What Is Radon Testing Types Costs And Results? Key Facts

Radon is a radioactive gas that comes from the natural breakdown of uranium in soil, rock, and water. You cannot see, smell, or taste it. Testing your home is the only way to know if you and your family are breathing dangerous levels. The main types of radon tests are short-term tests, long-term tests, and continuous monitors. Costs range from about $15 for a do-it-yourself test kit to $150 or more for professional testing. Results are measured in picocuries per liter of air (pCi/L), and the U.S. Environmental Protection Agency (EPA) recommends taking action if your level is 4 pCi/L or higher.

What Is Radon and Why Is Testing Important?

Radon forms when uranium in the ground breaks down. It moves up through the soil and enters buildings through cracks in foundations, gaps around pipes, and other openings. Radon decays into tiny radioactive particles. When you breathe these particles in, they can damage the lining of your lungs.

The EPA estimates that radon causes about 21,000 lung cancer deaths per year in the United States. It is the second leading cause of lung cancer overall and the leading cause among non-smokers. Smokers who are also exposed to high radon levels have a much higher risk. Because radon has no warning signs—no smell, taste, or color—testing is the only reliable way to know your risk.

Homes in every state have been found with elevated radon levels. The amount depends on local geology, construction type, and how the home is sealed. Newer and older homes can both have problems. The EPA and the Surgeon General recommend that all homes be tested for radon.

What Are the Different Types of Radon Tests?

There are three main categories of radon tests: short-term, long-term, and continuous monitors. Each type serves a different purpose and has trade-offs between speed and accuracy.

Short-term tests measure radon for 2 to 7 days. They are the quickest way to get a snapshot of radon levels. The most common short-term devices are charcoal canisters, charcoal liquid scintillation detectors, and electret ion chambers. Short-term tests are often used for real estate transactions because results are available fast. However, radon levels can vary from day to day and season to season, so a short-term result may not reflect your average exposure.

Long-term tests measure radon for more than 90 days, usually 3 to 12 months. These give a more accurate picture of year-round radon exposure. Alpha track detectors and electret detectors are common long-term devices. The EPA recommends long-term testing for deciding whether to fix a radon problem because it better captures normal living conditions and seasonal changes.

Continuous radon monitors are electronic devices that measure radon hour by hour and display ongoing readings. They are often used by professional testers or homeowners who want real-time data. These monitors cost more but can show daily patterns, such as higher levels at night when windows are closed. Some models plug into a wall outlet for continuous use.

You can buy a test kit and do it yourself or hire a qualified professional. Certified radon testers typically use continuous monitors or laboratory-grade short-term tests. For do-it-yourself testing, the most common choice is a charcoal canister short-term kit purchased online or from a hardware store. Follow the instructions exactly—the test must stay in a closed room with windows and doors shut for the entire testing period.

How Much Does Radon Testing Cost?

Do-it-yourself radon test kits cost between $10 and $50. A basic short-term charcoal canister from a hardware store typically runs $15 to $25. Long-term alpha track kits cost $20 to $40 and include lab analysis. Continuous radon monitors for home use start around $100 and go up to $200 or more.

Professional radon testing costs $125 to $300 per test, depending on your location and the type of test. Professional testers often use continuous monitors and follow strict protocols to ensure accurate results. Some professionals bundle testing with mitigation services if high levels are found.

If you are buying or selling a home, a professional radon test is common as part of the home inspection. The cost is typically paid by the buyer or split between parties. Most real estate radon tests are short-term and last 48 to 96 hours.

Keep in mind that testing is much cheaper than the health costs of lung cancer or the cost of fixing a radon problem later. Radon mitigation systems typically cost $800 to $2,500 depending on the house design and fan location. Testing first can save you from paying for unnecessary mitigation if levels are safe.

How Do You Interpret Radon Test Results?

Radon levels are reported in picocuries per liter of air (pCi/L). The EPA has established an action level of 4 pCi/L. If your long-term or average short-term result is 4 pCi/L or higher, the EPA recommends installing a radon mitigation system to reduce the level.

Levels between 2 and 4 pCi/L are still associated with some lung cancer risk. The EPA suggests considering mitigation for levels in this range, especially if you already smoke or have children in the home. The National Radon Action Plan recommends that all homes aim for a level as low as reasonably achievable, ideally below 2 pCi/L.

Short-term test results need careful interpretation. Because radon levels fluctuate, a single short-term test may not represent your true average. Many experts recommend following up a short-term test with a long-term test before making a final decision about mitigation. The EPA says that if a short-term test shows 4 pCi/L or higher, you should do a second short-term test or a long-term test to confirm.

For real estate transactions, the rules may be tighter. Some states require that the radon test be conducted by a certified professional and that specific testing conditions are met. Check your state’s radon program for requirements.

What Should You Do If Your Radon Level Is High?

If your test shows 4 pCi/L or higher, the next step is to hire a certified radon mitigation contractor. Mitigation reduces radon levels by preventing the gas from entering the home or by venting it safely outside. The most common method is sub-slab depressurization. A pipe is inserted through the basement floor or crawlspace to the soil below, and a fan continuously pulls radon from the ground and vents it above the roof.

Other methods include sealing cracks in the foundation, increasing ventilation in the home, or installing a heat recovery ventilator (HRV). The effectiveness of each method depends on your home’s construction and the source of radon. A certified professional can determine the best approach.

After mitigation, a follow-up test should be done to confirm that levels have dropped, ideally to below 2 pCi/L. Most systems can reduce radon levels by more than 99%. Maintenance is minimal—the fan runs continuously and should be checked periodically. Fans typically last 5 to 10 years before needing replacement.

Do not try to fix a radon problem on your own if you lack experience. Improper sealing or ventilation can make the problem worse. The EPA maintains lists of state-certified or proficiency-listed radon mitigators. You can also check with your state radon office for recommendations.

How Often Should You Test for Radon?

The EPA recommends testing your home for radon every two years, or after any major renovation that changes the structure of your home, such as digging out a basement or finishing a lower level. Also test after you install a mitigation system to verify it is working.

Radon levels can change over time. Changes in the soil, new construction nearby, or alterations to your home’s foundation can affect radon entry. If you buy a new home, test it soon after moving in even if the previous owner provided test results. The conditions may have changed.

If you have a continuous radon monitor, you can see real-time changes and get alerts if levels rise. That can help you decide when to retest with a more formal long-term kit. Some homeowners choose to test every year for peace of mind, especially in regions known for higher radon potential.