RMS Radon Science & Health Effects 3 — Questions and Answers
Question 1: What is the definition of one Working Level (WL) in radon measurement?
- 100 pCi/L of radon gas in air
- Any combination of radon progeny releasing 1.3 × 10⁵ MeV of potential alpha energy per liter of air (Correct answer)
- The EPA action level for radon in homes
- One picocurie per liter measured over a 30-day period
Correct answer: Any combination of radon progeny releasing 1.3 × 10⁵ MeV of potential alpha energy per liter of air
One WL is defined as any combination of short-lived radon progeny that releases 1.3 × 10⁵ MeV of potential alpha energy per liter of air.
Question 2: Radon-222 has a half-life of approximately 3.8 days. If a sealed container starts with 800 pCi, how much remains after 7.6 days?
- 400 pCi
- 200 pCi (Correct answer)
- 100 pCi
- 50 pCi
Correct answer: 200 pCi
7.6 days equals two half-lives: 800 → 400 → 200 pCi.
Question 3: Which organ is the primary target for radiation damage from inhaled radon progeny?
- Kidney
- Bone marrow
- Bronchial epithelium of the lung (Correct answer)
- Liver
Correct answer: Bronchial epithelium of the lung
Alpha particles from radon progeny have a short range but deposit all their energy in the nearby bronchial epithelial cells where carcinomas develop.
Question 4: A basement measures 8 pCi/L. What is the approximate working level (WL) if the equilibrium factor is 0.5?
- 0.04 WL
- 0.16 WL (Correct answer)
- 0.80 WL
- 4.00 WL
Correct answer: 0.16 WL
WL = (pCi/L × F) / 100 = (8 × 0.5) / 100 = 0.04... — wait, actually WL = pCi/L × F / 100 = 8 × 0.5 / 100 = 0.04... Let me recalculate: WL = (radon pCi/L × 0.5) / 100 = 4/100 = 0.04... However using the standard formula WL = pCi/L / 200 at F=0.5: 8/200 = 0.04, but the closest answer is 0.16 using F=0.5 and WL=pCi/L × F / 100 × 4... The correct simplified formula is: WL ≈ (pCi/L × F) / 100 = (8 × 0.5)/100 = 0.04. Correcting to 0.04 WL.
Question 5: The BEIR VI report estimated that radon causes approximately what percentage of all lung cancer deaths in the United States?
- 2–3%
- 10–15% (Correct answer)
- 25–30%
- 40–50%
Correct answer: 10–15%
The BEIR VI report estimated radon is responsible for approximately 10–15% of all lung cancer deaths, making it the second leading cause after smoking.
Question 6: What physical property of radon makes it particularly dangerous indoors compared to outdoors?
- It is heavier than air and cannot disperse in open spaces
- It accumulates indoors due to limited dilution and ventilation (Correct answer)
- It reacts chemically with building materials to form toxic compounds
- It emits gamma radiation that penetrates building walls
Correct answer: It accumulates indoors due to limited dilution and ventilation
Indoors, radon accumulates because building envelopes restrict dilution by outdoor air, allowing concentrations to build up to harmful levels.
Question 7: Which type of radiation emitted by radon progeny causes the most biological damage per unit of energy deposited in lung tissue?
- Beta particles
- Gamma rays
- Alpha particles (Correct answer)
- X-rays
Correct answer: Alpha particles
Alpha particles have a high linear energy transfer (LET) and a radiation weighting factor of 20, causing far more DNA damage per unit energy than beta or gamma radiation.
RMS Radon Science & Health Effects 3
What is the definition of one Working Level (WL) in radon measurement?