What is Radon?  Radon is an odorless, colorless, tasteless gas that is naturally present in our atmosphere. This radioactive gas is a byproduct of disintegrating rock in the ground. As the rock splits and crumbles, it releases radon gas into the air. The half-life of radon is 3.8 days. Radon is a non-reactive noble element. The radon gas itself is not the health hazard. The hazard is a result of the radioactive gas charging the minute dust particles in the air with gamma radiation. These radioactive particles are then inhaled into the human lung. In the lungs, these particles may adhere to the lung tissue, emit energy that can kill or damage sensitive cells and damage DNA molecules. The damaged lung tissue then becomes a condition conducive to developing lung cancer. The actual potential for developing lung cancer is a function of how much radon a human is exposed to and for how long. If a person is a smoker and is exposed to elevated levels of radon, the risk of contracting lung cancer is even greater.

The United States Environmental Protection Agency (EPA) has identified radon as being the second largest contributor to lung cancer in humans, right behind cigarette smoking. It is estimated that 21,000 deaths each year may be directly related to exposure to elevated levels of radon.

Any house can have a radon problem. New houses and older houses, well-sealed and drafty houses, and houses with or without basements may all be subject to elevated radon levels. The EPA estimates that nearly 1 out of 15 houses in the United States have elevated radon levels. These elevated radon levels have been found in all 50 states.

Because radon is related to naturally occurring uranium and radium found in the soil, radon levels can vary greatly within a small geographic region. Radon is less radioactive than both uranium and radium. The radon levels in any given location are related to the amount of uranium and radium found in the underlying rock structure and soil. The actual amount of radon entering a structure can be affected by the strength of the radon source, underlying soil type, water content of the soil, and empty spaces in the soil.


  • Zone 1: Average indoor radon screening level greater than 4 pCi/L (picocuries per liter)

  • Zone 2: Average indoor radon screening level between 2 and 4 pCi/L

  • Zone 3: Average indoor radon screening level less than 2 pCi/L

Radon is not considered a hazard unless it becomes concentrated in the living area of a home or work place and provides long term exposure to elevated levels. Exposure to radiation cannot be avoided and the majority of this exposure comes from natural sources. An average person's exposure to radiation in the United States comes from the following sources: