Transcript Radon Measurement

Radon 101 & Testing
Twa-le Abrahamson-Swan
Spokane Tribal Air Quality Department
509-626-4403
[email protected]
www.epa.gov/radon
Superfund Site: Midnite Uranium Mine

Contaminants: radionuclides and heavy metals in acid mine
drainage, radioactive decay, and particulate transport in air,
surface water, and groundwater.

In as soon as two years, millions of tons of contaminated
material will be moved using heavy equipment. A new
water treatment plant will be built. Remediation is
expected to take 8 to 10 years.
https://fortress.wa.gov/doh/wtn/WTNPortal/IndicatorPages/RadSmokeLC.aspx
What Is Radon –222 (radon)?

Radon is a gas

It is naturally occurring

You can not see or
smell it

It enters buildings from
the soil beneath them
Radon
3.8 days
Radium
1,600 years
Uranium
4.5 billion years
Things to know about radon
Naturally occurring Gas
 Undetectable by human senses

◦ Colorless, Odorless, Tasteless
Radioactive
 Does not chemically react
 No static electrical charge. Will not adhere to
other atoms or surfaces.

Average Contributions From Radon
Sources In U.S. Homes

Water
< 1%
Emanation
2 - 5%
Soil Gas
85 - 90%
Diffusion
1 - 4%
Radium Containing Soil

The movement of
soil gas into a home
is the predominant
entry route.
These are averages
- a particular home
can be different!
Radon Gas Spatial Distribution
<5
Radon enters from beneath
foundation and travels
upward.
5-6
◦ Diluted with outdoor air
infiltrating building


10
If radon is less than 4 pCi/L
in lower level, one can say
with reasonable confidence
that upper floors are also
less than 4 pCi/L.
Radon sources
Sources
Curies Per Year
Emanation: Soil
2,000,000,000
Ground Water
500,000,000
Emanation: Oceans
30,000,000
Phosphate Residues
3,000,000
Uranium Tailings Piles
2,000,000
Coal Residues
20,000
Natural Gas
10,000
Coal Combustion
900
Human Exhalation
10
Why are we concerned about radon?

Radon is a known carcinogen, in the highest
ranking category with tobacco products
U.S. SURGEON GENERAL HEALTH
ADVISORY
“Indoor radon is the second-leading cause of
lung cancer in the United States and breathing it
over prolonged periods can present a significant
health risk to families all over the country. It’s
important to know that this threat is completely
preventable. Radon can be detected with a
simple test and fixed through well-established
venting techniques.” – January 2005
Why Is Radon A Concern?
Radon decays into
radioactive particles
known as radon decay
products.
 These particles are
easily inhaled and
deposited in the lungs
where they can damage
sensitive lung tissue.

Radon Decay Products
Radon
Radon
What happens when radon is inhaled?
Alpha 
Decay
4He
Nucleus Ejected from
222Rn Nucleus
+
+
+
+
+
+
+2
+
+
+
Radon - 222
4He
+ 218Po
What Happens When Radon Decay
Products Are Inhaled?


Double Strand Breaks
Highly radioactive
particles adhere to
lung tissue, where
they can irradiate
sensitive cells.
Radiation can alter
the cells, increasing
the potential for
cancer.
Radon-222
4 day
,g
Polonium-218 3 min
,g
Lead-214
27 min
b,g
Bismuth-214 20 min
b,g
Polonium-214 0.2 ms
,g
Lead-210
218Po
and 214Po
deliver the
radiologically
significant dose to
the respiratory
epithelium.
22 yrs
b,g
Bismuth-210 5 day
b,g
Polonium-210 138 day
,g
Lead-206
Stable
Radon
Progeny
EPA & Surgeon General Recommend
Take action if a home is at or
above 4.0 pCi/L
(year long average)
4.0 pCi/L EPA ACTION LEVEL
Average indoor: 1.3 – 1.4 pCi/L
Average outdoor: 0.4 pCi/L
Testing for Radon

Initial short-term test (2-7 days)
◦ Closed house conditions
One testing device
 Place in lowest lived in part of house, ideally
bedroom, living room and most frequently
occupied rooms
 Not a closet, bathroom, kitchen, storeroom,
garage, crawlspace, attic.
 Follow-up test if results are ≥ 4 pCi/L

Purpose of Test Determines
Location
Lowest lived in
 Lowest suitable for Occupancy
w/o Renovation

YES
YES
NO
• Test in livable
room.
• Keep away from
drafts and
moisture.
Radon Measurement Devices
Activated charcoal device
 Electret Ion Chamber
 Continuous Radon Monitor

Activated Charcoal Devices
Measures radon
 Used by professionals and homeowners
 Different devices have different optimal
deployment periods.
 Requires no power to operate.
 In small container (paper, metal or plastic)
containing activated charcoal.
 Can only be read in the lab, not in the
field.

Activated Charcoal Device
Examples
For short-term tests
 Must be analyzed within 6 days

Advantages





Compact, convenient and
economical
Can be used for 48-hour
test
Can be easily mailed to lab
for analysis
Passive, does not require
power and silent
Quick and accurate analysis
Disadvantages

Limited to short-term
sampling

If radon peaks and valleys are
dramatic, the results validity is
questioned because of a
possible bias over the last 12
hours.

Provides no indication of
changes in radon during
measurement.

Tampering detection difficult.
Activated Charcoal Devices
Electret Ion Chamber (E-Perm)
Short-term and long-term measurements
 2 days-1 year, dependent upon:

◦ Configuration
◦ Type of disk used
◦ Anticipated radon concentration
Measuring Electret Voltages
Electrets are pre-charged by
manufacturer.
 Electret voltages are measured before and
after deployment.
 Reported radon is a function of:

 Voltage drop (Approximate 2 volts drop per day
per pCi/L)
Advantages



Short-term and long-term
measurements
Electret can be re-used
until voltage falls below the
desired operating voltage
for the device used (200
volts)
Can be recharged by
manufacturer ($30)
Disadvantages
Sensitive to external
gamma radiation.
Correction needed.
 Sensitive to altitude
changes. Correction
needed.
 Can be damaged by
touching surface, surface
contamination or impact.
 Pre/post voltages must be
measured at the same
temperature.

Electret Ion Chambers
Continuous Radon Monitors

Sun Nuclear (Solid State Silicon Detector)
◦
◦
◦
◦
◦
Impacts from alpha particles are counted.
Data plotted and averaged
Relatively low efficiency
Provides continuous measurements
Used for diagnostics
Advantages





Exposure variable: 48 hrs to
many months
Relatively good precision
Can track hourly variations
Options to down load or
print on site
Can indicate tampering or
ventilation.
Disadvantages
Higher priced
 Requires trained operator
 Annual calibration
 Bi-annual performance
tests.
 Can only test one room at
a time.

Continuous Radon Monitors
Results from a CRM
Do It Yourself Test Kits
Radon Mitigation Training
Twa-le Abrahamson-Swan
[email protected]
(509) 626-4403
April 8, 2014 at the US House Appropriations Committee – testifying on
cuts to radon funding and services for Tribes and Environmental Justice
Communities.
 http://docs.house.gov/meetings/AP/AP06/20140408/101853/HHRG-113AP06-Wstate-Abrahamson-SwanT-20140408.pdf
