Frequently Asked Questions about Radon

A: Radon is an odorless, invisible, radioactive gas that is naturally released from rocks, soil, and water. Radon can seep into homes and buildings through small cracks or holes, and it can build up in the air. 

A: Radon comes from the natural radioactive decay – or breakdown – of uranium, which is found in all rocks and soils. Radon can also be found in water. 

A: As radon gas breaks down, it forms radioactive particles that can get trapped in your lungs when you breathe. As they break down further, these particles release small bursts of radioactive energy – exposure that is similar to getting an X-ray, but a more concentrated level as radon builds up in your home. Over time, breathing in high levels of radon can cause lung cancer. 

A: Radon escapes from the ground into the air, where it decays and produces further radioactive particles. The soil under and around a house is usually the source of indoor radon. Uranium naturally exists in soil and bedrock, and radon is created when uranium decays. Radon can travel through air pockets in the soil and into your house.

A: The average indoor radon level in the U.S. is about 1.3 pCi/L* in air.

*A pCi/L means picocurie per liter; a curie is a unit used to measure radioactivity.  

A: The average indoor radon level in Colorado is about 6.4 pCi/L. Living in a home with average levels of radon in Colorado for 1 year is like having more than 200 chest x-rays every year. That's more than three chest x-rays per week, per person, per year. That is an unhealthy level of exposure to radioactivity. 

A: Radon is present wherever uranium naturally exists in soil. Radon is a natural byproduct of uranium's decay/breakdown process. Because Colorado is particularly dense in uranium, there is naturally a lot of radon, too. 

A: Senate Bill 23-206 was signed on June 5, 2023, by Gov. Polis and went into effect on Aug. 7, 2023. The bill is designed to increase transparency regarding a home's history of radon testing and the subsequent results for renters and potential homebuyers. Learn more here.  

A: 

• Environmental Protection Agency's Radon Hotlines and Information 
• Colorado Department of Public Health and Environment Radon Information
• National Radon Proficiency Program — find a professional near you

A: The Colorado Department of Health and Environment offers financial assistance to qualified applicants. Get more information on their website.