Public Comments to Regulatory Dockets
PUBLIC COMMENTS TO FEDERAL AGENCIES
This extensive record of formal written and oral comments to the U.S. EPA and other federal agencies demonstrates Dr. Frey’s steadfast commitment to dedicated public service and scientific integrity. His comments often critiqued proposed policy changes and procedural irregularities, particularly regarding the scientific review of National Ambient Air Quality Standards (NAAQS) for ozone and particulate matter. These interventions, such as his 73-page written statement on the particulate matter standard, went far beyond a typical academic role and showed his willingness to publicly challenge government actions he viewed as inconsistent with the law and established scientific principles. His most recent activity has been to identify and challenge legal, science policy, and scientific irregularities related to reconsideration of the 2009 EPA greenhouse gas endangerment finding. This work embodies his influential policy leadership by actively shaping the public discourse and regulatory process with meticulously documented, evidence-based arguments
Illustrative selected examples:
Frey, H.C., A.V. Diez Roux, J. Balmes, J.C. Chow, D.W. Dockery, J.R. Harkema, J. Kaufman, D.M. Kenski, M. Kleinman, R.L. Poirot, J.A. Sarnat, E.A. Sheppard, B. Turpin, and S. Vedal, “CASAC Review of EPA’s Integrated Science Assessment (ISA) for Particulate Matter (External Review Draft – October 2018),” 34 page letter and 100 pages of attachments submitted to Chair, Clean Air Scientific Advisory Committee, U.S. Environmental Protection Agency and to Docket EPA–HQ–ORD–2014-0859, December 10, 2018.
Hecht, S., N. Ashford, H.C. Frey, M.G. Morgan, E.S. Rubin, and M. Taylor, Comment Letter from Technological Innovation Experts Opposing EPA’s Proposal to Weaken Emissions Standards for New Coal-Fired Power Plants, Submitted to Docket ID No. EPA-HQ-OAR-2013-0495, U.S. Environmental Protection Agency, Washington, DC, March, 2019,
Frey, H.C., A.V. Diez Roux, P. Adams, G. Allen, J. Balmes, J.C. Chow, D.W. Dockery, J.R. Harkema, J. Kaufman, D.M. Kenski, M. Kleinman, R. McConnell, R.L. Poirot, J.A. Sarnat, E.A. Sheppard, B. Turpin, and S. Vedal, “03-07-19 Draft CASAC Review of EPA’s Integrated Science Assessment (ISA) for Particulate Matter (External Review Draft – October 2018),” 19 page letter submitted to Chair, Clean Air Scientific Advisory Committee, U.S. Environmental Protection Agency, Washington, DC, March 27, 2019.
Frey, H.C., P. Adams, J.L. Adgate, G. Allen, J. Balmes, K. Boyle, J.C. Chow, D.W. Dockery, H. Felton, T. Gordon, J.R. Harkema, J. Kaufman, P. Kinney, M. Kleinman, R. McConnell, R.L. Poirot, J.A. Sarnat, E.A. Sheppard, B. Turpin, and R. Wyzga, “Advice from the Independent Particulate Matter Review Panel (formerly EPA CASAC Particulate Matter Review Panel) on EPA’s Policy Assessment for the Review of the National Ambient Air Quality Standards for Particulate Matter (External Review Draft – September 2019),” 11 page letter and 192 pages of attachments submitted to Hon. Andrew Wheeler, Administrator, Docket ID No. EPA–HQ–OAR–2015–0072, and Clean Air Scientific Advisory Committee, U.S. Environmental Protection Agency, Washington, DC, October 22, 2019.
Frey, H.C., EPA’s Proposal to Regulate Science Should be Withdrawn: The Proposal is Not Required by Statute and Contradictory to Well-Established Scientific Best Practices, Written Statement to Docket EPA-HQ-OA-2018-0259, U.S. Environmental Protection Agency, Washington, DC, May 18, 2020, 23 pages.
Frey, H.C., Advice from the Independent Particulate Matter Review Panel (formerly the EPA CASAC Particulate Matter Review Panel) On Review of the National Ambient Air Quality Standards for Particulate Matter, Written Statement to Docket EPA–HQ–OAR–2015–0072, U.S. Environmental Protection Agency, Washington, DC, May 20, 2020, 5 pages.
Frey, H.C., Request for Correction: “A Critical Review of Impacts of Greenhouse Gas Emissions on the U.S. Climate,” Disseminated by the U.S. Department of Energy on July 29, 2025, Submitted to the U.S. Department of Energy, Washington DC, August 15, 2025. Also submitted to Docket: DOE-HQ-2025-0207 and Docket: EPA-HQ-OAR-2025-0194-0358 (comment ID EPA-HQ-OAR-2025-0194-0358)
Frey, H.C., Public Comment on Proposed Rule for Reconsideration of the 2009 Endangerment Finding: Follow the Science, Follow the Law, Be Transparent, and Follow the Agency Mission to Protect Human Health and the Environment, Submitted to the U.S. Environmental Protection Agency, Washington, DC, Docket ID No. EPA-HQ-OAR-2025-0194, August 25, 2025 (89 pages). Comment ID: EPA-HQ-OAR-2025-0194-0431.