 

(not including California) is 50 μg/m3, 

which is well below the level of the 

1997 24-hour PM2.5 NAAQS of 65 μg/ 

m3.27 Therefore, outside of California, 

there are no areas that we would expect 

to have difficulty in maintaining the 

1997 24-hour PM2.5 NAAQS. 

From the modeling analyses 

conducted for the Transport Rule 

Proposal, EPA identified a number of 

maintenance sites or receptors for the 

1997 8-hour ozone NAAQS: Several 

sites in the Texas area and other sites in 

Georgia, Pennsylvania, New York and 

Connecticut.28 For the modeling 

analysis conducted for states not 

included in the Transport Rule Proposal 

(i.e. states not included fully in the 12 

km Transport Rule Proposal modeling 

domain), EPA identified several 

maintenance sites in southern and 

central California using available 36 km 

modeling.29 The 12 km Transport Rule 

Proposal modeling domain extends from 

Texas northward to North Dakota and 

eastward from the Rocky Mountains to 

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55502 Federal Register / Vol. 75, No. 176 / Monday, September 13, 2010 / Proposed Rules 

the east coast and includes 37 states and 

the District of Columbia. 

Significantly, for both the 1997 PM2.5

NAAQS and the 1997 8-hour ozone 

NAAQS, EPA’s analysis did not identify 

any maintenance receptors in the states 

that border Idaho (Washington, Oregon, 

Nevada, Utah, Wyoming and Montana). 

(a) Interfere With Maintenance 

Evaluation for the PM2.5 NAAQS 

For the 1997 PM2.5 NAAQS, the 

closest maintenance receptor site 

identified by the Transport Rule 

Proposal was in Cook County, Illinois. 

Cook County, Illinois is over 1000 miles 

east of the closest point on Idaho’s 

border, and on the other side of the 

Rocky Mountains. Given the relatively 

long distance and the intervening 

mountainous topography between Idaho 

and Cook County, EPA believes it is 

reasonable to conclude that there is a 

very low probability that Idaho sources 

interfere with maintenance in that area. 

It is also reasonable to conclude that 

Idaho emissions would not have such 

impacts at other identified maintenance 

sites east of Cook County. 

In the west, the closest maintenance 

receptor to Idaho was in Fresno County, 

California. Fresno County is located 

almost 400 miles southwest of the 

closest point on the Idaho border and on 

the other side of the Sierra Nevada 

Mountains, which act as a natural 

barrier to air movement between Idaho 

and California. In addition, Fresno 

County, located in southern California, 

is not in the predominant direction of 

winds from Idaho. As noted earlier, 

transport winds across Idaho generally 

flow from west to east, and not toward 

the southwest. Given the relatively long 

distance between Idaho and southern 

California, the intervening mountainous 

topography, and the general direction of 

west-to-east transport winds across 

Idaho, EPA concludes that there is no 

reasonable basis to conclude that Idaho 

sources interfere with maintenance of 

the 1997 PM2.5 NAAQS in those areas. 

It is likewise reasonable to conclude 

that Idaho emissions would not have 

such impacts at other identified 

maintenance sites in California. Based 

on EPA modeling and all of these factors 

taken together, EPA believes it is 

reasonable to conclude that Idaho 

emissions under the SIP do not interfere 

with maintenance of the 1997 PM2.5

NAAQS in any other state. 

This conclusion is consistent with the 

information and analysis Idaho 

provided in its SIP submittal regarding 

interference with maintenance of the 

1997 PM2.5 NAAQS. With respect to 

PM2.5, Idaho used the WRAP TSS tools 

to provide general insight on how Idaho 

sources influence PM2.5 concentrations 

in surrounding states and to conclude 

that Idaho sources did not interfere with 

maintenance of the 1997 PM2.5 NAAQS 

in any other state. Due to the limitations 

and purpose of the WRAP TSS, Idaho 

only evaluated impacts on Class I areas 

in surrounding states using these tools. 

Because EPA’s analysis did not predict 

any of these Class I areas to have a 

difficulty with maintaining attainment 

of the 1997 PM2.5 NAAQS, any impact 

Idaho might have on those areas would 

not, by definition, interfere with 

maintenance. Therefore, further 

evaluation of Idaho’s analysis of PM2.5

impacts on those areas is unnecessary. 

(b) Interfere With Maintenance 

Evaluation for the 8-Hour Ozone 

NAAQS 

For the 1997 8-hour ozone NAAQS, 

the closest maintenance receptor site to 

the east of Idaho was the Dallas-Ft 

Worth area in Texas. Dallas-Ft Worth is 

located over 1,000 miles southeast of the 

closest point on Idaho’s border and on 

the other side of the Rocky Mountains. 

Given the relatively long distance and 

the intervening mountainous 

topography between Idaho and Dallas-Ft 

Worth, it is reasonable to conclude that 

Idaho sources do not interfere with 

maintenance in the Dallas-Ft Worth 

area. It is also reasonable to conclude 

that Idaho emissions would not have 

such impacts at other identified 

maintenance sites elsewhere further east 

or south of Dallas-Ft Worth. 

In the west, the closest maintenance 

receptor to Idaho was in Nevada 

County, California. Nevada County is 

almost 300 miles southwest of the 

closest point on Idaho’s border and 

located on the other side of the Sierra 

Nevada Mountains, which act as a 

natural barrier to air movement between 

Idaho and California. In addition, 

Nevada County is in central California 

and is not in the predominant direction 

of transport winds. As noted earlier, 

transport winds across Idaho generally 

flow from west to east. Although 

westerly winds are not always the case, 

meteorological data show that transport 

winds in Idaho tend to be southerly or 

westerly during hot and stagnant 

weather conditions conducive to ozone 

formation in California. Given the 

relatively long distance between Idaho 

and central California, the intervening 

mountainous topography, and the 

general direction of west-to-east 

transport winds across Idaho, EPA 

believes it is reasonable to conclude that 

Idaho sources do not interfere with 

maintenance of the 1997 8-hour ozone 

NAAQS in Nevada County, California. It 

is also reasonable to conclude that Idaho 

emissions would not have such impacts 

at other identified maintenance receptor 

sites elsewhere in central or southern 

California. Based on all of these factors 

taken together, EPA believes it is 

reasonable to conclude that Idaho 

emissions do not interfere with 

maintenance of the 1997 8-hour ozone 

NAAQS in any other state. 

This conclusion is consistent with the 

information Idaho provided in its SIP 

submittal regarding interference with 

maintenance of the 1997 8-hour ozone 

NAAQS. For this element for the 8-hour 

ozone NAAQS, Idaho evaluated NOX

and VOC emissions data to understand 

how Idaho’s emissions sources may 

contribute to ozone impacts in 

surrounding states and to conclude that 

Idaho sources do not interfere with 

maintenance of the 1997 8-hour ozone 

NAAQS in any other states. Because 

EPA modeling did not predict any of the 

areas in states surrounding Idaho to 

have difficulty with maintaining 

attainment of the 8-hour ozone NAAQS, 

any impact Idaho might have on those 

areas would not, by definition, interfere 

with maintenance. Therefore, further 

evaluation of Idaho’s analysis of ozone 

impacts on those areas is unnecessary. 

4. Conclusion Regarding Interference 

With Maintenance 

The data and weight of evidence 

analysis presented above support the 

conclusion that the Idaho Interstate 

Transport SIP (submitted on June 28, 

2010) is adequate and that emissions 

from Idaho do not interfere with 

maintenance in any other state for the 

1997 8-hour ozone or 1997 PM2.5

NAAQS, consistent with the 

requirements of element (2) of CAA 

section 110(a)(2)(D)(I). 

C. EPA’s Evaluation of Interference With 

PSD Measures in Other States 

The third element of section 

110(a)(2)(D)(i) requires a SIP to contain 

adequate provisions prohibiting 

emissions that interfere with any other 

state’s required measures to prevent 

significant deterioration of its air 

quality. EPA’s 2006 Guidance made 

recommendations for SIP submissions 

to meet this requirement with respect to 

both the 1997 8-hour ozone NAAQS and 

the 1997 PM2.5 NAAQS. 

EPA believes that Idaho’s submission 

is consistent with the 2006 Guidance, 

when considered in conjunction with 

PSD program revisions that EPA 

proposed to approve on March 18, 2010 

(75 FR 13058). EPA’s proposed approval 

of Idaho’s SIP for purposes of meeting 

the requirements of section 

110(a)(2)(D)(i)(II) is contingent upon the 

final approval of the PSD program 

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Federal Register / Vol. 75, No. 176 / Monday, September 13, 2010 / Proposed Rules 55503 

revisions in the form specified in EPA’s 

proposed approval, referenced above. 

The State’s submittal indicates in 

Section 4, ‘‘Interfere with Prevention of 

Significant Deterioration of Air Quality,’’ 

that the State’s SIP provisions include 

an EPA-approved PSD program. Idaho’s 

regulations for its PSD program were 

last approved by EPA and made part of 

the SIP on January 16, 2003 (68 FR 

2217), 40 CFR 52.670, effective February 

18, 2003. On March 18, 2010, EPA 

proposed to approve Idaho’s PSD rule 

revisions incorporating into the State’s 

rules the provisions of EPA’s PSD 

requirements as of July 1, 2008, 

including the November 29, 2005, Phase 

2 rule for the 1997 8-hour ozone 

NAAQS (70 FR 71612), and the May 16, 

2008, PM2.5 Implementation Rule (73 FR 

28321) for the 1997 PM2.5 NAAQS. We 

anticipate taking final action approving 

Idaho’s PSD rule revisions before taking 

final action on this interstate transport 

proposal. Therefore, EPA proposes to 

approve this SIP provision as adequate 

for purposes of section 110(a)(2)(D)(i)(II) 

if EPA has taken final action to approve 

the revisions to Idaho’s PSD 

requirements that are consistent with 

our proposed action. 

EPA believes that the PSD revision for 

the 1997 8-hour ozone NAAQS that 

makes NOX a precursor for ozone for 

PSD purposes and the PSD revision for 

the 1997 PM2.5 NAAQS that makes SO2

and NOX precursors for PM2.5 for PSD 

purposes, taken together with the 

revised PSD SIP that EPA proposed to 

approve on March 18, 2010, and the 

Interstate Transport SIP that EPA is 

proposing to approve in this action, 

satisfy the requirements of the third 

element of section 110(a)(2)(D)(i) for the 

1997 8-hour ozone NAAQS and the 

1997 PM2.5 NAAQS. That is, these 

provisions ensure that there will be no 

interference with any other state’s 

required PSD measures because Idaho’s 

SIP, as proposed for approval in this 

action along with the March 18, 2010 

proposed action on the revised PSD 

rules, will meet current CAA 

requirements for PSD. 

V. Proposed Action 

In light of the data and the weight of 

the evidence analysis presented above, 

EPA is proposing to approve revisions 

to the Idaho SIP, submitted on June 28, 

2010, which adequately demonstrate 

that for the 1997 8-hour ozone and 1997 

PM2.5 NAAQS, air pollutant emissions 

from sources within Idaho do not (1) 

significantly contribute to 

nonattainment of the NAAQS in any 

other state, (2) interfere with 

maintenance of the NAAQS by any 

other state, and (3) interfere with any 

other state’s required measures to 

prevent significant deterioration of its 

air quality, as required by section 

110(a)(2)(D)(i). 

As noted previously, EPA will 

address element (4), interference with 

any other state’s required measures to 

protect visibility, in a separate action. 

EPA will also take action on the portion 

of Idaho’s SIP that addresses the 2006 

PM2.5 NAAQS in a separate action. 

VI. Statutory and Executive Order 

Reviews 

Under the Clean Air Act, the 

Administrator is required to approve a 

SIP submission that complies with the 

provisions of the Act and applicable 

Federal regulations. 42 U.S.C. 7410(k); 

40 CFR 52.02(a). Thus, in reviewing SIP 

submissions, EPA’s role is to approve 

state choices, provided that they meet 

the criteria of the Clean Air Act. 

Accordingly, this action merely 

proposes to approve state law as 

meeting Federal requirements and does 

not impose additional requirements 

beyond those imposed by state law. For 

that reason, this action: 

• Is not a ‘‘significant regulatory 

action’’ subject to review by the Office 

of Management and Budget under 

Executive Order 12866 (58 FR 51735, 

October 4, 1993); 

• Does not impose an information 

collection burden under the provisions 

of the Paperwork Reduction Act (44 

U.S.C. 3501 et seq.); 

• Is certified as not having a 

significant economic impact on a 

substantial number of small entities 

under the Regulatory Flexibility Act 

(5 U.S.C. 601 et seq.); 

• Does not contain any unfunded 

mandate or significantly or uniquely 

affect small governments, as described 

in the Unfunded Mandates Reform Act 

of 1995 (Pub. L. 104–4); 

• Does not have Federalism 

implications as specified in Executive 

Order 13132 (64 FR 43255, August 10, 

1999); 

• Is not an economically significant 

regulatory action based on health or 

safety risks subject to Executive Order 

13045 (62 FR 19885, April 23, 1997); 

• Is not a significant regulatory action 

subject to Executive Order 13211 (66 FR 

28355, May 22, 2001); 

• Is not subject to requirements of 

Section 12(d) of the National 

Technology Transfer and Advancement 

Act of 1995 (15 U.S.C. 272 note) because 

application of those requirements would 

be inconsistent with the Clean Air Act; 

and 

• Does not provide EPA with the 

discretionary authority to address, as 

appropriate, disproportionate human 

health or environmental effects, using 

practicable and legally permissible 

methods, under Executive Order 12898 

(59 FR 7629, February 16, 1994). 

In addition, this proposed rule does 

not have tribal implications as specified 

by Executive Order 13175 (65 FR 67249, 

November 9, 2000), because the SIP is 

not approved to apply in Indian country 

located in the state, and EPA notes that 

it will not impose substantial direct 

costs on tribal governments or preempt 

tribal law. 

List of Subjects in 40 CFR Part 52 

Environmental protection, Air 

pollution control, Incorporation by 

reference, Intergovernmental relations, 

Ozone, Particulate matter, Reporting 

and recordkeeping requirements, 

Volatile organic compounds. 

Dated: September 2, 2010. 

Dennis J. McLerran, 

Regional Administrator, Region 10. 

[FR Doc. 2010–22773 Filed 9–10–10; 8:45 am] 

BILLING CODE 6560–50–P 

DEPARTMENT OF HEALTH AND 

HUMAN SERVICES 

42 CFR Part 100 

RIN 0906–AA74 

National Vaccine Injury Compensation 

Program: Revisions to the Vaccine 

Injury Table 

AGENCY: Health Resources and Services 

Administration (HRSA), HHS. 

ACTION: Notice of proposed rulemaking. 

SUMMARY: Through this proposed rule, 

the Secretary proposes to change the 

Vaccine Injury Table (Table) to create 

distinct and separate listings for 

hepatitis A, trivalent influenza, 

meningococcal, and human 

papillomavirus (HPV) vaccines. The 

Table includes a list of covered vaccines 

under the National Vaccine Injury 

Compensation Program (VICP). The 

VICP provides a system of no-fault 

compensation for certain individuals 

who have been injured by covered 

childhood vaccines. This proposed rule 

is technical in nature. The four 

categories of vaccines described in this 

notice are already covered vaccines 

under the VICP (starting in 2004) and 

are currently listed in a placeholder 

category (box XIII) in the Table. This 

document proposes to list these 

vaccines as separate categories on the 

Table, with no associated injuries noted 

at this time, in order to make the Table 

more clear to the public. 

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