Hope this does not get double-posted. Had a problem when I tried to
post just now.
Radon can be present in any home of any type of construction. A vapor
barrier in the slab is not a barrier to radon.
Painting the slab will not prevent radon from entering the home.
Cracks in the slab will allow radon to enter the home and so will
plumbing penetrations (e.g., toilets, tubs, waste piping, etc.),
joints between the slab and foundation wall, sump pits, etc. And even
if all these cracks, joints and penetrations are sealed radon can
still pass through concrete because concrete is not impermeable.
Every home should be tested for radon. A home that has had a radon
mitigation system installed should be tested (how else will you know
if the mitigation system is lowering the radon levels below 4 pc/l?).
EPA recommends that every home be tested every two years.
Consider conducting a long-term radon test to get a more real-world
reading of the radon levels present in the home. A long-term test can
be anywhere from 90 days to one year. A one-year test is more
meaningful because it is not as affected by seasonal highs and lows as
a shorter test. You can buy a long-term radon test device (alpha track
device) and conduct your own test for under $50. Make sure you follow
the EPA protocols so the readings are meaningful.
Radon is the second leading cause of lung cancer behind smoking. EPA
says over 20,000 people die in the US annually from lung cancer caused
by radon. If you smoke your risk associated with radon is increased
anywhere from 15 to 20 times that of a non-smoker. Children are
especially at risk to radon. Visit www.epa.gov and follow the radon
links to learn more about radon.
I am a NEHA (National Environmental Health Association) certified
Residential Measurement Provider so I do know what I am talking about.