Radon in Colorado

Radon in Colorado PSA

 El radón en Colorado

Map of Radon Testing Results in Larimer County

A sample of radon test results in Larimer County are displayed in the map above. Test results below the EPA recommended action level are shown in blue. The average of tests shown in this map is 7.8 pCi/L (picocuries per liter). Larimer County has radon levels higher than the national average of 1.3 pCi/L. The EPA recommends homes be fixed if the radon level is 4 pCi/L or more.  

More Information About Radon

Radon is a radioactive gas that forms naturally when radioactive metals break down in rocks, soil and groundwater. People can be exposed to radon primarily from breathing radon in air that comes through cracks and gaps in buildings and homes. Because radon comes naturally from the earth, people are always exposed to it.

In Colorado, about half the homes have radon levels higher than the U.S. Environmental Protection Agency recommended action level of 4 picocuries per liter (pCi/L).

Radon is the number one cause of lung cancer among non-smokers, according to EPA estimates. Overall, radon is the second leading cause of lung cancer. Radon is responsible for about 21,000 lung cancer deaths every year. About 2,900 of these deaths occur among people who have never smoked. 

Smokers are at higher risk of developing Radon-induced lung cancer. There is no evidence that other respiratory diseases, such as asthma, are caused by radon exposure and there is no evidence that children are at any greater risk of radon induced lung cancer than adults.

Home test kits are easy to use and inexpensive. Testing is the only way to know if you and your family are at risk from radon. The test kit should be placed in the lowest lived-in level of the home (for example, the basement if it is frequently used, otherwise the first floor); however if a furnace or central air conditioner unit is located on the lowest floor it may distribute air from that level into other parts of the home. 

During National Radon Action Month the Larimer County Department of Health and Environment has a limited number of test kits available for free. These kits come with postage to the lab prepaid, so you can test, drop in the mail and get your results.

Pick up a test kit at any of our offices during January 2024:

  • Fort Collins 1525 Blue Spruce Drive, Fort Collins, CO
    • M-F 8:30AM-4:00PM
  • Loveland 200 Peridot Ave Loveland, CO
    • M-F 8:30AM-4:00PM

All Colorado residents are also eligible for a free test kit through funding provided by the Colorado Department of Public Health and Environment. Kits are mailed from Alpha Energy Labs and the link below can be used to order your kit:

Free Test Kits for Colorado Residents

  • The Colorado Department of Public Health and Environment provides financial assistance for mitigating radon through its Low Income Radon Mitigation Assistance program. If you meet income requirements the program will pay up to 100% of the cost of mitigating radon from your home when a system is installed by a certified radon professional. More information about financial assistance to reduce radon in your home can be found on this CDPHE webpage here. 




Radon test reports are required to be kept on file at the child care facility and available for review by individuals that request to see them.

Test Results

Radon measurements show how much radon was present in the room during the test period. Radon gas is measured in units of picocuries per liter (pCi/L), a standard measure of radioactivity. The EPA set 4 pCi/L as a recommended action level.

If all results are less than 4 pCi/L, then no further action is needed. However, re-testing every 5 years is recommended so Radon levels can be actively monitored.

If one or more rooms have test results of 4 pCi/L to 8 pCi/L, it is recommended to conduct a long term Radon test in those room(s). If the long term tests have results above 4 pCi/L, mitigation is recommended.

If one or more rooms have a result greater than 8 pCi/L, a second short term test should be conducted in each room that tested greater than 8 pCi/L. If levels are still above 8 pCi/L after the second short term tests are completed, mitigation is recommended.


Although mitigation is not required by Colorado's child care regulations, mitigation is highly recommended when Radon levels are 4 pCi/L or higher. Mitigation cost depend on how the facility was built and the extent of the radon problem. A variety of mitigation methods may be used.

In rooms with results between 4 pCi/L to 8 pCi/L, radon levels can often be decreased with minor adjustments to the heating, ventilation and air conditioning systems by increasing air flow to these rooms.

Mitigation systems can also be installed such as sub-slab depressurization, drain tile suction, sump pit suction and block wall suction where Radon gas is removed and ventilated into the atmosphere. Radon mitigation systems should only be installed by a certified contractor. The Colorado Department of Public Health & Environment provides a list of certified contractors that can perform radon mitigation. See Testing and mitigating your home for radon.

Re-testing for radon should always be done after mitigation work has been completed to ensure levels have been reduced to below 4 pCi/L.

More Radon Information


  1. Any building that touches the ground is at greater risk from radon exposure, so the type of foundation the mobile home is on would be the biggest factor in determining whether testing should be completed. A mobile home on a concrete or block wall foundation would be the highest risk, homes on piers, blocks or axles, with skirting would be next, and homes without skirting would be the lowest risk. Radon will travel the path of least resistance so if it comes up from the ground and can find an easy way out of the space below a mobile home, the risk is low. If there are foundation walls or skirting blocking its path, it may find its way up into the living space. The Health Department recommends that anyone test their home for radon.