How to Test Radon Levels in Your Home
Safety Warning
Radon is a radioactive gas that accumulates in basements and lower levels of homes. Exposure to elevated radon levels over time increases lung cancer risk, particularly for smokers. This test kit itself is safe to use and poses no hazard during testing. However, if your test results show radon levels of 4 pCi/L (picocuries per liter) or higher, the EPA recommends taking action. If levels are significantly elevated (above 10 pCi/L), consider hiring a certified radon mitigation professional to install a ventilation system rather than attempting DIY remediation. Do not delay addressing high radon levels.
Radon is a colorless, odorless radioactive gas that seeps into homes from soil and rock, making it the second leading cause of lung cancer after smoking. Testing your home's radon levels is essential for protecting your family's health and is a task any homeowner can complete with an affordable test kit. Annual testing is recommended, and if elevated levels are detected, you can take steps to reduce radon or hire a professional mitigation company.
What You'll Need
Supplies
- •Radon Test Kit (Short-term 2-3 day)($15-30)
- •Radon Test Kit (Long-term year)(optional)($25-50)
- •Protective mailing bag or envelope(included with kit)
Tools
- •Pen or marker for recording dates and times
- •Measuring tape or ruler (to verify 20-inch placement)(optional)
Step-by-Step Instructions
Choose the Right Test Location
Select your basement or the lowest lived-in level of your home for testing. Radon accumulates in lower areas due to soil-gas pressure differences. Avoid placing the test kit in kitchens, bathrooms, or laundry rooms where humidity and air movement are high, as these can affect results. Choose a spot at least 20 inches away from windows, doors, and exterior walls to get an accurate reading of indoor radon levels.
Pro Tip: If you have a finished basement where you spend significant time, test there rather than an unfinished basement, as this reflects your actual radon exposure.
Prepare the Test Area
Close all windows and doors in your home, including basement windows, at least 12 hours before beginning the test and keep them closed throughout the testing period. Turn off exhaust fans, air conditioners, and other ventilation systems that pull air from outside. This stabilizes indoor air pressure and radon concentrations, ensuring accurate test results. Maintain normal heating and cooling during the test.
Pro Tip: If you forget to close windows before starting the test, simply restart your 2-7 day testing period with all windows and doors sealed.
Open and Activate Your Test Kit
Remove the radon test kit from its packaging and carefully open it according to the manufacturer's instructions. Most kits contain a sealed charcoal canister or alpha track detector. Do not touch the interior surfaces of the kit or breathe directly over it. Place the kit in your chosen location at least 20 inches away from walls, at a height between 20 and 60 inches (approximately counter-height to shoulder-height).
Pro Tip: Read the kit instructions thoroughly before opening it—different manufacturers have slightly different activation procedures.
Record Your Start Date and Time
Write the exact date and time you activated the test kit on the provided log sheet or in a notebook. This is critical because the testing period duration affects the accuracy of results. Most kits require either a 2-3 day short-term test or a full year for long-term testing. Note the location where you placed the kit in case you need to reference it later.
Pro Tip: Take a photo of the kit in its location with your phone to document where it was placed during testing.
Leave the Kit Undisturbed During Testing
Do not move, shake, or disturb the radon test kit during the entire testing period. Avoid placing items on top of the kit or blocking airflow around it. Keep the kit away from pets and children who might tamper with it. The kit needs to remain in a stable environment to accurately measure radon gas accumulation.
Pro Tip: Set a phone reminder for the last day of your testing period so you remember to retrieve and seal the kit promptly.
Seal and Prepare the Kit for Return
When your testing period is complete, seal the test kit according to the manufacturer's instructions—this usually involves closing a lid or envelope to prevent further radon exposure during transport. Write the end date and time on the kit. Place the sealed kit in a protective bag or the return envelope provided by the testing company. Do not open or reseal the kit after it has been sealed for return.
Pro Tip: Mail your kit within 24-48 hours of sealing it to ensure the testing lab receives it promptly and can provide accurate results.
Send Your Kit to the Testing Lab
Follow the manufacturer's instructions for returning your test kit, which typically involves mailing it to their accredited laboratory in a prepaid envelope. Record the tracking number or serial code for your reference. Most labs process results within 5-10 business days and will provide them via email or postal mail. Keep the results for your records.
Pro Tip: Many radon test kit companies allow you to check results online using a serial number or tracking code—look for login information in your kit's instructions.
Review Results and Take Action
When your results arrive, check the radon level in pCi/L (picocuries per liter). EPA recommendations: if below 2 pCi/L, radon is at acceptable levels but consider retesting; 2-4 pCi/L is the EPA action level where many experts suggest mitigation; above 4 pCi/L, the EPA strongly recommends radon reduction measures. If results are elevated, consider hiring a certified radon mitigation contractor to install a sub-slab depressurization system or other ventilation improvements. Plan to retest annually or after making any radon reduction improvements.
Pro Tip: If you received a short-term test result above 4 pCi/L, consider doing a long-term or follow-up test before spending money on mitigation, as radon levels can vary seasonally.
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