If you rent and you’re worried about radon, your tenant rights for radon in rental housing come from two places: the implied warranty of habitability that exists in nearly every state’s residential leases, and a smaller patchwork of state and local disclosure or testing laws. The practical threshold is 4 picocuries per liter (pCi/L). At or above that level, the EPA recommends mitigation,1US EPA. What Is EPAs Action Level for Radon and What Does It Mean and courts and housing agencies tend to treat that number as the point where a landlord has to act.
Radon is a radioactive gas that forms as uranium in soil decays and then seeps up through foundation cracks, pipe gaps, floor-wall joints, crawl spaces, and sump pits. It’s invisible and odorless, and it’s the leading cause of lung cancer among nonsmokers.2US EPA. Health Risk of Radon You won’t know you have a problem without testing.
Who Is Most at Risk
Ground-floor and basement units carry the highest exposure because radon enters through the foundation. If you rent a garden-level apartment or anything with below-grade living space, your risk is meaningfully higher than someone on the fourth floor of the same building. Upper floors can still show elevated readings depending on construction and ventilation, so a high floor isn’t a guarantee of safety. Testing is the only way to know.
The EPA notes there is no known safe level of radon exposure and suggests considering mitigation even when readings fall between 2 and 4 pCi/L.1US EPA. What Is EPAs Action Level for Radon and What Does It Mean Readings in that middle zone give you a reason for concern, but a reading at or above 4 pCi/L is the clearest legal basis for demanding repairs.
How to Test Your Unit
Testing comes in two forms. Short-term tests sit in the unit for two to 90 days. Long-term tests stay longer than 90 days and give a better picture of your year-round average. The EPA recommends starting with a short-term test and, if the result is 4 pCi/L or higher, confirming with a second short-term or a long-term test. If the first reading is above 8 pCi/L, follow up with another short-term test right away rather than waiting.3Environmental Protection Agency. A Citizens Guide to Radon
Place the detector in the lowest livable area of your unit. For any two- or three-day test, keep windows and exterior doors closed for at least 12 hours beforehand and throughout the test. Heating and air conditioning are fine. Fans that pull in outside air are not. Testing during heating season, when the building is sealed up, tends to capture the highest readings.
DIY kits run roughly $15 to $30 including lab analysis and are sold at hardware stores and through state radon programs. They work for your own knowledge and for an initial conversation with your landlord. If the dispute looks like it’s heading toward court, a professional test carries more weight because the technician can testify and the chain of custody is documented. Professional short-term testing typically costs $125 to $300. Where state or local law requires professional testing, the technician usually has to be certified through the National Radon Proficiency Program (NRPP) or the National Radon Safety Board (NRSB).
The EPA’s guidance for renters recommends either testing yourself or asking the building owner to test, and putting both the request and any results in writing.4Environmental Protection Agency. A Radon Guide for Tenants That paper trail matters later.
Putting the Landlord on Notice
The implied warranty of habitability requires landlords to keep rental property safe and fit to live in throughout the tenancy, including safe indoor air quality. Nearly every state recognizes it, and it exists whether or not the lease mentions it. When radon reaches or exceeds 4 pCi/L, you have a strong argument that the unit no longer meets habitability standards. Courts treat environmental hazards affecting air quality the way they treat a broken furnace or a sewage backup. The fact that radon occurs naturally doesn’t change the landlord’s duty; the duty isn’t to prevent radon in the soil, it’s to keep the indoor air safe.
No federal law requires landlords to test for radon or disclose results. A handful of states — Illinois, Maine, Colorado, and Florida among them — require landlords to disclose known radon hazards or share test results with tenants before or shortly after the lease begins. These laws typically call for a signed acknowledgment and often a state-approved pamphlet such as the EPA’s “A Citizen’s Guide to Radon.” Some local jurisdictions go further and require professional testing before certain types of properties can be rented out, with the specifics varying by property type and testing frequency.
Even where no law requires testing, the warranty of habitability still applies. If you provide test results showing elevated levels, the landlord cannot simply ignore them. Send the results in writing (email with a read receipt, or certified mail), state the reading, reference the 4 pCi/L EPA action level, and ask for mitigation on a specific timeline. Keep copies of everything.
On cost: mitigation is a building repair, not a tenant improvement. The landlord pays. The most common fix is active soil depressurization, which involves a pipe through the slab, a continuous fan, and a vent above the roofline. Installation typically runs $800 to $2,500 for a standard single-family home and more for complex layouts or multi-unit buildings. A well-installed system reduces indoor radon by 80 to 99 percent, and post-mitigation testing confirms it worked. The system stays with the building when you move out.
If the Landlord Won’t Act
If you’ve tested, the results are at or above 4 pCi/L, and the landlord ignores the problem, several remedies are available depending on your state. None are instant. All of them work better when every step is documented in writing.
Repair and Deduct
Many states let tenants fix a habitability problem and subtract the cost from rent. The process usually requires written notice, a waiting period (often 14 to 30 days), and then hiring a licensed contractor. Some states cap the deductible amount, sometimes at one month’s rent, sometimes at a fixed dollar figure. Because a mitigation system can run $800 to $2,500, you may need to spread the deduction across multiple months if your jurisdiction imposes a per-month cap. Save every receipt and every piece of written communication. This remedy works best when the landlord is simply neglectful rather than openly hostile, because you still have to live there.
Rent Abatement
Instead of moving, you can ask a housing court to reduce your rent for the period the unit was uninhabitable. The reduction is meant to reflect the gap between what the unit was worth as promised and what it was actually worth with the defect. Some courts use a straight percentage; others rely on expert testimony about fair rental value. Proving the breach usually requires professional test results, evidence that you notified the landlord, and documentation of how long the problem persisted.
Injunctive Relief
You can ask a court to order the landlord to install a mitigation system. Courts are more willing to grant this when you can show the landlord was notified, refused to act, and the health risk is ongoing. In some jurisdictions, a prevailing tenant can recover legal fees and court costs.
Constructive Eviction
If the conditions are severe enough to argue the property is fundamentally unsafe, you may be able to claim constructive eviction. The theory holds that a landlord’s failure to act has effectively forced you out. To succeed, you generally have to prove the interference was substantial, that you gave notice and reasonable time to fix it, and that you actually vacated. That last part is the catch: in most jurisdictions you have to move out to claim it. If a court agrees, you can terminate the lease without penalty and potentially recover moving costs and rent differential. If it disagrees, you remain liable for the rest of the rent. Get legal advice before you move.
Federally Assisted Housing
If you live in Section 8 (Housing Choice Voucher) housing, don’t assume HUD is testing your unit. HUD’s Office of Public and Indian Housing recommends but does not require radon testing in voucher-assisted properties, properties may only be assessed for radon every five years through the environmental review process, and HUD does not collect data on testing or mitigation in these units. A HUD Inspector General report found significant shortcomings in the agency’s radon policies for voucher-assisted properties. Testing yourself is the most reliable way to know your exposure.
FHA-insured multifamily properties operate under stricter rules. HUD’s Office of Multifamily Housing requires radon testing for most FHA-insured multifamily mortgages, including all ground-floor units and a sample of upper-floor units, performed by an NRPP-certified professional following the ANSI-AARST standard for multifamily buildings.
A broader HUD policy notice (CPD-23-103) took effect in April 2024, with a January 2026 compliance deadline for Tribal housing entities. It requires HUD and responsible entities to consider radon as part of the contamination analysis for projects where structures are occupied at least four hours per day. Where testing shows levels at or above 4 pCi/L, or where documented data shows the site is in a high-radon area, the environmental review record must include a mitigation plan. HUD will reject projects in documented high-radon areas without proposed or performed mitigation.5U.S. Department of Housing and Urban Development. CPD Notice on Departmental Policy for Addressing Radon in the Environmental Review Process The policy does not require testing in your unit. If you’re renting assisted housing and you want to know your radon level, the fastest route is still a test kit on your floor.