Radon mitigation system installed (C) Daniel FriedmanImpact of Radon on Home Sales & Property Values

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Impact of radon gas contamination in buildings on real estate property values & home sales:

This article explains the health risks of exposure to radon gas in air or water, and we describe the proper steps to remove radon and improve indoor air quality in homes.

We also provide a MASTER INDEX to this topic, or you can try the page top or bottom SEARCH BOX as a quick way to find information you need.

Effects of Radon Gas Hazards on Real Estate Values & Home Sales

Radon mitigation system as installed, outside view (C) Daniel FriedmanOrigin of the 4 pCi/L Radon Threshold "Standard"

The original US EPA recommendation of "further testing" for homes that measured at 4 pCi/L during a short term screening test has in our opinion led to the installation of thousands of radon mitigation systems in homes at which the average annual exposure to radon gas may have been considerably below that level.

How did this happen? In the U.S., corporations whose employees were often asked to move for business needs were provided an employee benefit: an employee relocation plan that would actually take over ownership of an employee's home if the employee could not complete the sale of their home before having to move to a new location. This benefit avoided the employee having to bear the cost of carrying two primary residences at the same time.

The employee relocation service companies who provided this home management and home resale service to their corporate clients did not want to "take over" responsibility for a home that might give a surprise expense at the time of its ultimate sale to a new owner.

Rather than waiting for the results of a long term radon test to measure the actual annual average radon exposure level, the relocation companies simply required an employee who was planning to place their home into the relocation plan to go ahead and install a radon mitigation system if the initial radon screening test showed a level of 4 pCi/L or above.

While it's not quite clear from the radon risk level table above, notice that little footnote: "based on a person's average exposure over a lifetime".

A thoughtful reading of the EPA's radon risk data showed that the risk of contracting lung cancer from exposure to radon gas at a level of 4 pCi/L could not be measured as any different from random chance in the general population until the duration of the exposure time exceeded 18 hours per day for 70 years.

In other words, for most people, the risk of contracting lung cancer from living in a home at 4 pCi/L is virtually nil.

Smokers are at a much higher cancer risk from radon than non-smokers (about 80 times more risk for the same exposure level as a non-smoker), and the level of risk of cancer from radon exposure increases significantly at higher radon levels.

Graph of level of consumer fear about radon, over time (C) Daniel FriedmanDo Home buyers fear radon? Initially some consumers who were considering buying a home where a radon mitigation system was seen installed were frightened, thinking that the home was dangerous, regardless of the effectiveness of the radon mitigation system and regardless of the original, possibly low initial radon level that led to the installation of that system.

At a home inspection in 1996 radon was tested and later found to be present at a level of less than 1 pCi/L.

The home buyer told the inspector that he intended to demand that radon level in his home be brought to zero, regardless of current best advice on the actual risk level.

Expert opinion was that mitigation of a home for radon at this level was not appropriate, wasted money, and risked stigamtizing the house.

Our graph (above left) plots the level of consumer fear of environmental hazards over time.

As we depict in this normal curve of environmental anxiety, for virtually all hazards, regardless of the level of actual health risk, consumer worry increases as media attention focuses on a given concern, then decreases over time as people become accustomed to the topic.

Currently the home buying public has become accustomed to radon mitigation systems and the remaining level of consumer worry is small in our opinion. However public fear about environmental hazards, once roused, never falls again to zero, regardless of the actual level of risk.


for a full discussion of the normal cycle of public fear that accompanies the discovery and publicity of various environmental hazards, including radon gas and see ENVIRO-SCARE - PUBLIC FEAR CYCLES for our article about consumer environmental safety worry cycles that change over time.

For a Thorough Background in Radon Hazards, Radon Mitigation, & the History of Radon Concerns in the U.S. also see these articles reprinted/adapted/excerpted with permission from Solar Age Magazine - editor Steven Bliss.

US EPA Radon Zone Map

Are Granite Countertops a Dangerous Source of Indoor Radiation Hazards?

Question: can you tell me how to test for dangerous radiation from granite kitchen countertops?

I am buying a home that has extensive granite countertops in the kitchen, bar, bathrooms, and a workshop. I'm worried that these may be a source of dangerous radiation. How can I test for radiation from granite countertops? - M.C., New York.


Radiation coming from granite countertops results from natural radioactive material in the granite. Identifying the presence and concentration of radioactive elements in granite requires expensive and sophisticated portable instruments or laboratory equipment.

These instruments and equipment require proper calibration, and interpretation of their readings requires a knowledgeable and trained user. At this time, there is no generally accepted home testing protocol for radiation in granite countertops.

At the website maintained by The Conference of Radiation Control Program Directors (CRCPD), you can find contact information for each state's radiation protection program. Please visit, , to find information for your state. - Quoting from Granite Countertops and Radiation Hazards, [PDF] U.S. EPA,

However we add that you should have your home tested for high levels of radon gas, as a normal "due diligence" test in buying a home, unless that testing has already been properly performed and documented, in which case you might first check to see those reports.

This article includes excerpts or adaptations from Best Practices Guide to Residential Construction, by Steven Bliss, courtesy of Wiley & Sons.

Radon Gas Hazards Articles


Continue reading at RADON MEASUREMENT GUIDE or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.

See RADON HAZARD TESTS & MITIGATION for details about radon in buildings, its health effects, how to measure radon, the effect of radon contamination on real estate values and home sales, and a guide on how to remove radon from buildings.

Or see ENVIRONMENTAL HAZARDS - INSPECT, TEST, REMEDY for our full list of environmental hazard identification and remedy related to buildings.

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RADON IMPACT ON HOME SALES at - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.


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