Radon FAQ

Radon is a cancer-causing, radioactive gas…

How Radon Enters a Residence

  • Radon is a radioactive, colorless, odorless, and tasteless gas. It is formed as natural deposits of uranium throughout the earth’s crust decay. As radon decay products are inhaled, they can alter the cells in the lungs. These alterations can increase the potential for getting lung cancer. Radon is the second leading cause of lung cancer behind smoking. An estimated 14,000 people die of radon related lung cancer each year.
  • The amount of radon in a building is dependent upon several factors. These factors include the geology, a driving force, pathways into the building, and the ventilation rate. As the concentration of uranium is in the underlying soil increases, so does the strength of the radon. Radon is transported to buildings more easily through permeable soils. Buildings can create pressure differentials that will draw in the soil gases. Radon can enter the building through many paths such as cracks in the foundation, utility penetrations, sumps, and floor drains. The ventilation rate of the building affects the final radon concentration.


Radon can be found all over the U.S….

US Radon Levels

  • Radon comes from the natural (radioactive) breakdown of uranium in soil, rock and water and gets into the air you breathe. Radon can be found all over the U.S. It can get into any type of building – homes, offices, and schools – and result in a high indoor radon level. But you and your family are most likely to get your greatest exposure at home, where you spend most of your time.

  • Excessive radon levels have been found in all of the 50 states. But in Colorado between one-third and one -half of the homes have radon levels in excess of the EPA recommended action.

Dangers of Radon?
Radon, the silent killer…
  • You cannot see, smell or taste radon and there are no noticeable symptoms you can detect from initial exposure, but it still may be a problem in your home! When you breathe air containing radon, you increase your risk of getting lung cancer. Also, if you’re a smoker and your home has high radon levels, your risk of lung cancer is especially high.
  • Radon is estimated to cause about 21,000 lung cancer deaths each year in the United States. Lung cancer is the only health effect which has been definitively linked with radon exposure. Lung cancer can develop in a little as a few years (5-25) after exposure.

See also radon health risks at www.epa.gov/radon/healthrisks.html


Radon Risk

“Radon, second to cigarette smoke in lung cancer related deaths.”

  • The Surgeon General has warned that, “radon is the second leading cause of lung cancer in the United States today” smokers being at a even higher risk of developing Radon-induced lung cancer. Other effects may include: gastrointestinal problems and stomach cancer.
  • Radon gas doesn’t discriminate: it is equally dangerous to all people, regardless of weight, sex, race, or age. However, the very young, the elderly, and

    those with a weakened immune systems are particularly at risk from the effects of radon exposure.

Radon in Colorado:

  • Most of Colorado contains high concentrations of radon
  • All Colorado homes should be tested for radon
  • Radon is unpredictable! Even if your neighbor has low levels, this does not mean you do not!
  • Surveys show that homes in most Colorado counties have the potential for radon levels above EPA’s recommended action level. (see map below)

About this Map:

Sections 307 and 309 of the Indoor Radon Abatement Act of 1988 (IRAA) directed EPA to list and identify areas of the U.S. with the potential for elevated indoor radon levels. EPA’s Map of Radon Zones assigns each of the 3,141 counties in the U.S. to one of three zones based on radon potential:

High counties have a predicted average indoor radon screening level greater than 4 pCi/L (pico curies per liter) (red zones) Highest Potential
Moderate counties have a predicted average indoor radon screening level between 2 and 4 pCi/L (orange zones) Moderate Potential
Low counties have a predicted average indoor radon screening level less than 2 pCi/L (yellow zones) Low Potentia

  • Colorado

Colorado Radon Levels