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2. environmental safety

Radon Testing & Risk in the Shenandoah Valley
A Brief Introduction
1/29/14
Ryan Paris – Radiation Safety Specialist & Radon
Coordinator
Virginia Dept. of Health, Div. of Radiological Health
[email protected]
Radon….
• is a naturally occurring radioactive decay product of Uranium
& has a radioactive half-life of approx. 3.8 days
• tends to accumulate at higher concentrations in the lowest
levels of the home
• Radon’s short-lived radon decay products (RDPs) are solids
that can adhere to dust particles and lung tissue
• Radon and two RDPs (Po-218 & Po-214) all emit alpha
particles which have limited range/penetrating power, but they
can do great damage to lung tissue if inhaled
Nearly 1 in 15 US homes is estimated to have elevated levels of radon.
Benchmark Radon Levels:
• Average US indoor radon levels ~ 1.3 pCi/L
• Average US outdoor radon levels ~ 0.4 pCi/L
• USEPA recommended indoor action level is 4.0 pCi/L or higher.
Most other countries that have set radon action levels now use 5.4
pCi/L (200 Bq/m3)
• Typical post-mitigation radon levels average between 0.5 -2.0 pCi/L.
It is not possible to get indoor radon levels down to zero.
Lung Cancer Risk Associated with Radon
Exposure
Radon is thought to be the second leading cause of lung cancer after
smoking. It may cause as many as 21,000 lung cancer deaths/yr. in the
USA – which includes approx. 670/yr. in Virginia!
Lung cancer risk below is calculated based on a full 70 year lifetime
of constant exposure to radon at a known level. The risk is also
thought to increase dramatically for those with a smoking history.
IF NEVER SMOKED:
At 20 pCi/L: = 36/1000
At 10 pCi/L: = 18/1000
At 4 pCi/L: = 7/1000
At 1.3 pCi/L = 2/1000
CURRENT SMOKER:
= 260/1000
= 150/1000
= 62/1000
= 20/1000
USEPA Radon Zone Map for the
Mid Atlantic States
Radon Test Results for Jurisdictions in: Alleghany, Central
Shenandoah, Lord Fairfax and Pittsylvania/Danville LHDs
County/City
Augusta
Botetourt
Clarke
Danville
Frederick
Harrisonburg
Page
Pittsylvania
Roanoke Co.
Roanoke City
Rockbridge
Rockingham
Salem
Shenandoah
Warren
Winchester
Avg. (pCi/L)
4.5
4.5
5.9
4.4
7.8
4.3
2.7
2.9
2.8
3.2
4.8
4.7
3.1
4.0
5.2
7.5
Tests
192
669
208
239
608
636
192
141
3734
3191
64
459
1008
272
219
480
% =/> 4.0 pCi/L
27
36
49
41
47
36
24
26
20
24
36
38
25
35
37
60
Test kits provided & analyzed by Air Chek from 1986-2013
minimum of 50 test results used to calculate average. Jurisdictions with <50 test results not shown.
How to Test?
•
Professional radon testers that are currently certified according to VA law
may be found on the websites of the National Radon Proficiency Program
(NRPP) (www.nrpp.info) or the National Radon Safety Board (NRSB)
(www.nrsb.org).
•
EPA recommends any one of these choices:
– ONE short term (48 hr. minimum) continuous radon monitor (CRM) test
– Or an average of TWO short term tests using other technologies
– Or ONE long-term test (90 day minimum)
•
A long term test lasting an entire year is the most accurate test method –
especially in borderline cases!
•
Consumers can purchase activated charcoal s.t. ($10-15) or alpha track l.t.
test kits ($20-30) directly from approved vendors.
Radon Test Devices
Continuous
Radon
Monitors
Continuous Digital
Radon Monitor
Electret Ion
Chambers
Long-term
Alpha Track
Detectors
Activated Charcoal
Test Kits
Radon in Water
•
Radon is usually only a potential problem in wells (ground water)
•
USEPA has yet to finalize ANY proposed health
standards/recommendations/methods regarding radon in water.
•
The proposed USEPA radon in water standard may eventually be finalized
at 4,000 pCi/L.
•
Radon in water poses a comparatively insignificant ingestion risk but radon
in water can evaporate into the air when the water is agitated (showers
faucets, dish/clothes washers).
•
10,000 pCi/L in water is thought to contribute 1 pCi/L to indoor radon air
levels.
•
Mitigating a home’s water with best available technology may cost up to
$4000-5000.
RRCT/RRNC Diagram
Properly installed passive RRNC is thought to reduce indoor radon
levels by approx. 50%!
What are Radon-resistant construction techniques?
The techniques may vary for different foundations and site
requirements, but the basic elements are:
Gas Permeable Layer
This layer is placed beneath the slab or flooring system to
allow the soil gas to move freely underneath the house. In
many cases, the material used is a 4-inch layer of clean
gravel.
Plastic Sheeting
Plastic sheeting is placed on top of the gas permeable layer
and under the slab to help prevent the soil gas from entering
the home. In crawlspaces, the sheeting is placed over the
crawlspace floor.
Sealing and Caulking
All openings in the concrete foundation floor are sealed to
reduce soil gas entry into the home.
Vent Pipe
A 3- or 4-inch gas-tight or PVC pipe (commonly used for
plumbing) runs from the gas permeable layer through the
house to the roof to safely vent radon and other soil gases
above the house.
Junction Box
An electrical junction box is installed in case an electric venting
fan is needed later.
Radon Law in Virginia:
• NO state or federal law currently REQUIRES radon testing or
mitigation prior to a real estate sale. It is entirely negotiable between
the parties involved!
• To date, very few eligible Zone 1 VA counties/cities have adopted
Radon Resistant Construction Techniques (RRCT) into their building
codes. As of 2009, only two eligible counties (Rockbridge and
Shenandoah) and 6 cities (Blacksburg, Buena Vista, Lexington,
Radford, Roanoke and Salem) have adopted that ordinance into
their building codes.
• VA law requires all school classrooms to be tested for radon.
Radon Mitigation for an Existing Home
Fan with coupling from PVC
to gutter downspout piping
Proper exterior riser pipe
Interior piping
schematic
Further Information
• Va. Dept. of Health – Office of Radiological Health: 804864-8150 Toll-free in VA: 800-468-0138
Radon Website:
www.vdh.virginia.gov/epidemiology/radiologicalhealth/ra
don/index
• Free USEPA Radon publications (most can be read or
downloaded on-line): www.epa.gov/radon/pubs
• 1-800-SOS Radon
• Spanish 1-800-725-8312
• Safe Drinking Water Hotline 1-800-426-4791
QUESTIONS?