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###### Environmental Protection Agency

          - [EPA-HQ-OAR-2023-0642; FRL: 11720-01-OAR]

# AGENCY:

Environmental Protection Agency (EPA).

# ACTION:

Notice.

# SUMMARY:

                        The Environmental Protection Agency (EPA) is requesting comment on its plan to retroactively apply the approved modification of the Federal Equivalent Method (FEM) designation for the Teledyne Advanced Pollution Instrumentation Model T640 particulate matter (PM) mass monitor including the 640X option (hereafter T640 and T640X) to all of the PM with a diameter 2.5 micrometers or smaller (PM2.5) concentration data from the T640 and                               ( print page 11832)                            T640X monitors in the EPA's Air Quality System (AQS) that was reported prior to the modification. This update, which will be applied to the unmodified hourly PM2.5                         concentration data in AQS using collocated ambient temperature when available, is expected to result in a much higher number of PM2.5                         monitoring sites using the T640 and T640X FEM methods meeting the bias measurement quality objectives (MQOs). More details related to this update can be found in the document titled, “Proposal to Update PM2.5                         Data from T640/T640X PM Mass Monitors,” located in the docket for this action and on the EPA's website at                         *https://www.epa.gov/​aqs/​aqs-memos-monitoring-and-policy.*                         Because of the importance of this air quality data for regulatory, scientific, and public use, the EPA is providing an opportunity for the public to comment on this update and the subsequent use of the updated data in regulatory and non-regulatory applications.                    

# DATES:

Comments must be received on or before March 15, 2024.

# ADDRESSES:

You may send comments, identified by Docket ID No. EPA-HQ-OAR-2023-0642, by any of the following methods:
      -  Federal eRulemaking Portal: https://www.regulations.gov/​                          (our preferred method). Follow the online instructions for submitting comments.                    
      -  Email: a-and-r-docket@epa.gov.                          Include Docket ID No. EPA-HQ-OAR-2023-0642 in the subject line of the message.                    
      -  Mail:                          U.S. Environmental Protection Agency, EPA Docket Center, OAQPS Docket, Mail Code 28221T, 1200 Pennsylvania Avenue NW, Washington, DC 20460.                    
      -  Hand Delivery or Courier (by appointment only):                          EPA Docket Center, WJC West Building, Room 3334, 1301 Constitution Avenue NW, Washington, DC 20004. The Docket Center's hours of operations are 8:30 a.m.-4:30 p.m., Monday-Friday (except Federal Holidays).                    

*Instructions:*                         All submissions received must include the Docket ID No. for this rulemaking. Comments received may be posted without change to                         *https://www.regulations.gov,*                         including any personal information provided. For detailed instructions on sending comments and additional information on the rulemaking process, see the “Public Participation” heading of the                         **SUPPLEMENTARY INFORMATION**                         section of this document.                    

# FOR FURTHER INFORMATION CONTACT:

                        Brett Gantt, Office of Air Quality Planning and Standards, Air Quality Assessment Division, Air Quality Analysis Group (Mail Code: C304-04), Environmental Protection Agency, 109 T.W. Alexander Drive, Research Triangle Park, NC 27711; telephone number: (919) 541-5274; email address                         *gantt.brett@epa.gov.*

# SUPPLEMENTARY INFORMATION:

## I. Proposed Data Correction

                    For detailed information regarding the retroactive correction of air quality data and the use of corrected data, please see the document titled, “Proposal to Update PM2.5                     Data from T640/T640X PM Mass Monitors,” located in the docket for this action and on the EPA's website at                     *https://www.epa.gov/​aqs/​aqs-memos-monitoring-and-policy.*

The EPA seeks comment on this document, including the proposed timing for the data correction and how the EPA and other monitoring authorities may use the data once corrected. The EPA will consider comments received prior to making a final determination on the retroactive application of the approved modification to the FEM for the Teledyne T640/T640X monitoring data.

## II. Public Participation

### A. Written Comments

                    Submit your comments, identified by Docket ID No. EPA-HQ-OAR-2023-0642, at                     *https://www.regulations.gov*                     (our preferred method), or using one of the other methods identified in the                     **ADDRESSES**                     section. Once submitted, comments cannot be edited or removed from the docket. The EPA may publish any comment received to its public docket. Do not submit to the docket at                     *https://www.regulations.gov*                     any information you consider to be Confidential Business Information (CBI), Proprietary Business Information (PBI), 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). Please visit                     *https://www.epa.gov/​dockets/​commenting-epa-dockets*                     for additional submission methods; the full EPA public comment policy; information about CBI, PBI, or multimedia submissions; and general guidance on making effective comments.                

Richard A. Wayland,

Director, Air Quality Assessment Division.

[FR Doc. 2024-02935 Filed 2-14-24; 8:45 am]

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