Surgeon General Health Advisory

“Indoor radon is the second-leading cause of lung cancer in the United States and breathing it over prolonged periods can present a significant health risk to families all over the country. It’s important to know that this threat is completely preventable. Radon can be detected with a simple test and fixed through well-established venting techniques.”

January 2005

Radon. It’s on a lot of minds these days, partly due to a recent report by the Environmental Protection Agency (EPA) showing that Multnomah County has one of the highest rates of radon in the Pacific Northwest. As a REALTOR™, radon is frequently on my mind because I need to protect my clients from environmental danger.

Here’s a map of the hottest zones in the Portland area

The indoor test results summary:

According to the EPA’s A Citizen’s Guide to Radon, “Radon is a cancer-causing, radioactive gas” (1). Radon is invisible, odorless, tasteless, and inert. You will never know it’s there without conducting a radon test in your home, but you can die from radon exposure. The Surgeon General has estimated that as many as 21,000 lung cancer deaths per year are caused by radon, and only smoking causes more lung cancer deaths. Approximately 2,900 people of that estimated 21,000 have never smoked.(2) Radon-induced lung cancer costs the United States over $2 billion per year in both direct and indirect health care costs. (3) The International Agency for Research on Cancer (part of the World Health Organization) and the National Toxicology Program both classify radon as a carcinogen.

Radon is a naturally occurring radioactive gas and comes from the natural breakdown (radioactive decay) of uranium. It is usually found in igneous rock and soil, but in some cases, well water may also be a source of radon.(4) Radon usually enters homes, offices, and schools through the surrounding bedrock, though it is possible that it enters the home and the human body through water from well water.

“Radon gas given off by soil or rock can enter buildings through cracks in floors or walls; construction joints; or gaps in foundations around pipes, wires, or pumps. Radon levels are usually highest in the basement or crawl space. This level is closest to the soil or rock that is the source of the radon. Therefore, people who spend much of their time in basement rooms at home or work have a greater risk for being exposed.”(5)

There is recent concern that radon may be released from granite countertops or tiles as well as from the home’s bedrock. The most concern stems from an article in the New York Times discussing radon in trendy granite countertops and that “with increased sales volume and variety, there have been more reports of “hot” or potentially hazardous countertops, particularly among the more exotic and striated varieties from Brazil and Namibia.”(6) A radioactive countertop might add a fraction of a millirem (a measure of energy absorbed by the body) of radon per hour, however, to dedicated chefs who lean against high radon level countertops, the exposure could be exponential. David J. Brenner, director of the Center for Radiological Research at Columbia University in New York, said the cancer risk from granite countertops, even those emitting radiation above background levels, is, “on the order of one in a million.”(7)

The EPA states that any radon exposure carries some risk(8) however the EPA recommends homes be corrected if the occupants’ long-term exposure will at or above 4 picocuries (the measure of the rate of radioactive decay) per liter (pCi/L) or higher.(9)

According to the EPA, the average indoor radon level is about 1.3 picocuries per liter (pCi/L). People should take action to lower radon levels in the home if the level is 4.0 pCi/L or higher. The EPA estimates that nearly 1 out of every 15 homes in the United States has elevated radon levels.(10)

What can you do?

According to the EPA, every home in the US should be tested for radon. Do-it-yourself radon test kits are available for $25 or less at most hardware stores.(11) Most home inspectors do the test for about $150 during a new home inspection. says this:

Both short-term and long-term tests are available to test for radon.

Short-term tests

Short-term tests are the fastest way to detect elevated radon levels in your home and are performed over a period of 2 to 90 days (most test kits are done over 2 to 4 days). Do-it-yourself short-term kits are available at most hardware stores, and can also be ordered online or by phone (see below).

Long-term tests

Long-term tests are conducted over a period more than 90 days. Radon levels fluctuate throughout the year and are highest during cold weather when heating is used, and windows are closed. These tests can give an indication of what the average level of radon is in your home year round.


Both passive and active devices can be used for radon testing. Passive devices, such as charcoal canisters, do not require power and are widely available. Active devices require power to run and can provide continuous monitoring of radon levels. These devices are usually used by a certified radon testing company rather than as a do-it-yourself test and are usually more expensive.

How to Test for Radon

Carefully read and follow the manufacturer’s directions on your radon test kit. Some of these are very specific – for example, if your test is left out for more than the required amount of time, improperly sealed, or there is a delay between the test time and when you mail the test, your sample may be rejected. Most test kits recommend the following:

• Place the test kit in the lowest area of living space in your home

• Keep windows and doors closed (except for entering and leaving) for 12 hours before testing your home, and throughout the duration of the test (short-term tests)

• Avoid placing the test kit in the kitchen, bathrooms, hallways, laundry room, and rooms that may be drafty

• Place the kit at least 20 inches off the floor


Take your reading. If your reading is at or above 4 pCi/L you will need to investigate mitigation options.