0. Measuring Radon in Residential Properties
What devices do we use to
measure radon?
Lesson 5
What devices do we use to measure radon?
Connecticut Radon Measurement
Training Program

1. How long will the test last?
Short-term test
2 to 90 days
Long-term test
91 to 365 days
Advantage
Provides quick answer
Disadvantage
Does not account for radon variations from day to day or season to season
Used for most real estate transactions
Advantage
Provides more information about year-round average radon level
Disadvantages
Takes longer to get results
Residents forget test is running

2. Sampling methods for radon and radon decay products
Time-integrated sampling
Average concentration over a period of time
Period may range from a few days (for most home inspections) to a year or more
Continuous sampling
Automatic sampling over set intervals of time
3. Grab sampling
Quick snapshot at a moment in time
Cannot be used in home inspections
Advantages
Can collect several samples in one day
Can observe conditions while sampling
Disadvantages
Not certain how well it correlates with long-term integrated measurement
Requires additional training and expensive equipment

3. Grab sample
Would you use a grab sample to determine whether a home needs radon mitigation?
Why or why not?
No, because
It provides only a snapshot or radon at brief moment in time
We don’t know how well it correlates with longer-term measurements
Decision about mitigation should be based on averages over longer periods of time
EPA does not recommend use of grab samples for pre-mitigation or post-mitigation testing or for follow-up measurements

4. Questions?
About sampling methods

5. Standards for devices
All devices must meet the requirements of the
National Environmental Health Association (NEHA)
or the
National Radon Safety Board (NRSB)
Read and follow the directions of the manufacturer of the device you use

6. Types of devices Passive devices
Do not require power (electricity or batteries) to operate
Less expensive
Used in most real estate transactions
Active devices
Require power to operate
More expensive
Require calibration

7. Types of passive devices
Activated charcoal adsorption
Charcoal liquid scintillation
Electret ion chamber (electrostatic radon monitor)
Alpha track detector

8. Passive devices Activated charcoal adsorption
Use for short-term tests
Airtight canister that contains granular activated carbon is opened
Radon from surrounding air enters canister and is adsorbed (held on its surface) by charcoal
At end of test period, canister is sealed and sent to approved lab for analysis
Two types
Open face
Diffusion barrier
(filter over face)

9. Passive devices Activated charcoal adsorption
Measuring Radon in Residential Properties
What devices do we use to
measure radon?
Passive devices Activated charcoal adsorption
Advantages
Requires no external power
Inexpensive
Easy to place
Simple to use
Easy to mail to lab
Measures over short time periods
Disadvantages
Biased toward end of sampling period
Works best for short sampling periods
May be affected by sampling conditions (temperature, humidity, and drafts)
Sampling conditions during test period may be unknown
Must be analyzed by approved lab soon after test period
Difficult to know if device has been tampered with
Connecticut Radon Measurement
Training Program

10. Passive devices: Charcoal liquid scintillation
Use for short-term tests
Small vial containing activated charcoal is opened
Radon from surrounding air enters vial and is adsorbed by charcoal
At end of test period, vial is sealed and sent to approved lab for analysis

11. Passive devices Charcoal liquid scintillation
Advantages
Same as for activated charcoal adsorption canister
Disadvantages
Same as for activated charcoal adsorption canister
Especially: device must be analyzed by approved lab soon after test period

12. Passive devices Electret ion chamber
Most common: electret-passive environmental radon monitor (E-PERM)
Use for short-term and long-term tests

13. Passive devices Electret ion chamber
Electrostatically charged disk (electret) is placed in small chamber
Radon diffuses into chamber and emits alpha particles during decay
Alpha particles ionize the air molecules
Ions move to charged surface of electret, thus reducing its initial charge
Voltage meter measures initial and final voltages
Rate of change of charge is proportional to concentration of radon in air

14. Passive devices Electret ion chamber
Advantages
Requires no external power
Provides true time-integrated measurements
Each electret may be reused many times
Can provide immediate results
Disadvantages
Requires additional training to use
Must measure and correct for background gamma radiation
May be affected by high humidity and dust
Temperature differences between initial and the final voltage readings may cause errors
Does not provide evidence of tampering

15. Passive devices Alpha track detector
Use for long-term tests only
Contains piece of film or plastic that records impacts (tracks) of alpha particles produced by decay of radon and its decay products
At end of test period, detector is returned to approved lab
Lab counts alpha tracks on film and computes radon concentration

16. Passive devices Alpha track detector
Advantages
Requires no external power
Inexpensive
Simple to use
Easy to mail
Provides true time-integrated measurements
Not biased toward most recent exposure
Can measure over long periods ( days)
Disadvantages
Cannot measure for short time periods
May not provide precise measurement when concentrations are low
May be affected by sampling conditions
Sampling conditions during test period may be unknown

17. Questions?
About passive measurement devices

18. Activity Handout 5-1A Type of device Length of test Advantages
Disadvantages
Activated charcoal adsorption
Charcoal liquid scintillation
Electret ion chamber
Alpha track detector

19. Active devices Electronic devices
Require power (batteries or electricity) to operate
Measure and record amount of radon or its decay products in air at regular intervals
At least once an hour
Results are average of these readings
Can show changes in radon levels during test period

20. Active devices Use for short-term tests
Continuous
radon monitor
Continuous
working level
monitor
Use for short-term tests
Air either diffuses or is pumped into a counting chamber

21. Active devices Continuous radon monitors
Advantages
Provide results on-site
Can track real-time variations in radon concentrations
Can measure various time intervals
Some models record temperature, humidity, barometric pressure, movement, and other environmental factors
Can indicate tampering
Disadvantages
Require power to operate
More expensive
Must be calibrated regularly
Require additional training to operate
Some are sensitive to humidity
Some are heavy and bulky

22. Questions?
About active radon measurement devices

23. Summary Length of tests
Short-term test
How many days?
2-90
Advantage?
Provides a quick answer about radon levels
Disadvantage?
Does not account for radon variations from day to day or season to season
Long-term test
How many days?
91-365
Advantage?
Gives more information about year-round average radon levels
Disadvantage?
Takes longer to get results

24. Summary Sampling methods
Time-integrated sampling
Continuous sampling
Grab sampling
Which methods should home inspectors use?
Time-integrated and continuous sampling

25. Summary Types of devices
Passive
Activated charcoal adsorption
Charcoal liquid scintillation
Electret ion chamber (electrostatic radon monitor)
Alpha track detector
Active
Continuous radon monitors
Continuous working level monitors

26. Questions?

27. Check your understanding
See handout 5-2