Updates to Freddie Mac Guidance regarding Radon Testing Standards in 2025

What Environmental Professionals Need to Know Regarding Radon Testing Standards

In March 2025, the Federal Housing Finance Agency (FHFA) rescinded its 2022 directive that had imposed standardized radon testing requirements on all multifamily properties financed through Fannie Mae and Freddie Mac. Subsequent public announcements regarding agency radon testing changes were made with Fannie Mae finalizing their guidance documents in April 2025. Now Freddie Mac is finalizing its guidance documents as of May 22, 2025. This article explains the updates to the Freddie Mac Guide Chapter 61 – Environmental Requirements and Exhibit 11: Radon Testing and Mitigation Standards. This update introduces several notable changes from the prior 2023 version, impacting Environmental Professionals (EPs), lenders, and property stakeholders involved in multifamily housing transactions. While the core principles of health risk reduction and mitigation compliance remain intact, the 2025 updates aim to streamline testing requirements and introduce greater flexibility in expanding the Environmental Professional’s discretion.

Below are five critical updates to understand:

1. Reduction in Required Testing Volume

• 2023 Standard: Environmental Professionals were required to test a minimum of 25% of all ground-contact units, with at least one test per building, or follow state requirements when testing is initiated in a regulated state.
• 2025 Standard: The new requirement has been lowered to 10% of ground-contact units, still maintaining one test per building, or follow state requirements when testing is initiated in a regulated state.

This reduces costs and accelerates due diligence timelines, especially beneficial on large properties or portfolios.

2. Narrowed Scope of Follow-Up Testing

• 2023 Standard: If a unit exceeds the 4.0 pCi/L action level, follow-up testing was required in at least 25% of ground-contact units in that building, including the elevated unit.
• 2025 Standard: Follow-up testing is limited to only those units with initial radon levels at or above 4.0 pCi/L.

This narrower scope minimizes disruption and simplifies mitigation decisions while maintaining health protections.

3. More Discretion to Waive Testing

• 2023 Standard: EPs were permitted to conclude that testing was not necessary; however, they were explicitly barred from using the EPA Radon Zone Map as the primary rationale.
• 2025 Standard: In a shift from prior guidance, Freddie Mac now allows consultants to include the EPA Radon Zone Map among the supporting factors when determining that testing is not warranted. The guidance states:

“Examples could include Property design, previous radon testing at the Property, radon testing data from environmental databases, research, or the consultant’s judgment and professional experience, including reference to the Environmental Protection Agency Map of Radon Zones designation.”

However, it remains important to understand the limitations of the EPA map. As summarized on the map: “The EPA Radon Zone Map, published in 1993, is intended to indicate predicted average indoor radon levels by county, not for site-specific risk evaluation.”

The EPA map can now be cited as part of a broader rationale; however, professional judgment, corroborating data, and site-specific observations remain essential to sound environmental decision-making.

4. Enhanced Documentation Requirements When Testing Is Waived

• 2023 Standard: Required rationale for waiving testing to be included in the executive summary of the environmental report.
• 2025 Standard: Adds a requirement that supplemental documentation must also be included in the report appendix.

This increases transparency and strengthens the record for underwriters or future reviewers, but may also require more detailed justification from the EP.

5. Radon Testing Exemption Change

• 2023 Standard: Included the radon testing exemption for properties under existing debt to Freddie or Fannie that had prior agency-compliant testing.
• 2025 Standard: The referenced exemption was removed; however, prior radon testing data can still be used.

This allows all prior testing data, if deemed reliable, to be used in the EP’s review of determining if radon testing is warranted.

Other Requirements Remain Unchanged:

• Mitigation triggers after a second round of testing, and post-mitigation testing thresholds remain at 4.0 pCi/L.
• An Operations & Maintenance (O&M) Program is still required for ongoing management of installed systems.
• Resident notification procedures are consistent between both versions.
• No ongoing radon testing is required unless outlined in the O&M plan.

Final Thoughts

Freddie Mac’s 2025 revisions restore flexibility to Environmental Professionals in providing site-specific conclusions, reduce burdens on borrowers, and reflect a more pragmatic, risk-informed approach to radon testing. The allowance to reference the EPA Radon Zone Map, when combined with other relevant site data, acknowledges the evolving landscape of radon science and policy while maintaining health and safety standards.

While these updates may offer efficiencies, they also underscore the importance of professional judgment, robust documentation, and a clear understanding of regulatory responsibilities. Partner can provide clarity and strategic direction, being a market-leading provider of due diligence and radon sampling for agency lenders with strong expertise in State radon regulations. We look forward to helping lenders navigate the new radon guidance effectively and efficiently.