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TECHNICAL SUPPORT DOCUMENT

EPA-R08-OAR-2013-0006

AIR TRAX II No. ATX-157

Environmental Protection Agency

Approval and Promulgation of Air Quality Implementation Plans; Wyoming;

Revisions to the Wyoming Air Quality Standards and Regulations;

Ambient standards for Particulate Matter and for Lead.

I. Background of Wyoming’s Submissions

On August 19, 2011 the State of Wyoming submitted to EPA a formal revision package 

detailing two rulemakings (R-4 and R-18) as revisions to Wyoming's State Implementation Plan 

(SIP). The package information was entered into EPA’s Airtrax II tracking system and ID 

number ATX-157 was assigned. The EPA docket number assigned is EPA-R08-OAR-2013-

0006. These revisions amend the WAQSR. In particular, Wyoming has revised chapter 2, 

“Ambient Standards,” section 2, “Ambient standards for particulate matter,” section 10, 

“Ambient standards for lead,” and section 12, “Incorporation by reference.”

The Wyoming Environmental Quality Council made these changes by amending chapter 

2, including sections 2, 10 and 12, via rulemakings R-4 and R-18 on February 18, 2000, and July 

8, 2010, respectively. In accordance with the Wyoming Administrative Procedures Act, the 

revisions were forwarded to the Wyoming Governor’s Office where it was approved, and then 

transmitted to the Wyoming Secretary of State’s office and became effective on March 30, 2000 

and September 7, 2010, respectively. All necessary state reviews and approvals have been 

secured.

In rulemaking R-4, Section 2, the particulate matter ambient standard, was amended to 

adopt the PM2.5 (particulate matter with an aerodynamic diameter less than or equal to a nominal 

2.5 micrometers) standard into the State rule. Rulemaking R-18 made the state PM2.5 ambient 

standards consistent with federal standards, but no more stringent than federal standards, while 

deleting the annual PM10 standard and retaining the 24-hour ambient air quality standard for 

PM10. R-18 also amended section 10, the Pb ambient standard, making Wyoming's Pb ambient 

standard consistent with, but no more stringent than, the federal standard, and added section 12 

to consolidate all incorporation by references for the chapter into one section.

II. EPA’s Evaluation of Wyoming’s Submissions

The SIP revisions in the August 19, 2011submittal involve chapter 2, “Ambient 

Standards,” section 2, “Ambient standards for particulate matter,” section 10, “Ambient 

standards for lead,” and section 12, “Incorporation by reference.” To determine if Wyoming's 

submissions should be approved by EPA, EPA evaluated the submissions for consistency with 

the CAA and EPA regulations.
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In rulemaking R-4, section 2, the particulate matter ambient standards were amended to 

adopt the annual and 24-hour PM2.5 (particulate matter with an aerodynamic diameter less than 

or equal to a nominal 2.5 micrometers) NAAQS into the State rule. This is consistent with the 

CAA as in 1997 EPA established annual and 24-hour NAAQS for PM2.5 for the first time. This 

requirement has been part of WAQSR since its incorporation on February 18, 2000.

In rulemaking R-18, section 2 was amended to make the State PM2.5 ambient standards 

consistent with federal standards, but no more stringent than federal standards. The section now 

sets the primary and secondary ambient air quality standards for PM2.5 at 15 micrograms per 

cubic meter (ug/m3) annual arithmetic mean concentration, and; 35 micrograms per cubic meter 

(ug/m3) – 98th percentile 24-hour average concentration. The change defines attainment of the 

annual and 24-hour standards in accordance with Appendix N of 40 CFR part 50. It further sets 

the measurement of PM2.5, for the purpose of determining attainment of the standards, as 

determined by a reference method based on 40 CFR part 50, Appendix L and designated in 

accordance with 40 CFR part 53 or an equivalent or alternate method designated in accordance 

with 40 CFR Part 53. The revision also retains the 24-hour PM10 ambient air standards for 

PM10 particulate matter at 150 micrograms per cubic meter 24-hour average concentration with 

not more than one expected exceedance per year, and defines attainment of the 24-hour standard 

as determined in accordance with Appendix K of 40 CFR part 50. These changes correlate with 

the requirements of 40 CFR parts 50 and 53 as of the August 19, 2011 date of Wyoming’s 

submittal. The State also removed the annual PM10 standard from their regulations. This is 

permissible as the EPA revoked the annual PM10 NAAQS in a 2006 rulemaking (71 FR 61224, 

October 17, 2006).

In rulemaking R-18, section 2 was further amended to make the State Pb ambient 

standards consistent with federal standards, but no more stringent than federal standards. The 

section now sets the primary and secondary ambient air quality standards for Pb at 0.15 

micrograms per cubic meter, arithmetic mean concentration over a 3-month period. It further 

defines the measurement of Pb in the ambient air as Pb either by: a reference method based on 40 

CFR part 50, Appendix G and designated in accordance with 40 CFR part 53, or an equivalent 

method designated in accordance with 40 CFR part 53. The section now defines that primary 

and secondary ambient air quality standards for Pb are met when the maximum arithmetic 3-

month mean concentration for a 3-year period, as determined in accordance with Appendix R of 

40 CFR part 50, is less than or equal to 0.15 micrograms per cubic meter. These changes 

correlate with the requirements of 40 CFR parts 50 and 53 as of the August 19, 2011 date of 

Wyoming’s submittal.

Finally, in rulemaking R-18, Chapter 2 was amended by adding a new section 12 

“Incorporation by reference.” This section was added to simply consolidate all adoption by 

reference for Chapter 2 in one place. It defines the CFRs cited in the chapter as those published 

as of July 1, 2008, and details where copies of the applicable CFRs can be found for public 

inspection and to obtain copies. These changes correlate with the requirements of 40 CFR parts 

50 and 53 as of the August 19, 2011 date of Wyoming’s submittal.
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III. Conclusion

EPA has reviewed Wyoming's rule amendments and additions analyzed above. These

rules mirror applicable language in 40 CFR Parts 50 and 53. The changes quoted above provide 

the regulation necessary for the State to determine compliance with the CAA for PM2.5, PM10 

and Pb NAAQS. Therefore, these WAQSR changes and additions are consistent with the CAA 

and EPA regulations. As a result, it is recommended that the EPA approve the State 

Implementation Plan (SIP) revision submitted by the State of Wyoming consisting of the above 

discussed applicable portions of rulemakings R-4 and R-18 submitted on August 19, 2011 to 

EPA Region 8.

IV. Consideration of Section 110(l) of the CAA

Under section 110(l) of the CAA, EPA cannot approve a SIP revision if the revision 

would interfere with any applicable requirements concerning attainment and reasonable further 

progress toward attainment of the NAAQS or any other applicable requirement of the Act. In 

addition, section 110(l) requires that each revision to an implementation plan submitted by a 

state shall be adopted by such state after reasonable notice and public hearing.

The Wyoming SIP revisions that are recommended for EPA approval do not interfere 

with attainment of the NAAQS or any other applicable requirement of the Act. The first revision 

(R-4) revises the WAQSR particulate matter ambient standard to adopt the annual and 24-hour 

PM2.5 standards into the State rule. The second revision (R-18) makes the State annual and 24-

hour PM2.5 and Pb ambient standards consistent with federal standards, but no more stringent 

than federal standards. This revision also adds a section that simply consolidates all adoption by 

reference for chapter 2 in one place. The revisions were adopted after reasonable public notice, 

and after public hearings held on February 17, 2000, and July 8, 2010, respectively. All 

necessary State reviews and approvals have been secured. Therefore, CAA section 110(l) 

requirements are satisfied.

V. Final Action

It is recommended that EPA approve the SIP revisions that Wyoming submitted to EPA 

Region 8 on August 19, 2011. The Environmental Quality Council of the Wyoming Department 

of Environmental Quality adopted revisions to Chapter 2, “Ambient Standards,” Section 

2,”Ambient standards for particulate matter,” Section 10, “Ambient standards for lead,” and 

Section 12, “Incorporation by reference,” of the WAQSR as revisions to the SIP. 

It is also recommended that EPA publishes this rule as a direct final rule without prior 

proposal because we view this as a noncontroversial amendment and anticipate no adverse 

comments. Accordingly, in the Proposed Rules section of the same day Federal Register

publication, a separate document will be published that will serve as the proposal to approve the 

SIP revision if adverse comments are filed. This rule would be effective 60 days after 

publication in the Federal Register without further notice unless we receive adverse comments 
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by 30 days after publication in the Federal Register. If we receive adverse comments, we will 

publish a timely withdrawal in the Federal Register informing the public that the rule will not 

take effect. We would then address all public comments in a subsequent final rule based on the 

proposed rule. We would not institute a second comment period on this action. If we receive 

adverse comment on an amendment, paragraph, or section of this rule and if that provision may 

be severed from the remainder of the rule, we may adopt as final those provisions of the rule that 

are not the subject of an adverse comment.

VI. Statutory and Executive Order Reviews

Under Executive Order 12866 (58 FR 51735, October 4, 1993), this action is not a 

“significant regulatory action” and therefore is not subject to review by the Office of 

Management and Budget. For this reason, this action is also not subject to Executive Order 

13211, "Actions Concerning Regulations That Significantly Affect Energy Supply, Distribution, 

or Use" (66 FR 28355, May 22, 2001). This action merely approves state law as meeting Federal 

requirements and imposes no additional requirements beyond those imposed by state law. 

Accordingly, the Administrator certifies that this rule will not have a significant economic 

impact on a substantial number of small entities under the Regulatory Flexibility Act (5 U.S.C. 

601 et seq). Because this rule approves pre-existing requirements under state law and does not 

impose any additional enforceable duty beyond that required by state law, it does not contain any 

unfunded mandate or significantly or uniquely affect small governments, as described in the 

Unfunded Mandates Reform Act of 1995 (Public Law 104-4). 

This rule also does not have tribal implications because it will not have a substantial 

direct effect on one or more Indian tribes, on the relationship between the Federal Government 

and Indian tribes, or on the distribution of power and responsibilities between the Federal 

Government and Indian tribes, as specified by Executive Order 13175 (65 FR 67249, November 

9, 2000). This action also does not have Federalism implications because it does not have 

substantial direct effects on the States, on the relationship between the national government and 

the States, or on the distribution of power and responsibilities among the various levels of 

government, as specified in Executive Order 13132 (64 FR 43255, August 10, 1999). This 

action merely approves a state rule implementing a Federal standard, and does not alter the 

relationship or the distribution of power and responsibilities established in the Clean Air Act. 

This rule also is not subject to Executive Order 13045 “Protection of Children from 

Environmental Health Risks and Safety Risks” (62 FR 19885, April 23, 1997), because it 

approves a state rule implementing a Federal standard.

In reviewing SIP submissions, EPA’s role is to approve state choices, provided that they 

meet the criteria of the Clean Air Act. In this context, in the absence of a prior existing 

requirement for the State to use voluntary consensus standards (VCS), EPA has no authority to 

disapprove a SIP submission for failure to use VCS. It would thus be inconsistent with 

applicable law for EPA, when it reviews a SIP submission; to use VCS in place of a SIP 

submission that otherwise satisfies the provisions of the Clean Air Act. Thus, the requirements 

of section 12(d) of the National Technology Transfer and Advancement Act of 1995 (15 U.S.C. 
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272 note) do not apply. This rule does not impose an information collection burden under the 

provisions of the Paperwork Reduction Act of 1995 (44 U.S.C. 3501 et seq).

The Congressional Review Act, 5 U.S.C. section 801 et seq, as added by the Small 

Business Regulatory Enforcement Fairness Act of 1996, generally provides that before a rule 

may take effect, the agency promulgating the rule must submit a rule report, which includes a 

copy of the rule, to each House of the Congress and to the Comptroller General of the United 

States. EPA will submit a report containing this rule and other required information to the U.S. 

Senate, the U.S. House of Representatives, and the Comptroller General of the United States 

prior to publication of the rule in the Federal Register. A major rule cannot take effect until 60 

days after it is published in the Federal Register. This action is not a “major rule” as defined by 

5 U.S.C. section 804(2).

Under section 307(b)(1) of the Clean Air Act, petitions for judicial review of this action 

must be filed in the United States Court of Appeals for the appropriate circuit within 60 days 

from date of publication of this document in the Federal Register. Filing a petition for 

reconsideration by the Administrator of this final rule does not affect the finality of this action 

for the purposes of judicial review nor does it extend the time within which a petition for judicial 

review may be filed, and shall not postpone the effectiveness of such rule or action. Parties with 

objections to this direct final rule are encouraged to file a comment in response to the parallel 

notice of proposed rulemaking for this action published in the proposed rules section of today’s 

Federal Register, rather than file an immediate petition for judicial review of this direct final 

rule, so that EPA can withdraw this direct final rule and address the comment in the proposed 

rulemaking. This action may not be challenged later in proceedings to enforce its requirements. 

(See section 307(b)(2).)

VII. Changes to CFR

40 CFR part 52 is amended as follows:

PART 52 – APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS

1. The authority for citation for part 52 continues to read as follows:

Authority: 42 U.S.C. 7401 et seq.

Subpart ZZ - Wyoming

2. In section 52.2620, the table in paragraph (c)(1) is amended under Chapter 2 by revising the entries for Sections 2 

and 10 and by adding an entry for Section 12 in numerical order to read as follows:

52.2620 Identification of plan

* * * * *

(c) * * *

(1) * * *

State Citation Title/subject State 

adopted and 

effective 

date

EPA approval 

date and citation

Explanations

* * * * * * *

Chapter 2
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Section 2 Ambient standards for 

particulate matter.

2/18/2000, 

7/8/2010 and 

3/30/2000, 

9/7/2010

[insert Federal 

Register 

publication 

date], 

[insert Federal 

Register page 

number where 

document 

begins]

* * * * * * *

Section 10 Ambient standards for lead. 7/8/2010, 

9/7/2010

[insert Federal 

Register 

publication 

date], 

[insert Federal 

Register page 

number where 

document 

begins]

* * * * * * *

Section 12 Incorporation by reference. 7/8/2010, 

9/7/2010

[insert Federal 

Register 

publication 

date], 

[insert Federal 

Register page 

number where 

document 

begins]

* * * * * * *

* * * * *