Update of PM2.5 Data From T640/T640X PM Mass Monitors

AGENCY:

Environmental Protection Agency (EPA).

ACTION:

Notice.

SUMMARY:

The Environmental Protection Agency (EPA) is retroactively applying 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 concentration data for PM with a diameter 2.5 micrometers or smaller (PM_2.5) from the T640 and T640X monitors in the EPA's Air Quality System (AQS) that was reported prior to the modification. The EPA processed the unmodified hourly PM_2.5 concentration data in AQS using collocated or paired ambient temperature when available.

DATES:

Updated data will be available in AQS by May 13, 2024. Although not required, the EPA recommends that air agencies review the updated data by May 28, 2024, and contact their EPA Regional office with any questions.

FOR FURTHER INFORMATION CONTACT:

Mr. 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. Public Comments

Because of the importance of this air quality data for regulatory, scientific, and public use, the EPA provided an opportunity for the public to comment on the EPA's plan to retroactively update the PM_2.5 data from T640/T640X PM mass monitors (89 FR 11831). The EPA received a total of 25 non-duplicative comments. For a summary of the comments received and EPA's responses, please see the document titled, “Summary of and Responses to Public Comments on the EPA's Plan to Update PM_2.5 Data from T640/T640X PM Mass Monitors,” located in the docket for this action at https://www.regulations.gov under Docket ID No. EPA-HQ-OAR-2023-0642 and on the EPA's website at https://www.epa.gov/aqs/aqs-memos-monitoring-and-policy.

II. Data Update Supplemental Information

For detailed information regarding the EPA's retroactive update of air quality data and how these data may be used, please see the document titled, “Supplemental Information on the EPA's Update of PM_2.5 Data from T640/T640X PM Mass Monitors,” located in the docket for this action at https://www.regulations.gov under Docket ID No. EPA-HQ-OAR-2023-0642 and on the EPA's website at https://www.epa.gov/aqs/aqs-memos-monitoring-and-policy.