Frequently Asked Questions About Radon
Testing Air for Radon
Radon Resistant Construction
Mitigating Radon Problems
Radon in Water
General Questions
What is radon?
Radon is a radioactive gas. It is colorless, odorless, tasteless, and chemically
inert. Unless you test for it, there is no way of telling how much is present.
Radon is formed by the natural radioactive decay of uranium in rock, soil, and water.
Naturally existing, low levels of uranium occur widely in Earth's crust. It can
be found in all 50 states. Once produced, radon moves through the ground to the
air above. Some remains below the surface and dissolves in water that collects and
flows under the ground's surface.
Radon has a half-life of about four days—half of a given quantity of it breaks down
every four days. When radon undergoes radioactive decay, it emits ionizing radiation
in the form of alpha particles. It also produces short-lived decay products, often
called progeny or daughters, some of which are also radioactive.
Unlike radon, the progeny are not gases and can easily attach to dust and other
particles. Those particles can be transported by air and can also be breathed.
The decay of progeny continues until stable, non-radioactive progeny are formed.
At each step in the decay process, radiation is released.
Sometimes, the term radon is used in a broad sense, referring to radon and its radioactive
progeny all at once. When testing measures radiation from the progeny, rather than
radon itself, the measurements are usually expressed in working level (WL) units.
When radiation from radon is measured directly, the amount is usually expressed
in picocuries per liter of air (pCi/L).
What health effects are associated with radon exposure?
The Surgeon General has warned that radon is the second leading cause of lung cancer
in the United States. There are currently no conclusive data on whether children
are at greater risk than adults from radon. No specific subtype of lung cancer is
associated with radon exposure.
Only smoking causes more cases of lung cancer. If you smoke and you are exposed
to elevated radon levels, your risk of lung cancer is especially high. The U.S.
Environmental Protection Agency (the EPA) provides radon risk comparison charts for people who smoke and those
who have never smoked. Stop smoking and lower your radon level to reduce your lung
cancer risk.
Radon gas decays into radioactive particles that can get trapped in your lungs when
you breathe. As they break down further, these particles release small bursts of
energy. This can damage lung tissue and lead to lung cancer over the course of your
lifetime. Not everyone exposed to elevated levels of radon will develop lung cancer,
and the amount of time between exposure and the onset of the disease may be many
years.
Breathing radon does not cause any short-term health effects such as shortness of
breath, coughing, headaches, or fever.
In 1998, the National Academy of Sciences (NAS) released the
Biological Effects of Ionizing Radiation (BEIR VI) Report, "The Health Effects
of Exposure to Indoor Radon." The study reviewed and evaluated data from many prior
studies and drew conclusions. It fully supports estimates by the EPA that radon
causes about 21,000 lung cancer deaths per year. Though some people debate the number
of deaths, it is widely agreed that radon exposure is the second leading cause of
lung cancer.
Research suggests that swallowing water with high radon levels may pose risks, too,
although risks from drinking water containing radon are much lower than those from
breathing air containing radon. A NAS report on radon in drinking water, "Risk Assessment of Radon in Drinking Water," was released
in 1999. It concluded drinking radon in water causes about 19 stomach cancer deaths
per year.
The EPA provides more information about health effects from radon in their publication,
Radon—A Physician's
Guide.
What is the "acceptable" level of radon in air?
The EPA states that any radon exposure carries some risk; no level of radon
exposure is always safe. However, the EPA recommends homes be fixed if an occupant's
long-term exposure will average 4 picocuries per liter (pCi/L) or higher.
What is a "picocurie" (pCi)?
A pCi is a measure of the rate of radioactive decay of radon. One pCi is one trillionth
of a Curie, 0.037 disintegrations per second, or 2.22 disintegrations per minute.
Therefore, at 4 pCi/L (picocuries per liter, the EPA's recommended action level),
there will be approximately 12,672 radioactive disintegrations in one liter of air
during a 24-hour period.
What is a "working level" (WL)?
Some devices measure radiation from radon decay products, rather than radiation
coming directly from radon. Measurements from these devices are often expressed
as WL. As noted above, conversions from WL to pCi/L are usually approximate. A level
of 0.02 WL is usually equal to about 4 pCi/L in a typical home.
If a working level (WL) value is converted to a radon level (pCi/L), the conversion
is usually approximate and is based on a 50 percent equilibrium ratio. If the actual
equilibrium ratio is determined (which is rare), it should be stated. The 50 percent
ratio is typical of the home environment, but any indoor environment may have a
different and varying relationship between radon and its decay products.
Technically speaking, 1 WL represents any combination of short-lived radon decay
products in one liter of air that will result in the ultimate emission of 1.3 x
105 MeV of potential alpha energy.
How often is indoor radon a problem?
Nearly one out of every 15 homes has a radon level the EPA considers to be elevated—4
pCi/L or greater. The U.S. average radon-in-air level in single family homes is
1.3 pCi/L. Because most people spend as much as 90 percent of their time indoors,
indoor exposure to radon is an important concern.
How does radon get into a building?
Most indoor radon comes into the building from the soil or rock beneath it. Radon
and other gases rise through the soil and get trapped under the building. The trapped
gases build up pressure. Air pressure inside homes is usually lower than the pressure
in the soil. Therefore, the higher pressure under the building forces gases though
floors and walls and into the building. Most of the gas moves through cracks and
other openings. Once inside, the radon can become trapped and concentrated.
Openings which commonly allow easy flow of the gases in include the following:
- Cracks in floors and walls
- Gaps in suspended floors
- Openings around sump pumps and drains
- Cavities in walls
- Joints in construction materials
- Gaps around utility penetrations (pipes and wires)
- Crawl spaces that open directly into the building
Radon may also be dissolved in water, particularly well water. After coming from
a faucet, about one ten thousandth of the radon in water is typically released into
the air. The more radon there is in the water, the more it can contribute to the
indoor radon level.
Trace amounts of uranium are sometimes incorporated into materials used in construction.
These include, but are not limited to concrete, brick, granite, and drywall. Though
these materials have the potential to produce radon, they are rarely the main cause
of an elevated radon level in a building.
Outdoor air that is drawn into a building can also contribute to the indoor radon
level. The average outdoor air level is about 0.4 pCi/L, but it can be higher in
some areas.
While radon problems may be more common in some geographic areas, any home may have
an elevated radon level. New and old homes, well-sealed and drafty homes, and homes
with or without basements can have a problem. Homes below the third floor of a multi-family
building are particularly at risk.
Can the radon level in a building's air be predicted?
No, it is not possible to make a reliable prediction.
The only way to determine the level is to test. the EPA and the Surgeon General
recommend testing all homes below the third floor for radon.
A map of radon zones
has been created to help national, state, and local organizations to target their
resources and to implement radon-resistant building codes. However, the map is not
intended to be used for determining if a home in a given zone should be tested for
radon. Homes with elevated levels of radon have been found in all three zones.
In addition, indoor radon levels vary from building to building. Do not rely on
radon test results taken in other buildings in the neighborhood—even ones next door—to
estimate the radon level in your building.
Contact your state radon
office for information about radon in your local area. The Internet is also
a source of information about radon levels in some states.
Where can I get more information about radon issues?
The National Safety Council's Radon Hotline provides a toll-free number, (800) 767-7236.
Through this automated number, callers can order a brochure on radon. It contains
information on ordering a low-cost short-term test kit. In addition, users are instructed
to call another one of our numbers, (800) 557-2366, if they wish to speak with our
information specialists. They are available to assist callers between 9:00 AM to
5:00 PM (Eastern) on business days. They can answer specific questions and mail
free, single copies of many radon documents, including
the EPA booklet, Home Buyer's and Seller's Guide to Radon.
Multiple copies of many the EPA documents can be ordered through the EPA's National Service Center for Environmental Publications (NSCEP),
(800) 490-9198, fax (513) 489-8695. Publication requests can also be mailed, called,
or faxed directly to:
U.S. Environmental Protection Agency
National Center for Environmental Publications (NSCEP)
P.O. Box 42419
Cincinnati, OH 42419
Please use the EPA Document Number when ordering from NSCEP. Allow several weeks
for delivery.
The EPA also supports operation of other related Hotlines. See the the EPA Web site for information about the following:
- Radon FIX-IT Program—assists consumers with elevated radon levels
of 4 pCi/L or higher by providing information that will allow them to take the necessary
steps toward fixing their homes
- Indoor Air Quality Information Clearinghouse (IAQ INFO)—helps locate
information about indoor air pollution
- The National Hispanic Indoor Air Quality Hotline—provides bilingual
(Spanish/English) information about indoor air pollutants that consumers may find
inside their homes, offices or schools
In addition, the EPA also supports operation of the Safe Drinking Water Hotline which answers questions about
radon in drinking water.
the EPA's Indoor Environments Division
provides information regarding indoor air quality issues, including radon, asthma, and environmental tobacco smoke/secondhand
smoke. Their radon page addresses issues including the EPA's position on radon,
health risks, radon resistant new construction, and their former National Radon
Proficiency Program (RPP). Many radon documents are also available there.
You can call the EPA's Safe Drinking Water Hotline, (800) 426-4791, for information
on radon in water. It also provides information that can help you identify a laboratory
to assist with testing drinking water.
The EPA's Office of Ground
Water and Drinking Water provides information on radon in drinking water.
On November 2, 1999, they published a
proposed rule on radon in drinking water. the EPA is soliciting formal comment
by publishing the proposed regulation in the Federal Register for a 60-day
review and comment period. Comments must be received 60 days after publication of
the notice. For more information, contact the Safe Drinking Water Hotline.
Many states provide radon information that is specific to their area. The National
Safety Council provides a list of state links on the right side of this page.
Testing Air for Radon
Why should I test my home for radon?
Radon is widely believed to be the second leading cause of lung cancer. Therefore,
the EPA and the Surgeon General recommend testing for radon in all homes below the
third floor.
Radon has been found in homes all over the United States. Any home can have a radon
problem. On average, one out of every fifteen U.S. homes have a problem. The only
way to know whether or not your home has a radon problem is to test for it.
Who can test a building for radon?
Anyone can use a "do-it-yourself" test kit to check their building. The one-use
kits are simple to use and are relatively inexpensive.
The National Safety Council's Radon Hotline (800-767-7236) makes test kits available
at a low cost to encourage testing. See the main radon
page for more information. After being exposed to the building air for a
product-specified time period, the kits must be returned to an analytic laboratory.
Radon test kits sometimes are available in hardware stores and other retail outlets.
They are also available through the Internet.
If you are not doing your own testing, a qualified/state-certified professional
should be hired. Many people find it preferable to hire a professional when testing
is being conducted as part of a real estate transaction.
Some states require providers of radon measurement services to participate in registration,
certification, or licensing programs. In states lacking their own certification
or licensing programs, you should hire a professional who participates in the national
qualification program for radon professionals.
Call your state radon
office to learn about local radon testing requirements and contractors.
You can also contact the National Environmental Health Association's (NEHA) National Radon Proficiency Program at (800) 269-4174 (radonprog@aol.com),
or the National Radon Safety Board
(NRSB) Program at (303) 423-2674 (info@nrsb.org)
for more information on radon testing professionals in your area.
What testing protocol should be followed?
The purpose of the measurements, as well as budget and time constraints, dictate
the protocol used. However, the EPA and the Surgeon General recommend testing all
homes below the third floor for radon. the EPA recommends that for homes, initial
measurements be short-term tests placed in the lowest lived-in level.
The protocol for measurements made for the purpose of assessing the need for mitigation
(reducing the radon level) is found in the EPA publication, A Citizen's Guide to Radon. Additional guidance is provided
in Section 2 of the EPA book, Protocols For Radon and Radon Decay Product Measurements In Homes.
Protocols for measurements made for real estate transactions are somewhat different.
They are described in the EPA document, Home Buyer's and Seller's Guide to Radon. Additional guidance
is provided in Section 3 of the EPA publication, Protocols For Radon and Radon Decay Product Measurements In Homes.
Why are short- and long-term tests used?
Radon levels within a building often change on a day-to-day basis. Highest indoor
levels are often found during the heating season. Weather conditions, operation
of furnaces and fireplaces, and opening/closing of windows and doors are among the
factors that cause these patterns.
Short-term test kits are the quickest way to test. These kits should remain in the
building from two to 90 days, depending on the device. Testing must be conducted
for at least 48 hours. Some devices must be exposed for a longer time. Because radon
levels tend to vary from day to day and season to season, a short-term test is less
likely than a long-term test to tell you your year-round average radon level.
The EPA recommends that for homes, initial measurements be short-term tests placed
in the lowest lived-in level. Short-term testing under closed-building conditions
helps to ensure that residents quickly learn if a home contains very high levels
of radon. If you are doing a short-term test, close your windows and outside doors
and keep them closed as much as possible during the test. If testing for just 2
or 3 days, be sure to close your windows and outside doors at least 12 hours before
beginning the test, too. You should not conduct short-term tests lasting just 2
or 3 days during unusually severe storms or periods of unusually high winds.
Because radon levels may fluctuate by as much as a factor of two or three, additional
testing is sometimes recommended to better assess the average radon level. Though
short-term tests are sometimes used, long-term tests are often recommended.
Long-term tests remain in your home for more than 90 days. A long-term test gives
a reading that is more likely to reflect the building's year-round average radon
level than a short-term test. Because of season variations in radon levels, the
closer the long-term measurement is to 365 days, the more representative it will
be of annual average radon levels.
If time permits (more than 90 days), long-term tests can be used to confirm initial
short-term results between 4 pCi/L and 10 pCi/L. When long-term test results are
4 pCi/L or higher, the EPA recommends the problem be corrected.
What kinds of test devices are used?
Two groups of devices are more commonly used for short-term testing.
Passive devices do not need power to function. The group includes
alpha track detectors, charcoal canisters, and charcoal liquid scintillation detectors.
Some charcoal technologies are prone to interference by high humidity, so may not
be appropriate for use in all buildings. They are sometimes available in drug, hardware,
and other stores, the Internet, and through some laboratories. Electret ion chamber
detectors, another type of short-term test device, are usually only available through
laboratories. After being used, passive devices are returned to a laboratory for
analysis.
Charcoal canisters for short-term use are sold through the National Safety Council's
Radon Hotline (800-767-7236). These test kits are designed to be used for two or
four days before being returned for analysis by the laboratory that provides it.
A return mailer is provided with the kit. See the main
radon page for more information.
Active devices require power to function. This group consists of
different types of continuous monitors and continuous working level monitors. Some
of the active monitors can provide data on the range of variation within the test
period. Some are designed to detect and deter interference. However, they usually
require operation by trained testers. These tests often cost more than passive testing
.
Alpha track and electret ion chamber detectors are commonly used for long-term testing.
Long-term test kits currently sold through the National Safety Council's Radon Hotline
(800-767-7236) are alpha-track detectors. They are designed to be used for three
months to a year before being returned to the providing laboratory for analysis.
See the main radon page for more
information.
Technical information on use of various devices used to measure radon or radon decay
products is found in the EPA publication, Indoor Radon and Radon Decay Product Measurement Device Protocols.
Continuous monitors are not available through the National Safety Council's Radon
Hotline at this time.
Where should home testing be done?
The EPA recommends that testing be done in the lowest level of the home suitable
for occupancy. This typically represents an area where greatest radon level may
occur. Ideally, the test should be conducted in a regularly used room on that level,
such as a living room, playroom, den, or bedroom. Avoid testing in a kitchen, bathroom,
laundry room, or hallway. High humidity and drafty conditions can bias results from
some test devices. Do not disturb the devices while they are sampling. Doing so
may alter their results, so they should be placed out-of-the-way.
If the lowest occupied level is not used much, consider also testing a higher-use
area. This may help you to better estimate your long-term exposure.
Because most indoor radon comes from naturally occurring radon in the soil, high
indoor levels are more likely to exist below the third floor. This is why the EPA
recommends testing all homes below the third floor. In some cases, high radon levels
have been found at or above the third floor, due to radon movement through elevators
or other air shafts in the building. If you are concerned about this possibility,
you may decide to test for radon.
More information on site selection can be found in the EPA publication,
Protocols for Radon and Radon Decay Product Measurements in Homes.
If a test result is less than 4 pCi/L (0.02 WL), what should be done next?
If the result of an initial short-term measurement is below 4 pCi/L, or 0.02 WL,
a follow-up test is not necessary. However, since radon levels change over time,
you may want to test again sometime in the future, especially if use patterns change
and a lower level of the building becomes occupied or used more often. Renovations,
changes in ventilation, earthquakes, settling of the ground beneath the building,
and other changes may cause indoor radon exposures to change.
If an initial short-term test result is 4 pCi/L (0.02 WL) or higher, what should
be done next?
The EPA recommends a follow-up measurement be used to confirm whether radon levels
are high enough to warrant mitigation. There are two types of follow-up measurements
that may be conducted. The choice depends, in part, on the results of the initial
test.
An initial measurement result of 10 pCi/L (or 0.05 WL) or greater should be quickly
followed by a second short-term test under closed-building conditions. If the average
of the initial and second short-term results is equal to or greater than 4 pCi/L
(0.02 WL), radon mitigation is recommended. If the average of the short-term test
results is less than 4 pCi/L, consider testing again sometime in the future.
If the result of the initial measurement is between 4 pCi/L (or 0.02 WL) and 10
pCi/L (or 0.05 WL), the follow-up test may be made with either a short-term or a
long-term method. If a long-term follow-up test result is 4 pCi/L (0.02 WL) or higher,
the EPA recommends remedial action. If the long-term follow-up test result is less
than 4 pCi/L, consider testing again sometime in the future.
If a short-term follow-up test is done and the result is 4 pCi/L or higher, radon
mitigation is recommended. If the average of the initial and follow-up short-term
tests is less than 4 pCi/L, consider testing again sometime in the future.
In certain instances, such as may occur when measurements are performed in different
seasons or under different weather conditions, the initial and follow-up tests may
vary by a considerable amount. Radon levels can vary significantly between seasons,
so different values are to be expected.
Radon Resistant Construction
What are radon-resistant features?
The techniques vary for different foundations and site requirements, but the basic
elements are:
- Gas Permeable Layer—This layer is placed beneath the slab or flooring
system to allow the soil gas to move freely underneath the house. In many cases,
the material used is a 4-inch layer of clean gravel.
- Plastic Sheeting—Plastic sheeting is placed on top of the gas permeable
layer and under the slab to help prevent the soil gas from entering the home. In
crawlspaces, the sheeting is placed over the crawlspace floor.
- Sealing and Caulking—All openings in the concrete foundation floor
are sealed to reduce soil gas entry into the home.
- Vent Pipe—A 3- or 4-inch gas-tight or PVC pipe (commonly used for
plumbing) runs from the gas permeable layer through the house to the roof to safely
vent radon and other soil gases above the house.
- Junction Box—An electrical junction box is installed in case an
electric venting fan is needed later.
Ways to reduce radon in your home are discussed in the EPA's publication, Consumer's Guide to Radon Reduction.
When should radon-resistant construction be considered?
Find out if you are buying a home in a high radon area. the EPA's map of radon zones indicates areas having the greatest potential
for elevated indoor radon readings. Homes in places with high potential, called
Zone 1 areas, should be built with radon-resistant features. Also contact your state radon office
to learn whether radon-resistant features are recommended or required in your area.
If you are planning to make any major structural renovation to an existing home,
such as converting an unfinished basement area into a living space, it is important
to test the area for radon before you begin the renovation. If your test results
indicate a radon problem, radon-resistant techniques can be inexpensively included
as part of the renovation. Because major renovations can change the level of radon
in any home, always test again after work is completed.
What are the benefits of radon-resistant construction?
Radon-resistant techniques are simple and inexpensive. Besides reducing radon levels,
they also lower concentrations of other soil gases and decrease moisture problems.
They make a home more energy efficient, and can save an annual average of $65 on
energy costs.
How much does it cost to reduce radon in an existing home?
If a home with a vent system is found to have an elevated radon level, a fan can
be added at a low cost. The total cost is much lower than adding the entire system
after the building is completed. The average cost to install radon-resistant features
in an existing home is $800 to $2,500. The average cost to install radon-resistant
features in a new home during construction is $350 to $500 (a 128% to 400% saving).
Who should I hire to install radon-resistant features?
Talk to your builder about installing a radon-reduction system during major renovations
or new construction. Radon-resistant features can be easily and inexpensively installed
with common building practices and materials. There is usually no need to hire a
special contractor or architect. Many builders already incorporate some of these
steps in the construction of their houses to control moisture or increase energy
efficiency.
The EPA's publication,
Radon Mitigation Standards, provides radon mitigation contractors with uniform
standards that will ensure quality and effectiveness in the design, installation,
and evaluation of radon mitigation systems in detached and attached residential
buildings three stories or less in height.
Should a home built with radon-resistant features be tested?
Yes. Every new home should be tested for radon after occupancy. Test your home even
if it has the radon resistant features. Test kits are inexpensive and may be purchased
at your local hardware store, or call the National Safety Council's Radon Hotline
(800-767-7236) to order a test kit. See the main radon page
for more information.
Mitigating Radon Problems
What is a radon mitigation system?
A radon mitigation system is any system or steps designed to reduce radon concentrations
in the indoor air of a building.
The EPA recommends that you take action to reduce your home's indoor radon levels
if your radon test result is 4 pCi/L or higher.
What are the benefits of radon mitigation?
Radon reduction systems work. In most new homes, use of radon-resistant features
will keep radon levels to below 2 pCi/L. Some radon reduction systems can reduce
radon levels in your home by up to 99 percent.
Homeowners should consider correcting a radon problem before making final preparations
to sell a home. This often provides more time to address the problem and find the
most cost-effective solution. In addition, the current occupants—not just the buyer's
occupants—will reap the benefit of reduced risk.
What can be done to reduce radon in a home?
Your house type will affect the kind of radon reduction system that will work best.
Houses are generally categorized according to their foundation design. For example:
basement, slab-on-grade (concrete poured at ground level), or crawlspace (a shallow
unfinished space under the first floor). Some houses have more than one foundation
design feature. For instance, it is common to have a basement under part of the
house and to have a slab-on-grade or crawlspace under the rest of the house. In
these situations a combination of radon reduction techniques may be needed to reduce
radon levels to below 4 pCi/L.
There are several methods that a contractor can use to lower radon levels in your
home. Some techniques prevent radon from entering your home while others reduce
radon levels after it has entered. the EPA generally recommends methods that prevent
the entry of radon.
In many cases, simple systems using underground pipes and an exhaust fan may be
used to reduce radon. Such systems are called "sub-slab depressurization," and do
not require major changes to your home. These systems remove radon gas from below
the concrete floor and the foundation before it can enter the home. Similar systems
can also be installed in houses with crawl spaces. Radon contractors use other methods
that may also work in your home. The right system depends on the design of your
home and other factors.
Sealing cracks and other openings in the floors and walls is a basic part of most
approaches to radon reduction. Sealing does two things, it limits the flow of radon
into your home and it reduces the loss of conditioned air, thereby making other
radon reduction techniques more effective and cost-efficient. The EPA does not recommend
the use of sealing alone to reduce radon because, by itself, sealing has not been
shown to lower radon levels significantly or consistently. It is difficult to identify
and permanently seal the places where radon is entering. Normal settling of your
house opens new entry routes and reopens old ones.
Any information that you may have about the construction of your house could help
your contractor choose the best system. Your contractor will perform a visual inspection
of your house and design a system that is suitable. If this inspection fails to
provide enough information, the contractor will need to perform diagnostic tests
to help develop the best radon reduction system for your home. Whether diagnostic
tests are needed is decided by details specific to your house, such as the foundation
design, what kind of material is under your house, and by the contractor's experience
with similar houses and similar radon test results.
How much does it cost to reduce radon in an existing home?
The cost of making repairs to reduce radon is influenced by the size and design
of your home and other factors. Most homes can be fixed for about the same cost
as other common home repairs, like painting or having a new hot water heater installed.
The average cost for a contractor to lower radon levels in a home is about $1,200,
although this can range from $500 to about $2,500. Your costs may vary depending
on the size and design of your home and which radon reduction methods are needed.
Who should I hire to correct a radon problem?
Lowering high radon levels requires technical knowledge and special skills. You
should use a contractor who is trained to fix radon problems.
The EPA stopped operating its National Radon Proficiency Program (RPP) on October
1, 1998. That program was designed to test radon contractors and provide a measure
of quality control. The RPP is now privately run. See the EPA's Web site regarding the RPP for information on how to identify
qualified contractors.
Many states certify or license radon contractors. Call your
state radon office for information about qualified service providers in
your state.
If you plan to fix the problem in your home yourself, you should first contact your
state radon office for the EPA's technical guide, "Radon Reduction Techniques for
Detached Houses."
Will any more testing be needed after a radon mitigation system has been installed?
Most radon reduction systems include a monitor that will alert you if the system
needs servicing. However, regardless of who fixes the problem, you should test your
home afterward to be sure that radon levels have been reduced. This test should
be conducted no sooner than 24 hours nor later than 30 days following completion
and activation of the mitigation system(s). Potential conflict of interest can be
avoided by using an independent tester.
In addition, it's a good idea to retest your home sometime in the future to be sure
radon levels remain low. Testing should be done at least every two years or as required
or recommended by state or local authority. Retesting is also recommended if the
building undergoes significant alteration.
Are funds available to reduce high radon levels in rental housing?
There are some federal programs that might be used to help fund radon reduction
in homes that are affordable to limited income families. These programs generally
give money to local agencies or groups, which then fund the work. Some examples
are:
- Community Development Block Grant (CDBG) program—funds rehabilitation
and repair of affordable housing. For more information, call the U.S. Department
of Housing and Urban Development (HUD) at (202) 708-3587.
- "203k" program—funds rehabilitation and repair of single family
homes. For more information, call HUD at (202) 708-2121.
- Environmental Justice Grants—funds community-based organizations
and tribal governments addressing environmental concerns of people of color and
low income communities. For more information, call the EPA's Office of Environmental
Justice at (800) 962-6215.
Some states have governmental programs that can provide loans for radon reduction
work in limited income housing. Some community groups are raising funds from private
companies and foundations to pay for radon reduction in limited income homes.
To find out more about federal and state programs, or about how community groups
have developed local projects to fix radon problems, owners and residents can contact
your state radon office.
Radon in Water
How does radon get in water?
When the ground produces radon, it can dissolve and accumulate in water from underground
sources (called ground water), such as wells. When water that contains radon is
run for showering, washing dishes, cooking, and other uses, radon gas escapes from
the water and goes into the air. Some radon also stays in the water.
Radon can be a concern if your drinking water comes from a well that draws from
an underground source, though not all water from underground sources contains radon.
If you get your water from a public water system that serves 25 or more year-around
residents, you will receive an annual water quality report. These water quality
reports include information on what is in your water, including radon if it has
been tested.
Radon from lakes, rivers, and reservoirs (called surface water) is of much less
concern. Most of the radon is released from the water before it enters the distribution
system.
Does radon in drinking water pose a risk?
In most cases, radon entering the home through water will be a small source of risk
compared with radon entering from the soil. The EPA estimates that indoor radon
levels will increase by about 1 pCi/L for every 10,000 pCi/L of radon in water.
Only about one to two percent of indoor radon in air comes from drinking water.
Based on a National
Academy of Science report, the EPA estimates that radon in drinking water
causes about 168 cancer deaths per year: 89 percent from lung cancer caused by breathing
released to the indoor air from water and 11 percent from stomach cancer caused
by consuming water containing radon.
Radon gas can enter the home through well water. It can be released into the air
you breathe when water is used for showering and other household uses. Research
suggests that swallowing water with high radon levels may pose risks, too, although
risks from swallowing water containing radon are believed to be much lower than
those from breathing air containing radon.
While radon in water is not a problem in homes served by most public water supplies,
problems have been found in well water. If you've tested the air in your home and
found a radon problem, and your water comes from a well, contact a lab certified
to measure radiation in water to have your water tested. Call the EPA's Safe Drinking Water Hotline, (800) 426-4791 to get information
on locating a certified lab.
If you're on a public water supply and are concerned that radon may be entering
your home through the water, call your public water supplier.
Should drinking water be tested?
Because radon in indoor air is the larger health concern, the EPA recommends that
you first test the air in your home for radon before testing for radon in your drinking
water. the EPA and the Surgeon General recommend testing all homes for radon in
indoor air (and apartments located below the third floor). The EPA recommends that
you take action to reduce your home's indoor radon levels if your radon test result
is 4 pCi/L or higher.
If you have tested the air in your home and found a radon problem, you may also
want to find out whether your water is a concern. If you get water from a public
water system, find out whether the comes from a surface (river, lake, or reservoir)
or a ground water (underground) source.
If the water comes from a surface water source, most radon in the water will be
released to the air before it reaches your tap. If the water comes from a ground
water source, call your water system and ask if they've tested the water for radon.
If so, ask for their Consumer Confidence Report.
If you have a private well, the EPA recommends testing your water for radon. The
Safe Drinking Water Hotline, (800) 426-4791, can provide phone numbers for your
state laboratory certification office. You can also call the National Safety Council's
Radon Hotline, (800) 557-2366, for your state radon office's phone number. Your
state laboratory certification office or state radon office can direct you to laboratories
that are able to test your drinking water for radon.
What do the results of a water test mean?
Estimate how much the radon in your water is elevating your indoor radon level by
subtracting 1 pCi/L from your indoor air radon level for every 10,000 pCi/L of radon
that was found in your water. (For example: if you have 30,000 pCi/L of radon in
your water, then 3 pCi/L of your indoor measurement may have come from radon in
water.) If most of the radon is not coming from your water, fix your house first
and then retest your indoor air to make sure that the source of elevated radon was
not your private well. If a large contribution of the radon in your house is from
your water, you may want to consider installing a special water treatment system
to remove radon. the EPA recommends installing a water treatment system only when
there is a proven radon problem in your water supply.
What levels of radon in water should I be concerned about?
There is currently no federally-enforced drinking water standard for radon.
The EPA does not regulate private wells, but is proposing to regulate radon in drinking
water from community water suppliers (water systems that serve 25 or more year-round
residents). the EPA proposed the rule in October 1999 and plans to finalize it in
August 2000.
The EPA is proposing two options.
The first option would require community water suppliers to provide water with radon
levels no higher than 4,000 pCi/L. Because about 1/10,000th of radon in water transfers
to air, this would contribute about 0.4 pCi/L of radon to the air in a home. This
level will be permitted if the state also takes action to reduce radon levels in
indoor air by developing the EPA-approved, enhanced state radon in indoor air programs
(called Multimedia Mitigation Programs). This is important because most of the radon
you breathe comes from soil under the house. This option gives states the flexibility
to focus on the greatest problems, encouraging the public to fix radon in indoor
air problems and to build homes that keep radon from entering.
A second option is provided for states that choose not to develop enhanced indoor
air programs. Community water systems in those states will be required to reduce
radon levels in drinking water to 300 pCi/L. This amount of radon in water contributes
about 0.03 pCi/L of radon to the air in your home.
Even if a state does not develop an enhanced indoor air program, water systems may
choose to develop their own local indoor radon program. This will require them to
meet a radon standard for drinking water of 4,000 pCi/L. This option enables overall
risks from exposure to radon, both through air and water, to be reduced.
How is radon removed from water?
Radon can be removed from water by using one of two methods: aeration treatment
or granular activated carbon (GAC) treatment.
Aeration treatments involve bubbling air through the water. This
helps to strip radon from the water. An exhaust fan is used to vent the radon outdoors.
GAC treatment filters water through carbon. Radon attaches to the
carbon and leaves the water free of radon. GAC filters tend to cost less than aeration
devices. However, radioactivity collects on the filter and may cause a handling
hazard and require special disposal methods for the filter.
For more information on aerators and GAC filters, you should contact two independent,
non-profit organizations: NSF International at (800) 673-8010 and the Water Quality
Association at (630) 505-0160.
In either treatment, it is important to treat the water where it enters your home
(point-of-entry device) so that all the water will be treated. Point-of-use devices,
such as those installed on a tap or under the sink, will only treat a small portion
of your water and are not effective in reducing radon in your water.
It is important to maintain home water treatment units because failure to do so
can lead to other water contamination problems. Some homeowners opt for a service
contract from the installer to provide for carbon replacement and general system
maintenance.
For more information about indoor air quality issues in schools, visit the EPA's Indoor Air Home Page.
