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United States
Environmental Protection
Agency
Office of
Air and Radiation
U.S. Department
Of Health and
Human Services
Centers for
Disease Control
August 1986
OPA-86-004
A Citizen's Guide
To Radon
What It Is
And What To Do
About It
. ,. . . . I \ ... .1 . . irx. i
' fi*'*> niiiii^t\t\.^
U.S. Environmental P
Region V, Library .
230 South Dearborn Str
Chicrrro. Illinois 60604
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The U.S. Environmental Protection Agency and the U.S.
Centers for Disease Control are concerned about the
increased risk of developing lung cancer faced by persons
exposed to above-average levels of radon in their homes.
This pamphlet is a joint effort by EPA and CDC. Its
purpose is to help readers to understand the radon
problem and decide if they need to take action to reduce
radon levels in their homes.
US. Em/fronmenta? Protection Agency
The U.S. Environmental Protection Agency and the U.S. Centers for
Disease Control strive to provide accurate, complete, and useful
information. However, neither the agencies, nor other persons
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 ariy 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, method, or process'
disclosed in this material. -..''*''•
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What is radon?
Radon is a radioactive gas which occurs in nature. You
cannot see it, smell it, or taste it.
Where does radon come from?
Radon comes from the natural breakdown (radioactive
decay) of uranium. Radon can be found in high
concentrations in soils and rocks containing uranium,
granite, shale, phosphate, and pitchblende. Radon may
also be found in soils contaminated with certain types of
industrial wastes, such as the byproducts from uranium or
phosphate mining.
In outdoor air, radon is diluted to such low
concentrations that it is usually nothing to worry about.
However, once inside an enclosed space (such as a home)
radon can accumulate. Indoor levels depend both on a
building's construction and the concentration of radon in
the underlying soil.
How does radon affect me?
The only known health effect associated with exposure to
elevated levels of radon is an increased risk of developing
lung cancer. Not everyone exposed to elevated levels of
radon will develop lung cancer, and the time between
exposure and the onset of the disease may be many years.
Scientists 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 die of lung cancer in 1986.
The Surgeon General attributes around 85 percent of all
lung cancer deaths to smoking.)
Your risk of developing lung cancer from exposure to
radon depends upon the concentration of radon and the
length of time you are exposed. Exposure to a slightly
elevated radon level for a long time may present a greater
risk of developing lung cancer -than exposure to a
significantly elevated level for a short time. In general,
your risk increases as the level of radon and the length of
exposure increase.
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How certain are scientists of the risks?
With exposure to radon, as with other pollutants, there is
some uncertainty about the amount of health risk. Radon
risk estimates are based on scientific studies of miners
exposed to varying levels of radon in their work
underground. Consequently, scientists are considerably
more certain of the risk estimates for radon than they are
of those risk estimates which rely solely on studies of
animals.
To account for the uncertainty in the risk estimates for
radon, scientists generally express the risks associated
with exposure to a particular level as a range of numbers.
(The risk estimates given in this booklet are based on the
advice of EPA's Science Advisory Board, an independent
group of scientists established to advise EPA on various
scientific matters.)
Despite some uncertainty in the risk estimates for radon,
it is widely believed that the greater your exposure to
radon, the greater your risk of developing lung cancer.
How does radon cause lung cancer?
Radon, itself, naturally breaks down and forms radioactive
decay products. As you breathe, the radon decay products
can become trapped in your lungs. As these decay
products break down further, they release small bursts of
energy which can damage lung tissue and lead to lung
cancer.
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When did radon become a problem?
Radon has always been present in the air. Concern about
elevated indoor concentrations first arose in the late 1960's
when homes were found in the West that had been built
with materials contaminated by waste from uranium
mines. Since then, cases of high indoor radon levels
resulting from industrial activities have been found in
many parts of the country. We have only recently become
aware, however, that houses in various parts of the U.S.
may have high indoor radon levels caused by natural
deposits of uranium in the soil on which they are built.
Does every home have a problem?
No, most houses in this country are not likely to have a
radon problem; but relatively few houses do have highly
elevated levels. The dilemma is that, right now, no one
knows which houses have a problem and which do not.
You may wish to call your state radiation protection office
to find out if any high levels have been discovered in your
area.
Many states, as well as the federal government, are
sponsoring work to identify areas of the country which are
likely to have indoor radon problems. However, early
results from this work are inconclusive. If you are
concerned that you may have an indoor radon problem,
you should consider having your home tested.
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How does radon get into a home?
Radon is a gas which can move through small spaces in
the soil and rock on which a house is built. Radon can
seep into a home through dirt floors, cracks in concrete
floors and walls, floor drains, sumps, joints, and tiny
cracks or pores in hollow-block walls.
Radon also can enter water within private wells and be
released into a home when the water is used. Usually,
radon is not a problem with large community water
supplies, where it would likely be released into the
outside air before the water reaches a home. (For more
information concerning radon in water, contact your
state's radiation protection office.)
In some unusual situations, radon may be released from
the materials used in the construction of a home. For
example, this may be a problem if a house has a large
stone fireplace or has a solar heating system in which heat
is stored in large beds of stone. In general, however,
building materials are not a major source of indoor radon.
Common Radon Entry Points
E^i Water Supply
..
•'Drain f'^ Sump •'•"•"••
' J °'
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How is radon detected?
Since you cannot see or smell radon, special equipment is
needed to detect it. The two most popular,
commercially-available radon detectors are the charcoal
canister and the alpha track detector. Both of these devices
are exposed to the air in your home for a specified period
of time and sent to a laboratory for analysis.
Charcoal Canisters
Test Period: 3 to 7 days
Approximate Cost: $10 to $25 for one canister
Alpha Track Detectors
Minimum Test Period: 2 to 4 weeks
Approximate Cost: $20 to $50 for one
detector; discounts for multiple detectors
There are other techniques—requiring operation by
trained personnel—which can be used to measure radon
levels, but such techniques may be more expensive than
the devices shown above.
Your measurement result will be reported to you in one
of two ways. Results from devices which measure radon
decay products are reported as "Working Levels" (WL).
Results from devices which measure concentrations of
radon gas are reported as "picocuries per liter" (pCi/1).
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How can I get a radon detector?
Homeowners in some areas are being provided with
detectors by their state or local government. In many areas,
private firms offer radon testing. Your state radiation
protection office may be able to provide you with
information on the availability of detection devices or
services.
The U.S. Environmental Protection Agency conducts a
Radon Measurement Proficiency Program. This voluntary
program allows laboratories and businesses to demonstrate
their capabilities in measuring indoor radon. The names of
firms participating in this program can be obtained from
your state radiation protection office or from your EPA
regional office.
How should radon detectors be used?
Obtaining a useful estimate of the radon level in your
home may require that several detectors be used to make
measurements in different areas. Following the steps
below should provide the information needed as you
decide whether or not further action is advisable. (In
making radon measurements, you should be sure to follow
the instructions of the manufacturer as to the proper
exposure period for the particular device you are using.)
Step One: The screening measurement
The first step you should take is to have a short-term
"screening" measurement made to give you an idea of the
highest radon level in your home. Thus, you can find out
quickly and inexpensively whether or not you have a
potential radon problem.
The screening measurement should be made in the
lowest livable area of your home (the basement, if you
have one). All windows and doors should be closed for at
least 12 hours prior to the start of the test, and kept closed
as much as possible throughout the testing period. This is
necessary to keep the radon level relatively conslant
throughout the testing period. Because of the need to keep
the windows closed as much as possible, we recommend
that you make short-term radon measurements during the
cool months of the year.
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Step Two: Determining the need for further measurements
In most cases, the screening measurement is not a
reliable measure of the average radon level to which you
and your family are exposed. Since radon levels can vary
greatly from season to season as well as from room to
room, the screening measurement only serves to indicate
the potential for a radon problem. Depending upon the
result of your screening measurement, you may need to
have follow-up measurements made to give you a better
idea of the average radon level in your home.
The following guidance may be useful to you in
determining the urgency of your need for follow-up
measurements.
If your screening measurement result is greater than
about 1.0 WL or greater than about 200 pCi/1, you should
perform follow-up measurements as soon as possible.
Expose the detectors for no more than one week. Doors
and windows should be closed as much as possible during
testing. You should also consider taking actions (see page
13) to immediately reduce the radon levels in your home.
If your screening measurement result is about 0.1 WL to
about 1.0 WL or about 20 pCi/1 to about 200 pCi/1, perform
follow-up measurements. Expose detectors for no more
than three months. Doors and windows should be closed
as much as possible during testing.
If your screening measurement result is about 0.02 WL
to about 0.1 WL or about 4 pCi/1 to about 20 pCi/1,
perform follow-up measurements. Expose detectors for one
year, or make measurements of no more than one week
duration during each of the four seasons.
If your screening measurement result is less than about
0.02 WL or less than about 4 pCi/1, follow-up
measurements are probably not required. It the screening
measurement was made with the house closed up prior to
and during the testing period, there is relatively little
chance that the radon concentration in your home will be
greater than 0.02 WL or 4 pCi/1 as an annual average.
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Step Three: The follow-up measurement
Follow-up measurements will provide you with a
relatively good estimate of the average radon concentration
to which you and your family are exposed. We strongly
recommend that you make follow-up measurements
before you make any final decisions about whether to
undertake major efforts to permanently correct the
problem.
Follow-up measurements should be made in at least two
lived-in areas of your home. If your home has lived-in
areas on more than one floor, you should make
measurements in a room on each of the floors. An example
is to take a measurement in the living room on the first
floor and another in a second-floor bedroom. The results
of the follow-up measurements should be averaged
together.
What do my test results mean?
The results of your follow-up measurements provide you
with an idea of the average concentration throughout your
home. The actual risk you face depends upon the amount
of time you are exposed to this concentration.
The figures on the facing page illustrate the number of
lung cancer deaths, out of a group of 100 people, that
scientists would attribute to exposure to specific levels of
indoor radon. The first three figures assume that these 100
individuals spent 75 percent of their time in the dwelling
for 70 years. The numbers below each picture indicate
what scientists consider to be a reasonable range of
estimates of lung cancer deaths that could be attributed to
the radon exposure. This is in addition to the number of
lung cancer deaths attributed to other causes. (On average,
about four people out of a hundred die of lung cancer
from all causes combined.) The pictures represent the
midpoint of the ranges.
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Lung Cancer Deaths
Associated With Exposure
To Various Radon Levels
Over 70 Years
WL = 0.02
pCi/1 = 4
Q
00
Between 1 and 5 out of 100
WL - o.i OOO»OOOOOO"OOOO
fCM-2" SSXO&DSKXm
Between 6 and 21 out of 100
WL = 1.0
pCi/1 = 200
•0"0"0«0"0««0
Between 44 and 77 out of 100
If these same 100 individuals had lived only 10 years
(instead of 70) in houses with radon levels of about 1.0
WL, the number of lung cancer deaths expected would be:
WL = i.o
PCM = 200
0
^5QQ«pQDQQ|i QO
•.OG«000«0"OO"0
Between 14 and 42 out of 100
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Another way to think about the risk associated with
radon exposure is to compare it with the risk from other
activities. The chart below gives an idea of how exposure
to various radon levels over a lifetime compares to the risk
of developing lung cancer from smoking and from chest
x-rays. The chart also compares these levels to the average
indoor and outdoor radon concentrations.
As you look at the chart, be sure to use the proper
radon-level column for your results (either WL or pCi/1).
Radon Risk Evaluation Chart
pCi/l WL
200 1
100 0.5
40 0.2
20 0.1
10 0.05
4 0.02
2 0.01
1 0.005
0.2 0.001
Estimated number o^
lung cancer deaths
due to radon exposure
(out of 1000I
440—770
270—630
120—380
60—210
30—120
13—50
7—30
3—13
1—3
Comparable
exposure levels
1000 times f||
average outdoor^H
level ^»««
£H«§
TOO times J||
average indoor 4H1
level III
f&
100 times
average outdoor ^
level ^
10 times average
indoor level ^
10 times
average outdoor ^
level *
Average indoor .
level ^
Average outdoor ,
level 4
I
Comparable
risk
More than 60 times
IIIP non-smoker risk
||L4 pack-a-day
|||r smoker
SSKwJ
K
20,000 chest
^^ x-rays per year
^t
^2 pack-a-day
smoker
In pack-a-day
smoker
^ 5 times
non-smoker risk
• •^200 chest x-rays
per year
k Non-smoker
r risk of dying
from lung cancer
r 20 chest x-rays
per year
10
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How quickly should I take action?
In considering whether and how quickly to take action
based on your test results, you may find the following
guidelines useful. EPA believes that you should try to
permanently reduce your radon levels as much as
possible. Based on currently available information, EPA
believes that levels in most homes can be reduced to about
0.02 WL (4 pCi/1).
If your results are about 1.0 WL or higher, or about 200
pCi/1 or higher:
Exposures in this range are among the highest observed
in homes. Residents should undertake action to reduce
levels as far below 1.0 WL (200 pCi/1) as possible. We
recommend that you take action within several weeks.
If this is not possible, you should determine, in
consultation with appropriate state or local health or
radiation protection officials, if temporary relocation is
appropriate until the levels can be reduced.
If your results are about 0.1 to about 1.0 WL, or about 20
to about 200 pCi/1:
Exposures in this range are considered greatly above
average for residential structures. You should undertake
action to reduce levels as far below 0.1 WL (20 pCi/1) as
possible. We recommend that you take action within
several months.
If your results are about 0.02 to about 0.1 WL, or about
4 pCi/I to about 20 pCi/1:
Exposures in this range are considered above average for
residential structures. You should undertake action to
lower levels to about 0.02 WL (4 pCi/1) or below. We
recommend that you take action within a few years,
sooner if levels are at the upper end of this range.
If your results are about 0.02 WL or lower, or about 4
pCi/1 or lower:
Exposures in this range are considered average or slightly
above average for residential structures. Although
exposures in this range do present some risk of lung
cancer, reductions of levels this low may be difficult, and
sometimes impossible, to achieve.
Remember: There is increasing urgency for action at
higher concentrations of radon. The higher the radon level
in your home, the faster you should take action to reduce
your exposure. If you find elevated radon concentrations
in your home, you should take the relatively easy,
short-term actions described on page 13.
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Are there other factors I should consider?
Most of the risk information given in this pamphlet, as
well as the recommendations for taking corrective action,
are based on the general case. Your individual living
patterns could influence your assessment of your risk and
your decisions about the need for further action. Your
answers to the following questions may help you evaluate
your personal risk.
• Does anyone smoke in your home? Scientific evidence
indicates that smoking may increase the risk of exposure
to radon. In addition, smoking significantly increases your
overall risk of lung cancer.
• Do you have children living at home? Although there
are no studies of children exposed to radon to determine
whether they are more sensitive than adults, some
scientific studies of other types of radiation exposure
indicate that children may be more sensitive.
Consequently, children could be more at risk than adults
from exposure to radon.
• How much time does any family member spend at
home? The risk estimates given in this pamphlet assume
that 75 percent of a person's time is spent at home. If you
or your family spend more or less time at home, you
should take this into consideration.
• Does anyone sleep in your basement? Since radon
concentrations tend to be greater on the lower levels of a
home, a person who sleeps in the basement is likely to
face a greater risk than a person who sleeps in a
second-floor bedroom.
• How long will you live in your home? The risk
estimates in this booklet are based on the assumption
that you will be exposed to the radon level found in your
home for roughly 70 years. As you evaluate your potential
risk, therefore, you might consider the total amount of
time you expect to live in your home. But remember: other
houses you have lived in—or will live in—may have the
same or higher radon levels.
U.S. Environmental Protection Agency
Region V, Library
230 South Dearborn Street
Chicago. Illinois 60604
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How can I reduce my risk from radon?
Your risk of lung cancer from exposure to radon depends
upon the amount of radon entering your home and the
length of time it remains in your living areas. Listed
below are some actions you might take to immediately
reduce your risk from radon. These actions can be done
quickly and with minimum expense in most cases.
• Stop smoking and discourage smoking in your home. By
doing so, you should reduce your family's overall chance
of developing lung cancer, as well as reducing your
family's risk from radon exposure.
• Spend less time in areas with higher concentrations of
radon, such as the basement.
• Whenever practical, open all windows and turn on fans
to increase the air flow into and through the house. This is
especially important in the basement.
• If your home has a crawl space beneath, keep the
crawl-space vents on all sides of the house fully open all
year.
While the above actions will help reduce your risk from
radon, they generally do not offer a long-term solution.
You can find more information about permanent,
cost-effective solutions to a radon problem in the EPA
publication, Radon Reduction Methods: A Homeowner's
Guide. A copy of this booklet may be obtained from your
state radiation protection office or from your EPA regional
office.
Before undertaking major modifications to your home,
we recommend that you consult with your state radiation
protection office to obtain whatever specific advice or
assistance they may be able to provide for your particular
situation.
13
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Sources of Information
If you would like further information or
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-
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—1
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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