Prior to purchasing a home, a family contacted John to conduct radon testing with electronic monitors, following the EPA’s protocol. Closed — house conditions were established 12 hours prior to testing and were maintained throughout the tests. During the testing, one of the electronic monitors located in the dining room indicated 12.5 picocuries of radon per liter of air, while a monitor elsewhere showed close to normal levels. The client was advised that the electronic readings were suspicious and that additional testing was necessary. As the investigation proceeded, it became clear that there was a radon source at one end of the home. In fact, the radon result for a test conducted on a night table in the guest bedroom was 27.0 picocuries, while that for the family room a short way down the hall was 7.0 picocuries. The farther the monitors had been placed from the guest bedroom, the lower the radon value.
Upon visual examination of the guest bedroom, it was noted that the headboards for the two beds were made of rock that appeared to be granite. The headboards were later tested with a small Geiger counter. While normal radioactive background levels away from the headboards were approximately 12 radioactive counts per minute, the counts close to the headboards were over 300. It was clear that the headboards were at least one source of radon in the room.
The headboards were in fact a decorative granite rock imported from Italy. Each headboard weighed several hundred pounds. The floors and walls had been especially constructed to hold the extra weight. It took six strong men to remove each of the headboards to a detached garage. The radon tests were repeated throughout the home with all values now under 1.0 picocurie. The home was given a radon clearance, contingent upon the proper disposal of the headboards.
Discussion
This was the first home John inspected in which a radon source was caused by a building material or furnishing. Although radon from the soil is the most common cause of elevated radiation levels in a home, there are many other possible sources. Since granite rock is sometimes high in uranium, it must be considered a potential source of radon when used in construction. Rock can be a superb building material, but it should always be tested prior to use for the rare possibility of radiation.
