Home & Building Inspection Services
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Testing for radon in the air is important to you and your family's health. However, I do not recommend the short term type of testing which is typically done as part of a real estate transaction. We offer the below excerpts as a concise way for you to understand the differences in short and long term testing of radon in the air. Since a home inspection should give you thorough and accurate information on the day of the inspection, we do not perform radon in the air testing. As you will read below, there are too many factors beyond our control that will have an effect on the accuracy of the test.

The following excerpts have been taken from the website of the US. Environmental Protection Agency and the New Hampshire Department of Environmental Services.

"Because radon levels vary from day to day and season to season, a short-term test is less likely than a long-term test to tell you your year-round average radon level."

A more frequent source of discrepancy between, or misinterpretation of test results stems from a lack of understanding that radon concentrations in homes fluctuate not only from place-to-place within the home, but also from hour-to-hour, day-to-day and month-to-month. The short-term testing devices most often used in real estate transactions are only capable of providing a reading representative of the radon concentration for the time and place the test was conducted. That reading may, or may not, be representative of the annual average concentration throughout the house. In general, the longer the testing period the more closely the result is likely to reflect the average annual concentration at that location. The one proviso is that for long-term test results to mimic annual average concentrations care should be taken to see that the specific testing period contains equal durations of the home heating season and the non-heating season.

For the purposes of real estate transactions the US EPA recommends taking two tests in the same location, either simultaneously or sequentially, and basing a decision concerning mitigation on the average of those two readings.

Certain conditions must be met for the short-term, passive type detectors commonly used to measure radon in indoor air during real estate transactions (activated carbon, alpha trac, and electret detectors). Those conditions include: duplicate tests in the same general location of the house, maintenance of closed-house conditions (close windows and doors and keep them closed, except for normal entry and exit) during the entire test period and for twelve (12) hours prior to starting the test, proper placement of the detectors, (placing the test device at least 20 inches above the floor in a location where it will not be disturbed and where it will be away from drafts, high heat, high humidity, and exterior walls) and a few other criteria.[listed below].

If these protocols are not followed, then the validity of the recommendation to take steps to reduce radon concentrations when they equal or exceed 4 pCi/L may not be applicable.

Preventing or Detecting Test Interference

There is a potential for test interference in real estate transactions. There are several ways to prevent or detect test interference:

• Use a test device that frequently records radon or decay product levels to detect unusual swings
• Employ a motion detector to determine whether the test device has been moved or testing conditions have changed
• Use a proximity detector to reveal the presence of people in the room which may correlate to possible changes in radon levels during the test
• Record the barometric pressure to identify weather conditions which may have affected the test
• Record the temperature record to help assess whether doors and windows have been opened
• Apply tamper-proof seals to windows to ensure closed house conditions
• Have the seller/occupant sign a non-interference agreement.
  Home buyers and sellers should consult a qualified radon test provider about the use of these precautions.

"When radon testing is done outside the confines of a real estate transaction there is time to conduct long-term tests in multiple locations within the building. That is the most reliable means of estimating average exposure and the associated risk.

Continuous monitors do have some advantages that go along with their higher cost of use. They measure radon at brief time intervals to produce a continual "real time" record of the radon concentration. This supplies the user with a picture of radon fluctuation within the house which may be useful in helping to determine the source of the radon and may also provide information concerning whether the testing conditions were maintained during the testing period and/or whether the test result may have been adversely influenced by weather conditions. "

"The most common approach is the use of sub-slab depressurization. In its simplest form the technique involves drilling a hole in the basement floor, excavating some dirt through that hole, inserting a 3" or 4" PVC plastic vent pipe, venting that pipe above the eave of the roof by routing it either through the body of the house (similar to the stack vent for the plumbing) or through the shell of the house and upward along the exterior of the house (similar to the down pipe of a drain gutter). The pipe is fitted with an in-line fan that exhausts outward and depressurizes the area under the basement slab, thus diverting the radon.

In New Hampshire, costs for this service normally range from $1000 - $2000, although this range may vary depending on the distance the contractor may have to travel, complexity of the job and normal market pressures."
For more detailed information, study the websites for the US Environmental Protection Agency at: www.epa.gov/radon/pubs/hmbyguid.html#5.a.

Having read this you understand all the conditions that must be in place in order to acquire an accurate reading of radon in the air of any given home. Since you and I cannot control these conditions prior to the purchase of the house, I would suggest the following course of action:

1. Use the money you might have spent on a short term radon test (whose results will probably not be accurate), and spend that money on a home inspector who has a reputation for thoroughly investigating all the other visible components of the house in question.

2. Once you know the conditions of all the other components, it is time to make the decision on whether or not to purchase the house. Do all the factors pertaining to the house, such as location, price, amenities, condition, etc., meet your criteria? Would you walk away from this house if you knew that radon on the air was higher than 4pci/L, even though reducing the radon could cost as little as $2,000.00?

3. If the other factors have been met, purchase the house. Once you have moved in, you are in a position of control, and can conduct a long term test knowing that the results will be accurate if you have met the conditions required for an accurate reading.

I recommend that all homes be tested for radon. But paying for a test whose results will most likely not reflect the true radon amount seems to me to be a waste of money. Wait until you own the house and have control over the condition of the test, then have a long term test performed.

…W. Liff