I cannot stress the importance
of the following information! Testing is the only way to know whether
or not your home has a Radon problem. Don't listen to people who tell
Many times neighbors or real-estate agents make claims such as, " I
know this neighborhood and there's no radon.", or "My neighbor down the
street didn't have radon, so I don't either.", or even "I have a new home.
Radon is only in older structures.". The list goes on and on.
In 1997 I encountered a classic example of the dangers of not testing
for radon. I was called to test a home for radon in Carroll County, Maryland.
The homeowner had been there for five years. The family was quite large
(5 children) and the lack of bedroom space required that three of the
children sleep in the basement.
After inspecting the house, I was told by the homeowner that when he
purchased the home his realtor had assured him that the house was radon
free. Fortunately for the homeowner, he had taken it upon himself to have
his home tested. He was quite confident that the house would have no problem
with radion. You can imagine his shock when he found out that the radon
level in the basement was 300 pCi/L!
The point I'm trying to make is, whether you believe in the radon issue
or not, EVERY HOME HAS THE POTENTIAL OF HAVING A RADON PROBLEM!
If you don't test, you'll never know.
Finally, consider the possibility you've decided to sell your home. Having
it tested for radon will allow you to more accurately adjust your asking
price. Testing will also save you the time and expense of correcting a
radon problem should a potential buyer decide to do his or her own test
just prior to settlement. Finally, a house that is advertised as tested
and mitigated for radon will be more attractive to buyers and will probably
There are two types of testing. Short Term Testing and Long Term Testing.
SHORT TERM TESTING:
This is the most common type of testing done in the industry
today. This type of testing is usually 2-7days of exposure to a testing
device. It is primarily used in real-estate transactions. Since most radon
addendums that are attached to real-estate contracts put time limits on
buyers to find out if a problem exists, this type of testing is the only
way to meet the time line.
The testing devices used in this type of testing are Charcoal Canisters,
E-perms, or Continuous Monitor Devices. There are pros and cons to each
type of short term test which are covered later.
LONG TERM TESTING:
Homeowners that are concerned with the overall annual radon
level usually use this type of testing. In some cases short term testing
may show levels of 3.9 pCi/L or 4.6pCi/L. In this situation the homeowner
may do a long term test which might show annual levels of only 2.6 pCi/L
which would not require a radon mitigation system. This type of testing
is ideal for radon levels that are close to the E.P.A. action level of
4 pCi/L. This type of testing device is called an Alpha-track.
NOTE: If you are involved in a real estate transaction this
test is not an option for you because of the time constraints.
What follows in an overview of radon testing devices, a brief description
of their functions, and pro's and con's of each devise. Your testing device
might look different or have directions contrary to this information.
Always follow the directions in the testing kit or those given by a licensed testing contractor.
Charcoal canisters: This device uses activated charcoal
in a canister to absorb the radon-laden air in the testing area. Exposure
time is 2-7 days. When testing is completed the charcoal canister needs to be analyzed as soon
as possible by the laboratory who sold the device. Radon levels are determined
by the gamma emissions coming from the canister.
- low cost testing
- simplicity of use
- easy to mail
- measurements biased to the last 12-24 hrs
- sensitivity to temperature and humidity
- sensitivity to air flow extremes
E-PERM: This testing device uses an electrostaticaly charged material that looks
like a Ritz cracker inside a plastic chamber. When radon enters the chamber
the voltage inside the chamber drops. Therefore, the amount of voltage reduction
is directly related to the radon concentration and the length of exposure.
- low cost testing
- measurement analysis can be done on site with
a special electric reader
- devise can be used multiple times until voltage
- trained tester needed to use devise
- special equipment
needed for results
- device sensitive to background radiation
Continuous Radon Monitors: This testing device uses electricity. It is a complex unit
that measures the radon in a tube called a scintillation cell/photomultiplier.
As the radon gas enters this chamber the devise counts the break down of
the gas. When radon decays it goes from a gas to a solid, when this happens,
a mini explosion occurs. This device counts the flashes of light the decaying
process produces. The number of flashes of light corresponds to a specific
quantity of radon.
- very accurate testing
- results not bias to last
- less sensitive to temperature, humidity, air flow
- this type
of testing ideal when time is of the essence
- more expensive than
- need specific knowledge to run devise and interpret results
Alpha Track Detectors: The only true long term testing device (90 day to
one year), this detector works very well and is not as delicate as other
The concept is very simple. Inside of a plastic casing is a special
film. As the radon gas decays from a gas to a solid, the solid produced
strikes the film in the casing leaving a mark on the film that looks like
a crater. After the device has been exposed for 90 day to a year it is sent
back to the lab. The technician counts the craters. The number of craters
multiplied by the length of the test corresponds to a specific radon level.
- low cost
- simple to use
- true integration ( not biased toward
most recent exposure)
- need skilled technician to interpret results
- sampling conditions during the measurement period which could affect results
may be unknown