1. WHERE DOES
RADON COME FROM?
Radon comes from the
natural radioactive decay of radium and uranium
found in the soil beneath the house. The amount of
radon in the soil depends on complex soil
chemistry, that varies from one house to the next.
Radon levels in the soil range from a few hundred
to several thousands of pCi/L. The amount of radon
that escapes from the soil to enter the house
depends on the weather, soil porosity, soil
moisture, and the suction within the house.
2. HOW DOES RADON
GET INTO THE HOUSE?
Houses act like
large chimneys. As the air in the house warms, it
rises to leak out the attic openings and around
the upper floor windows. This creates a small
suction at the lowest level of the house, pulling
the radon out of the soil and into the house. You
can test this on a cold day by opening a top floor
window an inch. You will notice warm air from the
house rushing out that opening; yet, if you open a
basement window an inch, you will feel the cold
outside air rushing in. This suction is what pulls
the radon out of the soil and into the house. You
might think caulking the cracks and the openings
in the basement floor will stop the radon from
entering the house. However, scientific studies
show, it only takes enough unsealed cracks or pin
holes in the caulking to equal a hole 1/2" in
diameter to let all the radon in. It is unlikely
that caulking the accessible cracks and joints
will permanently seal the openings radon needs to
enter the house. The radon levels will still
likely remain unchanged.
are other extremely effective means of keeping
radon out of your home. Throughout the country,
several million people have already tested for
radon. Some houses tested as high as 2,000-3,000
pCi/L; yet, there hasn't been one house that could
not mitigate to an acceptable level. Mitigation
usually costs between $500-$1500.
3. WHAT IS THE
RISK OF RADON EXPOSURE?
radon exposure is the second leading cause of lung
cancer. When radon decays, it shoots off alpha
particles. These are small, heavy, electrically
charged, sub-atomic particles consisting of two
protons and two neutrons. If an alpha particle
strikes the chromosomes in a lung cell, it could
alter the way that cell reproduces. Our bodies
immune system should recognize and destroy these
mutant cells before they can multiply over the
next 10 to 20 years into a recognizable cancerous
Some peoples immune
system is better than others. Because of these
inherent differences, radon doesn't affect
everyone the same.
4. HOW SERIOUS A
RISK IS RADON?
According to the
following EPA radon risk chart, radon is a serious
If 1,000 people were
exposed to this level over a life time who are:
Radon Level....Smokers.............Never Smokers
20 pCi/L....14% or135 people.....0.8% or 8 people could get lung cancer
10 pCi/L.....7% or 71 people.....0.4% or 4 people could get lung cancer
4 pCi/L......3% or 29 people.....0.2% or 2 people could get lung cancer
2 pCi/L......2% or 15 people.....0.1% or 1 person could get lung cancer
5. DO SCIENTISTS
AGREE THAT RADON IS DANGEROUS TO BREATHE?
There is little
disagreement that breathing the hundreds of pCi/L
of radon that caused thousands of uranium miners
to get fatal lung cancer is definitely harmful.
Many scientists disagree with the EPA about what
the level of radon should be before it should be
The EPA studied the
lung cancer risk of uranium miners exposed to 400
pCi/L. They assume the risk of a home owner
exposed to 4 pCi/L to be one hundredth as much.
Based on this assumption, the EPA guideline level
of 4 pCi/L represents a much greater risk than
allowed for other environmental pollutants.
have tested more than 70,000 homes across the
United States. This study shows the counties with
the highest average radon levels had the lowest
incidence of cancer. Perhaps, breathing the low
levels of radon found in the home environment,
might not be harmful. Neither study fully accounts
for all the different confounding factors that can
cause cancer. The truth probably lies somewhere
between these two theories.
6. WHO DO I
In 1988 the United
States Congress passed legislation, directing the
EPA to work toward a long term national goal, "The
air within buildings in the United States should
be as free of radon as the ambient air outside of
buildings." Real estate agents are hired and paid
by the sellers, to represent the sellers
economicintrests, in the sale of their house.
Understandably, you might get two completely
different opinions about radon, depending whether
you ask the EPA, or your real estate agent.
Because you have hired us to test for radon, and
explain the test results. We will offer our
opinion on the subject, and guidance on a prudent
course of action.
7. WHAT SHOULD I
DO ABOUT THE LEVELS OF RADON IN MY HOME?
represents our opinion, based on our understanding
of the radon issue from several sources.
- A... If the
house tests above 20 pCi/L most experts agree it
is prudent to install a system that can
permanently reduce your families exposure to
- B... If the
house tests below 4 pCi/L most experts agree
that there is a relatively low probability of
significant health risk at this low level of
exposure. However, we recommend retesting the
radon levels once you move in, to verify this
low reading. Industry surveys show that up to
30% of the radon tests in real estate
transactions are subject to some ventilation. LET
THE BUYER BEWARE. We once tested a house,
that measured 168 pCi/L in a child's bedroom.
The selling agent ordered a retest by a tester
known to test on the second floor with the
windows open. He told my clients the house only
measured 3.5 pCi/L and they didn't have a radon
problem. Although he never gave my clients a
written report stating this.
- C... If the
house tests between 4 and 20 pCi/L there is no
need for immediate panic, but you will have to
make some difficult decisions. About 50% of the
houses we test fall in this gray area. The
average Colorado home measures 5.9 pCi/L. The
national average is 1.5 pCi/L and outside air
measures about 0.35 pCi/L. The closer to 4 or 20
pCi/L the easier the decision should be. The
most difficult decisions are in the 10 to 12 pCi/L
8. WHAT OTHER
FACTORS SHOULD I LOOK AT IN DECIDING WHETHER TO
MITIGATE OR NOT?
should keep their exposure to radon as low as
possible. Smokers have eight times the risk from
radon as non smokers. Smokers who reduce their
radon exposure from 6 pCi/L to 2 pCi/L, will
receive as much beneficial risk reduction as the
non smoker who reduces their exposure from 34 pCi/L
to 2 pCi/L.
If the house was
tested in an infrequently used basement. It may
have measured a radon level that is two to three
times the actual level you are exposed to,
spending most of your time upstairs.
You can reduce your
families annual radon exposure about 40%, if you
open the basement windows a few inches to allow
cross ventilation from May till September. This
may be appropriate for slightly elevated houses
that don't need year round reductions.
People with young
children should be more concerned with the
possible consequences of radon exposure 20 years
from now than someone in their late sixties or
Families with a
hereditary predisposition of cancer should be more
concerned about radon exposure than families who
don't have any history of cancer.
If you work for a
company that might transfer you in the future, our
employer probably will hire a relocation company
to purchase your home. Today, most relocation
companies insist that the house test below 4 pCi/L
before they will buy it. Some buyers have adopted
this position; anything below 4 pCi/L is fine
while anything above 4 pCi/L is unacceptable. This
unfortunate misinterpretation of EPA guidance,
could cause you to pay for a radon mitigation
system when selling your home. At this time your
family would not receive any benefit from the
The decision, What
to do about radon? is a personal choice that only
you can make. Some people feel it is best to
reduce as many of life's risks as they can. Other
people feel the money spent installing and
operating a radon mitigation system on a
moderately elevated home could be put to better
use, having regular family medical and dental
check ups, or making other safety improvements in
9. WHAT IF, I
DECIDE TO REDUCE THE RADON LEVELS IN MY HOME?
If you feel the
radon levels are high enough to justify installing
a radon mitigation system, we recommend installing
a good quality, durable, energy efficient system.
All our radon reports testing above 4 pCi/L,
include detailed specifications, describing the
installation and materials needed to achieve this.
It is best to have all mitigation contractors bid
on installing the system exactly as specified in
this report. All too often the sellers or their
agents end up deciding, who will do the work, and
how it will be done. Their main concern is that it
be installed as cheaply as possible to get the
radon levels down below 4 pCi/L for the retest.
Often they have the contractor who installed the
system, do the retesting to verify it is below 4
pCi/L, before he gets paid. This could create a
possible conflict of interest.
10. WHAT SHOULD I
LOOK FOR IN A PROPERLY INSTALLED SYSTEM?
- A... Install
all fans outside the living area of the house,
so all interior piping is under negative
pressure. Many contractors find it cheaper and
easier to put the fan in the basement near an
existing electrical outlet. Often these fans and
piping develop leaks. This could allow the
system to start pulling the thousands of pCi/L
of radon out of the ground and blow it into the
basement or crawlspace; thus making the radon
levels in the house higher than they where
- B... The high
radon concentration air blowing from the fan
should discharge above the roof, or at least ten
feet from any doors, windows or decks. No one
wants to breathe hundreds or thousands of pCi/L
coming from these fans.
- C... Dig the
suction pit under the floor as large as
possible, or make sure it intersects the void
beneath a grade-beam foundation.
- D... Seal
crawlspaces with a gas membrane, made of
cross-laminated polyethylene, placed between two
layers of 30 lb. tar paper, to protect it from
damage. Make sure the membrane is tightly
fastened to the foundation walls, with plywood
strips and sealed with industrial grade urethane
caulking. It is cheaper to install one layer of
regular polyethylene directly over the soil, and
fasten it to the walls with duct tape, glue or
caulking. This method will reduce the radon
levels, but the single layer of regular
polyethylene gets torn when someone crawls
across it. Duct tape or glue usually falls off
the wall within a month or so. When this
happens, the system will still keep the radon
levels down, but the fan will start pulling
large amounts of heated air out of the house.
The added cold air could subject the crawlspace
plumbing to freezing and increase the cost of
heating your home as much as $200.00 to $300.00
a year. This unnecessary loss of heat could add
up to $20,000.00 to $30,000.00 over the hundred
year life of the house. The money saved on the
initial installation might not be such a bargain
- E... Caulk the
large cracks and joints in the concrete floor
slab to prevent unnecessary heat loss.
- F... Install a
manometer or warning device to alert you if
anything goes wrong with the system.
Permanently label all systems, with the
contractors name, phone number, operation and
maintenance instructions and a place to note all
radon test results. The people living in the
house 15 to 75 years from now will need to know
what this system is, and why it is needed.
11. WHO SHOULD
PAY TO GET THE RADON REDUCED?
If you are buying a
house, this is strictly a matter of negotiation
for which there are no hard and fast rules. Some
people will choose to follow one of the GOLDEN
RULES, Do unto others as you would have them do
unto you, or He
who has the gold makes the rules. No matter
who ends up paying for the system, it is in your
best interest that you be the one to select the
contractor and specify how the work will be done.
If you leave these decisions to others you might
not end up with the type of system you want to
have. Most contractors will give you a written bid
of exactly how much the system will cost when you
have them install it. Do not worry if the radon
can be successfully reduced; this is a sure thing.
In most cases, contractors will guarantee that
they will reduce the levels to below 4 pCi/L.
Properly installed systems usually get the radon
down to below 2 pCi/L and sometimes even below 1
pCi/L. We have tested several houses that
originally measured more than 100 pCi/L, that
where mitigated to levels below 2 pCi/L.
12. HOW MUCH DOES
IT COST TO OPERATE THESE SYSTEMS?
Most systems are
powered by a 90 watt fan that use less than $52.00
worth of electricity a year. These fans should
last about 14.7 years and presently cost $125.00
to replace. If the system is properly installed
and well sealed, there shouldn't be any noticeable
increases in the heating bills. However, if the
cracks and joints in a finished basement cannot be
sealed, the heating cost might increase slightly.
Check this on a cold day by feeling the amount of
warm air blowing from the fan.
13. HOW CAN I
LEARN MORE ABOUT RADON?
The EPA's hotline at
1 800-SOS-RADON will be happy to answer your
questions and send you their pamphlets about
radon. They can send you a list of radon
contractors and tell you how to get their
technical publications about radon and radon
You can call the
local Department of Health.
Position on Radon
Your local library
might have some of the following books.