Interpreting Results
of Radon Measurements
Initial Measurement
How soon to fix
your house
Initial Measurement
You can test your own home. Your first radon measurement should be made for a few days
(two days, minimum) in the lowest lived-in level of your home, with the windows kept
closed, as recommended in the U.S.
EPA's Citizen’s Guide to Radon. (exit DHS)
A basement can be considered lived-in (for radon testing purposes) if it is occupied at
least 7 hours per week. Otherwise the main floor is the best place to test or do a
follow-up test. Suitable radon detectors are available from hardware stores or through
your local public health agency or Radon Information Center for around $20, including
laboratory processing. (The testing
procedure recommendations for real estate, (exit
DHS)
in the case that a home is being sold, can
be somewhat different, and are given in the US EPA’s Home Buyers and Sellers Guide to
Radon.)
Your test results will be reported in units of pCi/L, a measure of radon concentration.
Appropriate follow-up actions, based on the results of your first measurement, are:
First result less than 4 pCi/L:
No follow-up needed. Your home has low radon levels.
First result between 4 and 8 pCi/L:
Do a year-long follow-up measurement with an alpha-track detector to determine your
average radon exposure. Radon levels may change with seasons, and are low when windows are
open. The average radon level in occupied floors of your home determines you lung cancer
risk from radon exposure.
First result above 8 pCi/L:
Do a short term or long term follow-up to confirm the accuracy of your first result.
If follow-up measurements indicate your radon exposure is higher than 4 pCi/L (the U.S.
EPA guideline), it can be significantly reduced. The higher your confirmed radon results
are, the more important it is to fix your home. Outdoor air has about 0.4 pCi/L, and this
is the lowest achievable level in a house. The average radon level in the lowest lived-in
floors of homes in Wisconsin is about 1.8 pCi/L. Twenty-five per cent of the homes in the
state have radon at over 4 pCi/L in basements, and in some regions
of
the state more than half the homes are over 4 pCi/L in the basement. But not all those
basements are significantly occupied. It is important to have tested the radon in spaces
that are occupied for several hours a day, where the occupants most often spend their
time.
High levels of radon are dangerous to you and your family. When follow-up
radon measurements in occupied levels of your home are high, you should take bids on radon
mitigation work by professionals included on the list of certified
radon mitigation contractors. Having
this work done will protect your family and it will increase the value of your house.
How Soon to Fix Your House
If results in occupied levels of your house are confirmed to be in the range of 4 to 20
pCi/L, it may reasonably take up to a year to get the work done. For confirmed results
above 20 pCi/L, mitigation action should probably be more prompt. Consult one of the Wisconsin Radon Information Centers, toll-free
at 888 569-7236.
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