What is radon testing, and is it necessary for my health and safety?

Jan. 10, 2024
Many homes in Colorado have high levels of indoor radon because of an abundance of uranium in rock and soil. For this reason, the Colorado Department of Public Health and Environment recommends all Colorado residents test their homes for radon. Photo: Getty Images.
Many homes in Colorado have high levels of indoor radon because of an abundance of uranium in rock and soil. For this reason, the Colorado Department of Public Health and Environment recommends all Colorado residents test their homes for radon. Photo: Getty Images.

For residents of the Rocky Mountain West, it’s a good idea to check your home for radon, a radioactive gas known to cause lung cancer.

Coloradans can get a discounted radon test kit from the state.

Radon comes from the natural breakdown of uranium in rock and soil, an abundant metal in the West. As it decays, it produces a gas that rises from soil. Radon can become trapped inside your home and years of exposure to high radon levels can cause cancer, according to the Colorado Department of Public Health and Environment.

Is radon testing really necessary?

“It’s worth testing for radon because it’s easy to test for and easy to mitigate… and cancer is such a devastating disease that’s best avoided,” said Dr. Douglas Kemme, an oncologist with UCHealth in northern Colorado.

Testing is recommended during a time of the year when all of the windows and doors are closed – such as the winter months like December, January and February.

What is radon?

Radon is odorless, tasteless and invisible, and symptoms do not arise when a person has been exposed to radon. In the air, radon is unstable and breaks down into other products. We inhale and exhale radon gas, but radon decay particles stay in the lungs. Over time, these particles can cause damage to cells, which can mutate and cause lung cancer.

If radon is in your home at high concentration levels — brought in through the natural vacuum between the soil and the foundation of your home — it becomes a Class A carcinogen, a risk for lung cancer similar to cigarette smoking.

Does radon cause cancer?

Radon is the number one cause of lung cancer among non-smokers, according to EPA estimates.

“We know it causes cancer because of the studies on miners,” Kemme explained. “They were able to see the difference in lung cancer risks between those miners working in uranium mines and those who did not, and that’s what clued them into radon exposure as a risk for lung cancer.”

The study by the National Institute for Occupational Safety and Health (NIOSH) looked at 3,238 White uranium miners and 757 mainly Navajo miners located in Colorado, Arizona, New Mexico and Utah who’d completed a medical exam between 1950 and 1960. The miners were exposed to high levels of radon gas. For White miners, the study expected to find about 64 deaths based on the states’ death rates for men. However, it found 371 — six times more than expected. And non-white uranium miners had a lung cancer death rate three times that of the states’ death rates.

The study provided important information about how much radon exposure causes lung cancer.

What are acceptable levels of radon?

Most of Colorado is a high radon area where indoor screening levels greater than 4 picocuries per liter (pCi/L) are common, according to the United States Environmental Protection Agency. The national indoor average is about 1.3 pCi/L, with an outdoor level of about 0.4 pCi/L.

The EPA recommends radon mitigation when levels exceed 4 pCi/L, and it is said that 50% of homes in Colorado have higher radon levels (see CDPHE radon map). The CDPHE recommends all homes — new and old — be tested every few years for radon.

Average indoor radon levels of some Colorado counties according to Air Chek.

  • Adams County: 3.6 pCi/L
  • Arapahoe County: 4.6 pCi/L
  • Boulder County: 4.4 pCi/L
  • Denver County: 3.4 pCi/L
  • Douglas County: 3.9 pCi/L El
  • El Paso County: 5.4 pCi/L
  • Grand County: 5.4 pCi/L
  • Jefferson County: 5.1 pCi/L
  • Larimer County: 6.2 pCi/L
  • Pueblo County: 8.7 pCi/L
  • Teller County: 12.0 pCi/L
  • Weld County: 4.1 pCi/L

*County levels updated Aug. 22, 2023 from radon.com

How to test for radon

People can purchase discounted radon test kits through the state’s website or at most home improvement stores. Radon testing kits cost $10 to $50.

What is radon testing?

There are two types of radon tests: long-term radon detectors that test over a three- to 12-month period and short-term radon testing kits that are completed in a matter of days.

The state recommends people start with a short-term test to see what potential radon risk may exist in a home. If that test shows 4 pCi/L or higher, the state recommends following up with another test, either a short or long-term test, before any radon mitigation is done.

The test kit is easy to use. After reading instructions, the small tester is placed in the lowest living area of the home, or for a single-level home, the room where residents spend the most time. However, don’t put the tester in the kitchen or bathroom, and never set it up in a crawl space. When the test is completed, follow instructions on how to mail it back to the lab. Within a few weeks, you will get your results.

No matter the results, radon testing should be done every few years.

The Map of Radon Zones shows where high radon levels are found throughout the United States, but it should not be used to determine if individual homes need to be tested. No matter where you live, test your home for radon — it’s easy and inexpensive. Fix your home if your radon level is 4 picocuries per liter (pCi/L) or higher (Zone 1). Consider fixing if your level is between 2 and 4 pCi/L (Zone 2). Source: EPA.gov.

What do I do if my results show unsafe radon levels?

Don’t panic. If your first test shows high results, then do another short-term or long-term test to verify the findings. The additional time it will take to do a long-term test will not result in a measurable increased risk of radon exposure. Long-term test results give a more representative picture of radon levels because they factor in the influences of changing temperatures and barometric pressure, according to the state.

The long-term test is recommended if the short-term test results are close to the 4 pCi/L mitigation threshold. However, a short-term test can be used to confirm an earlier test with very high radon levels, according to the state.

If those second results are similar to the first (4 pCi/L or higher), then mitigation should be considered. The state also recommends that people with high radon levels who also get their water from a private well should test the water for radon. Radon water testing kits are available online and at most home improvement stores.

How do I get rid of radon?

Because radon gas comes from the soil and leaks through cracks in a home’s foundation, several methods exist for capturing the gas and funneling it outdoors.

Radon mitigation systems work by overpowering the natural vacuum under the home and providing an alternative route for radon. Sealing cracks in the foundation or around piping will not reduce radon levels and mitigate the problem.

Radon systems cost $500 to $2,500, depending on the type and design of the home, according to CDPHE. Some federal programs might be able to help fund radon reduction in homes for limited-income families. The CDPHE also has a low-income radon mitigation assistance program for homeowners.

Can I mitigate radon myself?

Using a state-certified radon mitigation system installer who has the proper training to mitigate radon is recommended by the EPA. However, if you have home-improvement skills, you can mitigate yourself. Talk with your state radon office first for appropriate training and DIY manuals.

Check out this infographic for more information on radon testing and your health and safety.

The type of foundation in your home determines what radon mitigation is necessary. Do you have a basement or a crawl space? Or maybe your home is “slab-on-grade,” meaning its foundation sits directly on the ground.

Radon mitigation systems for homes with basements or slab-on-grade foundations redirect the radon gas from below the foundation to the outside via a vent pipe and a radon fan.

The earth floor in crawl spaces should be covered with a high-density plastic sheet, then use a vent pipe and fan to draw the radon from under the sheet and vent it outside.

What if I have high levels of radon in my well water, too?

Radon in your water poses an inhalation risk and a small ingestion risk. Radon in water released into the air, like with showering, poses a greater cancer risk than from drinking the water, according to the EPA.

If necessary, water can be treated for radon before entering the home or at the tap. You can get more detailed information through the EPA.

Is radon testing necessary?

In Colorado, more than 500 lung cancer deaths are attributed to radon each year, according to CDPHE.

“It’s such an easy thing to take care of, so why not?” Kemme said.

About the author

Kati Blocker has always been driven to learn and explore the world around her. And every day, as a writer for UCHealth, Kati meets inspiring people, learns about life-saving technology, and gets to know the amazing people who are saving lives each day. Even better, she gets to share their stories with the world.

As a journalism major at the University of Wyoming, Kati wrote for her college newspaper. She also studied abroad in Swansea, Wales, while simultaneously writing for a Colorado metaphysical newspaper.

After college, Kati was a reporter for the Montrose Daily Press and the Telluride Watch, covering education and health care in rural Colorado, as well as city news and business.

When she's not writing, Kati is creating her own stories with her husband Joel and their two young children.