Radon is a radioactive gas that is present in all soils around the world. It is a natural byproduct of the radioactive decay of Uranium. Because it is a gas, radon easily transmits through small gaps and holes inside homes, and is susceptible to natural pressure movements in the environment. The harmful effects of radon have only recently been discovered – a study in the 1950’s confirmed increased incidents of lung cancer in underground miners. Later, in the 1980’s, further studies determined that radon in homes can exceed exposures found for mine workers. It was only in 1988 that the EPA began recommending all homes be tested for radon.
As the leading cause of lung cancer among non-smokers, it is essential to determine exposure levels to this toxic gas. Testing is simple and inexpensive to do, and mitigation can be simple depending on the levels present in the home.
Any home can have a radon problem.
Testing is the only way to know.
Short Term Testing
Short term tests are measurements done between 2 and 90 days. Typically these are done in real estate transactions where there is a limited time frame to get results. Because radon can fluctuate significantly throughout the year, a short term measurement can not be extrapolated to estimate year long exposure. However, it is still incredibly useful information to help determine risk, and the transition occurring between the transaction is great opportunity to test the home.
Long Term Testing
Long term tests are measurements taken for longer than 90 days, and up to a year. These tests are the best way to determine year-long average exposure to radon. These tests are best for home owners who are concerned about the levels in their current home.
Great Home Inspection recommends testing for radon in every real estate transaction. If the test results are below EPA action levels, then risk for exposure is low, and a follow up short term test can be done in 4 to 6 months to be sure. If the results are at or above action levels then GHI recommends mitigation.
How Much Radon Is Too Much?
Because radon is found in almost all soils, it is also found in almost all air. The average amount of radon found in outdoor air is estimate to be 0.4 pCi/L. The average amount of radon in indoor air is estimated to be 1.3 pCi/L. While there is no safe level of radon, there is a practical minimum level that can be achieved through mitigation in homes.
The level that the United States Enviromental Protection Agency (EPA) recommends mitigation is at 4pCi/L, and encourages consideration if the levels are bewtween 2pCi/L and 4pCi/L.
Test Condition Requirements
Closed-building conditions are required to test for radon if the test is to last less than 91 days. This calls for several factors:
- Windows and doors need to stay closed for the duration of the test (doors can be used for normal entry and exit).
- Heating and cooling systems should remain in normal operation.
- Window units must be set to lowest outdoor ventilation settings.
- Ceiling fans should not be operated
- Fireplaces should not be operated unless they are a primary source of heat for the building.
- Avoid excessive operation of dryers, bathroom vent fans, and range hood fans.
For short term tests lasting 2 to 7 days, closed home conditions need to be in place at least 12 hours prior to testing, and through the entire duration of the test.
Choosing A Test Location
The test should be conducted in the lowest “lived in” level of a home. If the basement is not currently finished, but could serve as a work space, playroom, or will be finished in the future, a test should be conducted at this level.
Tests conducted above basements may fail to characterize radon hazard if heating / cooling systems are not active in order to circulate air throughout the home.
If a home is over 2,000 square feet additional test locations are recommended. More testing locations are also advised if different areas of the home are served by different HVAC systems and in areas above unique foundations.
It is not recommended to perform tests in bathrooms or kitchens due to thigh humidity levels, which can effect the testing equipment.