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Radon Outreach

Radon is a naturally occurring radioactive gas. It has no color, odor or taste and is chemically inert. It comes from the breakdown of uranium. As the uranium molecule decays to form stable lead, a process taking many, many years, it changes from one radioactive element to another in a sequence known as the Uranium Decay Cycle. Partway through this cycle, the element radium becomes radon which as a gas moves up through the soil to the atmosphere. 


Excessive radon levels have been found in all of the 50 states. In Colorado, approximately 50% of the homes have radon levels in excess of the EPA recommended action level of 4 picoCuries per liter (pCi/L). 


Radon is estimated to cause about 21,000 lung cancer deaths per year. The Surgeon General has warned that radon is the second leading cause of lung cancer in the United States today. Only smoking causes more lung cancer deaths. 


Radon moves from uranium-bearing granite deposits in the soil to the atmosphere because there is a lower concentration of radon in the atmosphere than in the soil. Your home is sited in its path and because the house is usually warmer than the surrounding soil, the air pressure is less and soil gases, including radon, move into the home. The most common routes are: 


  • Spaces between basement walls and slab
  • Cracks in foundations and/or walls
  • Openings around sump pumps and drains
  • Construction joints and plumbing penetrations
  • Crawl spaces
  • Using well water with high radon concentrations 


The age of a home is not a factor when it comes to whether excessive levels of radon are present. 


Test for radon. 



No, the State does not compete with private industry; we provide information and advice only.


No, there is no legal requirement in Colorado for the landlord to test. You will have to do it yourself unless you can persuade him/her to test. EPA has a renters guide for tenants. 



No, there is no legal requirement in Colorado for him/her to mitigate the radon level. 


There are many kinds of low cost "do it yourself" radon test kits which may be purchased from your local home improvement store. Be sure the kit says "certified by the National Radon Proficiency Program." You can also get coupons for test kits on our website.  


In retail outlets, test kits range from $10 - $50. 


YES, if you use a kit that meets National Radon Proficiency Program requirements, follow the instructions on the label exactly, and return it to the lab promptly as directed. 

Short-term tests take 48 - 120 hours to complete. The house is closed for 12 hours, then the testing device is activated or opened and left in place for 48 hours or more. Charcoal canisters are the device of choice although electronic instruments may be used. 


Long-term tests take 91 days - 1 year to complete and are conducted with the house under normal living conditions. Alpha track detectors or electronic detection instruments are used. 


Long-term test results give a more representative picture of the true radon levels in the home over time as fluctuations due to changes in ambient temperature and barometric pressure are detected and factored into the final average.

It depends if you are testing your home for a real estate transaction or for your own purposes. The recommendations are different for the two cases. If you are testing to determine if your home has radon levels warranting mitigation, the EPA recommends testing in the lowest living area of your home. For a real estate transaction, EPA recommends testing in the lowest area which could be modified to become a living area. 


A list of National Radon Proficiency Program-listed radon measurement contractors is available on this website. These contractors will use either a continuous monitor, which will permit them to give you test results at the end of the test period, or some other short term measurement device, which can be read at a lab and the value reported in short order.  


The only proven health effect caused by breathing radon is the development of lung cancer after years of exposure. You may have a radon problem, but the only way to know is to test your home. Radon is not what is causing your symptoms. It is possible that your home has other indoor air quality issues (i.e., mold, volatile organic compounds, allergens, etc.). 


The method of choice is usually a sub-slab (or if you have a crawl space, sub-membrane) depressurization system. Contact a National Radon Proficiency Program certified radon contractor to bid on the job. He/she will be able to tell you if your home requires a different approach. Most don't. 



The cost of a mitigation system in Colorado is approximately $800 - $1,200 unless aggregate or difficult foundation design problems are encountered. 


The Division can supply you with a list of National Radon Proficiency Program certified radon mitigation contractors that have passed the National Radon Contractor Proficiency Examination. We recommend you call several of them and get estimates for the mitigation. 



Perhaps, if you have good handy-man skills including electrical wiring skills. If you are unsure, it would be advisable to get an evaluation from one of the National Radon Proficiency Program certified contractors before you decide.  Learn more at Understanding Radon Mitigation - Do-It-Yourself Radon Mitigation Information (exit this website).


No. While caulking and sealing is done as part of the mitigation process, the purpose is not to keep radon out but to hold conditioned air in the dwelling. It is impossible to seal all cracks and the task is time-consuming, expensive and temporary (dries out over time), so this procedure is not recommended as a stand-alone technique.


If you have tested the air in your home and found a radon problem and your water comes from a private well, you should test the water. Water testing is available from the Colorado Department of Public Health and Environment's Laboratory Services Division.



The Colorado Department of Public Health and Environment has been collecting data on test results in Colorado homes since 2005. You may request the data by contacting the Radon Program at 303-692-3442 or 1-800-846-3986. 




Schools are at risk from radon just as homes are. Colorado statute requires all schools to have tested for radon, and to maintain records of the test results for disclosure on request. The regulation does not require schools that find a problem to mitigate. It is up to the District and its constituents to address mitigation issues.