Radon Testing in Washington: What Your Results Mean

What should you do if a radon test comes back with a number you do not recognize? 

If you are buying a home in Washington, a radon test can give you useful information about the air quality in the property but the results can be confusing if you do not know what the numbers mean.

Radon is a naturally occurring radioactive gas that can enter homes through soil, cracks in foundations, crawl spaces, and other openings. You cannot see, smell, or taste it, so testing is the only way to know how much is present.

The Washington State Department of Health recommends testing homes for radon as a first step in addressing potential exposure.

If your test results are already in hand, here is how to read them and what you may want to do next.

What is Radon?

Radon is a radioactive gas produced naturally as certain elements in soil and rock break down.

It can move through the ground and enter a house through openings around foundations, floors, pipes, and other areas.

Once inside, radon can build up, particularly in lower levels of a home. This makes basements and ground-level rooms important places to consider when testing.

Radon exposure over a long period can increase the risk of lung cancer. The risk is higher at greater radon concentrations and with longer exposure. 

The good news for homebuyers is that elevated radon levels can usually be addressed. Finding radon during the buying process gives you an opportunity to understand the issue and determine what needs to be done before you move in.

What Does a Radon Test Measure?

Radon results are usually reported in picocuries per liter, written as pCi/L.

The number represents the concentration of radon in the air during the testing period. A higher number means a higher concentration of radon.

The EPA recommends taking action to reduce radon when a home's level is 4.0 pCi/L or higher. It also recommends considering ways to reduce radon when results are between 2.0 and 4.0 pCi/L since there is no known completely safe level of radon exposure. 

Here is a simple way to look at your results:

These numbers are guidelines, not a statement that a home below 4.0 pCi/L has no risk.

Is a Low Radon Result a Good Result?

Yes.

If your test comes back below 2.0 pCi/L, that is a relatively low reading. However, it does not mean the home has zero radon.

Radon levels can change over time based on weather, ventilation, how the home is used, and other conditions. The Washington State Department of Health notes that even short-term tests provide a measurement of the conditions during the testing period.

For a home you are buying, it is also worth looking at where and how the test was performed. A low reading from an area where nobody spends time may not tell you much about the level in a basement bedroom or other frequently occupied space.

What If the Result Is Between 2 and 4 pCi/L?

This is where things can get a little less clear.

A result such as 2.5 or 3.2 pCi/L is below the EPA's action level of 4.0 pCi/L. That does not mean you necessarily need to walk away from the home.

The EPA recommends considering ways to reduce radon when levels are between 2 and 4 pCi/L.

As a buyer, you can use this result as a reason to learn more about the property. Depending on the circumstances, you may want to ask whether the home has been tested before, look at the testing conditions and length of the test, and factor any potential mitigation work into your purchase decision.

A moderately elevated result does not automatically make a home a bad purchase. It gives you another property issue to understand before making your final decision.

What If the Result Is 4 pCi/L or Higher?

A result of 4.0 pCi/L or higher is the point where the EPA recommends fixing the home to reduce radon.

If you are in the middle of buying the property, do not assume that a high result means you have to cancel the deal. Instead, find out what it would take to address the problem.

Radon mitigation systems can use techniques such as ventilation and a fan system to draw radon from beneath the home and release it outside. The right approach depends on the home's construction and where the radon is entering.

You may want to have a qualified radon professional evaluate the property and provide an estimate for the necessary work.

This information can also become part of your negotiations with the seller. Depending on your purchase agreement and the circumstances of the transaction, you may be able to negotiate for the issue to be addressed or account for the expected cost in your offer.

Where Should You Test for Radon?

The lowest level of the home that could be regularly occupied is generally an important place to test.

That could be a basement bedroom, finished basement, home office, or another room where you expect to spend significant time.

Washington's Department of Health specifically points out that testing a space such as a broom closet or an unoccupied crawl space may not tell you much about the exposure people in the home actually experience.

This is particularly important when buying an older Washington home. A house may have a crawl space, basement, or other foundation characteristics that affect how radon enters and moves through the property.

What Should You Do After a High Test?

If your results are elevated, start by confirming the test and understanding the conditions under which it was performed.

From there, consider getting advice from a qualified radon professional about mitigation. Washington's Department of Health recommends retesting after radon reduction work to determine whether the changes actually lowered the radon level. 

As a buyer, you should also keep the timing of the transaction in mind. If you are still within your inspection or due diligence period, you may have an opportunity to investigate the issue before moving forward.

Your real estate agent can help you understand how the issue fits into your purchase negotiations, while a qualified radon professional can help you understand the technical side of testing and mitigation.

What You Should Remember

A radon test result is not simply a pass-or-fail number.

A reading below 2 pCi/L is relatively low, while a result between 2 and 4 pCi/L is a reason to consider reducing radon. At 4 pCi/L or higher, the EPA recommends taking action to reduce the level. 

Most importantly, look at the full picture.

Consider the test duration, testing location, conditions during the test, the home's foundation, and what it would take to reduce the level.

If you are buying a home in Washington, radon testing can give you information that is easy to overlook during an already complicated purchase.

Knowing what your results mean can help you ask better questions, negotiate more confidently, and make a decision you feel comfortable with.