Revisiting Radon Gas and Radon Mitigation Systems

What is Radon Gas?

Radon is a colorless, odorless, radioactive gas which  occurs  naturally  from  the decomposition of uranium and is found in varying amounts in virtually all soils and in every state. It poses little to no health risk when allowed to dissipate in open air, but can present a significant health risk over time if it becomes trapped and accumulates in buildings. Radon gas rises through cracks and fissures in the earth’s surface, and enters homes through cracks or holes in the foundation or walls, in gaps around service pipes, around construction joints, and sometimes in water if the source is groundwater, rather than surface water.

What Level of Radon Gas is Safe?

Theoretically, any amount of radon poses some health risk since it is radioactive. The danger comes more from breathing radon. If radon is in the groundwater, then the gas is released whenever water is used. Radon gas decays into radioactive particles which become trapped in the lungs and as they continue to decay, they release small bursts of energy which can damage lung tissue and lead to lung cancer. The Environmental Protection Agency (EPA) recommends that indoor radon levels not exceed 4 picocuries per liter (pCi/l) of air.

Is the Presence of Radon Gas a Material Fact that Must Be Disclosed?

If a broker knows that dangerous levels of radon are present in any structure which will be occupied regularly by people, then the broker must disclose that to all prospective buyers or tenants.

A broker is not expected to test all properties for radon. However, a broker listing a property should have the homeowner complete the Residential Property and Owners’ Association Disclosure Form. Question 25 on that form deals with hazardous or toxic substances, including radon gas. If the broker has any reason to suspect that radon may be present at a hazardous level, the broker has a duty to inquire as to whether the property has been tested for radon. If the results of such a test were above the level recommended by the EPA, the broker has a duty to disclose this information to any prospective buyers. A buyer agent should always recommend to a buyer that the buyer have a radon test as a part of their due diligence, particularly if the broker knows that other buildings in the area have unusually high radon levels.

How Are Radon Levels Determined?

It is extremely easy to test for radon in a home or business. There are several “do-it-yourself” kits which may be purchased in hardware stores or from the EPA or over the internet and there are qualified testers trained to conduct such tests. A list of qualified testers may be obtained from the North Carolina Department of Environment and Natural Resources, Division of Radiation Protection at Test kits can be ordered from the same website. There are both short-term and long-term tests available. Radon levels may vary from day to day and season to season and may be influenced by severe storms or high winds. Short-term tests are less likely to render an accurate picture of the year-round average radon level but do provide immediate feedback. They generally take a couple of weeks to get results. If the results are 4.0 pCi/l or above, it is recommended that a second test, either short-term or long-term be conducted. Long-term testing generally takes more than 90 days. Long-term tests will provide a more accurate reading of the year-round average radon level.

What if the Seller Installed a Radon Reduction or Mitigation System?

If a seller had a radon problem in the past, but installed a radon reduction system to remediate the problem and bring the radon within acceptable EPA levels, is the broker required to disclose the presence of the system?  In the 2008-2009 Update Course, Commission staff stated that the system was installed to remedy an existing problem which could reoccur if the system failed to operate correctly and therefore the mere presence of the system should be viewed as a material fact and disclosed to prospective purchasers. However, since that time radon mitigation systems have become far more common and are often being installed in new construction homes with no history of radon gas. Such systems are often included as part of a green building program or as a feature in new homes since installation at the time of construction is much less expensive than installing an after-market system. In order to not stigmatize such homes as this feature becomes more prevalent, the Commission has since revisited the issue and determined that the mere presence of a system is not, in and of itself, a material fact but the best practice for a listing broker is to disclose and let potential buyers make a fully informed decision before they go under contract. When a radon mitigator system is evident, buyer agents should inquire as to why a mitigater system was installed. And, buyers should be advised to have the property tested for radon gas and have the mitigation system tested to be certain it is functioning properly as part of their due diligence if they are interested in purchasing the home.

The North Carolina Radon Program at provides much helpful information about radon including a map showing various radon levels across the state.

This article came from the May 2017-Vol48-1 edition of the bulletin.