Why view these Radon slides?
Protect your family’s health

Learn how to do a radon test

Understand the science

Learn about mitigation methods

Be informed
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© WPB slideshow
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Introduction to Radon &
Radioactivity
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© WPB slideshow
A Simple Model of an Atom
An atom is composed of:
a Nucleus in the Center of the Atom
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which is composed of:
Neutrons
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Protons and
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Orbiting around the Nucleus are:
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En
Electrons
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The positive charge of the protons
holds the negatively charged
electrons in orbit
If the nucleus was the size of a baseball, the electrons, the size of
a dust particle, would be a hundred yards to a mile away !!
© WPB slideshow
Radioactivity means an atom occasionally
gives off energy or a particle
The energy emission
is called a
radioactive decay
Beta emission
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Alpha
emission
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Alpha particle has
2 proton’s & 2 neutrons
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Radioactive decay changes the proton
count of the nucleus
Gamma
emission
Atomic Weight is the total count of
protons and neutrons in the nucleus
The number of protons
Atomic Number
defines the element (lead, bismuth, etc)
© WPB slideshow
Penetrating Power of
Alpha - Beta – Gamma
Alpha
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Beta
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Gamma
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Paper
Book
An alpha particle is 20 times more damaging
But it travels the least distance (only a few inches)
Concrete
© WPB slideshow
Radioactive Elements are identified by:
the Energy
given off
the Decay Rate
( Half Life )
or
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2
half lifes
50 %
25 %
remaining
remaining
3
half lifes
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1
half life
4
half lifes
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12.5 %
remaining
6.3 %
remaining
Half life is the amount of time required for
half the element to decay.
© WPB slideshow
Half of the Uranium 238 has decayed away
since the earth was formed 4 billion years ago
Uranium 238 (4 Billion yrs)
The half life of
each element
is listed in
the brackets
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Radium 226 (1620 yrs)
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Radon 222 (3.8 days)
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Radon Decay Products
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Polonium 214 ( u sec)
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Polonium 218 (3 min)
Bismuth 214 (20 min)
Lead 210 (20 yrs)
© WPB slideshow
The atomic mass (number of protons and neutrons) is listed after the element’s name
All the elements in the decay chain
of Uranium 238 are solid particles
except Radon
C
Radon is a NOBLE GAS
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Which means it does not
stick or cling to anything and it is:
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Naturally Occurring
Colorless, Odorless, Tasteless
and free to float through the soil
and up into our homes before
it decays into radon decay products
© WPB slideshow
Radon is measured in pCi/L units
Pico is a Trillionth
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Curie comes from Madame Curie
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A one liter jar
with 4 pCi/L has:
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Madame Curie discovered
a gram of radium produce
37 billion decays per second
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One PicoCurie or a trillionth
of a curie equals
2.22 decays per minute
10
radon
decays
per
minute
© WPB slideshow
How little is 4 pCi/L ?
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If 10 million molecules per
second was escaping, it would
take 1 million years to empty
this box
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Only 2500 radon atoms
are needed to reach
4 pCi/L in this
one cubic inch box
One Cubic
Inch Box
© WPB slideshow
Characteristics of Short Lived
Radon Decay Products (RDPs)
Polonium 218 (3 min)
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Polonium 214 ( u sec)
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Bismuth 214 (20 min)
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Lead 214 (27 min)
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They are sticky particles
Two Polonium’s emit Alpha Particles
20 times more dangerous than Radon
Measured in units of WL (working level)
© WPB slideshow
Radon Decay Products released from
the decay of Radon are measured
in units of WL
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Some RDPs escape
to the outside
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0.01 WL
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About ½ the RDPs
remain in the air
Some RDPs stick
to objects
in the room
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0.04 WL
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En
0.01 WL
0.02 WL
4.0 pCi/L
4.0 pCi/l produces about 0.02 WL in the air
© WPB slideshow
C
Health Affects
from Radon & Radon Decay
Products
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© WPB slideshow
History of Radon
1400’s
Underground miners were dying
from an unknown lung disease
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1950’s
Connection made between
Lung Cancer and RDPs
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1879
Lung Cancer first identified
in European miners
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1999
BEIR VI says about 18,500 Americans
die each year from exposure to radon
es
1984
Extremely high radon found
in Pennsylvania home (2700 pCi/L)
© WPB slideshow
The Radon Decay Products (RDP’s) produced by
radon are the primary health risk?
Unattached
Most dangerous
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Most exposure
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RDPs
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Radon
Attached
to Aerosols
Attached to
solid objects
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high
risk
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En
low
risk
No risk
© WPB slideshow
Alpha emissions from Radon and
Radon Decay Products damage Lung Cells
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OH-
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H 2O
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An alpha
particle
striking the
cell can
cause free
radicals
to be
formed
in the
cell
fluid
Double strand
DNA can be split by
an alpha particle
A Lung Cell
struck by an
alpha particle
will:
Die
or
Heal itself or
become Cancerous
© WPB slideshow
This is a micro-scope view of plastic that has
been struck multiple times by alpha particles
from radon and radon decay products
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This kind of
damage is
what your
lungs receive
from exposure to
radon
and
radon decay products
Photo by Dr. Jim Burkhart
© WPB slideshow
Radon risk is best determined by
actual people studies
Miner Studies
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Scientists believe the miner studies provide the best
determination of radon risk because of the number of miners
exposed to radon even though miners are mostly male
smokers exposed to other pollutants
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Case Control Studies
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This is the best type of study but expensive because it requires
a large carefully sampled group of lung cancer patients
and a similar group who do not have lung cancer
Geographic Studies
Studying the lung cancer rate by area is not considered a good study
© WPB slideshow
1988 BEIR IV study of 22,190
miners with 360 Lung Cancers
Expected
lung
cancer
17
Observed
lung
cancer
21
No change
1-2
39
op
46
No change
2-5
19
41
Double
5-1 0
13
40
Triple
1 0-2 0
11
39
3.5 times
3 6-9 6
15
66
F o u r times
9 6-2 0 0
5
45
N i n e times
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Lifetime
average
pCi/L
0
Relative
increase
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Notice that lung cancer rates doubled when miners were
exposed to the equivalent of 2 to 5 pCi/l over a lifetime
© WPB slideshow
‘94 Swedish Case Control Study
1360 Swedes with lung cancer.
2847 Swedes without lung cancer
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Averaged 27 years of Lived-in Radon measurements
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Less than 4 pCi/L average = no excess lung cancer
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4 to 10 pCi/L average = 30% increased lung cancer
Greater than 10 pCi/L average = 80% increased lung cancer
Sleeping with windows open = no excess lung cancer
© WPB slideshow
Lung Cancer is the leading cause of Cancer deaths
164,000 new cases of Lung Cancer in 2000.
There has been a dramatic increase of Lung Cancer in Woman
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Lung Cancer symptoms are so general that 75% of the time
it has spread to other organs by the time it is detected
Only 15% of lung cancer victims survive 5 years
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Radon causes Lung Cancer for 16,000 smokers
and 2500 non-smokers per year.
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Radon is responsible for 22% of non-smoker lung cancer
2nd hand Smoke causes 3000 deaths/yr and Asbestos 2000/yr
26% of the population smokes - 90% would like to quit but can’t
© WPB slideshow
Carcinogen Ratings
Class A
( demonstrated cancer causing ) asbestos
tobacco smoke, benzene, RADON
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( probable cancer causing ) DDT,
alar, PCB, chewing tobacco, cholesterol
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( limited animal evidence )
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Class C
Class D
( inadequate evidence )
saccharin
© WPB slideshow
There are Four Factors necessary for
a “Class A” carcinogen rating and
Radon has all of them
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 Physical Model of how it happens
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(alpha damage to lung cells)
Animal studies showing an effect
(animals exposed to radon had a higher rate of lung cancer)
Occupational or Residential studies
(miner studies and case control studies show a connection)
Opportunities for exposure
(more time spent indoors with house sealed up)
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
© WPB slideshow
EPA has calculated how many many
people would die of lung cancer if:
260 die out
of 1000
120
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Non-Smoker’s risk
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80
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60
Smoker’s risk
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40
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Number of
people who
would die of
lung cancer
if a 1000
of them
were exposed
to these
amounts of
radon
for a lifetime
20
0
1.3
2
4
8
20 pCi/l
Average radon concentration over a lifetime
© WPB slideshow
Comparison to other causes of Death
BEIR VI says radon may cause 23% of
25000
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all non-smokers lung cancers
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20000
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non-smokers
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15000
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smokers
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10000
5000
0
Drunk
driving
Radon
Drowning
Fires
Airline crashes
© WPB slideshow
Comparison of estimated deaths annually per
100,000 persons for different causes
Heart Attack
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20 pCi/L in Home
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Motor Vehicle Accident
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All Accidents in Home
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Murder
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Suicide
All Occupational Hazards
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1.3 pCi/L in Home
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Drownings
Poisons
Firearms Accidents
0
50
100
150
200
250
300
Jacobsen, c1990, University of Michigan
© WPB slideshow
Sources of Radiation Exposure to
the U.S. Population
Radon exposure is based on an average
indoor exposure of 1.3 pCi/L
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Other
1%
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Radon
55%
Medical X-Rays
11%
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Cosmic
8%
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Internal
11%
Nuclear Medicine
4%
Radon is by far
the greatest
single source of
radiation to the
general public.
Consumer Products
Terrestrial
3%
8%
© WPB slideshow
These Organizations consider
Radon to be Dangerous
American Lung Association
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American Medical Association
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Environmental Protection Agency
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National Academy of Sciences
US. Surgeon General
American Cancer Society
© WPB slideshow
EPA and Surgeon General
recommend that everyone
test their home for radon
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and
If your home
is above 4 pCi/L,
Fix It
© WPB slideshow
Radon Entry &
Behavior
Average outdoor
radon in the US is
about 0.4 pCi/L
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Radium
What causes
radon to vary in
vacant & occupied houses
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Radon
Average indoor
radon in the US is
about 1.3 pCi/L
Uranium
© WPB slideshow
Radon gets into our homes
in several ways
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Emanation
2-5%
Soil gas
85 - 97 %
Diffusion
1- 4 %
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Water
< 1%
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Radium in the Soil
© WPB slideshow
Warm air escapes out the top of our homes in
the heating season (stack effect)
vent-a-ridge
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Positive
house
pressure
PB
openings
The escaping
warm air creates
negative house
pressure in the
lowest level of
the house
Gas water
heater
Canal
Drain
Sump
Positive
soil pressure
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Rising
Heated
Air
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roof ventilator
Negative
house
pressure
The negative house
pressure draws in
radon laden soil gas
© WPB slideshow
A drafty house can still have radon
Outdoor
air
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Drafty houses can
have strong
Negative Pressure
which induces
soil gas entry as
well as outdoor air
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Soil Gas
es
Negative
house
pressure
There is no correlation between house age or
house ventilation levels and radon levels
© WPB slideshow
Indoor Radon Levels
depend on these factors:
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Building
Ventilation Rate
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Foundation openings
into the Soil
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Building to Soil
pressure difference
+
Radon Strength in the Soil
Soil Porosity
© WPB slideshow
There can be large variations
in radon levels in the soil
Does my house
have
Radon ?
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12,664
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es
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111
77,194
112
351
89,100
These were actual
radon levels
measured in the
soil around a home
in NJ
© WPB slideshow
Houses act like
Soil Vacuum Cleaners
Warm air
escapes out the
top of the house
vent-a-ridge
C
bath room
fan
PB
down draft
range exhaust
central vacuum
dryer
sump
gas water
heater
canal drain
Most houses
have no
mechanical
outdoor air
supply
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rising
heated
air
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Tight walls
keeps
pollutants
inside
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roof ventilator
Mechanical
equipment
exhausts air
Waterproofed
foundation
© WPB slideshow
Common household appliances can
cause negative pressures inside a home
Typical exhaust
30 cfm
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Air tight wood stove
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20 – 70 cfm
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Combustion Appliance
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100 cfm
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Clothes Dryer
25 – 90 cfm
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En
Bathroom Fan
Wood Fireplace
Downdraft range exhaust
170 cfm
300 – 400 cfm
cfm is airflow in cubic feet per minute
© WPB slideshow
Strong wind can affect the radon levels
Upwind
Downwind
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Negative
house
pressure
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Positive
house
pressure
© WPB slideshow
Heavy rain may also affect radon levels
Light rain has
little effect
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Dropping barometric pressure
can sometimes cause a short
upward radon spike
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Heavy rain may
cause a short upward
radon spike
Extended rain can block soil pathways
and reduce indoor radon levels
© WPB slideshow
Radon Levels are typically higher
during the heating seasons
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Rn
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Rn
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Rn
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Rn
Some houses have higher basement levels in the summer
© WPB slideshow
First floor tends to have 2 times to 6 times
lower radon levels than the basement
7
July
6
May
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0
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Jan
Sept Nov
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3
March
C
5
4
This data is
based on
multi-level
radon tests
done in 871
Pennsylvania
homes
In the Summer the 1st floor is 4 to 6 times lower than the basement
In the Winter the 1st floor is 2 to 3 times lower than the basement
The difference between floors is greater during the summer
© WPB slideshow
Radon levels fluctuate Hour by Hour
Usually radon levels are higher at night and lower during the day
12
C
10
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This graph
depicts common
Diurnal Variation
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pCi/L 6
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4
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2
0
Noon
Noon
Noon
Daily radon variation is usually greater in the summer
© WPB slideshow
Radon Measuring Devices
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© WPB slideshow
Two generic types of test devices
Continuous Radon
Monitor or CRM
Passive Detector
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16.5 pCi/L
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Passive detectors:
CRM provides:
radon levels hour by hour
&
tamper resistant features
provide only a
single average result
&
are less expensive
Both methods can be accurate
© WPB slideshow
Four Types of
Passive Detectors
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 Open Face Charcoal
( 2 - 4 day exposure )
 Diffusion Barrier Charcoal
( 3 - 7 day exposure)
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Electret Ion Chamber
( 2 - 7 days or 90 - 365 days exposure)
Alpha Track Detector
( 90 - 365 day exposure )
© WPB slideshow
Activated Carbon
Charcoal Detectors
Open Face
Radon
Radon
Radon
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Radon
C
H 2O
Diffusion
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Expose
2 to 4
days
Expose
3 to 7
days
Lab measures gamma from decay of RDP’s
Detector must be returned to the lab promptly
© WPB slideshow
Charcoal Detector characteristics


Easy to use
Least expensive
C
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Long shelf life
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Lab analyzes the results

Has reasonable accuracy
PB

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
Must expose a specific amount of time
Open Face are sensitive to high humidity
© WPB slideshow
Electret Ion Chamber (EIC) characteristics
The decay of Radon &
Radon Decay Products
inside the chamber causes
ionization. This causes the
electret to lose volts
Radon
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Radon
es
-
ris
++ + +
Electret voltage is read
before & after
exposure to determine
the radon levels
rp
-
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En
RDPs
PB
-
W
-
Electret
© WPB slideshow
Electret Ion Chamber (EIC) characteristics
C
EIC’s have demonstrate good accuracy
but it’s always best to expose Duplicates
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EIC’s are more tamper resistant than charcoal detectors
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En
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Can vary exposure from 2 to 365 days
depending on chamber size & electret
The testing company analyzes the result.
© WPB slideshow
Alpha Track Detectors
Radon entry
C
Alpha particles from
decay of Radon and RDP’s
damage the plastic chip
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Marks are enhanced at
the laboratory and
counted to determine
the average radon
level
es
RDP’s
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Radon
© WPB slideshow
Alpha Track characteristics
C
Alpha Tracks can measure the average
radon levels over 90 to 365 days
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They are not affected by the testing
environment
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Cannot be used for short term tests
© WPB slideshow
Continuous Radon Monitors (CRMs)
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16.5 pCi/L
PB
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CRMs record
hour by hour radon
variation by counting
alpha emissions
from Radon or
Radon & RDPs
Some CRMs can also monitor hourly temperature,
barometric pressure, motion, humidity etc.
© WPB slideshow
Are CRMs the best choice
for Real Estate testing ?
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CRM’s can have Tamper Resistant features
PB
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CRM’s have demonstrated excellent accuracy
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En
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CRM’s can indicate the impact of
weather on test results
© WPB slideshow
What are Remote calculated CRM’s ?
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A tester leases
a CRM from
an Equipment Supplier
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The tester modems the CRM data to
the equipment supplier who faxes
results back to the Tester’s office
© WPB slideshow
Grab Samples & Sniffer tests
Grab samples and sniffer tests
are used primarily by mitigators
to diagnose radon entry

These are diagnostic
measurements that cannot be
used to determine the need for
mitigation
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
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© WPB slideshow
Continuous Working Level Monitors
(CWM)
Filter
C
e
RDP’s
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CWM’s measure
alpha decays from
RDPs collected
on a filter
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Pump tubing
CWM only measure radon decay products (WL) not Radon (pCi/L)
CWM’s can measure very low concentrations
© WPB slideshow
How can you
determine a Tester’s
qualifications ?
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Is Tester state certified ?
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PB
In non-certifying states they should
be NEHA or NRSB listed
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&
es
www.radongas.org
www.nrsb.org
Does Tester use tamper resistant features?
Does Tester obtain a signed
“Non-interference Agreement”?
© WPB slideshow
You can always
test your own
home
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You can purchase charcoal detectors or long term
alpha tracks via the internet, calling a supplier or
from a local hardware or building supply store
PB
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Just follow the instructions. After exposing the
detectors, promptly mail them back to the
laboratory
© WPB slideshow
Measuring Radon
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The EPA specifies
the following
Testing Conditions
be followed
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© WPB slideshow
C
Short-term measurements
require
Closed House Conditions
for
12 hours prior to the start of the test
and all during the test
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
Fireplace damper closed
Window air conditioners set to recycle only
All windows & doors closed except for normal
entry and exit
Attic fans are OK but don’t use window or
whole house fans
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
PB

W

© WPB slideshow
Minimum test period is 2 days
Short Term test is 2 - 7 days
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with closed house conditions
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while a
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Long Term test is 3 to 12 months
es
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& does not require Closed House conditions
94% of the time Short Term tests provide the
same mitigation decision as a Long Term test
© WPB slideshow
Consider Retesting if :
Test conditions were not maintained

Extended heavy Rain or Winds speeds greater
than 25 mph for longer than an hour (a Severe
Storm )

One test result is less than 4 pCi/L and the other is
greater and the greater is twice the level of the
lesser result
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( Duplicate results of 2.5 pCi/L & 6.0 pCi/L )
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What rooms should be Tested ?
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Consider testing other
living areas, especially
over other foundation types
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Minimum one
test in lowest
Lived-in area
For Real Estate transactions test the Lowest Livable Area
© WPB slideshow
What does
“Lowest Livable” mean ?
Lowest area of the home that could be used as a
playroom, family room, workshop or office without
needing major structural change such as a concrete
floor or more headroom.
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If a basement only needs a carpet for children to
play in, it is considered Livable
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A small furnace room is not Livable
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Do NOT test:
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Closets, Bathrooms,
Kitchens, Storerooms, Garages,
Crawl Spaces, or Attics
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You can test:
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Bedrooms, Family Rooms,
Living Rooms, Dining Rooms,
Office, Study, Playroom, or Workshop
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How far must a Detector be
from windows & doors ?
At Least:
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1’ from
exterior walls
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3’ from an exterior
operable opening
4” Clearance from
other objects
20” Off Floor
© WPB slideshow
Consider exposing two detectors
at the same time. (Duplicates)
Duplicate radon results will vary. Duplicate
results greater than 4 pCi/L should be within 10%
to 30% of each other

If duplicates have a greater variation than this,
contact the Tester or the laboratory

The lower the radon levels, the greater the
percentage variation between duplicate results
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Commercial Buildings
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EPA has not defined workplace radon levels.
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4 pCi/L action level is typically used
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Use School Testing protocols for commercial buildings
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Radon fix typically involves HVAC equipment
Mitigators need commercial experience
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School Testing Protocols
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Test all rooms in contact with the soil
Test the whole building at the same time
Test during occupied days (work week)
Maintain closed building conditions
HVAC should be operating normally
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
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Radon Mitigation
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Four Mitigation Methods
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Creating negative
pressure in the soil is the
preferred method
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Ventilate it Out
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Create positive
pressure above Soil
+
Seal all openings
into the Soil
Create negative pressure in the Soil
© WPB slideshow
Sealing an open sump pit will usually not
reduce Radon Levels ?
C
One research project found it only took
the equivalent of ten feet of a 1/16” crack
in the basement floor to maintain
radon levels above the Guideline
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A 1/16” crack looks like a 100
mile cavern to a radon atom
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Can Radon Sealing
cause a water problem?
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A properly installed radon
system should not cause a
water problem nor will it
typically fix a wet
basement.
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Caution:
Flooding
during
heavy
rains
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Active Soil Depressurization (ASD)
Air is pulled
from under
each slab and
from under a
crawl space
membrane
Radon fan
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Radon piping
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Crawl
space
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Slab
foundation
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depressurization under concrete slabs
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Radon
suction
pit
Sub-membrane
depressurization
in this dirt floor
crawl space
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Where must the Radon Fan
be located?

Basement
Crawl Spaces
Below grade
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Outside
House Attic
Garage Attic
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Not OK
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Good location
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Radon Exhaust Requirements
Radon Exhaust must be:
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above the edge of roof
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2’ higher than
windows within 10’
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Minimum 10’ off
the ground
Radon fan
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The wall between garage and house is typically
a Firewall and needs fire protection
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Fan in Attic
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Firedampers
PB
Garage
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es
Basement
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Fan powered radon systems must have a
vacuum gauge or other indicator
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If oil is level,
system is off or stopped
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The difference in oil
levels indicates the
strength of the
vacuum in the system
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Note: Vacuum gauge does not
indicate Radon Levels
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Radon System must have a Label
Radon Reduction System
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Installer’s:
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Phone Number
Certification id #
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EPA recommends
Re-testing every 2 Years
There should be an information package
attached to the radon pipe
© WPB slideshow
Gas appliances require a
Backdraft Test
During backdraft test:
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Check backdraft after
radon system
is running
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Keep windows closed &
Air Handler running
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Run other house
exhaust fans
PB
Gas water
heater
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Dryer
Check chimney draft on all
gas appliances on start-up
© WPB slideshow
Post Mitigation Testing
Do a Short-term test within 30 days

Wait 24 hours before starting the test

Place short term test in the previous test location

An independent re-test is Best
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How do you know if a
Mitigator is qualified ?
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Mitigator must be Certified by the State
or in non certifying states he should be listed
with NEHA or NRSB
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www.radongas.org
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www.nrsb.org
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Does the Mitigator have referrals ?
Will the Mitigator be in business and provide
good service over the length of their warranty ?
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Radon in Water
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Issues to be
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familiar with
© WPB slideshow
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EPA states in the
“Home Buyers & Sellers
Guide to Radon”:
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“If you have tested the air in
your home and found a radon
problem, and your water comes
from a well, have the water tested.”
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Radon comes out of
the water when you:
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Expose the water to air
- Taking a shower
 Agitate the water
- Doing the laundry
 Heat the Water
- Using the Dishwasher

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© WPB slideshow
It takes a lot of radon in the water to
raise the radon levels in the air?
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If radon in water is 10,000 pCi/L then:
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Average water use in an
average size house
will raise the overall
radon average 1 pCi/L
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A 10 minute
shower
will raise
bathroom
to about
30 pCi/L
© WPB slideshow
Radon in Water Health Risk
Primary Risk is the increased
radon in the air from water usage
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10,000 pCi/L in the water raises
the average radon in air about 1 pCi/L
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There is a small risk of stomach & other
cancers from ingestion of water with radon
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There are no Federal Guidelines
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States
EPA
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EPA has suggested two options:
An MCL of 300 pCi/L or
an AMCL of 4000 pCi/L if the state has
a Multi-media radon in Air Program
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© WPB slideshow
Percentage of Pennsylvania
community wells that would not pass a
3000 pCi/L standard
1,336
percentage
above
3000 pCi/L
7%
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362
3300
to
10,000
people
more
than
10,000
people
65
41
4%
5%
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# in PA
500
to
3299
people
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25
to
499
people
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Communities
w/ground
water
systems
4%
© WPB slideshow
Testing the
Radon in Water
Order radon in water test kits over the internet
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A water sample is collected from fresh cold
tap water & shipped to analysis laboratory
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A certified tester can also provide this test for
a cost similar to testing the radon in the air
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© WPB slideshow
Radon in Water can be
reduced with:
Granular Activated Carbon (GAC)
5’ tall tank(s) filter the water
Cost about $900 - $1,500
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Aeration System
Radon is bubbled out of the water
Cost about $3,500 - $4,500
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Concerns about using
Granular Activated Carbon
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Other contaminants can reduce system
performance
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GAC can emanate gamma if radon in water is
very high
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GAC should only be used for levels below
20,000 pCi/L
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Carbon needs to be replaced every 1 - 5 years
© WPB slideshow
Some Aeration concerns
System must discharge above roof

System needs cleaning at least once per year

Can have Bacteria growth during non-use periods

Radon removal, however, is excellent
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© WPB slideshow
New Construction
and Radon
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Make it easy
to fix
or Just
install the
Whole
System
Prevent Entry
© WPB slideshow
Should land be tested
before construction ?
The soil can be tested but it is not
commonly done

A strong radon source from the soil
could be easily missed

It is better to use the cost of preconstruction soil testing for radon
resistant features
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© WPB slideshow
EPA has defined
Radon Zones
Zone 1 - expect 4.0 pCi/L or greater
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Zone 2 - expect 2.0 to 4.0 pCi/L
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Zone 3 - expect 2.0 pCi/L or less
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© WPB slideshow
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For more detailed state maps go to: www.epa.gov/iaq/radon/zonemap.html
© WPB slideshow
Recommendations for Zone 1
3” or 4” Passive vent to roof
Leave adequate room
for fan installation
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Treat all
slabs
Have attic wiring for the fan
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Do not install channel drains
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Run perforated piping
under all slabs
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Provide
Combustion
make-up air
Seal the Sump pit
Minimize concrete
cracks & openings
© WPB slideshow
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© WPB slideshow