Radon Testing

Radon Testing

testing_iconRadon Testing and Test Results

MDH recommends that all Minnesota homeowners test their homes for radon. A radon test is the only way to find out how much radon is in your home and if you and your family are at risk. Performing a radon test on your own is easy, inexpensive and takes only a few minutes of your time. The results of a properly performed radon test will help determine if you need to take further action to protect yourself from the health risks of radon.

Can a neighbor’s test results be an indication of whether my home has a problem?

A neighbor’s test result is a poor predictor of your radon risk because each home can have different indoor radon levels. Furthermore, previous test results may not reflect current or future radon levels if the home has been remodeled, weatherized or had changes to its heating, air conditioning or other ventilation systems (such as exhaust fans).

What type of radon test kit should I use?

There are two basic types of radon tests available to the public, short-term and long-term tests.

hare, representing short-term testing is quick, but not always best Short-term tests┬ámeasure radon levels for 2 to 7 days, or use a continuous radon monitor for a minimum of 48 hours, depending on the device. While short-term tests do not measure the annual average of level of radon, they do offer a quick and inexpensive way to “screen” for radon in a home.
turtle, representing long-term testing is slower, but is best Long-term tests determine the average concentration for a minimum of 90 days. Long-term tests are the best way to estimate the average amount of radon in the home during the year, particularly if a year-long test is done to include both heating and cooling seasons.


Radon test guidelines

  • Time of year to test: The amount of radon in homes is usually highest during the heating season. Long-term tests should span both heating and non-heating seasons.
  • Weather patterns: Weather patterns can influence how radon gets into your home. Short-term tests should not be conducted during severe weather or unusually high winds.
  • Test location: Test the lowest level of the home that is regularly used. For example, if you spend more than 8 to 10 hours a week in the basement, MDH recommends testing the basement.
  • Disturbances: Place the test kit at least 20 inches above the floor in a location where it won’t be disturbed — away from drafts, high heat, high humidity and exterior walls. Test kits that are distributed or moved during a test may provide inaccurate results.
  • Timeliness of analysis: Once you’ve finished, reseal the package and send it to the lab specified on the package. Radon test results may not be accurate if the test kits are not sent to the laboratory as soon as possible after completing the test.

How often should I test for radon?

  • MDH recommends every Minnesota home, even those built radon-resistant, be tested for radon.
  • You should retest your home every 2 – 5 years and save your results.
  • Be sure to test before and after you make any major structural renovations such as building an addition or finishing a basement. Radon-resistant techniques can be inexpensively included as part of the renovation, if needed.
  • You should also perform a radon test after buying a new heating system or adding central air conditioning.

Test Results

The table below provides recommendations on the action to take based on the type of radon test you used and the test results you received. These recommendations are different than test results during a real estate transaction.

Test Type Result (pCi/L) Recommended Action
Short-term Test

hare, representing fast test

Less than 2 Consider performing a long-term test.
2 to 8 Perform long-term test.
Greater than 8 Perform a second short-term test. Contact MDH before buying second test kit.
Short-term Test
hare, representing second fast test
Less than 4 Perform long-term test.
4 or greater Mitigation strongly recommended if first test result was also 4 pCi/L or greater.
Long-term Testturtle, representing slower Less than 2 Retest if major changes made to the home.
2 to less than 4 Consider performing mitigation.
4 or greater Mitigation strongly recommended.


What are the units of radon?

Picocuries per liter (pCi/L) which is a unit that measures levels of radon/radioactive gas.

What is the recommended action based on my results?

The Environmental Protection Agency and MDH set the recommended action level for radon at 4.0 picocuries/liter(pCi/L). To apply the recommended action level correctly, the results should be based on the annual average level of radon measured in a home. If the annual average level of radon in a home is above 4.0 pCi/L, the EPA and MDH recommend that steps be taken to lower it. While it isn’t possible to reduce radon to zero, the best approach is to lower the radon level as much as possible. Any amount of radon, even at or below the recommended action level, carries some risk.

How much radon is safe?

There is no safe level of radon. Your risk for lung cancer increases with higher levels of radon gas and increased exposure.

The following table estimates your lifetime risk of lung cancer death due to long-term exposure to radon.

(Annual Average)
Lung Cancer Risk
for People Who Never Smoked
Lung Cancer Risk
for People Who Smoke
20 pCi/L 36 out of 1,000 260 out of 1,000
10 pCi/L 18 out of 1,000 150 out of 1,000
8 pCi/L 15 out of 1,000 120 out of 1,000
4 pCi/L 7 out of 1,000 62 out of 1,000
2 pCi/L 4 out of 1,000 32 out of 1,000

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