HUD Notice Provides Policy Guidance for Addressing Radon in Environmental Reviews

HUD issued Notice CPD-23-103 on January 11, clarifying its policy regarding addressing radon in the environmental review process pertaining to most HUD-assisted projects. The Notice states that radon must be “considered” when conducting contamination analysis required by HUD’s environmental review regulations 24 CFR parts 50 or 58. The Notice does not impose radon testing requirements, though it does include guidance on strategies for considering radon in site contamination analysis. The Notice also provides best practices for considering radon.

Radon is a radioactive gas found in nearly all soils that can diffuse into the air and enter buildings through cracks. Building materials and groundwater may also be sources of indoor radon. Indoor air radon levels vary across the U.S. and from parcel to parcel due to differences in geology, climate, seasonal variation, building construction, and other conditions. Once inside a building, radon concentrations can reach high levels, regardless of the age, condition, or design of a building.

The most common way people are exposed to radon is simply by breathing indoors. Radon is the primary cause of lung cancer in non-smokers, generally due to long-term exposure to low or moderate radon levels in the home. Many radon-induced lung cancers can be prevented by testing and reducing radon levels in existing buildings and by using radon resistant construction techniques for new construction. The level of radon inside existing buildings can be reduced by installing and operating a radon reduction system that vents radon safely out of the building and removes radon gas under a home’s foundation before it can enter the home.

When radon testing determines indoor radon levels at or above 4 pCi/L, a property’s Environmental Review Record must include a mitigation plan that (1) identifies the radon level; (2) considers the risk to occupants’ health; (3) describes the radon reduction system that will be installed; (4) establishes an ongoing maintenance plan; (5) establishes a reasonable timeframe for implementation; and (6) requires post-installation testing. Table 4 of the Notice indicates that radon testing and mitigation is an eligible program expense for most key HUD programs.

Notice CPD-23-103 takes effect 90 days after January 11. However, the Notice does not take effect until January 11, 2026, for Tribes, Tribally Designated Housing Entities, and the Department of Hawaiian Homeland recipients because HUD needs to provide additional support for radon programs serving these groups.

Read Notice CPD-23-103 at:

Read more about healthy housing issues, including radon, on page 6-1 of NLHC’s 2023 Advocates’ Guide.