Radon is a colorless, odorless gas released from the breakdown
of uranium and radium, which is found in rocks and
soil and sometimes in water. The gas enters the house primarily
through cracks and gaps in the foundation, floor
drains, and sumps, and concentrations build up indoors.
Radon can also enter the home through well water and be
released during showering or other uses. In rare cases, it is
found in masonry building materials. Radon is thought to
be the second leading cause of lung cancer in the United
States, after smoking (Table 7-6).
Radon is drawn into buildings by the stack effect and
by depressurization from mechanical equipment. During
warm weather when the stack effect is reduced and buildings
are often well-ventilated, indoor radon levels are usually
one-third or more lower. Also, levels in the basement
are typically over twice the level on the first floor.
Health Effects of Exposure to Radon
Radon gas breaks down into short-lived
decay products that can be inhaled either unattached or attached
to other particles in the air and penetrate deeply into
the lungs. According to its 2003 Assessment of Risks from
Radon in Homes, the EPA estimates that radon causes
about 20,000 lung cancer deaths annually in the U.S.
This
makes radon the second leading cause of lung cancer in
the United States, where an estimated 1 out of 15 homes
has elevated levels. The cancer typically occurs 5 to 25
years after exposure, and the risk goes up dramatically if
the person is also a smoker (see Table 7-6, Lung Cancer Risk from Radon Exposure, below).
Lung Cancer Risk from Exposure to Radon
Levels of Radon in Drinking Water
While much less of a problem than
airborne radon, radon in water is also a concern. If
indoor radon levels are high and the household uses
well water, the water should also be tested. In
general, every 10,000 pCi/L of radon in household
water contributes about 1 pCi/L (picocuries per liter)
of radon to indoor air level.
The radon gas is released
from the water when it is aerated during showering,
washing dishes, or laundering. There also may be an
increased risk of stomach cancer from swallowing the water.
According to the Centers for Disease Control, ventilating bathrooms, kitchens, and laundry rooms is usually adequate to reduce risks from radon in water.
However, where water levels are high, the radon can be removed by aeration treatment or carbon filtering.
see Radon Enviro-Scare for a full discussion of the normal cycle of public fear that accompanies the discovery and publicity of various environmental hazards, including radon gas and see Enviro-Scare, the Cycle of Public Fear for our article about consumer environmental safety worry cycles that change over time.
For a Thorough Background in Radon Hazards, Radon Mitigation, & the History of Radon Concerns in the U.S. also see these articles reprinted/adapted/excerpted with permission from Solar Age Magazine - editor Steven Bliss.
"Radon's Threat Can Be Subdued", part 1 - William Turner, Terry Brennan, Solar Age MagazineRadon and its progeny are the slipperiest pollutants in the indoor environment, but there are simple ways to keep radon and its relations at bay.
"Radon's Threat Can Be Subdued", part 3 - standards for airborne radon levels in buildings and recommended levels of radon for action, how radon is best detected, and radon action plan.
"Radon's Threat Can Be Subdued", part 4 - radon prevention advice for new construction, radon in well water - how it is removed, sources of information about radon gas and radon contamination.
"Defeating Radon" part 1- Terry Brennan, Bill Turner, Solar Age Magazine - How does radon get into buildings, how do I know if a building has a radon gas problem, how can I solve radon problems in existing homes, and what can I do to prevent radon from entering new homes. Part 1: where Radon comes from, how to diagnose radon
Steven Bliss served as editorial director and co-publisher of The Journal of Light Construction for 16 years and previously as building technology editor for Progressive Builder and Solar Age magazines. He worked in the building trades as a carpenter and design/build contractor for more than ten years and holds a masters degree from the Harvard Graduate School of Education.
Excerpts from his recent book, Best Practices Guide to Residential Construction, Wiley (November 18, 2005) ISBN-10: 0471648361, ISBN-13: 978-0471648369, appear throughout this website, with permission and courtesy of Wiley & Sons. Best Practices Guide is available from the publisher, J. Wiley & Sons, and also at Amazon.com.
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