RMS Radon Measurement Techniques 3 — Questions and Answers
Question 1: Which radon measurement unit is used in the United States to express radon concentration in air?
- Becquerel per cubic meter (Bq/m³)
- Picocuries per liter (pCi/L) (Correct answer)
- Millisieverts per year (mSv/yr)
- Parts per million (ppm)
Correct answer: Picocuries per liter (pCi/L)
The United States uses picocuries per liter (pCi/L) as the standard unit for airborne radon concentration, while most other countries use Bq/m³.
Question 2: A charcoal canister radon test must be analyzed within how many days of retrieval to ensure valid results?
- 3 days
- 7 days (Correct answer)
- 14 days
- 30 days
Correct answer: 7 days
Charcoal canisters must be analyzed within 7 days of retrieval because adsorbed radon continues to decay and the charcoal's collection capacity diminishes over time.
Question 3: What does the term 'working level' (WL) measure in the context of radon?
- The radon concentration in soil at the foundation
- The concentration of radon progeny (decay products) in air (Correct answer)
- The mitigation system's sub-slab pressure differential
- The annual effective dose to building occupants
Correct answer: The concentration of radon progeny (decay products) in air
A working level (WL) is a unit measuring the concentration of short-lived radon progeny in air, defined as any combination releasing 1.3×10⁵ MeV of alpha energy per liter.
Question 4: Under EPA measurement protocols, which room is NOT an acceptable location for placing a radon test device?
- Finished basement bedroom
- First-floor home office
- Basement laundry room (Correct answer)
- Ground-level den
Correct answer: Basement laundry room
Bathrooms, laundry rooms, kitchens, and other rooms with high humidity or mechanical ventilation are not acceptable test locations under EPA protocol.
Question 5: A continuous radon monitor (CRM) must meet which data-reporting interval requirement under AARST/ANSI protocols?
- Report radon concentration at least every 4 hours
- Report radon concentration at least every 1 hour (Correct answer)
- Report a single integrated value for the test period
- Report readings only when concentrations exceed 4 pCi/L
Correct answer: Report radon concentration at least every 1 hour
AARST/ANSI protocols require CRMs to record and report radon concentrations at least every hour to detect anomalous fluctuations and tampering.
Question 6: When is it appropriate to average the results of two simultaneously deployed short-term radon tests?
- Always, to improve measurement precision
- When both devices are placed in the same room (Correct answer)
- When both devices are placed in different rooms on the same level
- When one device fails and a second was deployed as backup
Correct answer: When both devices are placed in the same room
Two devices deployed simultaneously in the same room can be averaged to improve precision, but devices in different rooms measure different radon concentrations and should not be averaged.
Question 7: What is the EPA action level for radon in homes in the United States?
- 2 pCi/L
- 4 pCi/L (Correct answer)
- 8 pCi/L
- 10 pCi/L
Correct answer: 4 pCi/L
The EPA recommends mitigation when radon levels reach or exceed 4 pCi/L, and considers action between 2–4 pCi/L, while the WHO recommends 2.7 pCi/L (100 Bq/m³).
RMS Radon Measurement Techniques 3
Which radon measurement unit is used in the United States to express radon concentration in air?