Since radon is a by-product of disintegrating rock, it is more likely to be present in rocky areas or where subterranean rock formations are known to exist, especially granite.

graphics4During a natural geologic process, rock becomes fractured and small amounts of radon are emitted. Because radon is a gas that contains a heavier molecule than oxygen, it will settle out of the air to the lowest levels of a structure when no ventilation is present to stir and move.

As radon seeps out of the soil, it enters buildings through foundation cracks, vent systems, pipe penetrations, plumbing and heat pipe ducts, and unsealed soil areas. Sometimes, the gas will be sucked into the structure because of negative pressure caused by heating systems, fireplaces, chimneys, etc. Negative pressure occurs when warm air in a house moves upward to create positive pressure in upper areas of the structure, resulting in negative pressure in lower areas where replacement air enters.

When radon mitigation is considered, all of the potential radon sources and entry paths into the structure are studied, along with the potential for introducing ventilation or adding additional ventilation in the areas with elevated radon levels.

Water can also be a source of radon gas. Municipal water supply systems are usually not a source of radon. But when the water supply for the house is a ground well through rock, or in bedrock that is releasing radon, it is possible for radon to become trapped in the water and released when the water becomes vapor, such as with a hot shower, laundry, or other steam producing uses for the water. Radon levels are known to increase as much as 200 times beyond the action level because of released radioactivity from a shower.

Measuring Radon Levels in a House

Radon is measured in picocuries per liter (pCi/L), which is a measurement of the radiation contained in a liter of air.

There is no current agreement among health professionals as to an acceptable or safe level of radon exposure. In the outdoors, radon levels average 0.4 pCi/L. The EPA has a suggested "action level" of 4.0 pCi/L. The following are the EPA recommendations for various radon measurement levels in a structure:

  • A result of less than 4.0 pCi/L is considered an acceptable, no-action-required level. The average indoor radon level is believed to be 1.3 pCi/L. It should be noted that no radon level is considered "safe." The 4.0 pCi/L "action Level" is based on current mitigation technology, which can usually reduce high radon concentration levels to below 4.0 pCi/L, and down to or below 2.0 pCi/L in about 70 - 80 percent of cases. Although Congress passed legislation in 1988 establishing a goal that indoor radon levels not exceed ambient outdoor radon levels (0.2 - 0.7 pCi/L), this goal is not yet technologically achievable.

  • An annual average between 4.0 and 20.0 pCi/L would indicate that action should be taken to reduce radon within a period of a few years, or sooner.

  • An annual average between 20.0 and 200.0 pCi/L would indicate that action should be taken within a few months to reduce the levels as far below 20.0 pCi/L as possible.

  • An annual average over 200.0 pCi/L would indicate that action should be taken within several weeks to reduce levels as far below 200.0 pCi/L as possible. Immediate remedial action might also be considered.

  • Radon Levels and the Risk of Lung Cancer

    Unfortunately, many people do not perceive radon as a serious health threat. In reality, annual deaths from radon in the United States exceed deaths from drowning, fire and air crashes combined. The risk for death from radon is influenced by three factors:

    • the radon exposure level;
    • the length of time exposed to elevated levels of radon; and
    • the person's status as a non-smoker or smoker.

    If a person is a smoker, the risk of cancer at various pCi/L readings per 1000 population is as follows:

    Radon Level

    Risk per 1000 people exposed to radon level over lifetime

    20 pCi/L

    135 per 1000

    10 pCi/L

    71 per 1000

    8 pCi/L

    57 per 1000

    4 pCi/L

    29 per 1000

    2 pCi/L

    15 per 1000

    1.3 pCi/L

    9 per 1000

    0.4 pCi/L

    3 per 1000

    If a person is a non-smoker, the risk of cancer at various pCi/L readings pCi/L readings per 1000 population is as follows:

    Radon Level

    Risk per 1000 people exposed to radon level over lifetime

    20 pCi/L

    8 per 1000

    10 pCi/L

    4 per 1000

    8 pCi/L

    3 per 1000

    4 pCi/L

    2 per 1000

    2 pCi/L

    1 per 1000

    1.3 pCi/L

    less than 1 per 1000

    0.4 pCi/L

    less than 1 per 1000

    If the person is a former smoker, the relative risk will be somewhere between the smoker and non-smoker.

    I'm personally not aware of any radon in Bend Oregon Homes or real estate but that does not mean it not there.  To search for homes in Bend click on the link.