CIH Physical Agents: Noise and Radiation 4 — Questions and Answers
Question 1: Which radioactive decay process results in the emission of a helium-4 nucleus?
- Beta decay
- Gamma decay
- Alpha decay (Correct answer)
- Neutron activation
Correct answer: Alpha decay
Alpha decay emits an alpha particle, which consists of 2 protons and 2 neutrons — identical to a helium-4 nucleus.
Question 2: What is the occupational annual effective dose limit for radiation workers in the United States under NRC regulations (10 CFR 20)?
- 1 mSv (100 mrem)
- 5 mSv (500 mrem)
- 50 mSv (5 rem) (Correct answer)
- 100 mSv (10 rem)
Correct answer: 50 mSv (5 rem)
NRC regulations set the annual occupational whole-body effective dose limit at 50 mSv (5 rem) per year for radiation workers.
Question 3: In noise control engineering, which approach is generally considered the most effective and preferred by the hierarchy of controls?
- Administrative controls such as job rotation
- Personal protective equipment (earplugs)
- Substitution of quieter equipment (Correct answer)
- Posting warning signs in noisy areas
Correct answer: Substitution of quieter equipment
Substituting a noisy process or equipment with a quieter alternative eliminates the hazard at the source and is preferred over controls that merely reduce exposure.
Question 4: Radon-222 is a significant occupational hazard primarily in which of the following work environments?
- Offshore drilling platforms
- Underground mines and poorly ventilated basements (Correct answer)
- Semiconductor fabrication cleanrooms
- Hospital radiology departments
Correct answer: Underground mines and poorly ventilated basements
Radon-222, a naturally occurring radioactive gas, accumulates in underground mines and poorly ventilated enclosed spaces, posing a significant lung cancer risk.
Question 5: What does the Noise Reduction Rating (NRR) on a hearing protector label represent?
- The actual real-world attenuation achieved by most workers
- The laboratory-measured attenuation under ideal fitting conditions (Correct answer)
- The minimum attenuation guaranteed under all conditions
- The attenuation averaged across all tested workers in field conditions
Correct answer: The laboratory-measured attenuation under ideal fitting conditions
The NRR is determined under ideal laboratory conditions using trained subjects, so real-world attenuation is typically significantly lower.
Question 6: Whole-body vibration at low frequencies (1–80 Hz) is most commonly associated with which occupational health effect?
- Noise-induced hearing loss
- Low back pain and spinal degeneration (Correct answer)
- Peripheral neuropathy of the hands
- Cataracts
Correct answer: Low back pain and spinal degeneration
Whole-body vibration transmitted through vehicle seats and platforms resonates with spinal structures, causing low back pain and accelerated spinal degeneration.
Question 7: Which instrument is the standard tool for measuring workplace noise levels in compliance surveys?
- A sound level meter with A-weighting and slow response (Correct answer)
- A dosimeter worn by the worker
- An octave-band analyzer set to flat response
- A vibration meter with accelerometer
Correct answer: A sound level meter with A-weighting and slow response
OSHA compliance noise surveys use a sound level meter set to A-weighting (reflecting human hearing sensitivity) and slow response for area measurements.
CIH Physical Agents: Noise and Radiation 4
Which radioactive decay process results in the emission of a helium-4 nucleus?