Quick Facts…

  • Radon is a colorless, odorless, radioactive gas that can enter the home.
  • Most of Colorado contains high concentrations of radon, considered the second highest cause of lung cancer.
  • All Colorado homes should be tested for radon.
  • Radon reduction methods can be planned for and installed during new home construction.
  • Home buyers and renters should ask if the home has been tested for radon and for the results.

What is Radon?

Figure 1. Radon entry locations.

Radon in Colorado

Figure 2: EPA map of radon zones for Colorado. Zone 1 (dark gray), high risk (greater than 4pCi/L). Zone 2 (light gray), moderate risk (2-4 pCi/L).
Table 1: Radon risk if you have never smoked (Developed by the EPA).
Radon
Level
If 1,000 people who never smoked were exposed to this level over a lifetime
The risk of cancer from radon exposure compares to WHAT TO DO
20 pCi/L* about 36 people could get lung cancer 35 times the risk of drowning Fix your home.
10 pCi/L* about 18 people could get lung cancer 20 times the risk of dying in a home fire Fix your home.
8 pCi/L* about 15 people could get lung cancer 4 times the risk of dying ina fall Fix your home.
4 pCi/L* about 7 people could get lung cancer The risk of dying in a car crash. Fix your home.
2 pCi/L* about 4 people could get lung cancer The risk of dying of poison. Consider fixing between 2 and 4 pCi/L
1.3 pCi/L* about 2 people could get lung cancer Average indoor radon level. (Reducing radon levels below
2 pCi/L is difficult.)
0.4 pCi/L* Average outdoor radon level. (Reducing radon levels below
2 pCi/L is difficult.)
*pCi/L: picocuries of radon per liter of air
NOTE: If you are a former smoker, your risk may be higher.

Radon Testing

Figure 3: Examples of test kits approved by the EPA.

Understanding Test Results

Radon Mitigation

Figure 4: Typical radon mitigation system (EPA).

Simple ways to reduce radon levels:

  • Keep windows open on both sides of the lower floor of your house when possible.
  • Ventilate crawlspaces under your house.
  • Open basement windows early in the spring and keep them open when possible until late fall.
  • Seal cracks in basement floors with polyurethane caulking compound.
  • Pour water in floor drains once a month to make certain that traps do not dry out.
  • Keep stairwell doors, fireplace dampers, and laundry chute doors closed when not in use; keeping them open can suck air from the basement into the living area of the house.

Radon Resistant New Construction

  • A passive sub-slab or crawlspace depressurization system.
  • Foundation barrier techniques such as a layer of gas permeable material under the foundation (usually four inches of gravel), plastic sheeting over that material, and sealing and caulking of all openings in the concrete foundation floor or the floor above.
  • Dedicated intake and/or combustion air for exhaust and combustion appliances.
  • Installation of a gas-tight three- or four-inch pipe that runs from under the foundation (under the sheeting covering the soil in crawlspaces) through the house to the roof.
  • A roughed-in electrical junction box for future installation of a fan, if needed.

Home Buyers and Renters

Resources Available From EPA:

  • A citizen’s guide to radon: The guide to protecting yourself and your family from radon
  • Building a new home: Have you considered radon?
  • Home buyer’s and seller’s guide to radon
  • Radon: The health threat with a simple solution

Phone Numbers:

  • American Lung Association: (800) 586-4872
  • Colorado Radon Hotline: (800) 846-3986
  • National Radon Information Line: (800) 767-7236
  • Radon Fix-It Program, Consumer Federation of America: ( 800) 644-6999

Web Sites: