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What is Certified Radon Testing?
Certified radon testing means that your radon results are interpreted
by a person who has completed training provided by a US EPA
regional radon training center and passed a rigorous national exam. In
addition certified radon testing also means:
Test results, tester placement protocols, maintenance procedures,
storage procedures etc. are all subject to a detailed internal quality
Electronic testers/monitors are calibrated, background and/or
performance checked regularly by a certified calibration facility.
Electronic testers/monitors receive annual maintenance reviews and
Electronic testers/monitors are limited in the number of hours they
can be exposed to higher radon levels annually.
Onsite testing procedures and requirements are reviewed verbally
and with handouts ensuring all requirements are understood and
not violated for the duration of the test.
We recommend the use of short-term electronic
“Continuous Radon Monitoring” for the following
The tester/monitor will provide 46-96 readings over the 2-4 days
testing period, versus the 2 readings from charcoal canisters.
The tester/monitor has built-in tamper resistant features indicating if
it was moved and/or loses power. This is vital for our QC program
ensuring the tester was not relocated to upper floor levels where
radon concentrations are often less.
° Charcoal canisters have no controls for monitoring movement after
the test has begun.
The results of the electronic test are known as soon as the test is
completed. Results from a charcoal canister take several days. The
charcoal canisters must be mailed to a lab and the lab must
generate its report.
The tester/monitor with its 46-96 readings will give an overall
impression of home’s Source Strength/Ground Concentration of
How is the Source Strength/Ground Concentration of
radon affected by the weather and the time of year?
The ground for the most part is at a higher barometric pressure than
the atmosphere we breathe. Air and radon gas are continuously
coming out of the ground. During periods of strong winds and/or
storms the barometer is typically lower. The pressure differential
between the ground and the atmosphere (during storms/winds) will
be higher. Gases/fluids naturally go from a high pressure to a low
pressure. This greater differential in barometric pressures between
the atmosphere and the ground will increase the likelihood of higher
quantities of air (radon gas) coming out of the ground and
potentially enter the home below the concrete slab. Factoring in the
potential higher source strength with the barometric pressure
differential, radon concentrations could be noticeably higher still.
The specific highs and lows may peak and ebb constantly during the
test. In addition to source strength, the time of year (snow/frozen
ground) blocks the normal exit of radon gas thus increasing the
potential below the unfrozen basement or main level slab. Proximity
(closeness) to source strength is important. If you live in a home with
only a slab (no basement) you could easily still have a high radon
reading. Besides source strength, proximity to the source strength,
weather events, and time of the year, openings (holes/cracks, etc.)
in the floor may also contribute to higher radon concentrations.
Small cracks/holes, depending on source strength can noticeably
increase radon levels. Taking into account all the variables
mentioned radon levels can range from less than one to double
digits during a short-term test. Charcoal canisters with only 2
readings will not detail the extremes our electronic testers/monitors
produce, thus are a less informative method of testing.
See actual results from test performed during heavy
rains in September 2010
Need more information on certified radon testing?
Charcoal Canisters (short term test): - Tests purchased
through your local hardware store and/or county health
Professional Home Inspection Company discontinued testing with
charcoal canisters in 2005. Charcoal canisters are an accurate,
acceptable means of testing for radon but are limited to only two
readings compared to electronic testers/monitors which will produce
hourly readings for the 2-4 day test. Due to the limited information
provided by a short term radon testing canister, Professional Home
Inspection Company uses only continuous radon monitoring
provided by a certified electronic tester for short term tests. Please
read the above information related to “Source Strength/Ground
Concentration for more information.
Alpha Track Test (long term test):
In the case where a long term test is desired, an Alpha Track
canister is placed in the home for 3 to 12 months. For this method,
the detector is a small piece of special plastic or film inside a small
container. Air being tested diffuses through a filter covering a hole in
the container. As a generally preferred but not mandatory rule, we
recommend running the tests for a longer period, generally 4-6
months in order to account for the seasonal variations of our region.
Alpha track testers are available for home use from a variety of
online and brick & mortar locations. Professional Home Inspection
Company has discontinued providing long term alpha track testing
because such testing kits are now directly available to the general
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