Radon FAQ

Radon is a known human carcinogen and is a leading cause of lung cancer in the United States. It is a naturally occurring radioactive gas that comes from the breakdown of uranium in the soil that can enter your home from the soil beneath it. Radon is a colorless, odorless, and tasteless gas, so testing your home for radon is the only way to know if your home has a radon problem. 

Radon produces radioactive particles that cause lung cancer when inhaled into the lungs.

Radon is common throughout Colorado. 

Breathing in radon over a long period of time increases your risk of lung cancer. Radon is the second-leading cause of lung cancer in the United States. Radon is the leading cause of lung cancer in people without a history of smoking. 

Lung cancer is the number one cause of cancer deaths in men and women in the United States. Each year, about 21,000 deaths in the United States are caused by radon-related lung cancer. 
 

The risk of lung cancer from radon is almost 10 times higher for those who currently smoke cigarettes compared to those who have never smoked. Individuals who quit smoking may have a lower risk of lung cancer from radon than those who currently smoke. Smoking and exposure to radon together create a greater risk of lung cancer than either one alone.

Cigarette smoke contains thousands of different chemicals, many of which are toxic or cause cancer. Cigarette smoke also greatly increases the number of tiny particles in the air in a home. The radioactive particles produced by radon gas readily attach to the smoke particles and stay suspended in the air for long periods of time for people and pets to inhale. There is no safe amount of firsthand or secondhand tobacco smoke. 

There is very little research on vaping and radon at this time. Since vaping produces even more fine particles than cigarettes, radon most likely attaches to vaping clouds as well as cigarette smoke.

Use your radon results and smoking history to check your radon risk with these charts.

There is very little research on the combined effects of radon and smoking or vaping cannabis at this time. However, like tobacco smoking and vaping, smoking or vaping cannabis indoors most likely increases the number of fine particles in the air. The radioactive particles produced by radon gas have a static charge and readily attach to small particles. They stay suspended in the air for long periods of time, allowing people and pets to inhale them.

Test your house for radon and mitigate if radon levels are above 4 pCi/L. You should test for radon even if your home has a radon mitigation system installed. 

Avoid smoking or vaping indoors to protect your loved ones. Consider quitting smoking or vaping to reduce your risk of lung cancer. 

Find free help to quit smoking

Testing your home for radon is an easy and important step to ensuring a healthy home. Everyone should test their homes for radon, regardless of whether you rent or own, live in a single family home, an apartment, or manufactured home.

There are many ways to conduct a radon test.

You can hire a licensed radon measurement professional for around $150, which is a good idea if you are in a real estate transaction. This is the best way to make sure the test is conducted correctly and the results are valid.

You can purchase a do-it-yourself radon test kit or request a free one from a public health agency. It is very important to follow the manufacturer’s instructions to make sure your results are valid.

Short-term radon tests are a good way to get started. These are the least expensive test kits and can deliver results within a couple of weeks. Learn more about using a short-term radon test.

Long-term radon test kits measure radon over a long period of time under normal living conditions. This is the best way to understand the radon levels in your home.

CDPHE offers free radon test kits, one per household per year, while supplies last. Visit the free radon test kit order form to see if kits are available. 

If you are not able to order a free radon test kit, contact your local public health agency to find out if there are free radon test kits available in your area. You can buy discounted test kits on our website.

The type of radon test used and whether you have a radon mitigation system in your home can impact the next steps. The results below are for do-it-yourself short-term radon test kits.

There is no radon mitigation system in my home

GREEN - Results under 2 pCi/L

If your results are less than 2.0 pCi/L, retest in 5 years

YELLOW - Results 2-3.9 pCi/L - 

If your results are between 2 pCi/L and 3.9 pCi/L, consider testing again with a long term test to understand your average radon levels over a longer period of time.
 
You can also consider mitigation if you or your family members are at a high risk for developing lung cancer.

Otherwise, retest in 5 years.

RED - Results at or above 4pCi/L

If your radon test result is at or above 4 pCi/L, your radon results are above the EPA action level. You should confirm your levels are elevated and reduce your radon levels by installing a radon mitigation system in your home.
 
It’s a good idea to conduct a second radon test to confirm your levels. If initial results are close to 4 pCi/L, you may want to conduct a long term radon test, which will give you the best data related to your average radon levels under normal living conditions.
 
If you own your home, read the section below to learn how to fix a radon problem. If you rent your home, notify your landlord in writing about the elevated radon levels.

There is a mitigation system in my home

GREEN - Results under 2 pCi.L

If your results are less than 2.0 pCi/L, retest in 2 years.

YELLOW - Results 2-3.9 pCi/L - 

If your results are between 2 pCi/L and 3.9 pCi/L, consider testing again with a long term test to understand your average radon levels over a longer period of time. 

Otherwise, retest in 2 years.

RED - Results at or above 4pCi/L

If your radon test result is at or above 4 pCi/L, your radon results are above the EPA action level. You should contact a licensed radon mitigation professional to inspect and service your system. 

It’s a good idea to contact the original installer in case your system is under warranty.

Find a licensed radon mitigation professional. You can find a list of licensed radon mitigation & measurement contractors on our licensed radon professional look up tool.

To learn more about radon mitigation systems, visit our radon mitigation information page. 

Like any home repair, it’s a good idea to get at least three bids. Be sure to ask for:
1) a guarantee that radon levels are reduced below 4 pCi/L or lower. 
2) a minimum five-year warranty on the radon fan and the workmanship of the system.

Traditional radon mitigation systems installed on existing single-family homes are approximately $1,300-$3,000. However, each home is different and asking for multiple bids from licensed mitigation professionals is the best way to get a fair price.

If your home has a passive radon system (e.g. built in during construction), it should cost about $500 to add a fan to activate the system.

Colorado has a financial assistance program to help low-income homeowners with radon mitigation expenses. Learn more about the Low Income Radon Mitigation Assistance (LIRMA) Program in the section below.

The Colorado Department of Public Health and Environment has a financial assistance program to help cover the cost of radon mitigation expenses for low-income homeowners.

Program eligibility criteria:

• The applicant must own the home and it must be the applicant’s primary residence.
• The applicant must be considered a low-income household and meet the low-income limits specified in the income table below. 

LIRMA Program Low Income Limits - Based on Adjusted Gross Income 

• A radon test result showing average radon levels are over 4 pCi/L within one year from the date of application, from a certified testing device.

Please review the LIRMA Policy and Procedure document for specific information. Visit the program website to apply for the program.

A radon mitigation system works by preventing radon gas from entering the living space of your home. Most radon mitigation systems operate through “active soil depressurization”, which relies on a radon fan and a barrier to pull radon gas out from the ground underneath your house and exhaust it above the roofline. The barrier can be a concrete foundation or 6mil poly sheeting in a crawlspace.

Access the brochure online and find other useful information on our Radon and Real Estate page.