General Radon Information

Washington specific radon and radon level information can be found throughout this site. You will be able to find information about certified radon inspectors in Washington, as well as detailed radon level information for every county in Washington.

Radon gas is a chemically inert, odorless, colorless, and tasteless naturally-occurring radioactive element found in soils and rocks that make up the earth's crust. It comes from the normal decay of radium. Because it is a gas, it can easily move through soil and water and enter the atmosphere. Radon gas has a half-life approximating four days, after which it decays into four daughter products. These solid decay products are not inert and often attach themselves to airborne particulates which may then enter the lungs. These particles with attached radon daughters may become lodged in the lungs where the radon daughters undergo rapid decay, emitting radiation that damages lung tissue.

Millions of homes and buildings contain high levels of radon gas. Many do not even know it is present. Nearly 1 out of 15 homes in the US is estimated to have elevated radon levels.The highest concentrations of radon in Washington are in the Eastern part of the State, around Spokane. A compilation of data from earlier studies of 172 homes in the Pacific Northwest indicated that approximately 65 percent of the 46 homes tested in the Spokane River Valley/Rathdrum Prairie region of eastern Washington/northern Idaho had heating season indoor radon (222Rn) concentrations above the U. S. EPA guideline of 148 Bq m-3 (4 pCi L-1). A subset of 35 homes was selected for additional study. The primary source of indoor radon in the Spokane River Valley/Rathdrum Prairie was pressure-driven flow of soil gas containing moderate radon concentrations (geometric mean concentration of 16,000 Bq m-3) from the highly permeable soils (geometric mean permeability of 5 x 10(-11) m2) surrounding the house substructures. Estimated soil gas entry rates ranged from 0.4 to 39 m3h-1 and 1 percent to 21 percent of total building air infiltration. Radon from other sources, including domestic water supplies and building materials was negligible. In high radon homes, winter indoor levels averaged 13 times higher than summer concentrations, while in low radon homes winter levels averaged only 2.5 times higher. Short-term variations in indoor radon were observed to be dependent upon indoor-outdoor temperature differences, wind speed, and operation of forced-air furnace fans. Forced-air furnace operation, along with leaky return ducts and plenums, and openings between the substructure and upper floors enhanced mixing of radon-laden substructure air throughout the rest of the building.

The Surgeon General has warned that radon is the second leading cause of lung cancer in the United States. Only smoking causes more cases of lung cancer. If you smoke and your home has high radon levels, your risk of lung cancer is especially high. Not everyone exposed to elevated levels of radon will develop lung cancer, and the amount of time between exposure and the onset of the disease may be many years. Breathing radon does not cause any short-term health effects such as shortness of breaths, coughing, headaches or fever.

Radon had long been an issue connected to Washington state's several uranium mills, but it had not been considered a residential health issue until events in Pennsylvania in the mid 1980s brought that aspect of radon to the public's attention. Why was radon not recognized as an indoor environmental health concern before the mid-1980s. There are probably several reasons, some of which are as follows:

First, no one measured radon in houses before the mid-1980's so it is unknown what role it may have played in lung-related illnesses. Also, there was a generic grouping of respiratory illnesses, many of which may have been cancers, some of which may have been radon-related. Second, in the past, homes were draftier and one might expect that radon concentrations were diluted. Also, a larger portion of the population was involved in agricultural pursuits that allowed for less time to be spent indoors. Third, after a cell is damaged in a manner that starts it on the road to lung cancer it may take several years before the consequences of that process become evident. In the past, the national average life expectancy was shorter than it is today. In the past 100 years the average life expectancy of a child who reached the age of ten has increased about 17 years. One of the consequences of this extended lifespan is that there is now more time to incur the necessary cellular damage and more time for a cancer that initiates later in life and develops slowly to become enough of a problem to be detected and ultimately be the cause of death.