U.S. ENVIRONMENTAL PROTECTION AGENCY
REPORT TO CONGRESS ON RADON MITIGATION DEMONSTRATION PROGRAM
UNDER
SECTION 118 (k)
THE SUPERFUND AMENDMENTS AND REAUTHORIZATION ACT OF 1986
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TABLE OF CONTENTS
Page
I . INTRODUCTION 1
A. Purpose of Report 1
B. Overview of the Radon Problem 2
C. EPA's Radon Action Program 3
II. HISTORY OF EPA'S PAST RADON MITIGATION ACTIVITIES 7
III . RADON MITIGATION AND PREVENTION 9
A. Radon Entry and Buildup in Houses 9
B. Reducing Radon Levels in Houses..... 11
1. Techniques for Preventing Radon from Entering
the House 12
2. Techniques for Ventilating and Removing Radon
from indoor Air 19
3. Techniques for Removing Radon from Drinking Water. 20
IV. STATUS OF MITIGATION AND PREVENTION PROGRAMS 27
A. Objectives of Mitigation and Prevention Activities.... 27
B. Program Description 28
1. Development and Demonstration Program 28
2. House Evaluation Program 41
3. Technology Transfer and Training 48
V. CONCLUSION 50
11.
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List of Figures
Figure
No.
1 Areas with potentially high radon levels 4
2 Major radon entry routes into detached houses 10
3 Sub-slab ventilation 13
4 Avoidance of house depressurization 16
5 Potential radon entry routes. 18
6 Forced air with heat recovery 21
List of Tables
Table
No. Page
1 Summary of Radon Reduction Techniques 22
2 Radon Reduction Techniques Demonstrations 30
iii.
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I. INTRODUCTION
A. Purpose of Report
The purpose of this document is to fulfill the requirements set
forth in Section 118(k)(2)(B) of the Superfund Amendments and
Reauthorization Act of 1986 (SARA), which requires the Administrator of
the United States Environmental Protection Agency (EPA) to submit to
Congress annual reports on the status of the Agency's radon demonstration
program beginning February 1, 1987.
This report includes an overview of the radon problem, a brief
description of the goals and objectives of the Agency's Radon Action
Program, fundamental information on radon entry routes, various
mitigation principles and techniques, and the status of specific
demonstration projects the Agency currently has underway. Details of
BPA's overall radon program within EPA can be found in Appendix A,
"Report to Congress on indoor Air Pollution and Radon under Title IV of
the SARA, Chapter 3." More specific information on radon reduction
techniques can be found in Appendix B, "Radon Reduction Techniques for
Detached Houses...Technical Guidance."
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B. Overview of the Radon Problem
Radon-222 is a radioactive gas produced by the radioactive decay of
radium-226, which occurs naturally in almost all soils and rocks. Radon
is present in the atmosphere everywhere due to its release from radium
decaying in the ground. Outdoor radon levels generally are low, on the
*
order of 0.2 picocuries per liter . Indoor levels are typically about
five times higher than average outdoor levels, but can be over ten
thousand times higher. Exposure to these elevated levels may greatly
increase an individual's risk of developing lung cancer. Further/ since
radon often concentrates in buildings, it is believed that this increased
exposure substantially contributes to the incidence of lung cancer in the
United States. The Environmental Protection Agency and other scientific
groups estimate that from about 5,000 to about 20,000 lung cancer deaths
a year in the United States may be attributed to radon. (The American
Cancer Society expects that about 130,000 people will have died of lung
cancer in 1986. The Surgeon General attributes approximately 85 percent
of all lung cancer deaths to smoking.)
While the Reading Prong area of Pennsylvania, New Jersey, and New
York is the best known high-radon area in the United States at this time,
*Radon gas is measured in picocuries per liter of air (pCi/1). A curie
is the standard measure of radioactivity. Pico indicates an amount equal
to one trillionth (10~12) of that measure.
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indoor radon-is potentially a widespread problem (GAD/RCED-86-no, Indoor
Radon Air Pollution). Elevated radon levels have been found in houses in
many States—not only where suspected geological factors or the presence
of uranium deposits suggest that radon might be a problem (Figure 1).
Preliminary data indicate that perhaps more than 10 percent of the
approximately 85 million homes in the United States may have radon levels
reaching or exceeding four pci/l—the level recommended by EPA as a
target for corrective action. This level was based both on health
considerations and on the limitations of current technology in reducing
radon levels below this target.
C. BPA's Radon Action Program
In response to a growing concern about elevated indoor radon
concentrations in houses situated on the Reading Prong and elsewhere, the
EPA Administrator established the Radon Action Program in
September 1985. The goals of the program are to:
• Determine the extent of the problem, information is needed not
only on the "hot spots" in the United States, but also on the
distribution of radon levels in homes throughout the country.
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AREAS WITH POTENTIALLY HIGH RADON LEVELS
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o Reduce exposure to radon in existing homes. The development and
demonstration of cost-effective reduction techniques will
eventually enable homeowners to correct a radon problem as easily
as they might correct a water or electrical problem in their
homes.*
o Prevent radon problems in new housing. By addressing the problem
in new construction, as well as in existing houses, EPA can help
reduce the potential risk to people who live in new houses and
consequently lower the national average concentrations of radon
in houses.
To meet these goals, EPA has developed a program that provides for
both information development and information delivery. The Agency is
developing and disseminating technical knowledge to encourage, support,
and facilitate the development of State programs and private sector
capabilities in the areas of radon assessment and mitigation. It is
acting as a catalyst to bring together the appropriate expertise and
responsibilities of Federal agencies, State and local governments, and
the private sector.
To better focus its efforts, EPA's radon program consists of five
major elements and objectives:
*EPA will regulate radon in public drinking water supplies by setting a
maximum contaminant level under the Safe Drinking.Water Act.
5
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• Radon exposure and health risk: To identify areas with high
levels of radon in houses and to determine the national
distribution of radon levels and the associated risks.
• Mitigation and prevention: To identify cost-effective methods to
reduce radon levels in existing structures and to prevent
elevated radon levels in new construction.
• Capability development; To stimulate the development of State
and private sector capabilities to assess radon problems in homes
and to help people mitigate such problems.
* public information: To work with States to provide information
to homeowners on radon, its risks, and what can be done to reduce
those risks.
• Federal coordination: To take advantage of the expertise,
responsibilities, and resources throughout the Federal Government
in addressing the radon issue and to coordinate the activities of
each agency to maximize the effectiveness of the overall Federal
effort.
This report deals primarily with the Agency's activities in the
areas of radon mitigation and prevention. For more detail about other
aspects of EPA's indoor radon program, see Appendix A.
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II. HISTORY OF EPA'S PAST RADON MITIGATION ACTIVITIES
over the past 20 years, EPA has assisted States with their response
to several occurrences of elevated indoor radon levels. In the late
1960's and early 1970's, EPA investigated homes in Grand Junction,
Colorado, contaminated by uranium mill tailings, a byproduct of uranium
mining. The elevated radon levels found in those homes led to the
issuance of the Surgeon General's guidelines regarding remedial action in
houses built on or with uranium mill tailings.
During the 1970's, EPA also investigated instances of elevated radon
levels in houses built on reclaimed phosphate mines in central Florida.
In 1979, EPA issued guidelines to the State of Florida for remedial
action in existing homes and for new home construction. Part of the work
conducted in Florida included the demonstration of remedial techniques,
both for new and existing houses, to control indoor radon levels. This
work was an important first step both in understanding the dynamics of
radon entry into a structure and in determining the relative effective-
ness of various methods to reduce indoor levels.
In 1983, the Agency began to clean up, under the Superfund program,
a number of homes in New Jersey that were built on industrial radium
waste sites. In this and the two previous instances, elevated indoor
radon levels resulted from "raanraade" sources of radon. Further,
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"elevated" radon levels in houses were typically between 10 and 20 pCi/1,
with very few exceeding 20 pci/1. In many cases, houses were permanently
mitigated by removing the source of radon.
National attention was focused on the problem of indoor radon in
December 1984, when a worker at a nuclear power plant in Pennsylvania was
found to be living in a house that contained extremely high levels of
radon. In this case, the radon was being emitted by the naturally
occurring elevated levels of uranium in the soil on which the house was
built. Subsequent investigations revealed that thousands of homes in the
Reading Prong, a geological formation that runs from Pennsylvania through
New Jersey and into New York, contained elevated levels of naturally
occurring radon. These facts led the Agency to focus its initial efforts
in the mitigation area on the development and demonstration of methods to
reduce radon that would (1) be effective in reducing extremely elevated
levels; (2) not rely on removal of the source material; and (3) be
relatively inexpensive, since the costs of mitigation would likely be
borne by the individual homeowner. EPA designed its initial mitigation
program with these parameters in mind.
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III. RADON MITIGATION AND PREVENTION
A more detailed coverage of the mitigation and prevention techniques
discussed in this section can be found in Appendix B, "Radon Reduction
Techniques for Detached Houses — Technical Guidance" (EPA/625/5-86/019).
A. Radon Entry and Buildup in Houses
Radon levels can vary greatly from house to house. For example,
radon levels have been measured in houses as low as 1 pci/l to greater
than 2,500 pci/l. Further, radon levels found in one house may be
dramatically different from those in the house next door, despite
apparent similarities in construction type. This suggests that a number
of factors can influence the level of radon gas found in a particular
structure.
Findings to date clearly indicate that the most significant pathway
of radon entry into a house is radon migration from soil into basements
or those portions of the house that are in contact with the soil. This
migration primarily takes place through cracks, penetration points for
utilities, and openings for prevention of moisture build-up in house
substructures, not by diffusion through solid materials or walls (Figure
2). Lesser concentrations of radon may enter a house through exposed
building materials that contain radon-emanating substances and potable
(drinking) water sources that contain dissolved radon.
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Figure 2_. Major radon entry routes into detached houses
Key to Major Radon'Entry Routes
Soil Gas
A Cracks in concrete slab
B Cracks between poured concrete (slab) and blocks
C Pores and cracks in concrete blocks
D Slab-footing joints
E Exposed soil, as in sump
f Weeping tile
G Mortar joints
H Loose fitting pipes
Building Materials
10
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The amount of radon transferred from the soil to the house is
affected by many factors, including the radon concentration in underlying
soil and the porosity of the soil (radon soil gas availability), house
construction and substructure type, and the pressure differential between
house and soil, since radon reduction techniques employed in a given
house may have to address a number of these factors and treat more than
one radon entry route, they must often be house-specific.
B. Reducing Radon Levels in Houses
There are primarily four ways to reduce radon levels in houses:
• Prevent radon from entering a house,
• Ventilate indoor air containing radon and its decay products from
the house,
• Remove radon and its decay products from indoor air, and
• Remove the source of the radon.
11
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Removing a naturally occurring source of radon is rarely practical,
and thus is usually not a viable mitigation option. Ventilating the
radon from a house or removing the radon and decay products from the
indoor air is only treating symptoms of the problem and may not be
practical on a year-round basis. Therefore, the Agency has concluded
that mitigation efforts should focus on preventing the radon from
entering the house.
1. Techniques for Preventing Radon from Entering the House
The techniques that are available for preventing radon from entering
the house are listed and discussed in the following paragraphs. A
summary of radon reduction techniques is listed in Table 1.
a. Venting Radon Away from the House through External Methods
The methods listed and discussed below can be used to vent radon
away from the house.
• Sub-slab ventilation (Figure 3)
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 that accumulates in the soil under the
slab can be vented away from the house by placing pipes through the slab
12
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Figure 3. Sub-slab ventilation
Close top voids
Close major mortar
cracks ar»d holes in
wall
Note:
1. Closing of major slab openings
(e.g., major settling cracks, utility
penetrations, gaps at the wait/
floor joint) is important.
Restored concrete
House air through unclosed
settling cracks,cold joints,
utility openings'
Connection
to other
suction point
Aggregate
-. rr: •. £T*."7Yr
Liner under
;. restored concrete
13
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and venting (or sucking) the radon away from the house before it has a
chance to enter the house (see Figure 3).
• Block-wall ventilation
The centers of concrete blocks used to construct many basement walls
contain voids that are connected both horizontally and vertically. Radon
can be ventilated or swept from the voids before entering the house by
drawing suction on this void network. The void network is maintained at
a pressure lower than that of both the surrounding soil and the
basement. Hence, any radon-containing soil gas that has entered through
cracks and openings in the blocks will be vented outward with the
basement air rather than into the basement.
• Floor/wall joint ventilation
The floor/wall joint around the inside perimeter, where the slab
rests against the house foundation footer and the block or poured cement
wall, is often a major entry route for radon soil gas into houses. Radon
can be ventilated or swept from the floor-wall joints by tightly sealing
a baseboard duct around the entire perimeter of a house and drawing
suction on that duct network. In houses with hollow block walls, holes
can be drilled into the block voids prior to installing the duct network,
thus effecting block wall ventilation as well.
14
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• Drain-tile suction
Water is drained away from the foundation of some houses by
perforated pipes called drain tiles. In cases where 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. In some
houses the drain tile is connected to an internal sump. In this case
suction should be drawn on the sump and the drain tiles.
b. Reducing Forces That Induce or Draw Radon into Houses
• Avoidance of house depressurization (Figure 4)
The house living space may be depressurized when certain household
appliances and fireplaces that use and exhaust house air to the outside
are in use. Depressurization of a house often occurs naturally in the
winter as a result of the rising of heated indoor air and its loss or
exfiltration to the outdoors. This is called the "stack effect" (as in
smoke stack). The winter stack effect or depressurization which draws
radon soil gas into houses is believed to be one of the main causes of
increased radon entry.
15
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Figure 4. Avoidance of house depressurization
Air intake
for woodstove
Air intake
J-'for
i
~v
clothes dryer
.Air intake
for furnace.
burner
16
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Any additional cause of depressurization, especially in basements or
rooms abutting or directly on the soil, can also contribute to increased
radon entry. Thus, if additional depressurization activities can be
limited or modified by the direct provision of outside makeup (combustion
or exhaust) air, increased radon entry can be avoided.
The American Society of Heating, Refrigeration, and Air-conditioning
Engineers (ASHRAE) has recommended the provision of outside makeup air
for combustion appliances, such as furnaces and water heaters, since
1981. This effort is also known to save energy in houses, since
appliances not provided outside makeup air will use heated or cooled
inside air for combustion and exhaust.
c. Sealing Radon Out of the House (Figure 5)
Exposed soil and rock under, around, and within a house can be a
major source and entry route of radon into the living area of a house.
Radon soil gas entry can be prevented by sealing all cracks, openings, or
other voids in the house structure that provide pathways for gas flow
from the soil into the house. Sealing of potential radon entry routes is
often considered as an initial radon reduction approach, especially in
houses with marginal problems. It is important to realize, however, that
seals must be periodically checked to assure continued effectiveness.
Sealing is often implemented in conjunction with other radon reduction
strategies.
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Figure 5. Potential radon entry routes
\
[ Top row
of block
Joint between
floor,and walls
Openings around pipes
Crack in floor
EXPOSED
ROCK AND SOIL
18
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2. Techniques for Ventilating and Removing Radon from indoor Air
When preventing radon from entering a house is not practical or
simply cannot be achieved, or when the initial level is relatively low,
techniques for ventilating and removing the air containing radon from th€
house may be employed. However, these techniques are not as effective ir
lowering indoor radon levels as those which prevent radon entry. In
addition, these techniques often carry an energy penalty since they
dilute and exhaust conditioned indoor air.
The methods listed and discussed below can be used to remove or
ventilate indoor air.
o Natural ventilation
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 environments. In the average American house,
all the interior air is replaced by outside air about once every hour.
Ventilation as a means for controlling radon levels should be effected i
the lowest level of a house, where it is in direct contact with the soil
(Figure 2). Tightly constructed houses with low air exchange rates are
likely to benefit more from ventilation increases than houses with
naturally high exchange rates.
o Forced ventilation
Forced ventilation uses a fan to replace radon-laden air with fresh
outdoor air by maintaining a desired air-exchange rate independent of
weather conditions. 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 th
walls or attic, where it can cause structural damage.
19
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Forced air ventilation with heat recovery (Figure 6)
This method also 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 may save up to 70 percent of the warmth (or coolness)
that would be lost in an equivalent ventilation system without the device,
3. Techniques for Removing Radon from Drinking Water
Radon gas being released from household water obtained from private
wells and small community drinking water supplies may contribute to
indoor radon problems. When radon released from drinking water has been
determined to be a source of elevated indoor radon levels, the following
technique may be employed to remove the radon from the drinking water
before it enters the house.
o Granular activated carbon
Disolved radon tends to become attached to activated carbon
particles. If the household water supply is passed through a tank
containing activated carbon up to 99 percent of the waterborne radon will
be captured.
20
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Figure 6. Forced air with heat recovery
Radon-laden
air exhaust
Heat Recovery Ventilator
Radon-laden
room air
intake
Warmed or cooled
air enters house
21
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Table 1. Surrmary of Radon Reduction Techniques
House
Principle Types
of Appli-
Method Operation cable
Sub-slab soil Continually BB
ventilation collect and PCS
exhaust S
soil -gas-
borne radon
from the
aggregate or
soil under
the concrete
slab
Confi-
Esti mated dence Operating
Annual Avg. in Conditions
Concentration Effec- and
Reduction, % tiveness Applicability
80-90 Moderate Continuous col-
as high to high lection of soil-
as 99 in gas-borne radon
some cases using one fan
(~ 100 cfm,
>0.4 in.; H20
suction) to ex-
haust aggregate
or soi 1 under
slab
For individual
suction point
approach,
roughly one
suction point
per 500 sq ft
of slab area
Estimated
Installation
and Annual
Operating Costs
Installation cost
for individual suc-
tion point approach
is about $2000
(contractor
installed)
Installation costs
for retrofit sub-
slab piping network
would be over $5000
(contractor
installed)
Operating costs are
$15 for fan energy
(if used) and up to
$125 for supple-
mental heating
Active ven-
tilation of
hoi low-
block
basement
walls
Continually
collect,
dilute, and
exhaust soil-
gas-borne
radon from
hollow-block
basement
walls
BB
Up to 99*
Moderate
to high
Piping network
under slab is
another approach,
might permit
adequate venti-
lation without
power-driven fan
Continuous col-
lection of soil-
gas-borne radon
using one 250
cfm fan to ex-
haust all hol-
low-block perim-
eter basement
walls
Installation costs
for a single suc-
tion and exhaust
point system is
$2500 (contractor
installed in un-
finished basement)
Operating costs are
$15 for fan energy
and up to $125 for
supplemental heating
22
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Table 1. (Continued)
Method
Active
ventilation of
floor/wall
joints
Drain tile
soil ventilation
Principle
of
Operation
Continually
collect,
dilute, and
exhaust soi 1
soi 1 -gas-
borne radon
from floor
wall joints
and hollow
block base-
ment walls
Continuously
collect,
dilute, and
exhaust soil-
gas-borne
radon from
the footing
perimeter of
houses
House
Types
Appli-
cable
BB
PCB
S
BB
PCB
S
Confi-
Estimated dence Operating
Annual Avg. in Conditions
Concentration Effec- and
Reduction, 1 tiveness Applicability
Up to 98 Moderate Baseboard wall
collection and
exhaust system
used in houses
with French
(channel) drains
Up to 98 Moderate^ Continuous col-
lection of soil-
gas-borne radon
using a 160 cfm
fan to exhaust a
perimeter drain
tile
Estimated
Instal lation
and Annual
Operating Costs
Installation cost
is between $3000
and $5000
Operating costs are
$15 for fan energy
and $125 for
supplemental heating
Installation cost
is $1200 by con-
tractor
Operating costs are
$15 for fan energy
and up to $125 for
supplemental heating
Active avoidance
of house depress-
urization
Sealing radon
entry routes
Provide
clean makeup
air to house-
hold appli-
ances which
exhaust or
consume in-
door air
Use gas-proof
sealants to
prevent soil-
gas-borne
radon entry
All
0-1 Oe
Moderate7
Applicable to
houses with a
complete perim-
eter footing level
drain tile system
Provide outside
makeup air to
appliances such
as furnaces,
fireplaces,
clothes dryers,
and room exhaust
fans
All
30-90
Extremely
case
specific
All noticeable
interior cracks,
cold joints,
openings around
services, and
pores in basement
walls and floors
should be sealed
Installation costs
of small dampered
duct work should
be minimal
Operating benefits
may result from
using outdoor air
for combustion
sources
Installation costs
range between
$300 and $500
23
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Table 1. (Continued)
Method
Sealing major
radon sources
Natural
ventilation
Forced air
ventilation
House
Principle Types
of Appli-
Operation cable
Use gas- All
proof barriers
to close off
and exhaust
venti late
sources of
soil -gas-
borne radon
Air exchange All3
causing re-
placement
and dilution
of indoor
air with
outdoor air
by uniformly
opening
windows and
vents
Air exchange All
causing re-
placement
and dilution
of indoor
air with
outdoor air
by the use
of fans
located in
windows or
vent openings
Confi-
Estimated dence Operating
Annual Avg. in Conditions
Concentration Effec- and
Reduction, 1 tiveness Applicability
Local exhaust Extremely Areas of major
of the source case soil -gas entry
may produce specific such as cold
significant rooms, exposed
house-wide earth, sumps, or
reductions basement drains
may be sealed
and ventilated
90^ Moderate Open windows
and air vents
uniformly
around house
Air exchange
rates up to 2
ach may be
attained
May require
energy and
comfort penalties
and/or loss of
living space use
90^ Moderate Continuous op-
eration of a
central fan with
fresh air
makeup, window
fans, or local
exhaust fans
Forced air venti-
lation can be
used to increase
air exchange
rates up to 2 ach
Estimated
Installation
and Annual
Operating Costs
Most jobs could be
accomplished for
less than $100
Operating costs for
a small fan would
be minimal
No installation
cost
Operating costs for
additional heating
are estimated to
range up to a 3.4-
fold increase from
normal (0.25 ach)
ventilation condi-
tions0
Installation costs
range up to $150
Operating costs
range up to $100
for fan energy and
up to a 3.4-fold
increase in normal
(0.25 ach) heating
energy costs0
May require energy
and comfort penal-
ties and/or loss
of living space use
24
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liable 1. (Continued)
Pfetbod
Forced air
ventilation with
heat recovery
House
Principle Types
of _ Appli-
Operation oable
Air exchange All
causing re-
pLaosrrent
and dilution
of indoor air
with outdoor
air by the
use of a fen
powered ven-
tilation
system
Oonfi-
Estinated dence Operating
Annual Avg. in Cbnditions
Oncentraticn Effec- and
Reduction, % tiveness Applicability
96*3 Moderate Oontirucus cp-
to high eration of units
rated at 25-240
cubic feet per
minute (cfin)
Air exchange in-
creased from
0.25 to 2 aeh
In cold cliirates
units can re-
cover up to 70%
of heat that
Estiirated
Installation
and Annual
Operating Costs
Installation costs
range from $400 to
$1500 for 25-240
cfin units
Operating costs
range ip to $100
for fan energy
plus ip to 1.4-
fold increase in
heating costs
assuming a 70%
efficient heat
recovery0
Granular acti-
vated carbon
(OC) *
Waterborne
radon is
trapped on
activated
oarten as
water is
through
GSC tank
would be lost
through house
ventOaticn
without heat
recovery
All up to 99 High Cbntinuiaus
Operation of
units which are
siaad to meet
household water
usaage and radon
reduction needs
•typically ere to
three cubic feet
OC tank
Installation cost
range from $650 to
$L200 depending on
sias of unit and
how it is installed
*Ncte that radon decay products buildHp in tanks irey present a direct radiation ejqposure hazard in sate
extreme cases. Installaticn sway from human contact, such as in an outdoor building should eliminate the
exposure problsn.
25
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••IBlock basement) houses with hollow-block (concIBB block or cinder block) basement or partial
basement, finished or unfinished
PCB (Poured concrete basement) houses with full or partial, finished or unfinished poured-concrete walls
C (Crawl space) houses built on a crawl space
S (Slab, or slab-on-grade) houses built on concrete slabs.
Field studies have validated the calculated effectiveness of four-fold to eight-fold increases in air
exchange rates to produce up to 90 percent reductions in indoor radon.
Operating costs are ascribed to increases in heating costs based on ventilating at 2 ach the radon
source level; as an example, the basement with 1) no supplementary heating or 2) supplementary heating
to the comfort range. It is assumed the basement requires 40 percent of the heating load and, if riot
heated, would, through leakage, still increase whole house energy requirements by 20 percent. Operating
costs are based on fan sizes needed to produce up to 2 ach of a 30x30x8 ft (7200 cu ft) basement or an
eight-fold increase in ventilation rate.
Recent radon mitigation studies of 10 inlet/outlet balanced mechanical ventilation systems have reported
radon reduction up to 96 percent in basements. These studies indicate air exchange rates were increased
from 0.25 to 1.3 ach.
This estimate assumes that depressurizing appliances (i.e., local exhaust fans, clothes dryers,
furnaces, and fireplaces) are used no more than 20 percent of the time over a year. This suggests that
during the heating season use of furnaces and fireplaces with provision of makeup air may reduce indoor
radon levels by up to 50 percent.
Studies indicate that significant entry of soil-gas-borne radon is induced by pressure differences
between the soil and indoor environment. Specific radon entry effects of specific pressurization and
depressurization are also dependent on source strengths, soil conditions, the completeness of house
sealing against radon, and baseline house ventilation rates.
Ongoing studies indicate that where a house's drain tile collection system is complete (i.e., it goes
around the whole house perimeter) and the house has no interior hollow-block walls resting on sub-slab
footings, high radon entry reduction can be achieved.
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IV. STATUS OF MITIGATION AND PREVENTION PROGRAMS
A. Objectives of Mitigation and Prevention Activities
To help meet the goal of reducing the national risk from indoor
radon, the Agency has identified the following four objectives for its
radon mitigation and prevention activities.
• To research and develop standard methods for diagnosing radon
movement through soils and buildings and for evaluating
house-specific radon reduction techniques.
• To develop, demonstrate, and evaluate cost-effective methods for
reducing radon concentrations in existing homes.
• To develop, demonstrate, and evaluate cost-effective methods for
preventing radon entry into new homes.
• To transfer appropriate information on radon reduction approaches
to Federal, State, and local government officials, designers and
builders, the private sector, and the public.
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B. Program Description
EPA is managing its mitigation and prevention activities through a
development and demonstration program, a house evaluation program, and
through special attention to technology transfer and training.
1. Development and Demonstration Program
BPA's Development and Demonstration Program (DDP) is an ongoing
program to research, develop, and demonstrate cost-effective radon
reduction and prevention methods for homes. This program started in 1984
in the Boyertown area of eastern Pennsylvania, and expanded into New York
and Mew Jersey in Fiscal Year 1986.
To meet EPA's goal of developing and demonstrating cost-effective
mitigation and prevention techniques for all types of houses in the
United States, the Agency has developed test matrices for the selection
of new and existing houses for study. Both matrices consider such
factors as radon reduction or preventive techniques, house substructure,
initial indoor radon concentration, geology, and climate. These matrices
have been reviewed by the Agency's Science Advisory Board, which has
endorsed this concept.
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Emphasis to date has been on field projects to develop and
demonstrate radon reduction in existing homes with basements and/or
slab-on-grade construction, with moderately high to very high radon
concentrations. As the following project summaries indicate, the Agency
is moving toward a more comprehensive coverage of diagnostic and
mitigation techniques and initial radon levels in homes. As of
December 1986, radon reduction techniques have been demonstrated in 55
houses (Table 2).
a. Existing Houses
(1) Eastern Pennsylvania Project
Eastern Pennsylvania was selected as the first site for a radon
mitigation field project because of the extremely high radon levels that
were discovered in some houses in the region. The testing there has
focused on developing low- to moderate-cost radon reduction techniques
which can achieve the very high reductions required (often 99+ percent)
in homes having substructures representative of the region.
The houses were selected with the cooperation of the Pennsylvania
Department of Environmental Resources (DER). In 27 of the 30 houses
selected to date, the primary reduction technique has been based upon the
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Table 2. Radon Reduction Techniques Demonstrations
Location
No. of
Homes
Funds
Testing
Techniques
Mitigation
Techniques
Results
Eastern
Pennsylvania
27
Active soil
ventilation
• 13 houses above 901
reduction
• 9 houses between 751
and 901 reduction
$400K
OJ
o
Pylon for
short-term
measurements;
Track Etch
for 3-month
winter
measurements
Heat recovery
ventilators
• 5 houses below 751
reduction
• 1 house between 751
and 901 reduction
1 house below 751
reduction
Wei 1 water
treatment
Essent i a11y comp1ete
elimination of 200
pCi/1 spikes when
clothes washer used
Clinton,
New Jersey
10
$169K
Blower door
sub-slab & block
pressure, fiber
optics, etc.
Sub-slab, sump
hole, & floor wall
suction. Exterior
block & sub-slab
suction. Anchor
drain & vapor
barrier in crawl
space.
Most 10 < pCi/1
a!9 < 20 pCi/1
961 removal on all
991 removal on 7/10
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Table 2. (continued)
Location No. of
Homes
New York State 16
(Orange/Putnam
Counties
Albany Vicinity)
Piedmont, 14
New Jersey
(Hunterton,
Somerset,
Morris Counties)
Funds
$250K
$375K EPA
$540K DOE
$150K NJOEP
Testing
Techniques
Blower door, sub-
slab & block
pressure, tracer
gases
Charcoal
canisters
Continuous
monitors
Grab samples
Mitigation
Techniques
To be determined
Sub-slab exhaust
Block wall soil gas
exhaust
Basement heat recovery
Results
To be determined
N/A
ventilators
French drain soil gas
exhaust
Weeping tile soil gas
exhaust
Basement pressurization
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principles of active soil ventilation, where a fan is used to draw or
force radon-containing soil gas away from the house before it can enter.
The soil ventilation approach has proven to offer the greatest potential
for achieving the very high reductions required at a moderate cost. In
two other houses, air-to-air heat exchangers (heat recovery ventilators)
were tested; in two houses activated carbon filters were tested to remove
radon that would enter the house from the well water.
Radon reductions greater than 90 percent have been achieved in
roughly half of the houses with soil ventilation; work is continuing in
most of the houses not yet having that degree of reduction. The
reductions achieved with heat recovery ventilators were somewhat lower,
as would be expected. The well water treatment units essentially
eliminated the spikes in airborne radon levels that had previously been
observed when water was used in the home. Radon levels below 4 pci/l
(during cold-weather testing) have been achieved in 14 of the 30 houses
to date, with work on-going in the remainder.
(2) Clinton. Mew Jersey Project
In Clinton, New Jersey, 56 houses in the Clinton Knolls development
were screened in an effort to select 10 houses for mitigation studies.
Radon levels in the 10 houses selected ranged from 400 pCi/1 to greater
than 1,000 pCi/1. The houses varied in their construction type.
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A variety of new and different diagnostic procedures were used to
identify potential entry routes for the radon and house-specific
construction parameters that might limit potential radon reduction
techniques. Radon reduction techniques that were found to be most
effective In Clinton included sub-slab suction and exterior block wall
suction. A floor wall joint suction method was applied to two homes, and
a crawl space was reduced through the use of vapor barriers and drains.
Radon reduction efforts were considered successful on all 10 houses in
Clinton.
Between April and October of 1986, five homeowners' meetings were
held in Clinton to describe the status of radon reduction efforts and to
provide homeowners with information concerning radon reduction approaches
that were being effective in reducing significant radon concentrations.
To assist homeowners with houses that varied significantly from those
being studied in Clinton, 20 house-specific radon mitigation plans were
developed for 20 different house designs in the Clinton area. These
plans and the plans for the 10 houses being studied were made available
to all the Clinton homeowners. A recent visit to several homes in
Clinton that were not included in the 10 test houses has shown that many
of the recommended radon reduction approaches have been successfully
applied by individual homeowners.
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(3) New York State Project
Eight existing houses in each of two distinctly different sections
of New York are the target for radon reduction efforts co-funded by EPA
and the New York State Energy Research and Development Authority.
Eighteen houses were recently screened in Orange and Putnam Counties
about 50 miles north of New York City. The 8 houses selected for
mitigation studies included several older homes and homes with exposed
granite outcroppings in the basement or crawl space. Eight additional
homes were selected in January 1987 during a 30-house screening effort in
the suburbs surrounding Albany. Radon concentrations range from 20-200
pci/l in the houses which have been selected. Diagnostic procedures
similar to those used in Clinton are being used in the New York project.
The New York State Health Department has taken the lead in making
the necessary contacts in each neighborhood being considered for
inclusion in this project. To date, they have supplied several hundred
charcoal canisters to New York homeowners to measure radon concentrations
in their homes. The New York Health Department has also measured radon
concentrations in soils and soil porosities, which has aided in the
identification and selection of the neighborhoods currently targeted for
radon reduction efforts.
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(4) Piedmont, New Jersey. Project
The N.J. Piedmont (14-House) Mitigation Research Project is a
multi-sponsored (EPA, Department of Energy, New Jersey Department of
Environmental Protection) research effort with multiple objectives:
1. To extend current understanding of the fundamental processes of
radon transport, entry, and distribution in houses, and improve
our basic knowledge of factors influencing these processes;
2. To improve current understanding of why certain radon mitigation
techniques work and of the operational ranges of key parameters
that affect the performance of radon mitigation techniques;
3. To provide diagnostic procedures that can be used in specifying
appropriate and effective mitigation measures;
4. To provide a field evaluation and refinement of interim
diagnostic analysis protocols: and
5. To provide for the successful mitigation of indoor radon
concentration in typical New Jersey piedmont residences.
Because this project is concerned with developing an understanding
of indoor radon problems (e.g., radon entry routes and driving forces) to
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enhance the-selection of appropriate reduction techniques, EPA will
conduct extensive continuous and periodic monitoring of environmental
conditions, house dynamics, and occupancy effects.
In addition to continuous and periodic baseline measurements,
diagnostic measurements will be made to quantify the radon reduction
effects and the dynamic effects of operating systems within a house.
Modification and optimization of installed mitigation systems will be
attempted, if appropriate. An interim (May 1987) and final report
(January 1988} interpreting the performance of installed reduction
techniques over the life of the project will be provided.
(5) Other Field Projects
A major competitive procurement for radon reduction field projects
was initiated in 1986. One contract was awarded in FY86 and a second
contract is still being negotiated. The first contract will involve
installation and testing of techniques in approximately 35 existing
houses in each of two phases. House types and radon reduction techniques
will be selected to cover combinations that have not been covered
sufficiently (or at all) in prior projects. EPA expects several
installations in this project to be of the passive type (without fans).
The EPA is currently working with the States of Pennsylvania and Maryland
to locate homes that could be studied in these projects.
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The second contract is identical in scope. The geographical
location of this project has not been selected. The selection will most
likely hinge on the availability of house types that have not been worked
with to date. One possibility is a location in the Bonneville Power
Authority (BPA) service area; BPA has expressed interest in a jointly
funded demonstration project in the Pacific Northwest. This project,
including the selection of location, will be underway in the spring of
1987.
b. New Houses
U) New York state Project
Approximately 15 new (under construction) houses with
radon-resistant design features will be selected as part of this
project. The new-house phase of this project will get underway once the
intensive work on existing homes has been completed. EPA currently
expects this to be in the spring of 1987.
(2) State of New Jersey/NJBA Project
The National Association of Home Builders (NAHB), along with the
State of New Jersey and the New Jersey Builders Association (NJBA), has
applied to EPA for partial funding of a project to build and test the
radon-resistance of approximately 100 new houses in New Jersey. Radon
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prevention techniques would be predominantly of the passive type (i.e.,
without mechanical ventilation of the soil gas). Negotiations are
currently underway. It the technical aspects of the proposed project are
satisfactory to both the EPA project officer and peer reviewers of the
proposal, this project is likely to get underway in the spring of 1987.
(3) Other Field Projects
Both of the contracts from the 1986 competitive procurement have
options to evaluate new-home installations as well as exist ing-home
ones. EPA is currently negotiating with a major developer/builder who is
very interested in installing radon-resistant features in a large number
of new houses in the eastern United states. EPA funds would be used to
help develop the design details of the radon-resistant features, to
measure indoor radon levels after occupancy, and to install and test
active (fan-driven) modifications in a selected number of the houses with
levels above 4 pCi/1. A preliminary proposal, received from the
developer in early December, is undergoing technical evaluation. A
contractual agreement by spring is possible.
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c. Other Activities
Although the major emphasis of the radon reduction development and
demonstration program is on field projects, there are several supporting
projects that are essential to the program. The status of some of the
key projects is summarized below.
(1) Diagnostic Procedures
Proper diagnosis of the factors influencing radon entry greatly
increases the probability that an appropriate technique, or set of
techniques, will be selected for any given house. Therefore, an
important part of the Development and Demonstration Program is aimed at
determining the most cost-effective measurements that an installer should
make, both before the selection is made and after the system is
installed. A preliminary report on diagnostic procedures will be
completed in February 1987. EPA is planning a workshop on diagnostic
measurements for radon entry and reduction in April 1987. Participants
invited to this workshop will include key field project people, eastern
U.S. regional and State officials with the greatest amount of residential
radon experience, and EPA researchers and program office personnel. As a
result of this workshop, a revised set of procedures will be published in
fall 1987.
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(2) Data Base on Radon Reduction Techniques
EPA is developing a computerized system for managing the data on
diagnostics, installation details, performance, and costs of radon
reduction techniques. It will be microcomputer-based and developed
primarily in-house by the Agency's staff. Although the initial emphasis
will be on results from EPA's own field projects, data from other work
that has been properly documented will be entered in the system. An
operating system is expected to be available for EPA use by the end of
1981.
(3) Expert System forRadon Reduction
As an adjunct to its technical manuals and homeowner brochures, EPA
is developing a personal computer-based "expert system" on radon
reduction techniques. The objective is to develop an interactive
software package on floppy disks that can help a contractor working on
radon reduction (or a do-it-yourself homeowner) determine the most
appropriate technique(s) for an individual house. The system will be
based on results from EPA field projects and structured interviews of
several acknowledged experts in residential radon reduction. A prototype
system is expected to be available by the fall of 1987.
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2. House Evaluation Program
BPA's House Evaluation Program (HEP) is an ongoing program designed
to apply and evaluate radon reduction methods in housing situations and
to pass on information gained to the private sector. As part of the
EPA's Radon Action Program, the HSP was initiated in 1986 to provide
technical assistance to the states and the private sector. This
assistance is in the form of information transfer, training for remedial
investigations, and data management.
Once radon reduction techniques have been developed and demonstrated
under research conditions in a selected number of houses, the HEP will
apply and evaluate these techniques under conditions which are likely to
be experienced by the average homeowner. This effort will include a
large number of varied housing types in states that have identified radon
problems.
The HEP has three primary objectives: (1) to apply and evaluate the
cost and effectiveness of demonstrated radon reduction techniques in the
private sector: (2) to train State and private sector personnel in radon
diagnostics and mitigation methods; and (3) to provide feedback to the
Agency's development and demonstration program.
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In carrying out the objectives of this program, the States, working
with EPA personnel, will diagnose houses having elevated radon levels and
then develop and offer the homeowners several alternative reduction
schemes which the homeowners may choose to install themselves or have
installed by local contractors. In exchange for this service, the
homeowners permit the State and EPA to obtain data on radon levels in the
house after the installation of control techniques. Thus, valuable
information is gained on the cost and effectiveness of the installed
techniques.
An Important facet of this program is that it is the homeowners'
choice whether to undertake the mitigation work, and the homeowners are
responsible for selecting the installation contractor. Their actions
will provide feedback on how the general public reacts to radon-related
risk and what amount of money they are willing to spend to reduce that
risk.
An additional benefit of this program is that it provides "hands-on"
training in radon diagnosis and mitigation to State, local government,
and private sector personnel. It also promotes the use of local
contractors to conduct this work, thus expanding the cadre of experienced
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mitigation professionals. It is expected that many homeowners will
attempt to install reduction techniques on their own. The results of
these efforts will provide information on the feasibility of radon
mitigation being conducted by homeowners and will serve to better focus
public informational materials.
a. Existing Houses — Phase I (Pennsylvania)
Phase I activities have addressed locations in the Reading Prong
region of Pennsylvania. To date, 80 houses have been evaluated and
reports on each house are being generated. The State will use these
reports to work with homeowners to select radon reduction options for
installation. The Commonwealth of Pennsylvania is funding the
installation of reduction techniques for up to 100 houses in that State,
After the State contractor has installed a given technique, house data
will be collected to evaluate the effectiveness of the mitigation
technique.
During Phase I, the HEP has provided hands-on training in radon
entry diagnostics and the design of radon reduction techniques to
approximately 45 Federal, State, and private sector individuals. As
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these techniques are selected by homeowners, the Commonwealth of
Pennsylvania is expecting to employ up to 20 private sector construction
and remodeling firms for their installations. This effort will train and
provide new mitigation contractor expertise in that State.
The HEP has worked with the Commonwealth of Pennsylvania to develop
house-by-house reports which present findings of house diagnostics in an
understandable manner, so that homeowners can make informed decisions
concerning reduction options. These reports also contain sufficient
detailed information on each option so that private sector construction
firms with little or no mitigation experience can effectively install the
selected mitigation techniques. These reports provide a valuable
Federal-State-private sector interface for the transfer of information on
radon reduction techniques.
Through multiple applications of standardized radon entry diagnostic
procedures, it has become evident that extensive efforts to
quantitatively identify all radon entry sources in a given house may not
always be necessary to develop reduction options for that house. The HEP
is investigating whether the primary focus of premitigatton measurements,
made in a house that is known to have elevated radon levels, should focus
on physical and structural characteristics which would allow for
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installation_and effective operation of established reduction
techniques. This approach to house diagnostics could reduce the cost per
house evaluation to approximately $1,000, or less, while providing
sufficient or perhaps even better information for selecting mitigation
options.
b. Existing Houses — Phase II (New York, New Jersey, and Others)
Phase II of the House Evaluation Program will be initiated in New
York, New Jersey, and other States that demonstrate a need through
State-wide radon surveys. To date, EPA has met with New York and New
Jersey State representatives and EPA representatives from Regions 2 and 3
to coordinate project initiation efforts. The plan is to evaluate
20 to 40 houses and provide "hands on" training in each State. These
States do not plan to provide financial assistance to homeowners for
mitigation. Cost per house evaluation is expected to decrease over Phase
I costs. In January 198"7, coordination efforts will be complete, and by
February or March evaluation work will have begun.
c. New Houses
The EPA is working with the National Association of Home Builders
(NAHB) and other new home organizations to identify builders interested
in including radon prevention techniques in their new construction
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efforts and to provide them with technical guidance. As part of this
effort, EPA is working with the NAHB to develop publications for
potential home builders and contractors that provide information on radon
prevention techniques in new homes.
The NAHB, under a grant funded by EPA, will provide a clearinghouse
for these and other technical materials relating to radon prevention in
new construction and for the development of a Builders' Radon Advisory
Group (BRAG) to provide input for the development and a builder's
perspective review of all materials.
The NAHB will also develop a one-day short course on radon
mitigation and prevention for builders and remodelers.
d. Other Activities
(1) Land Evaluation Studies
In conjunction with the U.S. Geological Survey, the Commonwealth of
Pennsylvania, and the State of New York, EPA is developing procedures for
measuring radon in soil gas. Soil gas measurements will be used to
determine the relationship between radon in soil and radon levels in
existing houses. The resulting data will aid in the development of
prediction models for the new construction industry. Three homes in the
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Reading Prong have been studied, and the measurement procedures are
presently under review, soil gas measurements will be taken from, all
houses that participate in the HEP. The Agency is also working with the
National Association of Home Builders to relate vacant lot soil gas
measurements to a potential for elevated indoor radon levels in new
construction.
(2) Model Building Codes
The Agency is working with the U.S. model building code organization
(Council of American Building Officials, the Southern Building Code
Congress International, the International Conference of Building
Officials, and the Building Officials Code Administration) to evaluate
findings of ongoing mitigation and prevention programs, in addition,
these organizations are evaluating new house construction programs to
determine those radon prevention techniques that will be most compatible
with existing model construction codes. These efforts will be supported
and reviewed by the NAHB/BRAG and will result in the development of
proposed model building code changes/additions which will be made
available to the States and local municipalities for incorporation into
local codes.
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3. Technology Transfer and Training
A critical element of every mitigation and prevention project in the
Agency is to transfer new information as soon as possible to the States,
the private sector, and the public. This information is developed and
disseminated through brochures and technical reports, training programs,
and presentations at national meetings.
In August 1986, the Agency published "Radon Reduction Methods: A
Homeowner's Guide" and "Radon Reduction Techniques for Detached Houses:
Technical Guidance." These publications will be updated in Fiscal
Year 198*7. They will contain expanded and more detailed information,
based largely on the field experience gained in the past year in the
Development and Demonstration Program, as well as from the House
Evaluation Program. In addition, several technical reports, including a
brochure on reducing radon from household water supplies, will be
developed to provide further technical guidance on reduction techniques
and the most current information on radon entry diagnostics, prevention
techniques, and health risks associated with elevated levels of indoor
radon.
An overview of ongoing State radon programs and mitigation
activities will be developed as a resource for additional States to use
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in developing their programs and for EPA program development. EPA will
also be working with the NAHB to prepare and distribute technical
guidance for radon reduction in new construction.
The Agency will continue to offer the three-day technical training
course for State and private sector organizations to learn the basics of
the physical characteristics of radon, measurement techniques, risk
evaluation, and mitigation methods. Fewer courses will be offered in
Fiscal Year 1987; however, the Agency is planning to produce a video-tape
of the course to expand its availability. The House Evaluation Program
will continue to offer field training for States. In addition, EPA will
continue to work with States to conduct regional training courses for
State officials to learn more about Federal and State radon programs.
Finally, EPA staff will make presentations at national conferences.
Several conferences are planned for Fiscal Year 1987 including the Air
Pollution Control Association, Administrators Specialty Conference on
Radon, which will be co-hosted by EPA in April, and the International
Conference on Indoor Air Quality to be held in Berlin in August.
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V. CONCLUSION
Findings to date clearly indicate that the most significant pathway
of radon entry into houses is radon migration from soil into basements or
those portions of the house that are in contact with the soil. This
migration primarily takes place through cracks and penetration points in
below ground walls and slabs rather than diffusion through solid
materials. The amount of radon transferred from the soil to the house is
affected by many factors, including radon content and porosity of the
soil (radon soil gas availability), construction and substructure type,
pressure differentials between house and soil, and others. The radon
reduction techniques employed in a given house must address a number of
these factors and will usually be house-specific.
Experience thus far indicates that the use of techniques that
primarily prevent radon entry into houses can often reduce indoor radon
levels by more than 95 percent, even in houses with very high initial
radon levels. In addition, costs of these techniques are expected to
range from less than $100 to possible $5,000 per house — though the cost
for most homes is expected to be less than $1,000. (The cost of radon
mitigation is expected to be in the accepted range of other household
expenses such as water and termite control.) It is also likely that,
when built into new houses, the same techniques will be even more
effective and should cost less — in the range of $100 to $400.
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The following conclusions can be drawn from the Agency's experience
to date.
• Radon is usually a controllable problem at a relatively low cost.
• Reduction techniques are usually house-specific, but certain
methods may be applicable to a wide variety of housing types.
• More than one reduction technique may have to be used to reduce
radon to an acceptable level in a given house.
EPA intends to continue its development and demonstration programs
and its application and evaluation programs in existing houses, and plans
to extend these programs into the new house construction in the Reading
Prong and elsewhere, in addition, the Agency intends to make its
mitigation and prevention programs available to States outside the
Reading Prong as surveys identify other areas with radon problems. This
will allow other State and contractor personnel to be trained in radon
mitigation, and the Agency will gain even more experience in a wider
variety of housing types and geological conditions.
Research results and other information that could lead to new
findings on the application and cost of radon reduction techniques will
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be used to revise and update the technical guidance manual in August
1987. That information will be reflected in the status report to be
submitted to Congress by February 1, 1988.
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