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Federal Register / Vol. 86, No. 103 / Tuesday, June 1, 2021 / Proposed Rules material may be found in the AD docket on the internet at https www.regulations.gov by searching for and locating Docket No.
FAA20210380.
2 For more information about this AD, contact Andrea Jimenez, Aerospace Engineer, COS Program Management Section, Operational Safety Branch, Compliance &
Airworthiness Division, FAA, 1600 Stewart Ave., Mail Stop: Room 410, Westbury, NY
11590; telephone 516 2287330; email andrea.jimenez@faa.gov.
Issued on May 21, 2021.
Lance T. Gant, Director, Compliance & Airworthiness Division, Aircraft Certification Service.
FR Doc. 202111187 Filed 52821; 8:45 am BILLING CODE 491013P

ENVIRONMENTAL PROTECTION
AGENCY
40 CFR Part 52
EPAR09OAR20210249; FRL10022
26Region 9

Rescission of Clean Data Determination and Call for Attainment Plan Revision for the Yuma, AZ 1987
PM10 Moderate Nonattainment Area Environmental Protection Agency EPA.
ACTION: Proposed rule.
AGENCY:

The Environmental Protection Agency EPA is proposing to rescind its previously issued clean data determination for the Yuma, Arizona Moderate nonattainment area for the 1987 24-hour national ambient air quality standard NAAQS for particulate matter with an aerodynamic diameter less than or equal to a nominal 10 micrometers PM10 because recent complete, quality-assured monitoring data show that the area has subsequently violated this NAAQS. We are also proposing to find that the Arizona State Implementation Plan SIP
is substantially inadequate to attain or maintain the PM10 standard and to call for Arizona to revise the SIP to address this inadequacy.
DATES: Any comments must arrive by July 1, 2021.
ADDRESSES: Submit your comments, identified by Docket ID No. EPAR09
OAR20210249 at http
www.regulations.gov. For comments submitted at Regulations.gov, follow the online instructions for submitting comments. Once submitted, comments cannot be edited or removed from Regulations.gov. For either manner of submission, the EPA may publish any comment received to its public docket.
Do not submit electronically any
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SUMMARY:

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information you consider to be Confidential Business Information CBI
or other information whose disclosure is restricted by statute. Multimedia submissions audio, video, etc. must be accompanied by a written comment.
The written comment is considered the official comment and should include discussion of all points you wish to make. The EPA will generally not consider comments or comment contents located outside of the primary submission i.e., on the web, cloud, or other file sharing system. For additional submission methods, please contact the person identified in the FOR
FURTHER INFORMATION CONTACT section.
For the full EPA public comment policy, information about CBI or multimedia submissions, and general guidance on making effective comments, please visit https www.epa.gov/dockets/
commenting-epa-dockets. If you need assistance in a language other than English or if you are a person with disabilities who needs a reasonable accommodation at no cost to you, please contact the person identified in the FOR
FURTHER INFORMATION CONTACT section.
FOR FURTHER INFORMATION CONTACT: John J. Kelly, Air Planning Office AIR2, EPA Region IX, 415 9474151, kelly.johnj@epa.gov.
SUPPLEMENTARY INFORMATION:
Throughout this document, we, us, and our refer to the EPA.
Table of Contents I. Background A. The 1987 PM10 NAAQS
B. Designation and Classification of the Yuma PM10 Nonattainment Area C. The Clean Data Policy and the 2006
Clean Data Determination II. Current Monitoring Data III. Proposed Action and Request for Public Comment IV. Statutory and Executive Order Reviews
I. Background A. The 1987 PM10 NAAQS
The EPA sets NAAQS for certain ambient air pollutants at levels required to protect human health and the environment. The primary NAAQS
represent ambient air quality standards the attainment and maintenance of which the EPA has determined are requisite to protect public health, including an adequate margin of safety.
The secondary NAAQS represent ambient air quality standards the attainment and maintenance of which the EPA has determined are requisite to protect public welfare from any known or anticipated adverse effects associated with the presence of such air pollutant in the ambient air. PM10 is one of these ambient air pollutants for which the
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EPA has established NAAQS. On July 1, 1987, the EPA promulgated two primary standards for PM10: A 24-hour standard of 150 micrograms per cubic meter mg/
m3 and an annual PM10 standard of 50
mg/m3. The EPA also promulgated secondary PM10 standards that were identical to the primary standards.1
Effective December 18, 2006, the EPA
revoked the annual PM10 NAAQS but retained the 24-hour PM10 NAAQS.2
Because they are identical, we refer to the primary and secondary 24-hour standards using the single term, NAAQS.
The 24-hour PM10 NAAQS is attained when the expected number of exceedances, averaged over a three-year period, is less than or equal to one. The expected number of exceedances averaged over a three-year period at any given monitor is known as the PM10
design value for that site. The PM10
design value for the nonattainment area is the highest design value from a monitor within that area. The methodologies for calculating expected exceedances for the 24-hour PM10
NAAQS are found in 40 CFR part 50, appendix K, Section 2.1a.
B. Designation and Classification of the Yuma PM10 Nonattainment Area Upon enactment of the 1990
Amendments to the Clean Air Act CAA
or Act, the Act itself designated specific areas as nonattainment by operation of law, and classified these areas as Moderate.3 These areas included all former Group I PM10
planning areas identified in Federal Register documents published on August 7, 1987,4 and October 31, 1990,5
and any other areas violating the 1987
PM10 NAAQS prior to January 1, 1989.
The EPA published a Federal Register document announcing the areas designated nonattainment for PM10
upon enactment of the 1990 CAA
Amendments, known as initial PM10
nonattainment areas, on March 15, 1991.6 The EPA published a subsequent Federal Register document correcting some of these areas on August 8, 1991.7
These nonattainment designations and Moderate area classifications were codified in 40 CFR part 81 on November 6, 1991.8 The EPA designated as unclassifiable all other areas in the Nation not designated nonattainment 1 52

FR 24634 July 1, 1987.
FR 61144 October 17, 2006.
3 42 U.S.C. 7407d4B, 7513a.
4 52 FR 29383.
5 55 FR 45799.
6 56 FR 11101.
7 56 FR 37654.
8 56 FR 56694.
2 71

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