Radon Measurement Professional Exam
Practice Questions And Correct Answers
(Verified Answers) Plus Rationale 2026
Q&A| Instant Download Pdf
1. A radon measurement professional is conducting a long-term test in an
occupied residence. Which testing duration best meets the standard
definition of a long-term radon measurement?
A. Less than 2 days
B. 2–7 days
C. 8–30 days
D. More than 90 days
Rationale: Long-term radon measurements are generally conducted for
more than 90 days to account for seasonal and daily fluctuations, providing
a more representative estimate of the annual average radon
concentration.
2. Which radioactive isotope is the primary source of indoor radon in
most residential buildings?
A. Thorium-232
B. Uranium-235
C. Uranium-238
D. Potassium-40
,Rationale: Radon-222 originates from the radioactive decay series of
Uranium-238, which is naturally present in soil and rock beneath buildings.
3. Radon-222 has an approximate half-life of:
A. 3.8 hours
B. 3.8 days
C. 38 days
D. 38 years
Rationale: Radon-222 has a half-life of approximately 3.82 days, allowing
it to migrate through soil into buildings before decaying.
4. Which decay product of radon contributes most directly to lung cancer
risk?
A. Radium-226
B. Uranium-238
C. Polonium-218 and Polonium-214
D. Thorium-230
Rationale: Radioactive decay products such as Polonium-218 and
Polonium-214 attach to airborne particles that can be inhaled and
deposited in lung tissue, delivering alpha radiation.
5. The primary health risk associated with prolonged radon exposure is:
A. Skin cancer
B. Liver disease
C. Leukemia
D. Lung cancer
Rationale: Radon exposure is the second leading cause of lung cancer
overall and the leading cause among nonsmokers.
6. Alpha particles emitted during radon decay are best described as:
, A. Highly penetrating electromagnetic radiation
B. Fast-moving electrons
C. Helium nuclei with low penetration but high ionizing ability
D. High-energy neutrons
Rationale: Alpha particles consist of two protons and two neutrons,
producing intense ionization over a very short distance.
7. The EPA action level for indoor radon is:
A. 2.0 pCi/L
B. 3.0 pCi/L
C. 4.0 pCi/L
D. 10.0 pCi/L
Rationale: The EPA recommends that corrective action be taken when
indoor radon concentrations reach or exceed 4.0 pCi/L.
8. One picocurie (pCi) represents:
A. One radioactive atom
B. 0.037 radioactive disintegrations per second
C. One disintegration per second
D. One million disintegrations per second
Rationale: A picocurie equals 0.037 becquerels, corresponding to
approximately 0.037 radioactive disintegrations per second.
9. The SI unit for radioactivity is:
A. Gray
B. Sievert
C. Roentgen
D. Becquerel
Practice Questions And Correct Answers
(Verified Answers) Plus Rationale 2026
Q&A| Instant Download Pdf
1. A radon measurement professional is conducting a long-term test in an
occupied residence. Which testing duration best meets the standard
definition of a long-term radon measurement?
A. Less than 2 days
B. 2–7 days
C. 8–30 days
D. More than 90 days
Rationale: Long-term radon measurements are generally conducted for
more than 90 days to account for seasonal and daily fluctuations, providing
a more representative estimate of the annual average radon
concentration.
2. Which radioactive isotope is the primary source of indoor radon in
most residential buildings?
A. Thorium-232
B. Uranium-235
C. Uranium-238
D. Potassium-40
,Rationale: Radon-222 originates from the radioactive decay series of
Uranium-238, which is naturally present in soil and rock beneath buildings.
3. Radon-222 has an approximate half-life of:
A. 3.8 hours
B. 3.8 days
C. 38 days
D. 38 years
Rationale: Radon-222 has a half-life of approximately 3.82 days, allowing
it to migrate through soil into buildings before decaying.
4. Which decay product of radon contributes most directly to lung cancer
risk?
A. Radium-226
B. Uranium-238
C. Polonium-218 and Polonium-214
D. Thorium-230
Rationale: Radioactive decay products such as Polonium-218 and
Polonium-214 attach to airborne particles that can be inhaled and
deposited in lung tissue, delivering alpha radiation.
5. The primary health risk associated with prolonged radon exposure is:
A. Skin cancer
B. Liver disease
C. Leukemia
D. Lung cancer
Rationale: Radon exposure is the second leading cause of lung cancer
overall and the leading cause among nonsmokers.
6. Alpha particles emitted during radon decay are best described as:
, A. Highly penetrating electromagnetic radiation
B. Fast-moving electrons
C. Helium nuclei with low penetration but high ionizing ability
D. High-energy neutrons
Rationale: Alpha particles consist of two protons and two neutrons,
producing intense ionization over a very short distance.
7. The EPA action level for indoor radon is:
A. 2.0 pCi/L
B. 3.0 pCi/L
C. 4.0 pCi/L
D. 10.0 pCi/L
Rationale: The EPA recommends that corrective action be taken when
indoor radon concentrations reach or exceed 4.0 pCi/L.
8. One picocurie (pCi) represents:
A. One radioactive atom
B. 0.037 radioactive disintegrations per second
C. One disintegration per second
D. One million disintegrations per second
Rationale: A picocurie equals 0.037 becquerels, corresponding to
approximately 0.037 radioactive disintegrations per second.
9. The SI unit for radioactivity is:
A. Gray
B. Sievert
C. Roentgen
D. Becquerel
