Radon

Has Your Home Been Tested for Radon?

Radon (Rn) is a naturally occurring radioactive gas that comes from the breakdown of uranium in soil and may enter homes and buildings. Radon may concentrate indoors to unsafe levels and increases the risk of lung cancer. The amount of radon in indoor air can be measured, and there are estimated risks to health depending on the concentration of the exposure. Smoking, in conjunction with radon exposure, greatly increases the risk of cancer. The EPA Risk Chart lists risks at different levels.

Free radon test kits are available for Missouri residents (limit one per household)

Test your home’s radon level and if it is above 4.0 pCi/L take action to lower the indoor radon concentration. For more information about radon, see "A Citizen's Guide to Radon."

Health Risk of Radon

Radon is the #1 cause of lung cancer among non-smokers.

EPA Radon

Helpful Resources

Request a Radon Test Kit

Use the coupon code "TESTING" to have a radon test kit sent to your home at no cost.

Radon Testing Instructions

Details about Radon Testing

Radon Mitigation and Home Buyers

Resources for residents to test and mitigate radon

Interactive Radon Maps

Radon Data Test Results ≥4 pCi/L

Radon Risk Charts

Health Risk of Radon

Where To Get a Radon Test Kit

We offer short-term radon test kits to Missourians at no cost while supplies last. These test kits are easy to use and require the resident to place the test in an appropriate area of their home for a few days, before sealing the sample up along with its paperwork and mailing it to a lab for analysis.

To get a free test, select "Request a Radon Test Kit" above and complete the form using the coupon code “TESTING”. A short-term radon test kit will then be mailed to you (limit one per household, while supplies last). Each test kit includes instructions for testing and a postage-paid envelope for returning the sample. For best results, please mail the sample back promptly once the test is completed.

Customers can also contact us at 573-751-6102 with questions about radon tests, or email inquiries to our program at radon@health.mo.gov.

Radon test kits may also be purchased at local hardware stores or online from radon laboratories or other retailers.

While radon test kits can be obtained from a variety of sources, radon professionals should be employed for radon testing pertaining to legal transactions.

How To Test Your Home for Radon

You may test your home for radon yourself or hire a contractor, unless it is for a legal transaction. For legal transactions radon professionals must be employed.

If you do the testing yourself, purchase a radon measurement device listed by EPA's Radon Measurement Proficiency Program and follow the directions carefully. Passive testing for radon is very easy to do. Contact us if you have any questions on sampling.

If a contractor is hired, we recommend selecting a contractor certified by the National Radon Safety Board (NRSB) or the National Radon Proficiency Program (NRPP). The contractor's identification number should be clearly visible on the test report.

If you are testing yourself the following checklist may be useful:

Before the Radon Test

When conducting a radon test yourself, use a radon measurement device listed by EPA's Radon Measurement Proficiency (RMP) Program. Read and follow the manufacturer's instructions that come with the device.
Check to see if an active radon reduction system is in the house. If a mitigation system is present, make sure the fan is operating, and the mitigation system is running for at least 24 hours before the beginning of the test.
EPA recommends that short-term radon testing, be done under closed-house conditions. Closed-house conditions means keeping all windows closed, keeping doors closed except for normal entry and exit, and not operating fans or other machines which bring in air from outside. Note that fans that are part of a radon reduction system, or small exhaust fans operating for only short periods of time, may run during the test.
When doing short-term testing lasting less than 4 days, it is important to maintain closed-house conditions for at least 12 hours before the beginning of the test and for the entire test period. Do not operate fans or other machines which bring in air from the outside.
Notify any occupants of the importance of proper testing conditions.
Determine the location you would like to test in. Test the lowest occupied level of the home that you or your family spend time in. The test should not be placed near exterior doors, windows, or directly above, below or within 1 meter of heating or air conditioning vents. The test should be placed 2-6 feet off the floor. The instructions may also include additional tips for selecting an appropriate location.

During the Radon Test

Maintain closed-house conditions during the entire short-term testing period (3-7 days).
Operate the home's heating and cooling systems normally during the test. For tests lasting less than one week, only operate air conditioning units that recirculate interior air.
Do not disturb the test device at any time during the test.
If a radon reduction system is in place, make sure the system is working properly and will be in operation during the entire radon test.

After the Radon Test

After the sampling period has ended, seal the test, complete any necessary information, and mail the test to the laboratory for assessment right away. If more than seven days pass between the end of the testing period and the date the lab received the test the lab will not be able to give an accurate radon result.
Record your test kit serial number and keep it somewhere it can be referenced later. The radon results should be sent to you within two weeks, but in the event a delay occurs the test kit serial number may be used to check the status of your test.
If you have questions regarding interpreting the radon results you may contact our program for assistance.

Next Steps if an Elevation is Found

If an indoor radon elevation is found, you may want to either retest to confirm the elevation, or begin taking action to fix the home.

Begin by asking: Have you retested to confirm that the levels are actually high? If a short-term test (2-7 days) was used, it is recommended that you take an additional test and average the two tests. Radon levels can vary from day to day so conducting one short-term test may not reflect the true level of your home.

If a radon level above 4.0 pCi/L has been confirmed, you should fix the home.

MDHSS recommends contacting radon mitigation contractors who are certified by the National Radon Proficiency Program (NRPP) or the National Radon Safety Board (NRSB). Professionals certified by these programs have specialized radon experience and equipment to help ensure mitigation systems they design and install in homes will be protective. The average cost of radon mitigation ranges from $500 to $2500 depending on the size and construction of the home. Please see EPA's "Consumer's Guide to Radon Reduction" for additional information and recommendations.

Health Risks of Radon

Radon is the leading cause of lung cancer in the U.S. among non-smokers and is the second leading cause of lung cancer overall, behind smoking.

Smoking, in addition to exposure to elevated radon levels, increases the health risks.

Radon is not known to cause asthma or other respiratory distress. Radon can be tested and is measured in picocuries per liter (pCi/L) of air. The estimated health risks resulting from the exposure depend on the concentration of radon and how long the exposure took place.

EPA Health Risks of Radon outlines the risks of radon at different levels.
CDC - Radon
American Cancer Society
American Lung Association
National Cancer Institute
Missouri Lung Cancer Coalition

Radon in Missouri

Radon is present in every county in Missouri. While radon occurs in low levels in outdoor air, it may gather in higher concentrations indoors. The EPA suggests that homeowners with radon levels of 2.0 pCi/L or higher consider taking action to lower indoor radon levels. The EPA also recommends that homes with radon levels of 4.0 pCi/L or higher should be fixed or mitigated for radon.
Data from our MDHSS residential radon testing program shows that 1 in 3 homes tested had indoor radon results that exceeded the recommended action level of 4.0 pCi/L.
The Missouri Radon Dashboard offers interactive maps and charts displaying Missouri residential radon testing results gathered by our program from 2003 to 2023. The results are displayed by county, and areas with low radon testing rates are indicated on the map.

Radon Testing in Schools

The Missouri Radon Program offers free radon testing services for Missouri public schools and commercial childcare centers. If your school district is interested in radon testing, contact Radon@health.mo.gov to find out more.

If your early care center is interested in safe siting and radon testing, please contact missouricsp@health.mo.gov.

Missouri Radon Poster Contest

The Missouri Poster Contest is held annually each fall. Students between the ages of 9-14 are asked to submit posters related to radon topics. Awards are issued to winning participants and their instructors, with the top prize of $200. Please see the contest guidelines for more information.

Radon Science Fair Project Ideas

Frequently Asked Questions

Where does Radon come from?

Radon gas is a radioactive material that is naturally occurring and comes from the soil. It is a decay product of Uranium, another radioactive material, which is also naturally occurring. Because radon is a gas it moves upward through the soil and may enter buildings through openings or cracks in walls or floors. Radon can accumulate in higher concentrations within buildings and may become a health risk in some situations.

What is the "acceptable" level of radon?

The US EPA has established the "action level" for deciding when you need to do something about the radon in your home, school, or workplace at 4 pCi/L. One pCi/L means that in one liter of air there will be 2.2 radioactive disintegrations (events) each minute. For example, at 4 pCi/L there will be approximately 12,672 radioactive disintegrations in one liter of air, during a 24-hour period. You can read or download a copy of the US EPA's "A Citizen's Guide to Radon". This publication goes into greater detail describing the meaning of your radon test results and what your personal hazard from the exposure may be.

What do I do when I find high radon levels in my home?

If you have confirmed that elevated radon levels are present in your home, take action to fix your home by contacting a certified radon contractor to install a radon mitigation system. Missouri Department of Health and Senior Services (DHSS) recommends using radon contractors that are certified by the National Radon Proficiency Program (NRPP) or the National Radon Safety Board (NRSB). A list of Missouri contractors certified by each organization can be found on their website. Although costs may vary depending on the work that needs to be done, radon mitigation typically costs less than $2500 for a 2000-square-foot home.

I'm thinking of buying a home with a radon mitigation system installed. What should I look for in order to make certain it is working properly?

Look at the system to locate any information regarding who installed it and any warranty information. This information may be found near the pressure gauge on the system. If none can be found, or the installer is no longer available, contact a certified mitigation specialist to inspect the system.

What are the advantages and disadvantages to having a mitigation system installed?

The primary advantage is a lower radon level in your home if the system is installed and operating correctly. A disadvantage is a small increase to your energy bill due to a small fan continually running. An additional disadvantage may be the noise of the fan from an improperly installed system.

We are thinking of selling our house and buying another. Where can we get some guidance on what to do about potential radon problems at either location?

Missouri currently has no regulations regarding radon testing, however, the EPA's Home Buyer's and Seller's Guide to Radon is loaded with testing suggestions and other information regarding real estate transactions that you may find very helpful. Radon testing is suggested whenever real estate transactions are made, and when selling a home radon mitigation systems should be noted on the Seller’s Disclosure.

Are there other symptoms of health problems, other than lung cancer, that are associated with radon gas exposure?

There are no short-term radon exposure symptoms that have ever been documented. You will not have any other bodily symptoms such as joint pain, stomach or intestinal problems, headaches, or rashes from short-term radon exposure at natural environmental levels. Radon is not chemically reactive with other substances, so radon will not cause allergy symptoms that may be experienced when encountering dust, pollen or mold.

Learn More About Radon

Missouri Radon Poster Contest Winners

2023 Winner

Radon Causes Lung Cancer

2022 Winner

Test Your Home for Radon

2022 Winner 2

Radon 2nd Leading Cause of Lung Cancer

2022 Winner 3

Rason Is...

2022 Winner 4

Radon, the Silent Killer

2021 Winner

Radon, please test

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