Radon is a naturally occurring
radioactive gas. It is produced in the ground through the normal
decay of uranium and radium. Dig up the top 6 feet of an acre of
land and you will find, on average, about 50 pounds of uranium.
Uranium decays to radium, which then decays to radon.
Radon itself is an inert gas &
poses no danger, but radon decays to polonium & lead particles.
These and later progeny are chemically very active as well as
radioactive. When you breathe, these radioactive progeny lodge in
your lungs, bronchi, and trachea. The radiation disrupts and mutates
cells and can, eventually, result in lung cancer. Radon is estimated
to be the second leading cause of lung cancer in the United States.
It is a potential problem in every state. Its health risk increases
with the length of exposure and concentration level of the radon.
Radon moves through small spaces
in the soil and rock on which a house is built and can seep into a
home through dirt floors, floor drains, sump pits, cracks in the
foundation and basement floor & up through hollow core block
foundation walls. Differences in air pressure between the basement
and the soil beneath the home also play a part in the migration of
radon gas.
The EPA has set the level of
concern at 4 picoCuries of radon per liter of air (4 pCi/L). This is
a concentration of 70,000 atoms of radon in each liter of air (about
2 million radon atoms in every cubic foot of air). This is a very
low concentration, roughly one radon atom in a billion-billion air
atoms, however, the radon atoms are radioactive and that makes the
difference. We breathe about 20 liters of air into our lungs each
minute. At 4 pCi/L we accumulate about 10,000 radioactive atoms in
our lungs, trachea, and bronchi every minute.
You must use qualified
methods. These include short term (2-7 days) tests with charcoal
accumulors, such as that patented by NITON, and long term (3-12
months) that do the testing by alpha track or electret. The EPA
recommends a short term charcoal test for first time testing.
Choose one that has passed EPA testing.
There are several remedies
for reducing radon concentrations in the home. The most widely
used method is the "sub-slab depressurization" system. This
involves the installation of pipes and fans. This system
prevents radon gas from entering the home from below the
concrete floor and the foundation. Radon reduction contractors
may also use other methods depending upon the design of the
home. In addition to the installation costs, there are also
operating costs. Ways to reduce radon are discussed in the EPA's
Consumer Guide to Radon Reduction, call you state
radon office to obtain a copy. Installation costs to lower radon
levels can range from $500 to about $1000. Be sure the
contractor is listed with the EPA's Radon Contractor Proficiency
Program.