Radon Mitigation

Radon is an invisible, radioactive gas found in nearly all soils that is created during the natural breakdown of uranium in rocks and soils. Radon typically moves up through the ground and into homes and buildings through cracks and other holes in the foundation, although there are other radon sources.

The EPA recommends taking action if radon levels inside your home are 4.0 pCi/l (pico Curies per liter of air) or higher. Homes with radon levels between 2.0 and 4.0 pCi/l are considered a risk and should also be considered for mitigation.

Health Effects of Radon Exposure

Radon usually does not present a health risk outdoors because it is diluted in the open air, but it can build up inside a home and create a serious health risk. Breathing air that contains radon can cause lung cancer. The United States Surgeon General has warned that radon is the second leading cause of lung cancer in the United States today and is the leading cause of lung cancer in nonsmokers. If you smoke and your home has high radon levels, your risk of lung cancer is especially high. The good news is that lung cancer from radon is preventable through testing and proper remediation methods.

All Homes Should Be Tested for Radon

Montgomery County has high levels of radon in the soil, so every home in Montgomery County should be tested for radon. Radon test kits can be found online or in home improvement stores. Follow the directions on the packaging for the proper placement of the device and where to send the device after the test to find out your radon level.

If you are a resident of Maryland, discounted radon test kits may be available from the State of Maryland.

Radon Laws for Home Sales

On July 18, 2022, the Mayor and Council adopted Ordinance 12-22 to apply Montgomery County’s radon testing laws to the sale of single-family homes (including townhomes) in Rockville. For questions, visit the county’s Radon and Buying or Building a Home and Radon Testing and Mitigation for Rental Properties pages.

Radon Law for Rentals

On March 27, 2023, the Mayor and Council adopted Ordinance 06-23 to require that rental facilities that are at or below grade be tested for the presence of radon. Landlords must provide a recent test result (within two years) at the time of lease signing. For questions, please email Jim Wasilak at jwasilak@rockvillemd.gov.

Radon Mitigation

Read our comparison of radon remediation methods and questions to ask a contractor. Before beginning a project, email the Inspection Services Division at permits@rockvillemd.gov to determine if the radon remediation method you intend to use requires building, electrical, or mechanical permits.

The City of Rockville has adopted IRC Appendix F: Radon Control Methods, which applies to new home builds, substantial additions, and substantial reconstruction.

The National Radon Proficiency Program and National Radon Safety Board can help identify professionals in your area who are certified in radon testing and mitigation.