How to Test Your Home for Radon Gas

Why it matters

Radon is a colorless, odorless, and tasteless radioactive gas that occurs naturally from the decay of uranium in soil and rocks. It enters homes through cracks in foundations, construction joints, and gaps around pipes. While invisible, it is the leading cause of lung cancer among non-smokers.

Testing matters because your home's radon level is unique; even if your neighbor's house tests low, your specific soil composition and foundation integrity could result in dangerous concentrations. Testing is the only way to determine if your family is at risk. Reducing high radon levels can lower your lung cancer risk significantly, and most modern mitigation systems are highly effective at lowering levels to below the EPA’s action threshold.

How often

The EPA recommends testing your home every two years. Even if you have a radon mitigation system installed, you should maintain this schedule to ensure the system is functioning correctly. Additionally, you should re-test after:

• Any significant renovation or structural change to the home.
• Finishing a basement or creating a new living space at the lowest level.
• Installing a new HVAC system.
• Major seismic activity or soil shifting in the area.

What you need

Testing for radon is a straightforward DIY task, though professional options are available. To do it yourself, you will need:

• A Radon Test Kit: Choose between a short-term kit (2–7 days) or a long-term kit (90 days to 1 year).
• Painter’s Tape: Useful for securing the test device if needed.
• A Watch/Timer: To record exact start and stop times.
• A Pen: To fill out the lab submission form.

Step-by-step: Using a Short-Term Test Kit

Short-term tests are the most common way to get a quick snapshot of your home’s air quality.

1. Select the timing: Choose a period when you can keep "closed-house conditions." Avoid testing during severe storms or high winds, as pressure changes can fluctuate radon levels.
2. Determine the location: Test the lowest lived-in level of your home (the basement if it is used, or the first floor if there is no basement). Choose a room used regularly, but not a kitchen, bathroom, or laundry room, as humidity and exhaust fans can interfere with results.
3. Position the device: Place the kit at least 20 inches above the floor and 12 inches away from exterior walls. Keep it away from drafts, direct sunlight, and heat sources.
4. Close the house: Keep all windows and exterior doors closed for 12 hours before starting the test and throughout the duration of the test. You may enter and exit the house normally, but do not leave doors open.
5. Start the test: Open the kit (charcoal canister or liquid scintillation vial) according to the package instructions. Record the exact date and time on the provided paperwork.
6. Wait: Leave the kit undisturbed for the duration specified on the packaging (usually 48 to 96 hours).
7. Seal and send: Once the time is up, seal the kit immediately. Complete the lab form, including the stop time and date. Mail it to the laboratory the same day; delays in shipping can invalidate the results.
8. Review results: Most labs provide results via email within a week. If the level is 4.0 pCi/L (picocuries per liter) or higher, the EPA recommends taking action.

When to call a pro

While DIY kits are accurate for screening, you should hire a certified radon professional in the following scenarios:

• Home Transactions: Most real estate contracts require a professional test performed by a certified third party to ensure neutral results.
• High Results: If your DIY test returns a level above 4.0 pCi/L, a professional can perform a follow-up "diagnostic" test to identify where the gas is entering the home.
• Mitigation Installation: Never attempt to install a radon mitigation system (active soil depressurization) yourself. This requires professional design to ensure gas is properly vented above the roofline.

Safety

Radon itself presents a long-term chronic health risk rather than an immediate acute danger. However, keep test kits out of reach of children and pets, as some kits contain charcoal or small parts. When handling a mitigation system, never block or power off the vent fan, as this can cause radon levels to spike rapidly inside the home.

Cost

Basic testing is one of the most affordable home safety tasks you can perform:

• Short-term DIY kits: $15–$30 (usually includes lab analysis fees, but check the box).
• Long-term DIY kits: $30–$50 (provides a more accurate annual average).
• Professional Testing: $150–$300 depending on the size of the home and local market rates.
• Mitigation Systems: If high levels are found, a professional mitigation system typically costs between $800 and $2,000.