Radon

Radon is a naturally occurring radioactive gas that comes from the radioactive decay of elements naturally found in rocks and soils. You can’t see it, smell it, or taste it. It could be in your home damaging your family’s health.

There is always a small amount of radon in the environment, and it can be trapped inside your home and concentrate to unhealthy levels. Indoor air quality is a public health concern.

Testing for radon is best practice and the first step for addressing indoor radon exposure.

Health Risks

When radon gas is inhaled and decays, it releases small bursts of radioactive energy, which cause tissue damage to the lungs. Exposure to elevated levels of radon over time increases the likelihood of developing lung cancer or other lung disfunction. Smoking or vaping combined with exposure to unhealthy levels of radon further increase the likelihood of serious health effects. According to the Environmental Protection Agency (EPA), radon exposure is the leading cause of lung cancer among nonsmokers. It’s responsible for about 21,000 U.S. deaths each year. It also significantly increases the likelihood of smokers to develop lung cancer. Get free help to stop smoking or vaping from the Tobacco Quitline.

Radon in Schools. DOH agrees with the recommendations of the EPA and the Office of the Superintendent of Public Instruction (PDF), that schools test for radon and reduce exposure to elevated levels. Ask your school’s administration or schoolboard if your child’s school has been tested, they should be able to provide test results. We work with Northwest Radon Coalition partners to sponsor an Annual Radon Poster Contest for children ages 9-14 to teach others about the risks of radon. More about radon in schools.

Prevent Exposure to Radon in Your Home

Fortunately, exposure to radon in your home is preventable. There are simple steps you can take to protect you and your family in your home from radon exposure:

Test your home for radon.
Reduce radon in your home.
Retest: did your actions lower radon to a safe level?

Test Your Home for Radon

Since you can’t see, taste or smell radon, testing is the only way to know whether you and your family are being exposed to dangerous levels of radon. Do-It-Yourself (DIY) test kits are easy-to-use and inexpensive. You can find one at your local hardware store, home improvement store, or online retailers. Whether you own or rent your home, testing for radon is the first step to knowing how much radon is in your home and being able to protect your family’s health from radon exposure.

We have a limited supply of free radon test kits. These resources are limited in supply, so please only request a free test kit if you are committed to testing your home. Request a radon test kit from DOH. Please allow 8 to10 weeks for delivery.

Where in Your Home to Test

Exposure to more and more radon takes less and less time to cause ill effect. Radon exists in very low concentrations everywhere (0.4 pCi/L in outdoor air), so there is no getting rid of all of it. When radon seeps into a home it can be trapped and concentrated to much higher levels. Exposure is composed of two questions: How much? and How long?

Since your home is where you and your family spend the most time, it’s important to understand the radon concentration level in your home. Where you test in your home is also important for understanding exposure. Testing a broom closet, or a crawl space where no one spends time will tell you very little about exposure.

Test in the area(s) where your family spends the most time. It is typical to find higher radon concentrations in below ground areas, such as basements, and less the further you go up in the home.

Testing a utility basement where you quickly switch out a few loads of laundry each week won’t provide much understanding of exposure. However, for a basement that includes a TV room, game room, bedroom, office, or craft room where your family spends hours each day testing is important.

Types of Radon Test Kits

Short-term, long-term or a continuous monitoring system all provide correct readings of the radon present at the time of testing. When interpreting test results, remember testing parameters, such as duration, and conditions during the testing period.

A short-term test provides an easy example for interpreting test results. You can trust a short-term (3-4 day) test conducted while doors and windows were kept closed to provide a good indication of the average level of radon in the home. On the other hand, a short-term test conducted while enjoying mild spring weather with windows open and the fresh breeze blowing through the home also provides accurate measure of the radon the test was exposed to; however, this result will be of little value because it will have measured the radon level in the outdoor air blowing through the home.

In most cases, a short-term test provides easy, quick, reliable results. The short testing period gets results quicker and is easier to use as it requires a shorter time to keep windows closed for a reliable test result

A long-term test will measure radon levels over a longer period (typically 3 months). If the long-term testing period is during mild weather when windows are often open, the results will have little value other than having measured the radon concentration in the outdoor air blowing through the home.

A continuous radon monitor may show short term spikes in radon concentration. It is important to review your home’s average radon concentration over an extended period of no less than three to four days.

Reduce Radon in your Home

If you tested your home and found elevated levels of radon, there are simple things you can do yourself (DIY) to reduce radon levels. Whether you, your landlord, or someone you hired makes the fixes necessary to reduce radon in your home, make sure you retest when the work is done. A retest will tell you whether the actions successfully lowered radon to a safe level. 

Often, easy DIY fixes have a big impact for reducing indoor radon levels. You can also hire a certified radon professional (see “Hiring a Certified Radon Professional” below) to help reduce radon levels in your home.

How Much Radon is too Much?

The elements that breakdown to produce radon gas are naturally present in rocks and soil, so radon exists in the outdoor environment all around us at very low levels (0.4 pCi/L). As the concentration of radon increases, damaging health effects are caused more quickly. The US EPA has identified a radon concentration of 10 times what is found in the natural environment (10 X 0.4 pCi/L = 4.0 pCi/L) as the level at which it recommends action be taken to reduce radon in your home. In other parts of the world actions to reduce in-home radon are recommended for radon concentrations at or above 2.7 pCi/L.

Whichever point you decide to take action; the goal is to reduce the radon in your home as much as reasonably possible.

Simple Things You Can Do

Increase air exchange with the outside. The quickest and easiest way to reduce high indoor radon levels is to increase exchange of indoor air with outdoor air. This can be as easy as opening a window. Open windows can be an effective intervention until you can get larger projects done but may not be appropriate during extremely cold or hot weather, or during wildfire smoke events. A home’s radon level will often test higher when windows and doors are closed for winter heating or summer cooling.
Make it harder for radon to get in. Caulk and seal cracks in your basement, foundation, and subfloor. Inspect and fix, or install, a good crawl space vapor barrier. Ensure a vapor barrier is in good condition with any seams, holes, or tears well taped. The goal is to have a gas-tight barrier between the inside of your home and the ground underneath that allows soil gas to escape only at the perimeter where foundation vent-blocks allow the gas to vent.
Make it easier for radon to go somewhere other than into your house. Make sure foundation vent-blocks are unobstructed, allowing good ventilation for your home's crawlspace.

Retest - Did Actions Lower Radon to a Safe Level?

When work to reduce radon in your home is done, it is important to retest to see if efforts have reduced radon to a safe level. To retest, use the instructions above under "Test Your Home for Radon".

If your retest shows you still need to lower your radon levels, consider hiring a Certified Radon Professional.

Hiring a Certified Radon Professional

You or your general contractor can hire a certified professional to design a system to reduce the amount of radon that enters your home or increase ventilation to remove radon from your home. If you live in an area too far away from the closest radon professional consider hiring a local general contractor who meets state requirements – see Labor and Industries' Hiring a Contractor. A general contractor working on your behalf can seek out and hire a certified radon professional to design a system for your home.

Below are links to search tools provided by the national certifying organizations:

Like most home features, a radon mitigation system can be installed much easier and at much less cost during construction. Radon-resistant new construction techniques can be used while a new house is being built to help ensure radon is kept outside of your home.

Radon Maps and Data

The Radon Program works with Washington Tracking Network (WTN) to present radon data and maps.

More Resources

Contacts

For more information about radon in Washington, contact DOH's radon program at doh.radon@doh.wa.gov or 360-236-3200.