Facts About Radon and Radon Testing

How to Perform Radon Tests when Buying a Home

Radon is a colorless, odorless, tasteless radioactive gas that's formed during the natural breakdown of uranium in soil, rock, and water. Radon exits the ground and can seep into your home through cracks and holes in the foundation. Radon gas can also contaminate well water.

Health officials have determined that radon gas is a carcinogen that can cause lung cancer. Studies show that radon is more of a risk to smokers, but nonsmokers have a slightly elevated chance of developing lung cancer, too. The only way to find out if your house contains radon gas is to perform radon tests.

EPA Radon Studies
The EPA offers a look at what they believe to be the risks of radon at different concentrations for 1,000 people who smoked and were consistently exposed to a certain level of radon during their lifetimes.

Radon Risks for Smokers
With exposure to 10 pCi/L, about 71 would get cancer, equal to 100 times the risk of dying in a home fire.

With exposure to 4 pCi/L, about 29 would get cancer, equal to 100 times the risk of dying in a plane crash.

Radon Risks for Non-Smokers
With exposure to 8 pCi/L, about 3 would get cancer, equal to 10 times the risk of dying in a plane crash.

With exposure to 4 pCi/L, about 2 would get cancer, equal to the risk of drowning.

Acceptable Radon Levels
The Environmental Protection Agency, EPA, recommends you install a system to reduce radon gas in your home if the level of gas is 4 picocuries of radon per liter (pCi/L) or higher.

Facts About Radon Gas
  • There are no average radon levels for a specific city, state, or region.
  • Houses without basements are as much at risk of radon contamination as houses with basements.
  • It doesn't matter if your neighbor's radon test was low or high, results for your home may be completely different.
Radon Gas Testing Methods
There are two basic types of radon gas testing devices, passive and active.

You can order a radon test kit and set it up yourself or you can hire a professional to perform the test.

Passive Radon Testing Devices
  • Do not need power to function.
  • Include charcoal canisters, alpha-track detectors, and charcoal liquid scintillation devices that are exposed to the air in your home for a specific amount of time and are then sent to a laboratory for analysis.
Active Radon Testing Devices
  • Require power to function.
  • Continuously measure and record radon in the air, making radon spikes and dips more apparent.
  • Include continuous working level monitors and continuous radon monitors.
  • May include anti-interference features that reveal if the unit is moved during testing.
  • Generally considered to be more reliable than passive radon devices.
  • Normally used only by home inspectors and air quality professionals.
How Long Should You Test for Radon Gas?
Long term radon tests take more than 90 days, but provide an accurate picture of the average amount of radon in your home. Since time is an issue, home buyers usually perform short term radon with either an active or passive testing device. Most short term radon tests are completed in 48 to 96 hours.

How To Test for Radon
The EPA recommends that you perform radon tests on the lowest level of the home that could be used for living space without doing renovations.
  • Choose a room that is used regularly, but do not use the kitchen, bathroom, laundry room or a hallway.
  • Sometimes two devices are used simultaneously or two 48-hour tests are done back-to-back to help establish average radon levels and to verify that devices are working properly.
  • Keep windows and doors in the tested room shut except for normal entry and exit. For tests lasting less than four days, make sure windows and outside doors are closed for at least 12 hours before beginning.
  • Do not do short term radon tests during times of high humidity, severe storms, or when winds are high.
  • Place the testing device at least 20 inches above the floor so that it is out of drafts and high humidity and will not be disturbed.
  • Follow the manufacturer's instructions to record starting and ending times. Reseal the tester package and return it to the lab for analysis.

If you use an active device, the tester will give you instructions about what you should and should not do during the test.

If Radon Levels Are Too High
About 0.4 pCi/L of radon is found in the outside air and the average indoor radon level is about 1.3 pCi/L. The EPA recommends you use mitigation techniques to reduce indoor radon if levels in your home are above 4 pCi/L (or 0.02 working levels [WL] if your lab uses that reporting method.)


Buyer's Guide

Tips for First Time Buyers

Buyer Frequently Asked Questions

10 Things Buyers Should Avoid

What To Do First: Buy or Sell?

Making an Offer


Simplify the Home Buying Process

Relieving the Stress of Packing

Land Buying Advice

Real Estate Glossary

Facts About Easements

Facts about Radon & Radon Testing

Lead Based Paint Facts & Disclosures

Mold in the Home

Saying "I Do" to First Homes

What is a CMA and Why Do You Need One?

How to Negotiate with Sellers



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