Certified Radon Measurement
Technician Exam Practice Test Questions
And Correct Answers (Verified Answers)
Plus Rationales 2026 Q&A Instant
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1. What is the primary source of radon gas in buildings?
A. Construction materials
B. Outdoor air
C. Soil and rock beneath buildings
D. Household appliances
Answer: C. Soil and rock beneath buildings
Rationale: Radon originates from the natural radioactive decay of uranium in
soil and rock and enters buildings through foundation cracks and openings.
2. What type of radiation is radon?
A. Alpha
B. Beta
C. Gamma
D. X-ray
,Answer: A. Alpha
Rationale: Radon emits alpha particles during radioactive decay, which are
hazardous when inhaled.
3. The half-life of radon-222 is approximately:
A. 2 hours
B. 2 days
C. 3.8 days
D. 10 years
Answer: C. 3.8 days
Rationale: Radon-222 has a half-life of 3.8 days, allowing it to travel from soil
into buildings before decaying.
4. Which device is commonly used for short-term radon testing?
A. Geiger counter
B. Charcoal canister
C. Infrared sensor
D. Smoke detector
Answer: B. Charcoal canister
Rationale: Charcoal adsorption devices are commonly used for short-term radon
measurement.
5. What is the EPA action level for radon in indoor air?
A. 1.0 pCi/L
B. 2.0 pCi/L
C. 4.0 pCi/L
D. 10.0 pCi/L
Answer: C. 4.0 pCi/L
Rationale: The EPA recommends mitigation at or above 4.0 pCi/L.
, 6. Radon entry into buildings is most influenced by:
A. Roof ventilation
B. Atmospheric pressure differences
C. Electrical wiring
D. Lighting systems
Answer: B. Atmospheric pressure differences
Rationale: Lower indoor pressure draws radon gas from the soil into buildings.
7. Which condition increases radon levels indoors?
A. Open windows
B. High ventilation
C. Negative pressure in building
D. Air conditioning use only
Answer: C. Negative pressure in building
Rationale: Negative pressure increases soil gas infiltration including radon.
8. What is the most accurate radon test method?
A. Short-term test
B. Long-term test
C. Passive charcoal test
D. DIY test kits only
Answer: B. Long-term test
Rationale: Long-term tests provide more accurate annual average radon
concentrations.
9. Which unit is used to measure radon concentration?
A. Becquerel per liter
Technician Exam Practice Test Questions
And Correct Answers (Verified Answers)
Plus Rationales 2026 Q&A Instant
Download Pdf
1. What is the primary source of radon gas in buildings?
A. Construction materials
B. Outdoor air
C. Soil and rock beneath buildings
D. Household appliances
Answer: C. Soil and rock beneath buildings
Rationale: Radon originates from the natural radioactive decay of uranium in
soil and rock and enters buildings through foundation cracks and openings.
2. What type of radiation is radon?
A. Alpha
B. Beta
C. Gamma
D. X-ray
,Answer: A. Alpha
Rationale: Radon emits alpha particles during radioactive decay, which are
hazardous when inhaled.
3. The half-life of radon-222 is approximately:
A. 2 hours
B. 2 days
C. 3.8 days
D. 10 years
Answer: C. 3.8 days
Rationale: Radon-222 has a half-life of 3.8 days, allowing it to travel from soil
into buildings before decaying.
4. Which device is commonly used for short-term radon testing?
A. Geiger counter
B. Charcoal canister
C. Infrared sensor
D. Smoke detector
Answer: B. Charcoal canister
Rationale: Charcoal adsorption devices are commonly used for short-term radon
measurement.
5. What is the EPA action level for radon in indoor air?
A. 1.0 pCi/L
B. 2.0 pCi/L
C. 4.0 pCi/L
D. 10.0 pCi/L
Answer: C. 4.0 pCi/L
Rationale: The EPA recommends mitigation at or above 4.0 pCi/L.
, 6. Radon entry into buildings is most influenced by:
A. Roof ventilation
B. Atmospheric pressure differences
C. Electrical wiring
D. Lighting systems
Answer: B. Atmospheric pressure differences
Rationale: Lower indoor pressure draws radon gas from the soil into buildings.
7. Which condition increases radon levels indoors?
A. Open windows
B. High ventilation
C. Negative pressure in building
D. Air conditioning use only
Answer: C. Negative pressure in building
Rationale: Negative pressure increases soil gas infiltration including radon.
8. What is the most accurate radon test method?
A. Short-term test
B. Long-term test
C. Passive charcoal test
D. DIY test kits only
Answer: B. Long-term test
Rationale: Long-term tests provide more accurate annual average radon
concentrations.
9. Which unit is used to measure radon concentration?
A. Becquerel per liter
