How Radon Moves Upstairs: What Every Homeowner Needs to Know

Understanding Radon and Its Movement in Homes

Radon is a radioactive gas that forms naturally from the breakdown of uranium in soil, rock, and water. It is colorless, odorless, and tasteless, making it impossible to detect without specialized testing. While many homeowners believe radon is only a concern for basements, scientific research and real-world case studies have demonstrated that radon can and does travel upstairs , affecting both main floors and upper stories of houses and apartment buildings [1] .

How Does Radon Enter and Move Through a Home?

Radon gas typically enters a building through cracks in the foundation, gaps around pipes, sump pits, or other openings in the structure. Once inside, it can migrate to different levels of the home through several mechanisms:

• Natural Air Movement: Air pressure differences inside and outside your home can pull radon upward through stairwells, ductwork, or wall cavities.
• Mechanical Systems: Forced-air heating and cooling systems, as well as exhaust fans, can distribute radon to upper floors.
• Stack Effect: Warm air rising inside a building creates upward airflow, drawing radon from lower levels to the upper stories or attic spaces.
• Elevator and Utility Shafts: In multi-story buildings, radon can travel through elevator shafts, pipe chases, and other vertical pathways, sometimes leading to elevated levels in upper-floor apartments [4] .

It is a misconception that radon stays confined to basements or crawl spaces. Studies have documented cases where the highest measured radon levels were found in main-floor bedrooms or second-story nurseries [1] .

Are Upper Floors Safe from Radon?

Many people assume radon is only a threat in basements. However, radon concentrations can be significant on upper levels. In some houses, radon levels on the second floor or even higher may match or exceed those in the basement , especially during the heating season when attics are well-insulated and basements are more drafty [3] . Pressure differences and changes in building ventilation can cause radon to accumulate in upper-level rooms, including bedrooms and nurseries.

For residents in apartments or multi-family buildings, radon risk is present on any floor, not just the ground level. Environmental consultants have reported radon exposure cases occurring on higher floors due to the movement of the gas through air shafts, stairwells, or elevator shafts [4] .

Testing for Radon on All Levels: Why and How

The only way to know if radon is present-and at what concentration-is to test. The EPA and most state health departments recommend testing the lowest livable area of your home, but experts urge homeowners and tenants to consider testing multiple levels , especially if people spend significant time upstairs [3] . Here’s how you can proceed:

Source: shunshelter.com

1. Obtain a Radon Test Kit: These are widely available at hardware stores or online. Make sure the kit is approved by your state’s radon program or the EPA.
2. Test Each Occupied Level: Place at least one kit in the basement or lowest living space, and another on the main floor or upper level, especially where bedrooms are located. Follow the instructions carefully for accurate results.
3. Send Kits to a Certified Lab: After the recommended testing period (usually 2-7 days), mail the kits to the provided address and wait for your results.
4. Interpret Results: The EPA action level for radon is 4 picocuries per liter (pCi/L). If your test shows levels at or above this threshold on any floor, mitigation is strongly recommended.

For tenants in apartments, contact your landlord or property manager to inquire about prior radon testing. If they have not conducted tests, request that they do so, or consider arranging your own test. In case of high readings, mitigation may require building-wide solutions [4] .

Mitigating Radon: Steps and Solutions

If your test reveals high radon levels in any part of your home-whether basement, main floor, or upstairs-take action promptly. The most common and effective solution is the installation of an active radon mitigation system . Here’s how the process typically works:

1. Hire a Certified Radon Mitigation Contractor: Look for professionals certified by the National Radon Proficiency Program (NRPP) or National Radon Safety Board (NRSB). Many state health departments can provide lists of certified providers.
2. System Design and Installation: The contractor will assess your home and design a mitigation system, most often a sub-slab depressurization system. This involves installing a vent pipe and fan to draw radon from beneath your home and vent it safely outside.
3. Retest After Installation: It is essential to confirm the system’s effectiveness by re-testing radon levels throughout the home, including upper floors.
4. Regular Maintenance: Periodic checks-typically every 2-3 years-ensure the mitigation system remains effective [5] .

Costs for radon mitigation can vary based on home size, construction type, and system complexity. Homeowners and tenants should consider the long-term health benefits, as radon is the second leading cause of lung cancer after smoking [5] .

Source: njradonmitigation.com

Practical Steps and Alternative Approaches

If immediate professional mitigation is not feasible, you can take interim steps to reduce radon exposure:

• Increase ventilation throughout your home by opening windows and using fans, especially in basements and upper levels.
• Seal obvious cracks and openings in floors and walls where radon could enter.
• Ensure exhaust fans in kitchens and bathrooms are functional and vented to the outside.

These are temporary measures, as only a certified mitigation system can consistently reduce radon to safe levels. Always follow up with professional testing and mitigation for long-term safety.

How to Access Radon Testing and Mitigation Services

To find reputable radon testing and mitigation providers:

• Contact your state or local health department for certified radon professionals.
• Search for “certified radon mitigation contractor” along with your city or state on reputable review platforms or professional directories.
• Request references and proof of certification before hiring any contractor.

For apartment dwellers, discuss testing and mitigation with your landlord or property manager. Some states require landlords to test for and mitigate high radon levels, so consult your local housing authority for regulations.

Key Takeaways

Radon is a hidden danger that can affect any home or apartment, on any floor. The only way to know your risk is to test -not just in basements, but on all occupied levels. If high levels are detected, certified mitigation professionals can install systems to protect you and your family. Take proactive steps today to safeguard your home, and encourage your neighbors and community to do the same.

References

• [1] Jerry’s Waterproofing (2025). How Radon Moves Through Your Home.
• [2] VERTEX (2018). High Rising Radon – Why the upper floors aren’t necessarily safe.
• [3] Syracuse Radon Mitigation (2018). The Importance of Testing for Radon on Upper Levels.
• [4] Environmental Doctor (2025). Radon in Apartments Is Serious Risk to Tenant Health.
• [5] Prevent Cancer Foundation (2024). My house had high levels of radon – here’s how I fixed it.