Certified Radon Measurement Technician
Exam Practice Questions And Correct
Answers (Verified Answers) Plus Rationales
2026 Q&A | Instant Download Pdf
1. What is the primary radioactive gas measured in radon testing?
A. Thoron
B. Uranium
C. Radon
D. Radium
Answer: Radon
Rationale: Radon is a naturally occurring radioactive gas produced from the
decay of uranium in soil, rock, and water. Thoron and radium are related but
not the primary gas measured in indoor air testing.
2. Which unit is commonly used to express radon concentration in air in
the U.S.?
, A. Becquerels per liter (Bq/L)
B. Picocuries per liter (pCi/L)
C. Both A and B
D. Sieverts
Answer: Both A and B
Rationale: Radon can be expressed in pCi/L in the U.S. and Bq/L in SI units. 1
pCi/L = 37 Bq/m³ approximately.
3. What is the EPA’s recommended action level for radon in homes?
A. 2 pCi/L
B. 3 pCi/L
C. 4 pCi/L
D. 5 pCi/L
Answer: 4 pCi/L
Rationale: The EPA recommends taking action to reduce radon levels in
homes when readings reach 4 pCi/L or higher.
4. Which type of radon test device is used for short-term testing (2-7
days)?
A. Alpha-track detector
B. Electret ion chamber
, C. Charcoal canister
D. Continuous radon monitor
Answer: Charcoal canister
Rationale: Charcoal canisters are inexpensive, short-term devices used for
quick radon measurements. Alpha-track detectors are long-term, while
continuous monitors are more expensive and precise.
5. Long-term radon testing is recommended for which duration?
A. 1-3 days
B. 7-14 days
C. 90 days to 1 year
D. 24 hours
Answer: 90 days to 1 year
Rationale: Long-term tests average out daily and seasonal fluctuations,
providing a more accurate annual exposure estimate.
6. Which factor most affects indoor radon levels?
A. Outdoor temperature
B. Air pressure differences between indoors and outdoors
C. Humidity
D. Room color
, Answer: Air pressure differences between indoors and outdoors
Rationale: Lower indoor pressure draws radon from the soil into buildings,
making pressure differences a key determinant of radon concentration.
7. What type of radon measurement is generally considered the most
accurate for determining average annual exposure?
A. Short-term charcoal test
B. Grab sample
C. Long-term alpha-track detector
D. Continuous monitor over 1 day
Answer: Long-term alpha-track detector
Rationale: Long-term detectors average out fluctuations, giving the most
reliable estimate of annual radon exposure.
8. Which factor should be minimized to ensure accurate short-term
radon testing?
A. Ventilation changes during the test
B. Wall color
C. Furniture placement
D. Flooring type
Exam Practice Questions And Correct
Answers (Verified Answers) Plus Rationales
2026 Q&A | Instant Download Pdf
1. What is the primary radioactive gas measured in radon testing?
A. Thoron
B. Uranium
C. Radon
D. Radium
Answer: Radon
Rationale: Radon is a naturally occurring radioactive gas produced from the
decay of uranium in soil, rock, and water. Thoron and radium are related but
not the primary gas measured in indoor air testing.
2. Which unit is commonly used to express radon concentration in air in
the U.S.?
, A. Becquerels per liter (Bq/L)
B. Picocuries per liter (pCi/L)
C. Both A and B
D. Sieverts
Answer: Both A and B
Rationale: Radon can be expressed in pCi/L in the U.S. and Bq/L in SI units. 1
pCi/L = 37 Bq/m³ approximately.
3. What is the EPA’s recommended action level for radon in homes?
A. 2 pCi/L
B. 3 pCi/L
C. 4 pCi/L
D. 5 pCi/L
Answer: 4 pCi/L
Rationale: The EPA recommends taking action to reduce radon levels in
homes when readings reach 4 pCi/L or higher.
4. Which type of radon test device is used for short-term testing (2-7
days)?
A. Alpha-track detector
B. Electret ion chamber
, C. Charcoal canister
D. Continuous radon monitor
Answer: Charcoal canister
Rationale: Charcoal canisters are inexpensive, short-term devices used for
quick radon measurements. Alpha-track detectors are long-term, while
continuous monitors are more expensive and precise.
5. Long-term radon testing is recommended for which duration?
A. 1-3 days
B. 7-14 days
C. 90 days to 1 year
D. 24 hours
Answer: 90 days to 1 year
Rationale: Long-term tests average out daily and seasonal fluctuations,
providing a more accurate annual exposure estimate.
6. Which factor most affects indoor radon levels?
A. Outdoor temperature
B. Air pressure differences between indoors and outdoors
C. Humidity
D. Room color
, Answer: Air pressure differences between indoors and outdoors
Rationale: Lower indoor pressure draws radon from the soil into buildings,
making pressure differences a key determinant of radon concentration.
7. What type of radon measurement is generally considered the most
accurate for determining average annual exposure?
A. Short-term charcoal test
B. Grab sample
C. Long-term alpha-track detector
D. Continuous monitor over 1 day
Answer: Long-term alpha-track detector
Rationale: Long-term detectors average out fluctuations, giving the most
reliable estimate of annual radon exposure.
8. Which factor should be minimized to ensure accurate short-term
radon testing?
A. Ventilation changes during the test
B. Wall color
C. Furniture placement
D. Flooring type
