What is Radon?
Radon is a radioactive gas which comes from
the normal breakdown of uranium in rocks, soil and water throughout the world.
You can’t smell, taste or see radon
in the air. But it’s in the environment both outside and indoors, and is unique in that it is an indoor air contaminant
from a natural source.
Concern about levels of radon in homes and businesses is the result of extensive research that
has proved exposure to the gas causes lung cancer in underground miners who work with uranium.
How Radon Causes Disease
Radon has a half-life of three and a half to four
days. In other words, half of a given amount of radon takes over three days, but less than four, to decay.
The breakdown
products of radon, also known as radon progeny or the daughter products of radon, are a series of solid elements including
lead-214, polonium-214 and polonium-218. These elements give off alpha particles of radiation. Alpha particles, unlike gamma
radiation, cannot deeply penetrate the tissues of your body, but they do contain sufficient energy to permanently change the
structure of your DNA.
If the breakdown elements of this gas reach your lungs, these alpha particles can damage the
cells lining your lungs and increase your risk of developing lung cancer, especially with chronic, long-term exposure.
Lung Cancer in Miners
Radon is a very well-studied carcinogen. The
scientific community has learned how inhaling radon delivers radiation to the lungs, and how the particles from the radon
progeny can damage human cells.
The link between working in underground mines and high death rates was recognized in
the mid-1500s, before radon was even identified as an element.
In the early 20th century, scientists linked lung cancer
in miners with the high levels of radon found in mines in Czechoslovakia and Germany. In the 1950's, researchers determined
it was radon’s breakdown elements and not the gas itself that caused cancer.
In the United States, increased incidence
of lung cancer in Mormon and Native American miners was of particular interest since these groups normally have low rates
of the disease overall.
subsequent epidemiologic studies in the 1950’s and 1960’s confirmed the direct connection
between radon exposure and lung cancer in miners.
Radon exposure in cigarette smokers is particularly dangerous, because
radon breakdown elements attach to the particles in cigarette smoke and lodge in the lungs. The combination of the two carcinogens
creates a much greater risk for lung cancer than either factor by itself.
How
Much Radon is Safe?
Radon levels inside most homes are normally significantly lower than in uranium
mines. However, it has been discovered that the range of levels of exposure found in heavily contaminated homes can be the
equivalent of levels found in mines, and may actually exceed the established standards permitted for underground miners!
The
EPA has developed guidelines for maximum tolerable levels of radon in homes by extrapolating data from high occupational exposures
in the mining industry to the much lower residential exposures.
Radon is measured in picocuries per liter of air, or
pCi/L. A measurement of 0.4 pCi/L is a typical level of radon in outdoor air and 1.3 pCi/L is the average level for indoor
air.
According to the EPA, an average annual indoor level at or above 4 pCi/L is unacceptable. Regularly inhaling that
amount of radon inside your home or office carries about the same risk for lung cancer as smoking half a pack of cigarettes
a day ...
At the end of this article I will give you some guidelines for how to measure and minimize the radon levels
inside your home.
Sources of Radon Exposure
You
and your family are exposed to radon in your home, at the office, at school, in commercial buildings -- inside every structure
you enter.
Radon in the outside air disperses before it reaches high levels of concentration, but in tightly sealed
or poorly ventilated indoor spaces, even low levels of radon can accumulate and pose a significant health hazard.
The
radon gas emitted by soil and rock can seep into buildings through gaps in the foundation, construction joints, and through
cracks in floors and walls. Since radon levels are highest in rooms closest to the ground, if you spend a lot of time in basement
rooms at home, work or school, your risk for exposure could be greater.
Soil radon levels vary widely across the United
States and depend on the geology of the area. Regions of the Mid-Atlantic States and the upper Midwest have higher radon levels
than those found in the southeast and west into Texas, and along most of the west coast.
In 1998, the EPA estimated
that as many as eight million U.S. homes have elevated radon levels. To find out what the natural radon levels are in your
area, check out the EPA’s radon map.
Keep in mind that elevated radon levels have been found in almost every state,
so be careful not to make assumptions about the safety of your own home based on this map. You will still need to measure
the radon levels in your home or office to determine whether or not you may be exposing yourself and your family to dangerous
levels.
What is Your Exposure Risk?
Your radon
exposure risk will depend on:
The levels of radon in your indoor environments
The amount of
time you spend in those environments
Whether or not you are a smoker
Naturally, your radon
exposure is likely to be very high if you work in an underground mine (uranium and some other types as well) or a uranium
processing facility, if you live near a uranium mine (although few facilities are still in operation), or if you come in contact
with phosphate fertilizers.
You can also be exposed to radon gas through drinking water. As the radon is released from
the water into the air, you can inhale it into your lungs.
The risk of exposure from water is minimal, unless you happen
to use a deep, underground well sunk into rock with a high radium concentration. Water from such a well could have a high
level of radon, but surface water from lakes and rivers has very low radon levels.
Radon exposure can also come from
certain building materials, including:
Silicone-rich magmatic rocks, particularly granite, and especially the
more exotic granites like the red, pink and purple varieties
Gypsum waste products
Cement
Concrete
Pumice
Basaltic
rock
How to Test Your Indoor Environments for Radon
There
are a number of things that can cause indoor radon concentrations to vary. The EPA recommends you perform long-term rather
than short-term measurements in order to make the most accurate assessment of consistent radon levels in your home or office.
Indoor
radon concentrations can be affected by;
The type and operation of ventilation systems
All forces
which affect indoor air pressure, such as window openings, window fans, driers, and fireplaces
Weather
Water
usage
The time of day
Different areas inside your home or other structure
Common
types of test kit detectors include charcoal canisters, alpha track devices, electret ion chambers, continuous monitors, and
charcoal liquid scintillation detectors.
Test kits are placed in your home for several days, up to as long
as three months, and then are mailed to a laboratory for analysis.
Using a Geiger
Counter to Measure Radiation
If you want to find out if items in your home are emitting
radiation (for example, if you have a specific concern about your granite countertops and in what amounts, you can use a Geiger
counter.
A Geiger counter measures alpha, beta and gamma radiation. It won’t detect the presence of radon gas
in your indoor air, however it can be a useful tool to locate the sources of radiation inside your home or other building.
What You Can Do To Reduce Radon Levels in Your Home
It is estimated that
one in 15 homes has a radon level at or above the EPA action level of 4 pCi/L. Scientists estimate deaths from lung cancer
could be reduced by two to four percent, or about 5,000 deaths, by lowering radon levels in homes exceeding the EPA’s
action level.
You can reduce your own and your family’s health risk even further by lowering radon exposure in
your indoor environments to levels well below EPA guidelines, and I would strongly encourage you to do so.
There are
a variety of ways to reduce radon levels in your home, including:
Sealing cracks in floors and walls
Increasing
ventilation through sub-slab depressurization with pipes and fans
Removing granite countertops if they are
emitting high levels of radon
The cost of radon reduction measures depends on the size and design of
your home and the specific methods needed. Costs range from $800 to $2,500, with an average cost of $1,200.
If you’re
building a home or other structure, insist on building materials that are more resistant to the naturally occurring radon
in the outdoor environment.
The five basic features of a radon-resistant home are:
Gravel laid below
the foundation which allows radon in the soil to circulate freely underneath your house
Plastic sheeting or
other vapor retarder laid over the gravel to stop soil gases from entering the structure
Vent pipe run vertically
from the gravel layer up to the roof to safely vent radon from the soil outside the house
Sealing and caulking
of all cracks, crevices and other openings in the concrete foundation and the walls of the structure
Electrical
junction box installed in the attic for use with a vent fan, should one be needed
For more information on
Radon-Resistant New Construction (RRNC), visit the EPA website
