 |
Indoor Environments Division (6609J)
EPA 402-K-07-009, Revised May 2007
EPA Recommends:
-
If you are buying a home or selling your home, have it tested for
radon.
-
For a new home, ask if radon-resistant construction features were
used and if the home has been tested.
-
Fix the home if the radon level is 4 PicoCuries per liter (pCi/L) or
higher.
-
Radon levels less than 4 pCi/L still pose a risk, and in many cases,
may be reduced.
|
Download PDF version of this
document (revised 5/2007-861kB)
 |
|
Based on information contained in the National Academy of Sciences
report, The Health Effects of Exposure to Indoor Radon, radon is
estimated to cause between 15,000 and 22,000 lung cancer deaths per
year. Data on (non-radon) causes of death are from Injury Facts,
1999 Edition, National Safety Council, Itasca, IL. |

This Guide answers important
questions about radon and lung cancer risk. It also answers
questions about testing and fixing for anyone buying or selling a home.
Radon is a cancer-causing, radioactive
gas.
You can't see radon. And you can't smell it or taste it. But it may be a
problem in your home.
Radon is estimated to cause many thousands of deaths each year. That's
because when you breathe air containing radon, you can get lung cancer. In
fact, the Surgeon General has warned that radon is the second leading cause
of lung cancer in the United States today. Only smoking causes more lung
cancer deaths. If you smoke and your home has high radon levels, your risk
of lung cancer is especially high.
|
National Academy of
Sciences Report on Radon
In February 1998, the National
Academy of Sciences (NAS) released its report on radon and lung
cancer, The Health Effects of Exposure to Indoor Radon (the
BEIR VI report). The NAS is an independent, non-governmental,
scientific organization. The NAS estimates that radon causes
between 15,000 and 22,000 lung cancer deaths each year in the United
States and that 12 percent of all lung cancer deaths are linked to
radon. The BEIR VI Committee (Biological Effects of Ionizing
Radiation) concluded that after smoking, radon is the second leading
cause of death due to lung cancer in the United States. |
You Should Test for Radon
Testing is the only way to know if you and
your family are at risk from radon. EPA and the Surgeon General recommend
testing all homes below the third floor for radon. EPA also recommends
testing in schools.
Testing is inexpensive and easy - it should only take a few minutes of your
time. Millions of Americans have already tested their homes for radon
You Can Fix a Radon Problem
Radon reduction systems work and they are
not too costly. Some radon reduction systems can reduce radon levels in your
home by up to 99%. Even very high levels can be reduced to acceptable
levels.

Radon is a radioactive gas. It comes from
the natural decay of uranium that is found in nearly all soils. It typically
moves up through the ground to the air above and into your home through
cracks and other holes in the foundation. Your home traps radon inside,
where it can build up. Any home may have a radon problem. This means new and
old homes, well-sealed and drafty homes, and homes with or without
basements.
Radon from soil gas is the main cause of radon problems. Sometimes radon
enters the home through well water (see "Radon in Water" below). In a small
number of homes, the building materials can give off radon, too. However,
building materials rarely cause radon problems by themselves.
RADON GETS IN THROUGH:
1. Cracks in solid floors
2. Construction joints
3. Cracks in walls
4. Gaps in suspended floors
5. Gaps around service pipes
6. Cavities inside walls
7. The water supply
Nearly 1 out of every 15 homes in the
United States is estimated to have an elevated radon level (4 pCi/L or
more). Elevated levels of radon gas have been found in homes in your
state. Contact your state radon office for information about radon in your
area.
Testing is the only way to know if you and
your family are at risk from radon. EPA and the Surgeon General recommend
testing all homes below the third floor for radon.
Visit our radon
test kit & detector Product Catalog
You cannot predict radon levels based on state, local, and neighborhood
radon measurements. Do not rely on radon test results taken in other
homes in the neighborhood to estimate the radon level in your home.
Homes which are next to each other can have different radon levels.
Testing is the only way to find out what your home's radon level is.
In some areas, companies may offer
different types of radon service agreements. Some agreements let you
pay a one-time fee that covers both testing and radon mitigation, if needed.
Contact your state radon office to find out if these are available in your
state.
|
Surgeon General of the United States Health Advisory
"Indoor radon gas is a national health problem. Radon causes
thousands of deaths each year. Millions of homes have elevated
radon levels. Most homes should be tested for radon. When elevated
levels are confirmed, the problem should be corrected." |

If you are thinking of selling your home
and you have already tested your home for radon, review the
Radon Testing Checklist to make sure that the test was done
correctly. If so, provide your test results to the buyer.
No matter what kind of test you took, a
potential buyer may ask for a new test especially if:
- The Radon Testing Checklist items were
not met;
- The last test is not recent, e.g.,
within two years;
- You have renovated or altered your
home since you tested; or
- The buyer plans to live in a lower
level of the house than was tested, such as a basement suitable for
occupancy but not currently lived in.
A buyer may also ask for a new test if
your state or local government requires disclosure of radon information
to buyers.
Have a test taken as soon as possible. If
you can, test your home before putting it on the market. You
should test in the lowest level of the home which is suitable for
occupancy. This means testing in the lowest level that you currently
live in or a lower level not currently used, but which a buyer could use
for living space without renovations.
The radon test result is important information about your home's radon
level. Some states require radon measurement testers to follow a
specific testing protocol. If you do the test yourself, you should
carefully follow the testing protocol for your area or EPA's Radon
Testing Checklist. If you hire a contractor to test your
residence, protect yourself by hiring a qualified
individual or company.
You can determine a service provider's
qualifications to perform radon measurements or to mitigate your home in
several ways. Check with your state radon office. Many
states require radon professionals to be licensed, certified, or
registered. Most states can provide you with a list of
knowledgeable radon service providers doing business in the state.
In states that don't regulate radon services, ask the contractor if they
hold a professional proficiency or certification credential. Such
programs usually provide members with a photo-ID card, which indicates
their qualifications and its expiration date. If in doubt, you
should check with their credentialing organization. Alternatively,
ask the contractor if they've successfully completed formal training
appropriate for testing or mitigation, e.g., a course in radon
measurement or radon mitigation.

Back Home
If you are thinking of buying a home, you
may decide to accept an earlier test result from the seller, or
ask the seller for a new test to be conducted by a qualified radon
tester. Before you accept the seller's test, you should determine:
- The results of previous testing;
- Who conducted the previous test:
the homeowner, a radon professional, or some other person;
- Where in the home the previous test
was taken, especially if you may plan to live in a lower level of the
home. For example, the test may have been taken on the first
floor. However, if you want to use the basement as living space,
test there; and
- What, if any, structural changes,
alterations, or changes in the heating, ventilation, and air
conditioning (HVAC) system have been made to the house since the test
was done. Such changes may affect radon levels.
If you accept the seller's test, make
sure that the test followed the
Radon Testing Checklist.
If you decide that a new test is needed,
discuss it with the seller as soon as possible.
Make sure that a radon test is done as
soon as possible. Consider including provisions in the contract
specifying:
- Where the test will be located;
- Who should conduct the test;
- What type of test to do;
- When to do the test;
- How the seller and the buyer will
share the test results and test costs (if necessary); and
- When radon mitigation measures will be
taken and who will pay for them.
Make sure that the test is done in the
lowest level of the home suitable for occupancy. This means the lowest
level that you are going to use as living space which is finished or
does not require renovations prior to use. A state or local radon
official or qualified radon tester can help you make some of these
decisions.
If you decide to finish or renovate an
unfinished area of the home in the future, a radon test should be taken
before starting the project and after the project is finished.
Generally, it is less expensive to install a radon-reduction system
before (or during) renovations rather than afterwards.

Radon-resistant techniques work.
When installed properly and completely, these simple and inexpensive
passive techniques can help to reduce radon levels. In addition,
installing them at the time of construction makes it easier to reduce
radon levels further if the passive techniques don't reduce radon levels
below 4 pCi/L. Radon-resistant techniques may also help to lower
moisture levels and those of other soil-gases. Radon-resistant
techniques:
 |
Making Upgrading Easy:
Even if built to be radon-resistant, every new home should be tested
for radon after occupancy. If you have a test result of 4
pCi/L or more, a vent fan can easily be added to the passive system
to make it an active system and further reduce radon levels. |
 |
Are Cost-Effective:
Building radon-resistant features into the house during construction
is easier and cheaper than fixing a radon problem from scratch
later. Let your builder know that radon-resistant features are
easy to install using common building materials. |
 |
Save Money: When
installed properly and completely, radon-resistant techniques can
also make your home more energy efficient and help you save on your
energy costs. |
In a new home, the cost to install
passive radon-resistant features during construction is usually between
$350 and $500. In some areas, the cost may be as low as $100.
A qualified mitigator will charge about $300 to add a vent fan to a
passive system, making it an active system and further reducing radon
levels. In an existing home, it usually costs between $800
and $2,500 to install a radon mitigation system.
Radon-resistant techniques (features) may
vary for different foundations and site requirements. If you're
having a house built, you can learn about EPA's Model Standards (and
architectural drawings) and explain the techniques to your builder.
If your new house was built (or will be built) to be radon-resistant, it
will include these basic elements:
-
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. This gas-permeable layer is used only in
homes with basement and slab-on-grade foundations; it is not used in
homes with crawlspace foundations.
- 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
crawl spaces, the sheeting (with seams sealed) is placed directly
over the crawlspace floor.
- Sealing and Caulking: All
below-grade openings in the foundation and walls are sealed to
reduce soil gas entry into the home.
- Vent Pipe: A 3- or
4-inch PVC pipe (or other gas-tight pipe) runs from the
gas-permeable layer through the house to the roof, to safely vent
radon and other soil gases to the outside.
- Junction Boxes: An
electrical junction box is included in the attic to make the wiring
and installation of a vent fan easier. For example, you decide
to activate the passive system because your test result showed an
elevated radon level (4 pCi/L or more). A separate junction
box is placed in the living space to power the vent fan alarm.
An alarm is installed along with the vent fan to indicate when the
vent fan is not operating properly.
|
 |

Radon testing is easy and the only way to
find out if you have a radon problem in your home.
Since you cannot see or smell radon,
special equipment is needed to detect it. When you're ready to
test your home, you can order a radon test kit by mail from a qualified
radon measurement services provider or laboratory. You can also
hire a qualified radon tester, very often a home inspector, who will use
a radon device(s) suitable to your situation. The most common
types of radon testing devices are listed below.
Passive Devices
Passive radon testing devices do not
need power to function. The passive device group includes
alpha track detectors,
charcoal canisters,
charcoal liquid scintillation detectors, and electret ion chambers.
The active device group consists of different types of
continuous monitors. All are available at
http://www.testproducts.com/safecart. These devices are
exposed to the air in the home for a specified period of time and then
sent to our laboratory for analysis. Both short-term and long-term
passive devices are generally inexpensive. Some of these devices may
have features that offer more resistance to test interference or
disturbance than other passive devices. Qualified radon testers may use
any of these devices to measure the home's radon level.
Active Devices
Active radon testing devices require
power to function. These include
continuous radon monitors and continuous working level monitors.
They continuously measure and record the amount of radon or its decay
products in the air. Many of these devices provide a report of
this information which can reveal any unusual or abnormal swings in the
radon level during the test period. A qualified tester can explain this
report to you. In addition, some of these devices are specifically
designed to deter and detect test interference. Some technically
advanced active devices offer anti-interference features. Although
these tests may cost more, they may ensure a more reliable result.
A state or local radon official can
explain the differences between devices and recommend the ones which are
most appropriate for your needs and expected testing conditions.
Make sure to use a radon measurement
device from a qualified laboratory. Certain precautions should be
followed to avoid interference during the test period. See the
Radon Testing Checklist for more information on how to get a
reliable test result.
Radon Test Device
Placement
EPA recommends that testing device(s)
be placed in the lowest level of the home suitable for occupancy.
This means testing in the lowest level (such as a basement), which a
buyer could use for living space without renovations. The test
should be conducted in a room to be used regularly (like a family
room, living room, playroom, den or bedroom); do not test in
a kitchen, bathroom, laundry room or hallway. Usually, the
buyer decides where to locate the radon test, based on their
expected use of the home. A buyer and seller should explicitly
discuss and agree on the test location to avoid any
misunderstanding. Their decision should be clearly
communicated to the person performing the test. |
There is a potential for test
interference in real estate transactions. There are several ways to
prevent or detect test interference:
- Use a test device that frequently
records radon or decay product levels to detect unusual swings;
- Employ a motion detector to determine
whether the test device has been moved or testing conditions have
changed;
- Use a proximity detector to reveal the
presence of people in the room which may correlate to possible changes
in radon levels during the test;
- Record the barometric pressure to
identify weather conditions which may have affected the test;
- Record the temperature record to help
assess whether doors and windows have been opened;
- Apply tamper-proof seals to windows to
ensure closed house conditions; and
- Have the seller/occupant sign a
non-interference agreement.
Home buyers and sellers should consult a
qualified radon test provider about the use of these precautions.
What’s the
difference between short-term and long-term testing?
Radon gas levels in a home are not the same every day.
Changes in the weather, how often windows and doors are opened and closed,
the type of air conditioning/heating systems you use, and your family's
lifestyle all contribute to the level of radon gas in your home each day. A
short-term test may show unusually high or low levels due to the weather and
activity in your home. A long-term test will average your exposure to radon
levels over a period of time, and experts agree that this gives a more
conclusive test result.
There Are Two General Ways To Test
Your Home for Radon:
Because radon levels 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. However, if
you need results quickly, a short-term test may be used to decide
whether to fix the home.
 |
Short-Term Testing |
The quickest way to test is with
short-term tests. Short-term tests remain in your home from two days to
90 days, depending on the device. There are two groups of devices which
are more commonly used for short-term testing. The passive device group
includes
alpha track detectors,
charcoal canisters,
charcoal liquid scintillation detectors, and electret ion chambers.
The active device group consists of different types of
continuous monitors.
|
Whether you test for radon yourself or hire a state-certified tester
or a privately certified tester, all radon tests should be taken for
a minimum of 48 hours. A longer period of testing is required for
some devices. |
Visit our radon
test kit & detector Product Catalog
 |
Long-Term Testing |
Long-term tests remain in your home for
more than 90 days. Alpha track, and electret ion chamber
detectors are commonly used for this type of testing. A long-term
test will give you a reading that is more likely to tell you your home's
year-round average radon level than a short-term test. If time permits
(more than 90 days) long-term tests can be used to confirm initial
short-term results. When long-term test results are 4 pCi/L or higher,
EPA recommends fixing the home.
If you are testing in a real estate
transaction and you need results quickly, any of the following three
options for short-term Tests are acceptable in determining whether
the home should be fixed. Any real estate test for radon should include
steps to prevent or detect device interference with the test device.
|
When Choosing a
Short-Term Testing Option...
There are trade-offs among the
short-term testing options. Two tests taken at the same time
(simultaneous) would improve the precision of this radon test.
One test followed by another test (sequential) would most likely
give a better representation of the seasonal average. Both
active and passive devices may have features which help to prevent
test interference. Your state radon office can help you decide
which option is best. |
|
Short-Term Testing Options |
What to do Next |
Passive:
Take two short-term tests at the same time in the same location for at
least 48 hours.
or
Take an initial short-term test for
at least 48 hours. Immediately upon completing the first test,
do a second test using an identical device in the same location as
the first test. |
Fix the home if the average of two tests is 4 pCi/L or more.
Fix the home if the average of the
two tests is 4 pCi/L or more. |
Active:
Test the home with a continuous monitor for at least 48 hours. |
Fix the home if the average radon level is 4 pCi/L or more. |
If You Do the Test Yourself
When
you are taking a short-term test, close windows and doors and keep them
closed, except for normal entry and exit. If you are taking a
short-term test lasting less than four days, be sure to:
- Close your windows and outside doors
at least 12 hours before beginning the test;
- Do not conduct short-term tests
lasting less than four days during severe storms or periods of high
winds;
- Follow the testing instructions and
record the start time and date;
- Place the test device at least 20
inches above the floor in a location where it will not be disturbed and
where it will be away from drafts, high heat, high humidity, and
exterior walls;
- Leave the test kit in place for as
long as the test instructions say; and
- Once you have finished the test,
record the stop time and date, reseal the package and return it
immediately to the lab specified on the package for analysis.
You should receive your test results
within a few weeks. If you need results quickly, you should find out how
long results will take and, if necessary, request expedited service.
 |
If You Hire a Qualified Radon
Tester |
In many cases, home buyers and sellers
may decide to have the radon test done by a qualified radon tester who
knows the proper conditions, test devices, and guidelines for obtaining
a reliable radon test result. They can also:
- Evaluate the home and recommend a
testing approach designed to make sure you get reliable results;
- Explain how proper conditions can be
maintained during the radon test;
- Emphasize to occupants of a home that
a reliable test result depends on their cooperation. Interference
with, or disturbance of, the test or closed-house conditions will
invalidate the test result;
- Analyze the data and report
measurement results; and
- Provide an independent test.
The average indoor radon level is
estimated to be about 1.3 pCi/L; roughly 0.4 pCi/L of radon is normally
found in the outside air. The U.S. Congress has set a long-term goal
that indoor radon levels be no more than outdoor levels. While this goal
is not yet technologically achievable for all homes, radon levels in
many homes can be reduced to 2 pCi/L or below.
|
Radon Test Results
Reported in Two Ways
Your radon test results may be
reported in either picoCuries per liter of air (pCi/L) or working
levels (WL). If your test result is in pCi/L, EPA recommends you fix
your home if your radon level is 4 pCi/L or higher. If the test
result is in WL, EPA recommends you fix the home if the working
level is 0.02 WL or higher. Some states require WL results to
be converted to pCi/L to minimize confusion. |
Sometimes short-term tests are less
definitive about whether the home is at or above 4 pCi/L; particularly
when the results are close to 4 pCi/L. For example, if the average of
two short-term tests is 4.1 pCi/L, there is about a 50% chance that the
year-round average is somewhat below 4 pCi/L.
However, EPA believes that any radon
exposure carries some risk; no level of radon is safe. Even radon levels
below 4 pCi/L pose some risk. You can reduce your risk of lung
cancer by lowering your radon level.
As with other environmental
pollutants, there is some uncertainty about the magnitude of radon
health risks. However, we know more about radon risks than risks from
most other cancer-causing substances. This is because estimates of radon
risks are based on data from human studies (underground miners).
Additional studies on more typical populations are under way.
Your radon measurement will give you an
idea of your risk of getting lung cancer from radon. Your chances of
getting lung cancer from radon depend mostly on:
- Your home's radon level;
- The amount of time you spend in your
home; and
- Whether you are a smoker or have ever
smoked.
Smoking combined with radon is an
especially serious health risk. If you smoke or are a former smoker, the
presence of radon greatly increases your risk of lung cancer. If you
stop smoking now and lower the radon level in your house, you will
reduce your lung cancer risk.
Based on information contained in the
National Academy of Sciences 1998 report, The Health Effects of
Exposure to Indoor Radon, your radon risk may be somewhat higher
than shown; especially if you have never
smoked. It's never too late to reduce your risk to lung cancer.
Don't wait to test and fix a radon problem. If you are a smoker,
stop smoking.
It's never too
late to reduce your risk of lung cancer.
Don't wait to
test and fix a radon problem.
If you are a
smoker, stop smoking.
Radon Risk If You
Smoke
|
Radon Level |
If 1,000 people
who smoked were exposed to this level over a lifetime*... |
The risk of
cancer from radon exposure compares to**... |
WHAT TO DO:
Stop smoking and... |
| 20 pCi/L |
About 260 people could get
lung cancer |
250 times the risk of drowning |
Fix your home |
| 10 pCi/L |
About 150 people could get
lung cancer |
200 times the risk of dying in
a home fire |
Fix your home |
| 8 pCi/L |
About 120 people could get
lung cancer |
30 times the risk of dying in
a fall |
Fix your home |
| 4 pCi/L |
About 62 people could get lung
cancer |
5 times the risk of dying in a
car crash |
Fix your home |
| 2 pCi/L |
About 32 people could get lung
cancer |
6 times the risk of dying from
poison |
Consider fixing between 2 and
4 pCi/L |
| 1.3 pCi/L |
About 20 people could get lung
cancer |
(Average indoor radon level) |
(Reducing radon
levels below 2 pCi/L is difficult.) |
| 0.4 pCi/L |
About 3 people could get lung
cancer |
(Average outdoor radon level) |
Note: If
you are a former smoker, your risk may be lower.
pCi/L (pico Curies per Liter)
* Lifetime risk of lung cancer deaths from EPA Assessment of
Risks from Radon in Homes (EPA 402-R-03-003).
** Comparison data calculated using the Centers for Disease
Control and Prevention's 1999-2001 National Center for Injury
Prevention and Control Reports. |
Radon
Risk If You've Never Smoked
|
Radon Level |
If 1,000 people
who never smoked were exposed to this level over a lifetime*... |
The risk of
cancer from radon exposure compares to**... |
WHAT TO DO: |
| 20 pCi/L |
About 36 people could get lung
cancer |
35 times the risk of drowning |
Fix your home |
| 10 pCi/L |
About 18 people could get lung
cancer |
20 times the risk of dying in
a home fire |
Fix your home |
| 8 pCi/L |
About 15 people could get lung
cancer |
4 times the risk of dying in a
fall |
Fix your home |
| 4 pCi/L |
About 7 people could get lung
cancer |
The risk of dying in a car
crash |
Fix your home |
| 2 pCi/L |
About 4 person could get lung
cancer |
The risk of dying from poison |
Consider fixing between 2 and
4 pCi/L |
| 1.3 pCi/L |
About 2 people could get lung
cancer |
(Average indoor radon level) |
(Reducing radon
levels below
2 pCi/L is difficult.) |
| 0.4 pCi/L |
|
(Average outdoor radon level) |
Note: If you are a
former smoker, your risk may be higher.
pCi/L (pico Curies per Liter)
* Lifetime risk of lung cancer deaths from EPA Assessment of
Risks from Radon in Homes (EPA 402-R-03-003).
** Comparison data calculated using the Centers for Disease
Control and Prevention's 1999-2001 National Center for Injury
Prevention and Control Reports. |
|
Back Home

For reliable test results, follow this
Radon Testing Checklist
carefully. Testing for radon is not complicated. Improper
testing may yield inaccurate results and require another test.
Disturbing or interfering with the test device, or with closed-house
conditions, may invalidate the test results and is illegal in some
states. If the seller or qualified tester cannot confirm that all
items have been completed, take another test.
 |
Before Conducting a Radon Test: |
- Notify the occupants of the importance
of proper testing conditions. Give the occupants written instructions or
a copy of this Guide and explain the directions carefully.
- Conduct the radon test for a minimum
of 48 hours; some test devices have a minimum exposure time greater than
48 hours.
- When doing a short-term test ranging
from 2-4 days, it is important to maintain closed-house conditions for
at least 12 hours before the beginning of the test and during the entire
test period.
- When doing a short-term test ranging
from 4-7 days, EPA recommends that closed-house conditions be
maintained.
- If you conduct the test yourself, use
a qualified radon measurement device and follow the laboratory's
instructions. Your state may be able to provide you with a list of
do-it-yourself test devices available from qualified laboratories.
- If you hire someone to do the test,
hire only a qualified individual. Some states issue photo
identification (ID) cards; ask to see it. The tester's ID number,
if available, should be included or noted in the test report.
- The test should include method(s) to
prevent or detect interference with testing conditions or with the
testing device itself.
- If the house has an active
radon-reduction system, make sure the vent fan is operating properly.
If the fan is not operating properly, have it (or ask to have it)
repaired and then test.
| Closed-house conditions means
keeping all windows closed, keeping doors closed except for normal
entry and exit, and not operating fans or other machines which bring
in air from outside. Fans that are part of a radon-reduction
system or small exhaust fans operating for only short periods of
time may run during the test. |
 |
During a Radon Test: |
- Maintain closed-house conditions
during he entire time of a short term test, especially for tests shorter
than one week in length.
- Operate the home's heating and cooling
systems normally during the test. For tests lasting less than one week,
operate only air-conditioning units which recirculate interior air.
- Do not disturb the test device at any
time during the test.
- If a radon-reduction system is in
place, make sure the system is working properly and will be in operation
during the entire radon test.
 |
After a Radon Test: |
- If you conduct the test yourself, be
sure to promptly return the test device to the laboratory. Be sure
to complete the required information, including start and stop times,
test location, etc.
- If an elevated level is found, fix the
home. Contact a qualified radon-reduction contractor about lowering the
radon level. EPA recommends that you fix the home when the radon
level is 4 pCi/L or more.
- Be sure that you or the radon tester
can demonstrate or provide information to ensure that the testing
conditions were not violated during the testing period.

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. It is better to correct a radon problem before placing
your home on the market because then you have more time to address a
radon problem.
If elevated levels are found during the
real estate transaction, the buyer and seller should discuss the timing
and costs of the radon reduction. The cost of making repairs to
reduce radon levels depends on how your home was built 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 can
range from $800 to about $2,500.
A variety of methods can be used to
reduce radon in homes. Sealing cracks and other openings in the
foundation is a basic part of most approaches to radon reduction. EPA
does not recommend the use of sealing alone to limit radon
entry. Sealing alone has not been shown to lower radon levels
significantly or consistently.
In most cases, a system with a vent
pipe(s) and fan(s) is used to reduce radon. These "sub-slab
depressurization" systems do not require major changes to your home.
Similar systems can also be installed in homes with crawl space.
These systems prevent radon gas from entering the home from below the
concrete floor and from outside the foundation. Radon mitigation
contractors may use other methods that may also work in your home. The
right system depends on the design of your home and other factors.
Techniques for reducing radon are
discussed in EPA's
"Consumer's
Guide to Radon Reduction." As with any other household
appliance, there are costs associated with the operation of the
radon-reduction system.
Radon and home
renovations
If you are planning any major
renovations, such as converting an unfinished basement area into
living space, it is especially important to test the area for radon
before you begin.
If your test results indicate an
elevated radon level, radon-resistant techniques can be
inexpensively included as part of the renovation. Major renovations
can change the level of radon in any home. Test again after
the work is completed. |
You should also test your home again
after it is fixed to be sure that radon levels have been reduced. If
your living patterns change and you begin occupying a lower level of
your home (such as a basement) you should retest your home on that
level. In addition, it is a good idea to retest your home sometime in
the future to be sure radon levels remain low.
Select a qualified radon-reduction
contractor to reduce the radon levels in your home. Any mitigation
measures taken or system installed in your home must conform to your
state's regulations. In states without regulations covering
mitigation, the system should conform to EPA's
Radon
Mitigation Standards.
EPA recommends that the mitigation
contractor review the radon measurement results before beginning and
radon-reduction work. Test again after the radon mitigation work
has been completed to confirm that previous elevated levels have been
reduced.
A qualified radon-reduction (mitigation)
contractor should be able to:
- Review testing guidelines and
measurement results, and determine if additional measurements are
needed;
- Evaluate the radon problem and provide
you with a detailed, written proposal on how radon levels will be
lowered;
- Design a radon-reduction system;
- Install the system according to EPA
standards, or state or local codes; and
- Make sure the finished system
effectively reduces radon levels to acceptable levels.
Choose a radon mitigation contractor to
fix your radon problem just as you would for any other home repair.
You may want to get more than one estimate, ask for and check their
references. Make sure the person you hire is qualified to install
a mitigation system. Some states regulate or certify radon
mitigation services providers.
Be aware that a potential conflict of
interest exists if the same person or firm performs the testing and
installs the mitigation system. Some states may require the
homeowner to sign a waiver in such cases. If the same person or
firm does the testing and mitigation, make sure the testing is done in
accordance with the Radon Testing Checklist.
Contact your state radon office for more information.
The radon in your home's indoor air can
come from two sources, the soil or your water supply. Compared to
radon entering your home through water, radon entering your home through
soil is a much larger risk. If you've tested for radon in air and
have elevated radon levels and your water comes from a private well,
have your water tested. The devices and procedures for testing
your home's water supply are different from those used for measuring
radon in air.
The radon in your water supply poses an
inhalation risk and an ingestion risk. Research has shown that
your risk of lung cancer from breathing radon in air is much larger than
your risk of stomach cancer from swallowing water with radon in it.
Most of your risk from radon in water comes from radon released into the
air when water is used for showering and other household purposes.
Radon in your home's water in not usually
a problem when its source is surface water. A radon in water
problem is more likely when its source is ground water, e.g., a private
well or a public water supply system that uses ground water. Some
public water systems treat their water to reduce radon levels before it
is delivered to your home. If you are concerned that radon may be
entering your home through the water and your water comes from a public
water supply, contact your water supplier.
If
you've tested your private well and have a radon in water problem, it
can be fixed. Your home's water supply can be treated in one of two
ways. Point-of-entry treatment can effectively remove radon from
the water before it enters your home. Point-of-entry treatment
usually employs either granular activated carbon (GAC) filters or
aeration devices. While GAC filters usually cost less than
aeration devices, filters can collect radioactivity and may require a
special method of disposal. Point-of-use treatment devices remove
radon from your water at the tap, but only treat a small portion of the
water you use, e.g., the water you drink. Point-of-use devices are
not effective in reducing the risk from breathing radon released into
the air from all water used in the home.

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