RMS Radon Science & Health Effects 2 — Questions and Answers
Question 1: Which decay product of radon-222 is responsible for the majority of lung dose during inhalation?
- Polonium-218 and Polonium-214 (Correct answer)
- Lead-210 and Bismuth-210
- Bismuth-214 and Lead-214
- Radon-220 (thoron)
Correct answer: Polonium-218 and Polonium-214
Po-218 and Po-214 are the short-lived alpha-emitting progeny that deposit most of the radiation dose to bronchial tissue.
Question 2: What is the relationship between radon concentration and lung cancer risk according to the linear no-threshold (LNT) model?
- Risk increases only above 4 pCi/L
- Risk increases proportionally with any exposure level (Correct answer)
- Risk plateaus above 10 pCi/L
- There is no risk below 2 pCi/L
Correct answer: Risk increases proportionally with any exposure level
The LNT model assumes any amount of radiation exposure carries some proportional risk, with no safe threshold.
Question 3: Radon is produced through the decay of which element that is naturally present in soil and rock?
- Uranium-238 (Correct answer)
- Thorium-232
- Potassium-40
- Cesium-137
Correct answer: Uranium-238
Uranium-238 decays through a chain that includes radium-226, which then decays to produce radon-222.
Question 4: The EPA classifies radon as a Group A carcinogen because it is:
- Suspected but not confirmed to cause cancer in humans
- Known to cause cancer in humans based on sufficient evidence (Correct answer)
- Possibly carcinogenic based only on animal studies
- Not classifiable due to insufficient data
Correct answer: Known to cause cancer in humans based on sufficient evidence
Group A carcinogens have sufficient human epidemiological evidence linking them to cancer, as established by miner studies.
Question 5: Which population subgroup faces the greatest relative risk from chronic radon exposure?
- Elderly adults over 70
- Non-smoking adults
- Children under 18
- Current cigarette smokers (Correct answer)
Correct answer: Current cigarette smokers
Smokers face a synergistic, multiplicative increase in lung cancer risk because radon and tobacco smoke act together to damage lung tissue.
Question 6: What term describes the equilibrium ratio between radon and its short-lived decay products in air?
- Attachment fraction
- Equilibrium factor (F) (Correct answer)
- Working level (WL)
- Activity median aerodynamic diameter
Correct answer: Equilibrium factor (F)
The equilibrium factor (F) ranges from 0 to 1, with 1.0 indicating complete secular equilibrium; indoor air typically has F ≈ 0.4.
Question 7: Radon gas enters the human body primarily through which mechanism?
- Skin absorption
- Ingestion of contaminated water
- Inhalation of air containing radon and its progeny (Correct answer)
- Direct gamma radiation from soil
Correct answer: Inhalation of air containing radon and its progeny
Radon and its short-lived alpha-emitting progeny are inhaled and deposit energy directly onto bronchial epithelial cells.
RMS Radon Science & Health Effects 2
Which decay product of radon-222 is responsible for the majority of lung dose during inhalation?