Learn everything you need to know about radon testing; how to test, which method to choose, what it costs, when to test, and how to understand your results. Whether you're using a DIY radon test kit or a digital radon detector, this guide will help you choose the right testing method for your needs.
Radon is a radioactive gas that can cause lung cancer, and the only way to know your home’s risk is to test.
You can choose a short-term test (48 hours–90 days) for quick screening, a long-term test (90+ days) for the most accurate yearly average, or a digital continuous monitor for ongoing tracking. Testing is affordable, starting from around $15–$50 for basic kits and $100–$300 for digital monitors, while professional testing typically costs $150–$800.
Test during colder months if possible, place the device on the lowest lived-in level, and avoid moving it during testing. If results are high, confirm with additional testing and contact a certified mitigation professional. Fixing radon is usually straightforward and provides long-term peace of mind.
Radon testing is the only way to know if your home has dangerous levels of this radioactive gas. You can't see, smell, or taste radon, making testing essential for protecting your family's health.
The stakes are high: In the US, radon is the second leading cause of lung cancer after smoking, causing 21,000 deaths each year.
Radon levels can vary dramatically from one home to the next, even in the same neighborhood. While Airthings radonmap.com shows regional radon trends using data from thousands of detectors, the EPA recommends testing every home, school, and business individually to understand your specific risk - it’s thought that around 1 in 15 homes in the US have unsafe radon levels.
The good news? Testing and fixing radon problems is straightforward. When done correctly, mitigation provides a permanent solution and lasting peace of mind.
And if you’ve never tested before then you’re not alone; most homeowners haven’t. Testing is simple and affordable, and most fixes are straightforward.
The CDC recommends testing your home for radon in these situations:
It’s best to test your home during the colder months (late fall through to early spring) when homes are sealed tight with windows and doors closed, this is when radon levels typically peak.
For the most accurate picture of your home's year-round exposure, conduct a second test during warmer months as well.
Before choosing a radon test, it's important to understand the different methods available. Each type of testing has different advantages and disadvantages, depending on your goal, budget and timeline.
Below we take a quick look at each.
Short term radon tests provide a snapshot of your home’s radon levels. These types of test are ideal if you need a fast read-out, for example if you’re buying or selling a home. They are cheap and available at most hardware stores.
There are different types of short-term, DIY “passive” radon gas tests, for example:
Short-term tests like these are affordable and simple to use (typically $15-$50). However, remember that, as they are short-term, they likely won’t reflect your home's year-round radon exposure since levels fluctuate with weather, season, and ventilation patterns. Instead, they offer a snapshot of radon levels at one location. Even though these are short tests, the full process can take longer than expected once you include setup, testing time, mailing to a lab, and waiting for results.
Long-term radon tests run for a minimum of 90 days, with many homeowners testing for a full year to capture seasonal variations. These tests provide a more accurate picture of your home's average radon exposure, which is crucial when making decisions on whether you need to mitigate. These cost between $25-$75
The EPA and the CDC both recommend long-term testing for the most reliable results, as radon levels typically peak during winter months when homes are sealed tight against cold weather. A long-term test averages out these fluctuations, and should factor in heating and non-heating seasons, to give you a true baseline of your home’s radon level.
Continuous digital detectors, or monitors, can be battery-powered or plugged into a mains source. They provide results over time and keep a record of radon levels measured, often with a digital display to see real time and historical radon readings. Unlike the passive charcoal or alpha track detectors, they do not require any analysis by a lab. They can monitor and record radon readings over weeks, months, and even years, provided a great overall picture of your home’s average radon levels. Costs vary between $100 - $300.
What are the benefits of digital radon monitors?
Digital radon detectors like the Airthings View Plus, Corentium Home, and Corentium Home 2 combine radon testing with other air quality measurements, giving you a more complete picture of your indoor environment. These monitors have been included in several “Best Radon Detectors of 2025” lists.
Professional radon testing services employ certified technicians who use calibrated equipment and follow strict EPA protocols. Professional testing is often required for real estate transactions and provides legally defensible results.
Professional radon testing typically costs $150-$800 depending on your location and home size. While more expensive than DIY options, professional testing may be necessary when:
Choose a short-term test if:
Choose a long-term test if:
Choose a digital continuous monitor if:
In terms of location, select a room on the lowest lived-in level of your home where people spend time regularly (e.g. family room, office, or bedroom). If you live in an apartment or condo, place the detector in the bedroom.
Place the radon testing device on a flat surface such as a desk, table, bookcase, or shelf. For a continuous digital radon monitor, be sure to place in a room with below 85% relative humidity as otherwise it can damage the radon sensor.
Then leave undisturbed during the testing period - do not move it to another location until testing is complete.
According to the EPA, there is no safe level of radon exposure, so it recommends that every home or dwelling be tested for radon.
How radon is measured, and the levels at which action is recommended, do vary around the world.
In the USA, radon is measured in pCi/L, or picocurie per liter.
EPA guidelines for when to mitigate radon:
In regions that have adopted the metric system, radon is measured in Bq/m3 (Becquerels per cubic meter). For reference, 1 pCi/L, or picocurie per liter, is equal to 37 Bq/m3
The World Health Organization (WHO) guidelines for when to mitigate radon:
The EPA has compiled a comprehensive guide on how to fix your home at:
“A consumer’s guide to radon reduction: How to fix your home”
Don’t panic. The American Lung Association recommends testing at least twice to verify the reading. If it still looks high, there are a number of DIY-methods that can help to lower the levels. Read their blog: So your home has high radon levels, now what?
Some steps you can take are to seal cracks in building foundations to help stop radon gas seeping in from the ground. You can also increase ventilation. For more tips on DIY mitigation, you can also read our blog: DIY Radon Mitigation: A Step-by-Step Guide to a Radon-Free Home
However, if the numbers still look high after DIY steps have been taken, then the EPA recommends contacting a professional radon measurement or mitigation expert, as you may need a radon mitigation to be installed. Most mitigation systems are super quick to install, and bring levels down quickly and permanently.
For this example, we’ll look at likely mitigation costs in the USA.
If your radon test reveals levels above 4 pCi/L, you'll need to factor in mitigation costs, which typically range from $800-$2,500 for a professionally installed system. However, catching high radon levels early through testing can prevent lung cancer and save lives, making any testing investment worthwhile.
The EPA estimates that radon causes 21,000 lung cancer deaths annually in the United States. With that in mind, spending $100-$300 on reliable radon testing provides invaluable peace of mind and protection for your family's health.
If your radon levels are such that mitigation is required, be sure to use an industry-approved professional. Below are some information sources for the USA and Canada.
USA
Canada
For most homeowners, a digital radon monitor offers the best value proposition: comprehensive continuous monitoring at a lower long-term cost than repeatedly purchasing disposable test kits. If you're simply conducting an initial screening or need results for a real estate transaction, a passive test kit may be sufficient. For certified results required in legal or commercial contexts, professional testing remains the gold standard.
Airthings is a global leader in radon and indoor air quality monitoring, providing reliable, science and research-led technology used in homes, workplaces, and public buildings worldwide. Whatever testing method you choose, consistent measurement and awareness are the keys to long-term peace of mind.
We believe that every home should measure radon.
How can I test my home for radon?
Use a short-term kit (48 hours–90 days), a long-term test (90+ days), or a digital continuous monitor. Follow the instructions, place it in a lived-in lower level, and leave it undisturbed.
When is the best time to test?
Colder months are ideal because homes are sealed and radon levels are typically highest. For the best accuracy, do a second test in warmer months.
Where should I place the radon test?
Place it in the lowest lived-in level (like a family room, office, or bedroom), on a flat surface, away from drafts, windows, and high humidity.
What do my radon results mean?
In the U.S., fix your home if levels are 4 pCi/L or higher and consider fixing between 2–4 pCi/L. There is no completely “safe” level, so lower is always better.
What should I do if my radon levels are high?
Confirm with a follow-up test (ideally long-term or professional), then contact a certified radon mitigation professional. Mitigation is usually straightforward and effective.