IFA-36-CC!
-/EPA
United States
Environmental Protection
Agency
August 1986
OPA-86-005
Research and Development
Radon Reduction
Methods
A Homeowner's
Guide
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The U.S. Environmental Protection Agency strives to provide accurate,
complete, and useful information. However, neither EPA, nor any other
person contributing to or assisting in the preparation of this booklet—nor
any person acting on the behalf of any of these parties—makes any
warranty, guarantee, or representation (express or implied) with respect
to the usefulness or effectiveness of any information, method, or process
disclosed in this material or assumes any liability for the use of—or for
damages arising from the use of—any information, methods, or process
disclosed in this material.
U.S. Environmental Protection Agency
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EPA Study
Unique
Problems
The U.S. Environmental Protection Agency (EPA)
is studying the effectiveness of various ways to
reduce high concentrations of radon in houses.
While our work is far from complete, we have
gained some information which may be of
immediate use to homeowners. We are publishing
this booklet to share what we have learned with
those whose radon problems demand immediate
action. The booklet describes methods that have
been tested successfully—by EPA and/or other
research groups—on houses with high indoor
radon levels. The information presented here is
concerned primarily with radon which enters a
house from the underlying soil. Additional
information will be published as it becomes
available.
The first lesson to learn about radon reduction is
this: No two houses are alike. Even houses that
look the same have small differences in
construction that can affect radon entry and the
design and effectiveness of reduction techniques.
Underlying soils also may vary, even among
houses which sit close together. These differences
can affect the results obtained from using the
radon-reduction methods described here.
General This booklet is intended primarily for homeowners
Information who already have had their homes tested for radon
and have decided that they need to take some
action to reduce radon levels. If you are uncertain
of the meaning of such test results, or if you need
general information about radon in houses, read
the EPA leaflet, A Citizen's Guide to Radon: What
It Js And What To Do About It. To get a copy,
contact your state radiation protection office. If you
have difficulty locating this office, you may call
your EPA regional office (see list at the end of this
booklet) to obtain the appropriate address and
telephone number.
Using Most radon remedies require the skilled services of
Contractors a professional contractor who is experienced in
radon-reduction procedures. (EPA and the states
are currently working to increase the number of
experienced contractors.) Due to the skills
required, do-it-yourself efforts are not
recommended, and this booklet does not attempt to
give- the hometrwner detailed instructions for
corrective action. But, the information here should
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Technical
Information
Methods
Follow-up
help you make informed decisions on what type of
remedy is needed, and may assist you in
evaluating proposals from contractors.
We cannot overemphasize the importance of
carefully selecting a contractor and reviewing any
proposal for radon-reduction work at your house.
Asking for business references and checking with
your local Better Business Bureau or Chamber of
Commerce will help you ensure that a contractor is
qualified. Getting a second opinion from another
contractor or from one of your state's radiological
health officials can help you decide if a proposal is
reasonable. You should be certain to get a written
estimate of costs which stipulates the work to be
done. Because radon reduction work is so new,
contractors generally will be unable to guarantee a
reduction in radon levels. In fact, promises of great
results should be viewed with some scepticism.
Those homeowners who are confident they have
the tools, equipment, and skills to do the job
themselves may want to read EPA's more detailed
manual, Radon Reduction Techniques for Detached
Houses (EPA/625/5-86/019). To get a copy write:
U.S.EPA
Center for Environmental Research Information
26 West St. Glair Street
Cincinnati, Ohio 45268
This booklet describes various methods which may
reduce the level of radon in your house—either by
preventing its entry or by replacing contaminated
indoor air. Some of the methods are simple, some
are complex, some are much more expensive than
others.
The effectiveness of any one method will depend
upon the unique characteristics of each house, the
level of radon, the routes of radon entry, and how
thoroughly a job is done. No one can guarantee
that these methods will work as they did in the
test houses.
Sometimes, a single method may be sufficient,
but often—especially where levels are
high—several methods will need to be combined
to achieve acceptable results.
Once an action (or combination of actions) has
been performed, it is important that you have
further testing done. If the radon levels have not
been satisfactorily lowered, other steps may be
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taken, and the testing process repeated. All tests
should be performed in exactly the same manner
as the test which confirmed the high radon
levels in your house.
Due to the many factors affecting the
performance of any reduction technique, a
trial-and-error approach usually will be necessary
to achieve lasting radon reductions.
Other Avoiding Depressurization
Concerns An important factor in determining the rate at
which radon enters your home is the difference
between the air pressure indoors and the air
pressure in the soil. When the air pressure indoors
is less than the gas pressure in the surrounding
soil, radon can be drawn through cracks and
openings into your house. Lowered air pressure in
your house can be caused by several factors,
including: windows open only on the downwind
side of the house, exhaust fans such as those in
your kitchen or attic, and consumption of air by
appliances such as furnaces and clothes dryers.
Air Cleaners
Air cleaners are devices that filter particles—such
as dust—from the air. Existing information does
not clearly document the effectiveness of air
cleaners in reducing the risk of developing lung
cancer from exposure to indoor radon. EPA and
other groups are currently gathering information to
make this determination. Until more is known,
EPA believes that the data do not warrant
discontinuing the use of air cleaners already
installed, nor can we suggest installing air cleaners
to reduce your risk.
Radon in Water
Radon in water can be released into the air when
the water is agitated, aerated, or heated. However,
the level of radon in household water must be very
high to influence the overall level in the air within
a house.
In some cases, water from private wells or small
community wells does contain sufficient radon to
contribute significantly to elevated levels within a
house. Water coming from large community water
.supplies releases most of its radon before it reaches
individual houses.
For more information concerning radon in water,
contact your state radiation protection office.
3
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Method
Natural Ventilation
How It
Works
Replaces radon-laden indoor air with outdoor air.
Some natural ventilation occurs in every house
as air is drawn through tiny cracks and openings
by temperature and pressure differences between
indoor and outdoor air. In the average American
house, all the interior air is replaced by outside air
about once every hour. In technical terms, this is
called 1.0 ach (air changes per hour). Newer
houses, which are generally "tighter," may have
air-exchange rates as low as 0.1 ach (one-tenth that
of the average house). The rate in older houses, on
the other hand, may be twice the average (2.0 ach).
Cost
There are no installation costs unless devices must
be purchased to hold windows or vents in an open
position, or to detect or prevent unauthorized entry
through these openings.
Use of natural ventilation in cold weather will
increase your heating costs substantially, however.
For example, if you were to increase the air
exchange rate to eight times its normal level in
your basement and still maintain comfortable
temperatures there, your annual house heating bill
could be as much as three-and-one-half times
greater than normal.
If you normally run an air conditioner in hot
weather, cooling costs will be similarly greater.
Reductions Tightly constructed houses with low air-exchange
rates are likely to benefit more from ventilation
increases than are houses with naturally high
exchange rates. Radon reductions as high as 90
percent can be achieved using ventilation to
increase the exchange rate in a "tight" house from
0.25 ach to 2.0 ach.
Ventilation can only do so much, however.
There is a point at which increasing ventilation
will have no further significant effect on radon
levels in the house.
Limitations While natural ventilation can be tried easily
enough in most houses, it probably will not
sufficiently lower radon levels that are above 0.2
WL (40 pCi/1).* Also, for much of the year, in most
*WL (Working Levels) and pCi/1 (pico curies per liter) are two
commonly used measurement units for radon.
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Procedure
of the country, the trade-off in decreased comfort
and/or excessive heating or cooling costs may prove
unacceptable. Shifts in the force and direction of
the wind will make it nearly impossible to
maintain a constant air exchange rate over time.
You should ventilate the lowest level of your
house, where it is in direct contact with the
primary source of radon: the soil. If you have a
basement or crawl space, that is the area to
ventilate. (If you ventilate your basement, you may
find it more economical or comfortable to close it
off and limit its use.) If your house sits on a
concrete slab, then your only choice is to ventilate
the living area. Opening windows around all levels
of your house (including the main living area) is
recommended whenever outdoor conditions
permit.
As noted earlier, radon is drawn into your house
when the air pressure in the basement or lowest
level is less than the air pressure in the
surrounding soil. Therefore, it is imperative that
any ventilation system does not further reduce the
air pressure within your house and increase this
"pull." To guard against this, be certain to open
vents or windows equally on all sides of the house.
Also, minimize the use of exhaust fans.
When ventilating unheated areas, be sure to take
precautions to prevent pipes from freezing.
Air flow
through area
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Method
Forced Ventilation
How It
Works
Replaces radon-laden indoor air with outdoor air.
Uses fans to maintain a desired air-exchange rate
independent of weather conditions. (Much of the
information in the preceding section on "Natural
Ventilation" is applicable to "Forced Ventilation"
as well.)
Installation
When using forced ventilation, the flow of air
between entry and exhaust points must be properly
balanced. Otherwise, additional radon could be
drawn in, or moist air could be forced into the
walls or attic, where it can cause structural
damage. Therefore, we suggest that design,
installation, and testing be done by competent and
experienced contractors.
Cost
The total cost of fans with the air-moving capacity
to meet typical needs should be no more than
$150.
The cost of electricity to operate the fans could
be as much as $100 per year.
Use of forced ventilation throughout cold
weather will substantially increase your heating
costs. If, for example, you were to increase the air
exchange rate to eight times its normal level in
your basement while maintaining comfortable
temperatures there, your annual house heating bill
could be as much as three-and-one-half times
greater than normal.
If you normally have an air conditioner running
in hot weather, your cooling costs will be similarly
greater.
Reductions
As pointed out in the preceding section, "tight"
houses with low air-exchange rates are likely to
benefit more from ventilation increases than are
houses with high exchange rates. Depending upon
the amount of radon entering your house, there
will be some level below which increased
ventilation will cease to be effective.
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Limitations
Forced ventilation, like natural ventilation, can be
employed in most houses, but, by itself, is unlikely
to provide sufficient reductions of radon levels that
are above 0.2 WL (40 pCi/1). And, in many cases,
the trade-off in decreased comfort and/or excessive
heating or cooling costs may prove unacceptable.
Procedure
You should ventilate the lowest level of your
house. (Closing off and not using a basement may
be advisable.) Ventilating all levels is
recommended whenever outdoor conditions
permit. Air should be blown into the house and
allowed to exit through windows or vents on
adjacent or opposite sides. The use of an exhaust
fan to pull air out of the house may decrease the
interior air pressure and draw more radon inside.
Air distribution and ventilation rate can be
controlled by the sizing and location of fans and
the use of louvered air deflectors. EPA's experience
suggests that you should install two or three fans
rated at twice the air moving capacity calculated to
be needed for the desired increase in ventilation.
When ventilating unheated areas, be sure to take
precautions to prevent pipes from freezing.
Fan forces
outdoor air
into house
Radon-laden air
exits through
windows
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Method
Heat-Recovery Ventilation
How It
Works
Replaces radon-laden indoor air with outdoor air.
A device called a "heat recovery ventilator"
(sometimes referred to as an "air-to-air heat
exchanger") uses the heat in the air being
exhausted to warm the incoming air. In an
air-conditioned house in warm weather, the
process is reversed: the air being exhausted is used
to cool the incoming air. This saves up to 70
percent of the warmth (or coolness) that would be
lost in an equivalent ventilation system without
the device.
Installation Requires installation and testing by competent,
experienced professionals.
Cost
Installation costs (materials and labor) will range
from $400 to $1500, depending on the size of the
unit needed.
The cost for electricity to operate the equipment
could be as much as $100 per year.
Use of a heat recovery ventilator in your
basement could increase your heating bill as much
as 40 percent, depending upon your need to
replace the heat that is lost.
Reductions Heat-recovery ventilation, by itself, is not likely to
provide sufficient reductions of radon levels that
are above 0.2 WL (40 pCi/1). In some houses, heat
recovery ventilators in the basement have been
used to reduce radon levels by up to 96 percent.
Limitations Heat recovery ventilators can be installed in any
type of house, but are generally not used in crawl
spaces. Replacing the heating or cooling energy
lost (at least 30 percent) can be costly.
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Procedure
To effectively reduce high radon concentrations a
house-sized heat exchanger should probably be run
continuously (in the basement, if you have one).
The precise location and configuration of the
ventilation ductwork will depend upon the type of
heating and ventilation you have now, and the
source and entry points of the radon.
For lower radon concentrations, a window-sized
unit may be enough. In which case, replacing the
lost heating or cooling energy would be less costly.
Radon-laden
air exhaust
Heat Recovery Ventilator
Radon-laden
room air
intake
Warmed or cooled
air enters house
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Method
Air Supply
How It
Works
Reduces the amount of radon drawn into your
house.
Some home appliances or features—such as your
furnace, clothes dryer, and fireplace—lower the air
pressure in your house by consuming air and/or
exhausting it to the outside. The lower the air
pressure in your house, the more radon-laden air
will be drawn inside from the underlying soil.
While there are several other causes of low
indoor-air pressure, providing appliances with
separate sources of external air can reduce the
amount of radon entering the house.
Installation We recommend that you use the services of a
contractor with the knowledge and experience to
determine the amount of air needed for appliances
to function properly and safely.
Cost
Installation costs will vary greatly depending upon
the type and location of the appliances.
For some appliances, there may be a slight
increase in operating cost due to the lower
temperature of the air being heated.
Reductions Because each situation is different, it is impossible
to predict the reduction in radon levels that can be
expected as a result of supplying appliances with
sources of outside air. Results will depend upon
the operating condition of the appliance, the
source of the radon, and other conditions within
your house at any given time.
Limitations The usefulness of supplying outside air to
appliances is mostly limited to increasing the
effectiveness of other methods. For example, if a
block-wall suction system (see page 18) functions
less effectively in the winter, the problem could be
that the draft caused by a fireplace or woodstove is
overpowering the system.
10
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Procedure
Ductwork or piping can be run from any suitable
exterior wall to the appliance. The appliance's
normal vents or inlets for room air must be sealed
shut. A manual or automatic damper should be
placed in the ductwork to prevent entry of cold air
when the appliance is not in operation. The
outside end of the ductwork should be screened to
prevent entry of debris, insects, etc.
Air intake
for woodstove
Air intake
for clothes dryer
11
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Method
Covering Exposed Earth
HOW It Reduces the flow of radon into the house.
Works Exposed earth—in basement cold rooms, storage
areas, drain areas, sumps, and the like, as well as
in crawl spaces—is often a major entry point for
radon.
Installation Requires installation by competent, experienced
contractors or highly skilled homeowners.
Cost
Covering or sealing small areas (arid ventilating
covered air spaces as necessary) often costs under
$100.
The annual costs for operating small exhaust
fans, should they be needed, is minimal.
Reductions Since radon can seep through any small opening,
the degree of radon reduction achieved by sealing
any particular area cannot be predicted. Effectively
blocking a major entry point, however, should
result in significant reductions of the overall radon
level in your house. In houses with marginal radon
problems, covering exposed earth, along with
sealing cracks and openings (see page 14) may be a
sufficient remedy.
Covering exposed earth is also likely to enhance
the effectiveness of most other radon-reduction
methods, such as block-wall ventilation and
sub-slab suction.
Limitations As a house settles and reacts to external and
internal stresses, covered areas can open again
Therefore, periodic checking and maintenance are
required.
12
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Procedure
Any basement earthen floor should be excavated as
necessary and a poured concrete floor installed.
Small areas may be capped with an impermeable
covering such as aluminum sheet metal. All joints
must be carefully sealed. When the covering
encloses an air space, such as that around a sump
pump, a small fan should be installed to exhaust
the air to the outside.
A crawl space connected to a basement can be
covered, ventilated,and/or sealed off from the
basement.
A crawl space not connected to a basement can be
ventilated (as discussed in the section on natural
ventilation) or the earthen floor can either be covered
with a gas-proof liner (with passive vents to the
outside) or covered with concrete.
Outside fan
draws radon
away from house
Sealant
Sheet metal
covers exposed
area
^Sealant
13
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Method
Sealing Cracks and Openings
How It
Works
Reduces the flow of radon into the house.
Radon is a gas that can pass through any
opening in a floor or wall which touches the soil,
and enter your house through openings around
utility pipes, joints between basement floors and
walls, the holes in the top row of concrete blocks,
and tiny cracks and openings (such as the pores in
concrete block) not easily seen by the human eye.
Sealing such cracks and openings is often an
important preliminary step when other methods
are used. For houses with marginal radon
problems, sealing alone may be sufficient.
In some houses, certain areas will be difficult, if
not impossible, to seal without significant expense.
These include: the top of block walls, the space
between block walls and exterior brick veneer, and
openings concealed by masonry fireplaces and
chimneys.
Installation
Since effective sealing generally requires
meticulous surface preparation and carefully
controlled application of appropriate substances,
the work should only be done by experienced and
competent contractors or highly skilled
homeowners.
Cost
Cost of materials is generally minimal. The amount
of labor involved can vary widely depending upon
the number of routes to be sealed and their
accessibility. Most jobs can be done for $300 to
$500.
Reductions When sealing is used alone, you should expect
only low to moderate reductions in radon levels. If
sealing is done thoroughly—and all exposed earth
is covered—reductions may be sufficient in
some houses. Sealing is required for block-wall
ventilation and sub-slab suction to work effectively
(see pages 18 and 20).
14
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Limitations It is very difficult to find all the cracks and gaps in
your house, and the settling of the house and other
stresses may create more cracks as time passes.
Also, the openings in the top row of concrete
blocks in a wall are often inaccessible or otherwise
difficult to seal tightly. As a house settles and
reacts to external and internal stresses, old seals
can deteriorate and new cracks can appear.
Therefore, periodic checking and maintenance are
required.
Procedure
If possible, the holes in the top row of concrete
blocks in the basement walls should be sealed with
mortar or urethane foam.
Seal wall and floor joints with polyurethane
membrane sealants and a protective concrete cap.
Cracks and utility openings should be enlarged
enough to allow filling with compatible, gas-proof,
non-shrinking sealants.
Porous walls (especially block walls) require the
application of waterproof paint, cement, or epoxy
to a carefully prepared surface.
Top row
of block
Joint between
floor,and walls
Openings around pipes
Crack in floor
Cracks in wall
15
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Method
Drain-Tile Suction
How It
Works
Water is drained away from the foundation of
some houses by perforated pipes called drain tiles.
If these drain tiles form a continuous loop around
the house, they may be used to pull radon from the
surrounding soil and vent it away from the house.
Installation Normally requires installation and testing by
competent, experienced professionals.
Cost
Installation costs (labor and materials) could be
approximately $1200. The fan, trap, and riser
probably could be added to an existing drain-tile
system for around $100.
Annual operating costs would typically be $140
or less.
Reductions In some houses, the installation of a drain-tile
suction system could result in radon reductions as
great as 98 percent.
Limitations This method is applicable only to houses having
drain tiles which are connected in a continuous
loop around the entire house and are not closed at
any point by silt or other debris. (Sometimes,
minor blockage can be overcome by a more
powerful fan.)
Drain-tile suction will usually not work
effectively if there are block walls dividing the
interior of your basement.
This method is unlikely to provide sufficient
reductions of radon levels that are above 1.0 WL
(200 pCi/1).
16
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Procedure Water collected by drain tiles normally flows
through a pipe to a drainage area away from the
house or into a sump. Radon can be pulled from
the soil beneath a house by attaching an exhaust
fan to the collection pipe or to the sealed sump.
To prevent outside air from being drawn from
the end of the collection pipe, a water-filled trap
should be installed in the pipe beyond the point
where the fan is attached. This trap (similar to the
trap beneath a kitchen sink) must be placed below
the freeze line.
Drain-tile system
Fan draws radon
from drain tiles
Riser for
f > . maintaining
water level
Drain exit
\
Water in trap
prevents air flow
from drain exit
J
17
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Method
Block-Wall Ventilation
How It
Works
Installation
Cost
Reductions
Limitations
18
Draws radon from the spaces within concrete block
walls before it can enter the house ("wall suction")
or blows into block walls so that radon is
prevented from entering the walls ("wall
pressurization").
Draws radon from the spaces within concrete block
walls before it can enter the house.
The concrete blocks used to construct many
basement walls contain hollow spaces which are
connected both horizontally and vertically. Radon
from the soil—which enters the wall through joints
or tiny pores and cracks—can travel through these
connected spaces and enter the basement through
similar openings on the interior side or through the
openings in the top row of block.
Requires installation and testing by competent,
experienced professionals.
The installation of a series of exhaust pipes in an
unfinished basement would cost about $2500. A
baseboard collection system in a similar basement
would cost about $5000 to install.
Operating costs would typically be $140 or less
per year.
In some homes, the operation of a wall ventilation
system can reduce radon levels by as much as 99
percent or more.
Applicable only to houses with hollow block
basement walls. Block-wall suction may not be
successful if you cannot seal the top of the walls,
the space between the walls and any exterior brick
veneer, and openings that could be concealed by
masonry fireplaces or chimneys, in addition to
sealing noticeable cracks and openings. If you
cannot, so much air may leak into the walls that
the fan will be unable to maintain suction. In this
case, reversing the system and using wall
pressurization may be a better approach.
Block walls dividing the interior of a basement
sometimes penetrate the floor and touch the
underlying soil. Exhaust pipes must be installed in
all such walls.
Although this method can be used for any radon
level, it is best suited to levels above 0.2 WL (40pCi/l).
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Procedure There are two basic approaches to block-wall
ventilation. The easiest way is to insert one or two
pipes into each wall and use fans to draw radon
out of the walls and vent it outdoors, or use fans to
pressurize the walls to prevent radon entry. The
other approach involves the installation of a sheet
metal "baseboard" duct around the perimeter of
the basement. Holes are drilled behind the ducts
into the hollow spaces within the blocks. This
second approach oroduces more uniform
ventilation, and may be more pleasing in
appearance.
In houses which have channel drains cast in the
concrete floor under the block walls, the baseboard
approach should work particularly well, since it
would ventilate the drains as well as the walls.
For either wall-ventilation approach to work, all
major holes must be sealed. As we pointed out
previously, this might be difficult—if not
impossible—to do in certain places. (Both of the
approaches are shown below in the "suction"
mode.)
Outside fan
draws radon
away from house
\
Sheet metal
baseboard
Sealant
Radon is drawn
through holes
drilled in blocks
Baseboard Approach
Outside fan
.draws radon
away from house
n
n
n
n
Sealant.
Radon is drawn
/ / from walls
through pipes
Pipe-ln-Wall Approach
19
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Method
Sub-Slab Suction
How It
Works
The lowest floor of most houses, other than
those built over crawl spaces, consists of a
concrete slab poured over the earth or on top of
crushed rock (aggregate). Radon which
accumulates under the slab can be drawn out and
vented away from the house.
Installation Requires installation and testing by competent,
experienced professionals.
Cost
Installation costs for a multiple-pipe through-the-
slab system would be about $1000 to $2000.
Annual operating costs would typically be $140
or less.
Reductions Installation of a sub-slab suction system can reduce
indoor radon levels by 80 to 90 percent. In some
cases, 99 percent reductions have been achieved.
Limitations Sub-slab suction is most useful with foundations
built on good aggregate or on highly permeable soil.
In some cases, it may be difficult to create
enough suction to prevent radon from penetrating
hollow-block basement walls. In these cases, major
openings in the walls—including the holes in the
top row of blocks—should be sealed. If this is not
sufficient, more pipes may have to be inserted in
the slab, or a wall-ventilation system may have to
be added.
The sub-slab suction method is probably not
suitable for houses with radon levels above
2.0 WL (400 pCi/1).
20
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Procedure
The most common approach is to drill holes (two
may be enough) through the slab and insert pipes
which are connected to an outside fan. The holes
around the pipes must be tightly sealed.
Outside fan
draws radon
away from house
Pipes penetrate
beneath slab
Sealant
21
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Comparison of Features
Method
Natural ventilation:
Basement or
lowest floor
Crawl space
Forced ventilation:
Basement or
lowest floor
Crawl space
Air supply
Heat recovery ventilation
Covering exposed earth
Sealing cracks and spaces
Drain-tile suction
Block-wall ventilation
Sub-slab suction
Installation
Cost
Minimal
Minimal
Low
Low
Low to
moderate
Moderate to
high
Moderate
Minimal to
moderate
Moderate to
high
High to very
high
High to very
high
Operating
Cost
Very high
Moderate
Very high
Moderate
Low
Moderate
Low
None
Low
Low
Low
Maximum
Possible
Reductions*
Up to 90 %
Up to 90 %
Up to 90 %
Up to 90 %
Site specific
Up to 90+ %
Site specific
Site specific
Up to 97+ %
Up to 97 + %
Up to 97+ %
* These represent the best reductions that a single method can accomplish. You may get
higher or lower reductions depending on the unique characteristics of your house. It is
likely that reductions in your house wil not be as great as those shown. Especially with
high initial radon levels, several methods may have to be combined to achieve acceptable
results.
22
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Comment
Useful, immediate step to reduce high
radon levels.
More controlled than natural ventilation.
May be required to make other methods
work.
Air intake and exhaust must be equal.
Required to make most other methods work.
Required to make most other methods work.
Works best when drain tiles are
continuous, unblocked loop.
Applies to block-wall basements.
Sub-slab suction may be needed to
supplement.
Important to have good aggregate or highly
permeable soil under slab.
23
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Sources Of H you would like further information or
Information explanation on any of the points mentioned in this
booklet, you should contact your state radiation
protection office.
If you have difficulty locating this office, you
may call your EPA regional office listed below.
They will be happy to provide you with the name,
address, and telephone number for your
appropriate state contact.
State—EPA Region
Alabama—4
Alaska—10
Arizona—9
Arkansas—6
California—9
Colorado—8
Connecticut—1
Delaware—3
District of
Columbia—3
Florida—4
Georgia—4
Hawaii—9
Idaho—10
Illinois—5
Indiana—5
Iowa—7
Kansas—7
Kentucky—4
Louisiana—6
Maine—1
Maryland—3
Massachusetts—1
Michigan—5
Minnesota—5
Mississippi—4
Missouri—7
Montana—8
Nebraska—7
Nevada—9
New Hampshire—1
New Jersey—2
New Mexico—6
New York—2
North Carolina—4
North Dakota—8
Ohio—5
Oklahoma—6
Oregon—10
Pennsylvania—3
Rhode Island—\
South Carolina—4
South Dakota—8
Tennessee—4
Texas—6
Utah—8
Vermont—1
Virginia—3
Washington—10
West Virginia—3
Wisconsin—5
Wyoming—8
EPA Regional Offices
EPA Region 1
Room 2203
JFK Federal Building
Boston, MA 02203
(617) 223-4845
EPA Region 2
26 Federal Plaza
New York, NY 10278
(212) 264-2515
EPA Region 3
841 Chestnut Street
Philadelphia, PA 19107
(215) 597-8320
EPA Region 4
345 Courtland Street, NE.
Atlanta, GA 30365
(404) 881-3776
EPA Region 5
230 South Dearborn Street
Chicago, IL 60604
(312) 353-2205
EPA Region 6
1201 Elm Street
Dallas, TX 75270
(214) 767-2630
EPA Region 7
726 Minnesota Avenue
Kansas City, KS 66101
(913) 236-2803
EPA Region 8
Suite 1300
One Denver Place
999 18th Street
Denver, CO 80202
(303) 283-1710
EPA Region 9
215 Fremont Street
San Francisco, CA 94105
(415) 974-8076
EPA Region 10
1200 Sixth Avenue
Seattle, WA 98101
(206) 442-7660
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US. Environmental Protection Agency
Region V, Library
230 South Dearborn Street
Chicago, Illinois 60604
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