Certified Radon Measurement Technician
Exam Questions And Correct Answers
(Verified Answers) Plus Rationales 2026
Q&A | Instant Download Pdf
QUESTIONS 1–25: RADON SCIENCE, HEALTH EFFECTS, AND FUNDAMENTALS
Question 1
What is radon?
A. A combustible hydrocarbon gas
B. A radioactive noble gas
C. A manufactured refrigerant
D. A common atmospheric pollutant produced by vehicles
Answer: B. A radioactive noble gas
Rationale: Radon is a naturally occurring radioactive noble gas. It is colorless,
odorless, and tasteless, so it cannot be detected by human senses. Radon is
produced naturally through the radioactive decay of uranium and radium in soil,
rock, and water.
Question 2
What is the primary source of indoor radon in most buildings?
A. Household cleaning products
B. Combustion appliances
C. Soil and rock beneath or surrounding the building
D. Carbon dioxide produced by occupants
,Answer: C. Soil and rock beneath or surrounding the building
Rationale: The principal source of indoor radon is uranium-bearing soil and rock
beneath and around a structure. Radon generated in the ground can enter
buildings through cracks, joints, gaps, drains, sump openings, and other pathways.
Question 3
Which property makes radon particularly difficult for occupants to recognize
without testing?
A. It has a strong odor
B. It produces visible smoke
C. It is highly colored
D. It is colorless, odorless, and tasteless
Answer: D. It is colorless, odorless, and tasteless
Rationale: Radon cannot be detected by sight, smell, or taste. Reliable
measurement therefore requires an appropriate radon detection or measurement
device operated according to an established protocol.
Question 4
Radon is formed primarily as part of which radioactive decay series?
A. Hydrogen series
B. Uranium-238 decay series
C. Carbon-14 decay series
D. Oxygen-16 decay series
Answer: B. Uranium-238 decay series
Rationale: Radon-222 is generated in the uranium-238 decay chain through the
decay of radium-226. Because uranium and radium occur naturally in geological
materials, radon can be generated continuously in soil and rock.
,Question 5
What is the approximate half-life of radon-222?
A. 3.8 days
B. 38 days
C. 3.8 hours
D. 380 years
Answer: A. 3.8 days
Rationale: Radon-222 has a half-life of approximately 3.8 days. This means that, in
a closed system, approximately half of the radon-222 atoms present will decay
during each 3.8-day period.
Question 6
Why are radon decay products important from a health perspective?
A. They increase oxygen concentration indoors
B. They can attach to airborne particles and be inhaled
C. They neutralize radioactive materials
D. They prevent radon from entering buildings
Answer: B. They can attach to airborne particles and be inhaled
Rationale: Radon decay products, also called radon progeny, can attach to airborne
particles. When inhaled, some progeny can deposit in the respiratory tract, where
their radioactive decay can damage lung tissue.
Question 7
What is the principal health effect associated with long-term exposure to elevated
indoor radon?
, A. Lung cancer
B. Skin cancer from ultraviolet radiation
C. Hearing loss
D. Bone fractures
Answer: A. Lung cancer
Rationale: Radon exposure is an established cause of lung cancer. Risk is associated
with cumulative exposure and is especially important when radon exposure occurs
together with cigarette smoking or other tobacco exposure.
Question 8
Which statement best describes the relationship between smoking and radon
exposure?
A. Smoking eliminates radon risk
B. Smoking and radon exposure can combine to increase lung cancer risk
C. Smoking converts radon into oxygen
D. Smoking makes radon detectors inaccurate in every situation
Answer: B. Smoking and radon exposure can combine to increase lung cancer risk
Rationale: Tobacco smoke and radon are both important lung cancer risk factors.
Their combined effect can be substantially greater than either exposure alone,
making radon testing particularly important in homes occupied by smokers.
Question 9
Which unit is commonly used in the United States to express indoor radon
concentration?
A. Parts per million only
B. Picocuries per liter
C. Grams per cubic meter
D. Liters per minute
Exam Questions And Correct Answers
(Verified Answers) Plus Rationales 2026
Q&A | Instant Download Pdf
QUESTIONS 1–25: RADON SCIENCE, HEALTH EFFECTS, AND FUNDAMENTALS
Question 1
What is radon?
A. A combustible hydrocarbon gas
B. A radioactive noble gas
C. A manufactured refrigerant
D. A common atmospheric pollutant produced by vehicles
Answer: B. A radioactive noble gas
Rationale: Radon is a naturally occurring radioactive noble gas. It is colorless,
odorless, and tasteless, so it cannot be detected by human senses. Radon is
produced naturally through the radioactive decay of uranium and radium in soil,
rock, and water.
Question 2
What is the primary source of indoor radon in most buildings?
A. Household cleaning products
B. Combustion appliances
C. Soil and rock beneath or surrounding the building
D. Carbon dioxide produced by occupants
,Answer: C. Soil and rock beneath or surrounding the building
Rationale: The principal source of indoor radon is uranium-bearing soil and rock
beneath and around a structure. Radon generated in the ground can enter
buildings through cracks, joints, gaps, drains, sump openings, and other pathways.
Question 3
Which property makes radon particularly difficult for occupants to recognize
without testing?
A. It has a strong odor
B. It produces visible smoke
C. It is highly colored
D. It is colorless, odorless, and tasteless
Answer: D. It is colorless, odorless, and tasteless
Rationale: Radon cannot be detected by sight, smell, or taste. Reliable
measurement therefore requires an appropriate radon detection or measurement
device operated according to an established protocol.
Question 4
Radon is formed primarily as part of which radioactive decay series?
A. Hydrogen series
B. Uranium-238 decay series
C. Carbon-14 decay series
D. Oxygen-16 decay series
Answer: B. Uranium-238 decay series
Rationale: Radon-222 is generated in the uranium-238 decay chain through the
decay of radium-226. Because uranium and radium occur naturally in geological
materials, radon can be generated continuously in soil and rock.
,Question 5
What is the approximate half-life of radon-222?
A. 3.8 days
B. 38 days
C. 3.8 hours
D. 380 years
Answer: A. 3.8 days
Rationale: Radon-222 has a half-life of approximately 3.8 days. This means that, in
a closed system, approximately half of the radon-222 atoms present will decay
during each 3.8-day period.
Question 6
Why are radon decay products important from a health perspective?
A. They increase oxygen concentration indoors
B. They can attach to airborne particles and be inhaled
C. They neutralize radioactive materials
D. They prevent radon from entering buildings
Answer: B. They can attach to airborne particles and be inhaled
Rationale: Radon decay products, also called radon progeny, can attach to airborne
particles. When inhaled, some progeny can deposit in the respiratory tract, where
their radioactive decay can damage lung tissue.
Question 7
What is the principal health effect associated with long-term exposure to elevated
indoor radon?
, A. Lung cancer
B. Skin cancer from ultraviolet radiation
C. Hearing loss
D. Bone fractures
Answer: A. Lung cancer
Rationale: Radon exposure is an established cause of lung cancer. Risk is associated
with cumulative exposure and is especially important when radon exposure occurs
together with cigarette smoking or other tobacco exposure.
Question 8
Which statement best describes the relationship between smoking and radon
exposure?
A. Smoking eliminates radon risk
B. Smoking and radon exposure can combine to increase lung cancer risk
C. Smoking converts radon into oxygen
D. Smoking makes radon detectors inaccurate in every situation
Answer: B. Smoking and radon exposure can combine to increase lung cancer risk
Rationale: Tobacco smoke and radon are both important lung cancer risk factors.
Their combined effect can be substantially greater than either exposure alone,
making radon testing particularly important in homes occupied by smokers.
Question 9
Which unit is commonly used in the United States to express indoor radon
concentration?
A. Parts per million only
B. Picocuries per liter
C. Grams per cubic meter
D. Liters per minute
