Radon Testing Done Right: Tips and Techniques for Accurate Results
Radon gas is a naturally occurring radioactive gas that can seep into your home undetected and cause lung cancer if exposed to high levels over time. Because it’s colorless and odorless, you won’t know if it’s there without testing for it. Thankfully, testing for radon is simple—and goes a long way toward protecting your family's long-term health.
If you're worried about radon in your home, testing is the first step toward a safer environment. This guide to radon testing will help you understand how radon test kits work, how to get reliable results (including what not to do during a radon test), and answer your questions about how long radon testing takes, where radon tests should be placed, and more. This is radon testing done right!
Radon Testing Procedures: Test Kits & How They Work
The first thing to know is that nowhere is completely free of radon gas—including your home. But don’t let that frighten you! In the US, the average radon level found in homes is around 1.3 pCi/L. That’s well below actionable levels (4.0 pCi/L). Some regions may have more or less radon depending on the amount of uranium decay in the soil. Testing is the only way to determine how much radon you’re dealing with.
With that in mind, let’s dive into the types of radon testing kits or test devices you may want to use to determine the exact radon levels in your home.
Types of Radon Tests
There are two types of testing devices used for home radon detection: passive devices and active devices. Here’s a closer look at each:
Passive Testing Devices
Passive devices are testing kits that don’t require a power source to detect radon. They rely on natural processes to capture radon gas over time. Common passive test devices include:
Charcoal Canister Detectors: Use activated charcoal to absorb radon. After exposure, the kit is sealed and sent to a lab for analysis.
Charcoal Liquid Scintillation Detectors: Activated charcoal absorbs radon gas and is then mixed into a liquid solution to measure radon decay.
Alpha Track Detectors: Contains a plastic film that captures and records alpha particles emitted by radon decay over a longer period of time.
Electret Ion Chamber Detectors: Uses an electrically charged Teflon disc that measures reductions in charge when hit by radon decay.
Home radon test kits like these are a simple and affordable way to get your home tested, whether you have an upcoming inspection for a real estate transaction or simply want to know your home is safe. All of these testing kits can be set up in your home but must be sent to a lab for analysis once the testing period is complete.
Active Testing Devices
Active testing devices, like many of the products we recommend, require power to function. These are typically digital continuous monitors that record and display radon levels in real-time to give you immediate feedback on radon fluctuations in your home.
If you want a surefire way to get accurate radon testing results, contact The Radon Guys for help choosing a continuous monitor that lets you know your radon levels at any time.
How Long Does Radon Testing Take?
Generally, at-home radon testing kits can be broken down into two categories: short-term and long-term. Because radon levels vary from day to day as well as seasonally, the longer your testing period, the clearer the picture will be of your home’s average radon levels.
Short-Term Testing
Short-term tests, such as charcoal canisters and charcoal liquid scintillation, are the quickest way to test for radon. However, they only provide a snapshot of your home's radon levels. Short-term tests require a minimum of two days but can be set up for as long as 90 days.
Be sure to follow the instructions carefully for whichever test you use so you don’t invalidate your results. Many charcoal canister tests, like the ones you might receive from your state radon office, should not be left out for more than seven days.
If short-term testing reveals elevated radon levels in your home, it’s best to follow up with a long-term test for more accurate results and consider radon mitigation efforts.
Long-Term Testing
Long-term testing, such as alpha track detectors and electret ion detectors, are set up in your home for 90 days or longer, sometimes as long as one year. These kinds of tests provide a more accurate idea of radon levels because you’re able to average out fluctuations due to changes in weather and ventilation over a longer period of time.
How Do Radon Test Kits Work? A Step-by-Step Guide
If you’ve decided to test your home for radon yourself, here are some key guidelines to follow for accurate results:
Where Should a Radon Test Be Placed?
The EPA recommends installing a radon test device in a central room on the lowest level of your home that is suitable for occupancy—like a finished basement, family room, or bedroom.
Avoid placing test kits near windows, doors, kitchens, bathrooms, or areas with drafts and high humidity. Choose a spot near breathing height (around 2-6 feet high) where the kit will remain undisturbed for the entire testing period.
Step-by-Step Guide to Setting Up Your Radon Test Kit
Preparation: Close all windows and exterior doors at least 12 hours before you begin. This helps isolate the indoor air and prevent radon from escaping.
Placement: Depending on your test type, either set your radon test kit on a flat surface or hang it in the air at least two feet above the floor but not above breathing height.
Activation: Follow the instructions on your radon test kit precisely. Record the start date and time as soon as you activate the kit.
Monitoring: Leave the kit undisturbed for the specified duration, at least 48 hours for short-term tests.
Completion: After the testing period, seal the kit, record the date and time of the test’s completion, and send it to the lab for analysis.
Getting Accurate Results: What Not to Do During a Radon Test
Getting accurate results when testing for radon is crucial to your safety. Before testing, you should consider weather and seasonal activity (winter is the best time to test!)—because radon levels fluctuate, and when you test matters.
For the best results, avoid the following things:
Do NOT test during extreme weather conditions. Snowstorms, heavy rain, and even high winds can affect indoor radon levels by altering air pressure.
Do NOT set up your test kit in kitchens, bathrooms, or hallways where air flow or humidity might skew results.
Do NOT place the test device in direct sunlight.
Do NOT place the test device in drafty areas, such as near furnaces, vents, or fireplaces.
Do NOT operate systems that bring outside air into your home during testing, such as air conditioning and exhaust fans. Systems that recycle air inside the home, such as central air, can be operated as usual.
Do NOT move the test kit during the testing period.
How to Read a Radon Manometer
Maybe you already have a radon mitigation system installed and are testing to see if it’s working properly. One quick and easy way to determine if your radon fan is working to move radon out of your home is to check the U-tube manometer on the system. (Note: The manometer does not measure radon. It measures vacuum pressure to indicate whether your mitigation system is functioning properly.)
This U-shaped tube is installed on the pipe near the suction point and contains a colorful liquid that shows airflow:
Uneven liquid levels (higher on one side of the U than the other) indicate that the fan works.
Even liquid levels suggest the fan might not be running or there’s a blockage in the system.
If you suspect a problem with your mitigation system, don’t let radon build up in your home. Call The Radon Guys right away for help getting radon levels back in check.
How to Interpret Radon Test Results
So, you’ve tested your home for radon and got the results. Now what? Whether you need to take action or not depends on a certain threshold of radon exposure.
When you read your radon test results, you’ll typically see radon measured in picocuries per liter of air (pCi/L). Picocuries are simply the standard unit used to measure radon levels in the US.
The EPA recommends you take action to mitigate exposure if your radon levels are higher than 4 pCi/L. Here’s how to interpret radon test results so you can determine your next steps:
Higher than 4 pCi/L: If you used a short-term test, verify your results with another short-term or long-term test and average the pCi/L levels between the two. If the average still reads 4 pCi/L or above, contact your local NRPP-certified professionals at The Radon Guys to install a radon mitigation system right away.
Between 2-4 pCi/L: No amount of radon is safe. Consider installing a radon reduction system to lower exposure, then retest a few months later to see if radon levels have improved.
Lower than 2 pCi/L: No immediate action needed. Consider testing your home again every few years or if you start living on a lower level, like in a finished basement.
Ready to Test Your Home? We’re Ready to Help.
Ensuring accurate radon testing is crucial for your home’s safety. If you're ready to test your home or if previous tests have shown high radon levels, reach out to The Radon Guys. We offer professional radon testing services and mitigation solutions to ensure you and your family have clean indoor air to breathe. Don't gamble with your health—contact us for expert advice and reliable radon management options.
