How to Check Your Home for Radon Gas

Test your home for radon using a DIY test kit or professional service, focusing on the lowest lived-in level of your home where radon naturally accumulates.

1. Pick Your Testing Strategy. Pick between a short-term test kit (2-90 days) for quick results or a long-term test kit (90+ days) for more accurate annual average readings. Short-term tests work well for initial screening, while long-term tests give you a better picture of year-round radon levels. You can buy test kits at hardware stores for $15-25 or hire a professional for $150-300.
2. Find the Perfect Test Spot. Place your test in the lowest level of your home where people spend at least 4 hours daily. This is usually a basement, ground floor, or crawl space area. Avoid kitchens, bathrooms, laundry rooms, and areas near exterior doors or windows. The test needs to sit on a table or shelf 20 inches to 8 feet off the floor, away from drafts, heat sources, and high humidity areas.
3. Seal Your Home Properly. Keep all windows and exterior doors closed 12 hours before and during the entire test period, except for normal entry and exit. Turn off window fans and close fireplace dampers. Don't use whole-house ventilation systems unless they run continuously. These closed-house conditions help capture your home's normal radon levels without outside air diluting the results.
4. Start the Clock Now. Follow the kit instructions exactly for placement and timing. Most charcoal canisters sit exposed for 2-7 days, while alpha track detectors stay out for 90+ days. Don't move the detector once placed, and keep it away from children and pets. Mark your calendar for the pickup date since timing affects accuracy.
5. Decode Your Results. Mail the test device to the lab using the prepaid envelope within the timeframe specified. Results typically return in 1-2 weeks showing radon levels in picocuries per liter (pCi/L). Levels of 4 pCi/L or higher require action. Levels between 2-4 pCi/L suggest considering mitigation. Below 2 pCi/L is generally acceptable, though no radon level is completely safe.
6. Mitigate if Necessary. If your short-term test shows 4 pCi/L or higher, conduct a second test to confirm results before investing in mitigation. If levels remain high, contact a certified radon mitigation contractor to install a reduction system. These systems typically cost $800-2000 and can reduce radon levels by 80-99%. Retest every 2-5 years or after major home renovations.