Radon is a colorless, odorless, and invisible gas that rises up from the soil and can enter homes. Long-term exposure to high radon levels can increase the risk of developing lung cancer.


About radon

Radon comes from the breakdown of uranium in soils and rocks. Radon enters homes through small cracks in floors or walls, construction joints, or gaps in foundations around pipes, wires, or pumps.

There are many areas throughout Idaho that have high levels of radon; about 2 out of 5 homes that have been tested in the state have levels above 4.0 pCi/L. Select the link at the bottom of the page for the Idaho Radon Map to view elevated radon levels in Idaho by zip code.

Radon Awareness Video 
Utah woman warns others about radon after cancer diagnosis video
Conozca los riesgos para la salud del gas radón y por qué es importante realizar una prueba de detección de radón en su nido
Introduction to Radon Gas in Homes Webinar


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Radon information


The health effects of radon exposure in smokers versus nonsmokers varies. The risk of lung-cancer from radon exposure over a lifetime greatly increases among smokers. Improve your health by quitting smoking and fixing your home if radon levels are above 4 pCi/L.

To learn more about health effects of radon and smoking download the Radon and Lung Cancer brochure.

Level (pCi/L) 
If 1,000 smokers were exposed to this level of radon over a lifetime, about this many people could get lung cancer*  If 1,000 non-smokers were exposed to this level of radon over a lifetime, about this many people could get lung cancer* 
 0.4  3 --
 1.3  20 2
 2.0 32 4
 4.0 62 7
 8.0 120 15
 10 150 18
 20 260 36

Note: if you are a former smoker, your risk may be lower.

*Lifetime risks of lung cancer deaths from EPA Assessment of Risks from Radon in Homes (EPA 402-R-03-003)

Guidelines for home owners and renters

Buying a Home

Before you buy a house, you should have it tested for radon. The most common procedure for testing during a real estate transaction is for the potential buyer to request the radon test as part of the overall home inspection. If the test is above 4.0 pCi/L, you can try to negotiate with the seller to have a radon mitigation system installed with the goal of bringing radon levels below 4.0 pCi/L. 

To learn more about radon in real estate transactions, download the Radon & Real Estate in Idaho brochure.

Resources for home buyers and sellers.

Building a Home

Incorporating radon reduction techniques into the construction of your new home is the most cost-effective way to reduce the radon levels in your home. Discuss radon reduction techniques with your builder. 

Renting a Home with Radon

Your landlord is not legally required to test for radon. You may conduct the test yourself or ask your landlord to conduct the test. 

If you test your rental home and the results come back high, your landlord is not legally required to reduce the levels in your home. However, you may notify the landlord of the results and discuss the need for radon reduction repairs. 

Health risks

When radon gas decays, it breaks down into radioactive particles that can get trapped in your lungs when you breathe. As the particles continue to decay, they release small bursts of energy that can damage lung tissue and may lead to lung cancer in some people. 

Radon is the leading cause of lung cancer in nonsmokers. The Environmental Protection Agency (EPA) estimates that radon causes 21,000 lung cancer deaths each year in the U.S. The risk of developing lung cancer from radon depends on the level of radon you are exposed to over your lifetime, whether or not you are a smoker, and other genetic and environmental factors.


Testing for radon is easy and inexpensive. You should perform the test on the lowest floor of your home that you spend time in. If you have a basement and you spend time there, test in the basement. Otherwise, test on the first floor in a bedroom or spare room.

Download the Radon in Idaho brochure to learn more about radon and how to test your home.

Types of Tests

Radon levels can vary season to season and highest levels are generally found in the winter so it is best to do a short-term test in the winter or a long-term test for the full year. 

1) Short-term

A short-term test provides a quick radon value within a brief period of time (typically 3-7 days).

2) Long term

 Long-term tests are typically placed in the home for up to a year. Long-term test kits give a better estimate of the amount of radon in your home throughout the year.

Where to Get Tests

Idaho residents can order a reduced price radon test kit from Air Chek. Test kits can also be purchased from a local hardware store, home improvement center, or other retail outlets.

You can order a test kit from Air Chek by:

You may also choose to have your home tested by a professional. Nationally-certified mitigation professionals can be contacted by visiting the National Radon Proficiency Program and the National Radon Safety Board. You can locate a certified radon service provider by typing in your state or zip code in the search bars.

Interpreting Radon Test Results

Radon levels are measured in picocuries per liter of air or pCi/L. The Environmental Protection Agency (EPA) EPA recommends homes be fixed if the radon level is 4 pCi/L (picocuries per liter) or more. Because there is no known safe level of exposure to radon, EPA also recommends that Americans consider fixing their home for radon levels between 2 pCi/L and 4 pCi/L. This can be done by installing a mitigation system. You may also want to test your home again to confirm your levels or to determine a year-round average. 

The risk associated with radon depends on the amount that you are exposed to, the length of time that you are exposed, as well as other factors such as if you smoke. See the risk charts below. 

Test Results & Recommended Actions

Radon Level (pCi/L)Actions to Take
 0.4-1.3This is an average indoor radon level. Keep in mind that radon levels can change over time, so test again every 2 years. 
 2.0-3.9Consider running a long-term radon test. Consider fixing your home
4.0 and higherFix your home! You may choose to do this yourself or hire a radon mitigation professional



Fixing Radon Issues

Cost to Remove Radon in a Home

  • The average cost for parts to install a system ranges from $300-$600. The cost to have a certified radon mitigation professional install the system in an existing home ranges from $1,500-$3,500. Cost of mitigation may vary based on home structure, location, and travel distance. 
  • The cost to install radon-resistant features during the construction of new homes runs from $300-$500.


When installing a radon mitigation system, one should follow the international residential code list below.

The provisions contained in this appendix are not mandatory unless specifically referenced in adopted ordinances in a jurisdictions within the State of Idaho.


Mitigation funds

There are some federal programs that may be used to help fund radon reduction in homes for limited income families. Some examples are:

Housing and Urban Development (HUD) Community Block Grant program

  • Funds rehabilitation and repair of affordable housing.
  • For more information, call HUD at 202-708-3587.

HUD "203k" program

  • Funds rehabilitation and repair of single-family homes.
  • For more information, call HUD at 202-708-2121.

Environmental Justice Grants

  • Funds community-based organizations and tribal governments addressing environmental concerns of people of color and low income communities.
  • For more information, call the Environmental Protection Agency's Office of Environmental Justice at 800-962-6215.

U.S. Department of Agriculture Single Family Housing Repair Loans & Grants

DHW Environmental Health Program
Contact us with questions about radon.

Idaho-specific resources

Find information about radon levels of every Idaho county. This includes radon level maps and radon level graphs specific to Idaho.
Find a Radon Mitigation or Measurement Professional
Watch the video to learn more about the prevalence of radon in Idaho.