Radon Measurements Mitigation

8/6/2019 Radon Measurements Mitigation

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Same number of protons as another atom, but adifferent number of neutrons

Example: Radon 220 is isotope of Radon 222

Both have 86 protons

Radon 220 has 134 neutrons

Radon 222 has 136 neutrons


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K Radiation

E Radiation

Occurs spontaneously

Due to change in # ofprotons, atombecomes -2 charge

Radiation released


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Alpha Radiation (E)

Particle released when the nucleus

kicks out 2 neutrons and 2 protons Relatively massive

Relatively slow

Total charge of +2

Mass number changes by 4 and atomic

number changes by 2


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Beta Radiation (F)

Particle released when the nucleus

changes a neutron into a proton and abeta particle

Relatively small mass

Relatively fast moving

Total charge of -1

Atomic Mass Number remains constant

F

PN


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Gamma Radiation (K)

Pure energy. Released from the

nucleus when an alpha or a beta isemitted

No mass

Speed of light

No charge

NO CHANGE


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E

K

F


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Radon-222 is a radioactive gas released duringthe natural decay of thorium and uranium

Colorless

Odorless

Tasteless

Radon cannot be detected with the human senses

Naturally Occurring in rock and soil

Radioactive

Inert


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Radon decays into

Radon DecayProducts

It is these products that produce the harmfulradiation!

Polonium 214

Polonium 218


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Decay Products of Radon are charged ions

Have a static charge

Easy attachment to

water vapor

dust

smoke particles


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ie. Granite, shale, phosphate,

and pitchblende


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(Solid)

Halflife: 4.47 billion years

(Solid)

Halflife: 1,620 years

(Gas)

Halflife: 3.8 days

Polonium 214 & 210


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E K

F K

F K

F K

F K

F K

F K

E K

E K

E K

E K

E K

E K

E K


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It is the E

emitters from theRDPs that causethe most damage

to lung tissuewhen they are

inhaled.

E K

F K

F K

E K

radon progeny (daughters)radioactive isotopes oflead, bismuth, and poloniumcan be inhaled and deposited in the lungs


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S f R di ti E i U


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Sources of Radiation Exposure in U

Medical X-rays

11%

Radon54%

Cosmic8%

Terrestrial8%

Consumer Products3%

Nuclear Medicine4%

Internal11%

Other1%


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SOURCESOF RADON

Outdoors radon poses significantly less risk than indoors.

Indoors radon can accumulate to significant levels.

The magnitude of radon concentration indoors depends

primarily on a building's construction and the amount of radon

in the underlying soil.

Radon gas can enter a buildings from the soil through cracks

in concrete floors and walls, floor drains, sump pumps,

construction joints, and tiny cracks or pores in hollow-block

walls. Radon levels are generally highest in basements and ground

floor rooms that are in contact with the soil.

Well water is another source of radon.


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HOW RADON ENTERS A BUILDING

A. Cracked slab

B. Spaces between bricks

C. Pores in concrete blocks

D. Floor-wall joints

E. Exposed soil

F. Weeping drain tile

G. Mortar joints

H. Loose fitting pipeI. Open tops of block walls

J. Building materials (rock)

K. Well water


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Air movement through soil

Cracks in foundations

Through well water

Also through some buildingmaterials (ie. Concrete)

that have the potential tocontain and emit Radon.


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When exhaust fansremove air from a

building, much of the

replacement aircomes from the soil

underneath thebuilding.


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When indoor temperaturesare higher than outdoortemperatures and thewarm air rises, it is

replaced with the cooler,more dense air from theoutside. Some of this airmoves through the soil

and carries radon with it.


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Radioactive decayof Radon atom

Emits E radiation Emits K radiation

Radon Decay Products

Polonium 218

Polonium 214


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RDPs stickto the lung

tissue.


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Damage to

lung tissue

Lung TissueCell


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Between 48 hoursand less than 90days duration

Closed houseconditions 12 hrsprior to testing

Commonly usedduring real estatetransactions


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Duration longer than 90days

Closed house conditions12 hrs prior to testing

Provide more accuratereadings

Take into account all

variables: weather

occupancy

heating/cooling


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RADONTESTING

Professional radon testing services can cost as high as $300. Home radon test kits can cost as little as $10 per kit.

Two types of methods to detect radon.

Radon Gas Measurement Methods: Detect the amount of

radon gas build-up.

Radon Decay Measurement Methods. These look at the

source material and measure how much radioactive decay

has taken place.

The most accurate and reliable radon measurements are those

that continuously monitor radon.


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Activated CharcoalAdsorption

Radon is absorbed into a charcoal canisterShort-term detector (equilibration over 2-7 days)

Laboratory analysis by scintillation (gamma-ray)

Alpha Track Detection

A plastic film is exposed (1 to 12 months)

Alpha particles from radon decay produce damage tracksNumber of damage tracks determined

Integrating detector

Continuous Radon Monitoring (Scintillation counter)

Radon decay event causes electric current pulse in device

Real-time detector

Signal can be electronically integrated (pulse counting)

Electret Ion Chamber (Electrostatically charged disk detector)

Radon decay ionizes air

Air conductivity increases, reducing voltage across chamber

Real-time detector

Signal can be electronically integrated

RADON GASMEASUREMENT METHODS


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RADONGAS MEASUREMENT METHODS

1. AC - Activated Charcoal Adsorption

Uses an airtight container with activated charcoalthat is opened in the area to be sampled and radon

in the air adsorbs onto the charcoal granules. At the end of the sampling period, the container issealed and may be sent to a laboratory for analysis.

The gamma decay from the radon adsorbed to thecharcoal is counted

Charcoal adsorption detectors, depending ondesign, are deployed from 2 to 7 days.

Use of a diffusion barrier over the charcoal reducesthe effects of drafts and high humidity.


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2.Alpha Track Detection (filtered)

The detector is a small piece of special plastic or filminside a small container.

Air being tested diffuses through a filter covering ahole in the container. When alpha particles from radonand its decay products strike the detector, they causedamage tracks. At the end of the test the container issealed and returned to a laboratory for reading.

Exposure of alpha track detectors is usually 3 to 12months, but because they are true integrating devices,alpha track detectors may be exposed for shorterlengths of time when they are measuring higher radonconcentrations.


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3.Unfiltered Track Detection

The unfiltered alpha track detector operates on the

same principle as the alpha track detector, exceptthat there is no filter present to remove radon decay

products and other alpha particle emitters.

EPA currently recommends that these devices not

be used when the equilibrium fraction is less than

0.35 or greater than 0.60 without adjusting the

calibration factor.


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4. Charcoal Liquid Scintillation This method employs a small vial containing

activated charcoal for sampling the radon.

After an exposure period of 2 to 7 days (depending

on design) the vial is sealed and returned to a

laboratory for analysis.

Analysis is accomplished by treating the charcoal

with a scintillation fluid, then analyzing the fluid

using a scintillation counter. The radon concentration

of the sample site is determined by converting from

counts per minute.


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5. Continuous Radon Monitoring

This method category includes those devices that

record real-time continuous measurements of radon gas.

Air is either pumped or diffuses into a counting

chamber. The counting chamber is typically a

scintillation cell or ionization chamber.

Scintillation counts are processed by electronics, and

radon concentrations for predetermined intervals are

stored in the instrument's memory or transmitted

directly to a printer.


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6. Electret Ion Chamber: Long-Term & Short-Term

For this method, an electrostatically charged diskdetector (electret) is situated within a small container(ion chamber).

During the measurement period, radon diffusesthrough a filter-covered opening in the chamber, wherethe ionization resulting from the decay of radon and itsprogeny reduces the voltage on the electret.

EL detectors may be deployed for 1 to 12 months.Since the electret-ion chambers are true integratingdetectors, the EL type can be exposed at shorterintervals if radon levels are sufficiently high.


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8. Grab Radon/Activated Charcoal

Requires a skilled technician to sample radon by

using a pump or a fan to draw air through acartridge filled with activated charcoal.

Sampling takes from 15 minutes to 1 hour.

After sampling, the cartridge is placed in a sealed

container and taken to a laboratory where analysis is

approximately the same as for the AC or LS

methods.


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9. Grab Radon/Pump-Collapsible Bag

10. Grab Radon/Scintillation Cell

11. Three-Day Integrating Evacuated Scintillation Cell

12. Pump-Collapsible Bag (1-day)

13. Continuous Working Level Monitoring

14. Grab Working Level

15. Radon Progeny (Decay Product) Integrating SamplingUnit


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RADON MITIGATIONSTRATEGIES

EPA generally recommends methods which preventthe entry of radon.

Reducing radon entry by:

- Collecting it prior to entry into the building anddischarging it to a safe location.

- Modifying building pressure differentials or sealing

entry points.

Methods that reduce radon concentrations afterentry by:

- Dilution with increased ventilation.

- Filtering radon from the air.


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SUB-SLAB DEPRESSURIZATION

Reduces radonconcentrations 80-99%

Works best if air

can move easilythrough the soil underthe slab.

Costs normally are

under $3000 with anannual heat/airconditioning loss of$150-200.


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SUMP/DRAIN-TILE DEPRESSURIZATION

Reduces radonlevels by 90-99%.

It works best if

drain tiles form acomplete loop aroundthe building.

Costs normally areunder $2000 with anannual heat/airconditioning loss of$150-200.


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BLOCK WALL DEPRESSURIZATION

Reduces radon 50-99%.

Works only in

buildings that havehollow block walls.

Requires sealing ofthe openings.

Costs $3000 withan annual loss of$150-300 for air

conditioning/ heating.


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SUB-SLAB PRESSURIZATION

Works best withtight basementsisolated from outdoorsand upper floors.

Discourages entryof radon.

Reduces radon by

50-99%

Costs $500-1,500.


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VENTILATION

There are various ventilation approaches such as:

Isolating and ventilating substructures such ascrawl spaces.

Passively adding fresh air make-up to workingspaces.

Actively adding fresh air make-up to a workingspace while removing interior air with some means ofheat recovery.

It should be noted that during ventilation methods,there is significant heat and air conditioning air lossresulting in higher utility bills.


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CHARCOAL ADSORPTIONFOR LOW

LEVELSOF RADON


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HEPA FILTRATIONOF RADON

DECAY PRODUCTS

High Efficiency Particulate Air (HEPA) filters

screen the finest particles out.

Many Radon Decay Products (RDPs) plate out on

the surface of the filter.

HEPA filters screen out other air contaminants.

HEPA filters must be placed in many rooms or in

the central air conditioning system. Use of a HEPA filtration system of Radon Decay

Products still requires radon test monitoring.


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ELECTROSTATIC AIR CLEANERS

Electrostatic air cleaners remove dust particles

that have Radon Decay Products attached. These

cleaners do not effect the radon.

As dust particles are removed from the air, theunattached fraction of RDPs can increase in the

room.

These cleaners remove other air contaminants and

like the HEPA filter they must be placed in everyroom or in a central air conditioner.

Electrostatic air cleaners must have a radon

testing device to measure their effectiveness.


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OTHER TECHNIQUESSealing Cracks

Sealing cracks and other openings in the foundation isa basic part of most approaches to radon reduction.

Sealing does two things, it limits the flow of radoninto the building and reduces the loss of conditioned air.

EPA does not recommend the use of sealing alone toreduce radon

Pressurization

Pressurization uses a fan to blow air into the

basement or work area from either upstairs oroutdoors.

It creates enough pressure at the lowest level indoorsto prevent radon from entering into the building.


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OTHER TECHNIQUES

Heat Recovery Ventilator Heat recovery ventilators (HRV), also called an

air-to-air heat exchangers, can be installed to

increase ventilation.

An HRV will increase building ventilation whileusing the heated or cooled air being exhausted to

warm or cool the incoming air.

HRVs also can improve air quality in buildings

that have other indoor pollutants. There could be

significant increase in the heating and cooling costs

with an HRV, but not as great as ventilation without

heat recovery.


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RADONINWATER

Radon is able to dissolve in water.

The radon gas later escapes from the water and

goes into the air, raising the rooms radon content.

Each year, 183 people die from exposure to radon

in drinking water.

The primary health risks from radon in drinkingwater are lung cancer, from inhaling radon

discharged from water used in the home.


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RADONINWATER

There is currently no federally-enforced drinkingwater standard for radon.

EPA is proposing to regulate radon in drinking

water from community water suppliers.

EPA does not regulate private wells.

EPA is proposing to require community water

suppliers to provide water with radon levels no higher

than 4,000 pCi/L, which contributes about 0.4 pCi/Lof radon to the air in your building.


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RADONINWATER

Radon can be removed from water by using one oftwo methods: aeration treatment or granular activatedcarbon (GAC) treatment.

Aeration treatment involves spraying water ormixing it with air, and then venting the air from the

water before use. Aeration is more efficient than GAC. GAC treatment filters water through carbon. Radonattaches to the carbon and leaves the water free ofradon.

Some building owners opt for a service contractfrom the installer to provide for carbon replacementand general system maintenance.


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Radon Measurements taken in the lowest occupied levelof the home.

If the initial measurement is> 4pCi/L then repeat test in

same location. If the second measurementis > 4pCi/L, consult with acertified Radon Mitigator aboutmitigation.

If the initial measurement is< 4pCi/L then use results.

Mitigation is not necessary.


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THE IMPORTANCE OF A CLEAN

ENVIRONMENT

I would ask all of us to remember that protecting our

environment is about protecting where we live and

how we live.

Let us join together to protect our health, our

economy, and our communities -- so all of us and our

children and our grandchildren can enjoy a healthy

and a prosperous life.

Radon Measurements Mitigation

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