Radon in Apartments and Condos: What Renters and Owners Need to Know

Radon guidance often focuses on single-family homeowners, but renters and condominium owners face radon exposure too—often with less clarity about who’s responsible for testing and mitigation. This guide addresses the specific questions people in multi-family and shared housing face.

Does Radon Affect Apartments?

Yes, but it depends heavily on where in the building you live. Radon enters buildings through foundation cracks, floor-wall joints, and construction gaps in contact with the soil. This means:

Ground-floor and basement units are at significantly higher risk than upper-floor units. Radon concentrations drop rapidly with height above the foundation—a 10th-floor apartment is unlikely to have elevated levels, while a first-floor unit in the same building might.

The building’s foundation type matters: basement apartments have the most direct soil contact, slab-on-grade units have moderate contact, and elevated units above a parking garage have minimal direct radon exposure.

Building age and construction affect how much radon enters. Older buildings with block foundation walls, cracked slabs, and gap-prone construction allow more radon in than newer, tightly sealed buildings.

Should Renters Test for Radon?

If you live in a ground-floor or basement unit, testing is worth doing—particularly if you live in a high-radon region. Test kits cost $10–$30 and are available online or at hardware stores.

What to know about testing a rental unit:

• You don’t need landlord permission to place a passive test kit in your unit
• Test at the lowest level of your living space (bedroom or living area, not bathroom)
• Keep windows closed and doors in normal operating mode during the test period

If the test shows elevated levels (above 4 pCi/L), the next step depends on your jurisdiction and lease terms.

Who’s Responsible for Mitigation in Rentals?

This varies significantly by state. A handful of states have enacted laws specifically addressing radon in rental housing:

States with landlord radon disclosure or testing requirements: As of 2026, Illinois, Florida, Maine, and a small number of others have specific requirements. Many more states are considering legislation.

In most states: There are no specific radon laws for rentals. Responsibility falls to the landlord under general habitability standards—the argument being that a home with unsafe radon levels may be considered uninhabitable.

Your options if your landlord refuses to act:

1. Document your test results and request mitigation in writing
2. Research your state’s habitability laws and tenant protections
3. Contact your local health department—some provide radon testing assistance and can apply pressure
4. Consult a tenant rights organization for jurisdiction-specific guidance

Mitigation in a multi-unit building is more complex than a single-family home because the system needs to address common foundation areas, not just your individual unit.

Radon in Condominiums

Condo ownership adds complexity because individual units own their airspace but the building structure, foundation, and common areas are managed by the HOA.

Who handles mitigation? In most cases, radon mitigation in a condo building is the HOA’s responsibility because it involves the common foundation and building structure. Individual unit owners typically cannot install a mitigation system without HOA approval and coordination.

How to approach the HOA:

1. Test your unit and document elevated levels
2. Formally request that the HOA conduct building-wide radon assessment
3. Present the EPA action level guidance and note that elevated radon is a liability issue for the association
4. If the HOA refuses, consult a real estate attorney regarding your rights

Ground-floor units and units directly above a parking garage or crawl space are the most likely to have elevated levels. If you own one of these units and the HOA is unresponsive, consulting legal counsel may be necessary.

What Does Mitigation Look Like in Multi-Family Buildings?

Mitigation in multi-unit buildings is typically a shared-infrastructure project:

• Sub-slab depressurization systems are installed in common foundation areas, with multiple suction points serving multiple units
• Crawl space systems involve sealing and depressurizing shared crawl space areas beneath multiple units
• Shared ventilation systems can be modified to reduce radon accumulation in common areas

The cost per unit is often lower than a single-family home mitigation because one system can address multiple units—but the project must be coordinated at the building level.

Testing Before Buying a Condo or Apartment

If you’re purchasing a ground-floor or low-level condo unit, radon testing should be part of your inspection process. Request that the seller allow testing, or negotiate for a radon contingency clause.

A short-term test during the inspection period is standard practice. If results come back elevated, you can negotiate for the seller or HOA to fund mitigation before closing, or adjust your purchase price accordingly.

Frequently Asked Questions

I live on the 5th floor—do I need to worry about radon? Very unlikely. Radon levels drop significantly above the first floor. You can test for peace of mind, but elevated levels in a fifth-floor unit would be extremely unusual.

My landlord says radon isn’t their problem. What can I do? Document everything in writing. Research your state’s tenant habitability laws. Contact your local or state health department for guidance. If your state has no specific radon law, a tenant rights attorney can advise whether the general habitability standard applies in your situation.

Can I install my own radon mitigation system in a rental? Generally, no—not without landlord permission, since it involves modifications to the building’s foundation. Talk to your landlord first; some will agree if you handle the cost.

Is radon disclosure required when selling a condo? In most states, sellers must disclose known radon issues. The specifics vary by state, and some states require testing or disclosure only in certain circumstances. Consult a real estate agent familiar with your state’s requirements.

What’s the average radon level in apartments vs. single-family homes? Studies show that ground-floor apartment units have similar radon levels to single-family homes in the same area. Upper-floor units consistently show lower levels. The building-wide average tends to be lower because upper-floor units reduce the mean.

For cost information, see our radon mitigation cost guide.

Find Local Radon Testing and Mitigation Help

Even in rental or condo situations, knowing your exposure level is the first step. Use RadonLocal to find certified radon professionals in your area who can test your unit and advise on next steps for your specific housing situation.