Landlord Responsibility for Radon in Rental Housing

Radon, a naturally occurring radioactive gas associated with lung cancer, is found in rental properties throughout the U.S. In order to provide tenants with habitable rentals, landlords must address radon problems in their rental properties. Because the gas is invisible and odorless, however, it's not always easy to know if radon is present, as is the case with other environmental and health hazards, such as mold and bed bugs.

Here's how to get started identifying and fixing any radon problems that occur in your rental property—and your potential liability if you don't.

Why Radon Is a Risk

Radon exposure is the second leading cause of lung cancer in the United States after cigarette smoking. The U.S. Environmental Protection Agency (EPA) estimates radon might be responsible for more than 21,000 lung cancer deaths each year. Among non-smokers, radon is the leading cause of lung cancer.

Testing for radon is essential because it's such a hard toxin to detect:

• it's odorless, tasteless, and colorless
• there are no immediate symptoms from radon exposure, and
• lung cancer typically develops anywhere from 5 to 25 years after exposure.

To learn more about radon, check out the EPA's website—it contains helpful educational materials, including "A Citizen's Guide to Radon" and "A Radon Guide for Tenants." The American Lung Association's website also goes into depth on the risks of radon and offers a wealth of resources for the general public and real estate professionals.

Landlord Liability for Radon Problems

Landlords can be liable for any harm caused to tenants by radon under a number of legal theories, such as:

• Breach of warranty of habitability. All states require landlords to provide habitable rentals to tenants. Because radon is an environmental hazard that poses a risk to health, having levels in excess of what's considered safe might breach the implied warranty of habitability. When a landlord breaches the implied warranty of habitability, tenants can take any measures allowed under their state laws, such as withholding rent or making the repairs themselves and deducting the expense from rent.
• Failure to disclose a known hazard. Landlords in most states have a duty to disclose known dangerous situations at their rentals. Aside from the fact that the landlord would have a duty to remedy the issue, the landlord could be further liable if they were aware of the condition and purposely concealed it or failed to disclose it.
• Premises liability. If it can be demonstrated that a tenant's injury—such as lung cancer or death—was caused by high levels of radon in the rental, and that the landlord was negligent in addressing it, the tenant or their surviving family members might have a premises liability claim against the landlord.

This list isn't exclusive—creative lawyers often come up with novel theories of liability based on local and state laws. Landlords facing a lawsuit from a tenant who claims to have been harmed by exposure to radon should consult a local landlord-tenant attorney.

State Laws Regarding Radon in Rental Properties

As of 2025, only four states have passed laws specifically address radon in rental properties.

• Colorado: Before signing a lease or rental agreement, Colorado landlords must disclose in writing a specific warning about radon and any knowledge the landlord has about radon levels in the property. The disclosure must be signed by the tenant. Landlords must also give tenants a copy of a brochure about radon from the department of public health and environment. (Colo. Rev. Stat. § 38-12-803 (2025).)
• Florida: Florida landlords must provide tenants with a specific written disclosure about radon before or at the time they sign the lease or rental agreement. (Fla. Stat. § 404.056 (2025).)
• Illinois: When a tenant applies for a rental (or upon request after moving in), landlords in Illinois must provide the tenant with the state's pamphlet "Radon Guide for Tenants," copies of any reports or records about radon at the rental, and a Disclosure of Information on Radon Hazards to Tenants form. The law also gives the tenant 90 days after move-in to test for radon and, if the levels are high, move out. (420 Ill. Comp. Stat. § 46/26 (2025).)
• Maine: The law requires Maine landlords to test new rentals for radon. For existing rentals, landlords must test at certain intervals when requested to do so by a tenant. Within 30 days of receiving the results of a test (or before a tenant signs a lease or rental agreement), landlords must provide tenants with written notice about the presence of radon in the building, inform them whether mitigation has been done, and let them know that they have the right to test for radon. If a test reveals high levels of radon, the landlord or the tenant can terminate the tenancy with 30 days' notice. (Me. Rev. Stat. tit. 14, § 6030-D (2025).)

Regardless of state law requirements, a landlord who owns rental property in an area known to have radon problems (see the EPA Map of Radon Zones for details), but doesn't test, warn tenants, or take action, could be sued for harm that tenants suffer as a result.

How to Test for Radon

Radon might be a problem in your rental property—especially if the property is in an area that's naturally rich in uranium soil and rock. The EPA recommends radon mitigation if a test reveals that the radon level is 4 pCi/L (picocuries per liter) or higher.

You don't need any special skills to test for radon on your own: Radon testing kits are widely available and easy to use. Pick one up at a local home improvement store, or purchase one online. Kansas State University's National Radon Program Services sells inexpensive radon kits and has useful information on the subject. Also, each state has its own office or agency that addresses radon, and many offer free or discounted test kits to residents.

As an alternative to a DIY test, you might prefer to hire a professional radon contractor to perform the test. Your state's radon office or agency is probably the best place to find a local contractor who meets any state licensing requirements; you can also find contractors through the National Radon Proficiency Program and the National Radon Safety Board.

What to Do When Radon Levels Are High

Solving a radon problem means keeping radon out of the building. Good ventilation (opening windows, using fans) will disperse the gas in many situations, but these are really only temporary methods. Effective, long-term solutions include sealing cracks and openings in the foundation in order to keep radon out, or sucking the radon out of the soil before it enters the foundation or basement, and venting it into the air above the roof through a pipe.

A professional radon contractor can suggest the best options for your particular rental property—usually, radon mitigation is not a DIY project. Costs typically range from $1,000 to $2,500.

What Tenants Can Do About Radon in a Rental

If a tenant is concerned about radon, they are free to test for it on their own—landlord permission isn't necessary. The DIY tests discussed above are often free or inexpensive, and won't cause any harm to the rental.

If you run the test and find high levels of radon, let your landlord know in writing immediately. Point your landlord toward this article and the resources mentioned here. Note that you are concerned about the long-term effects of living in a place with elevated radon levels on yourself and your family.

Hopefully, your landlord will take measures to mitigate the radon. If, however, your landlord fails to act, consider contacting a local landlord-tenant attorney or tenants' organization to find out more about your rights under state and local law. Taking drastic action—such as moving out or stopping paying rent—before you know your legal options could result in your landlord starting the eviction process.