CIH Physical Agents: Noise and Radiation 5 — Questions and Answers
Question 1: Hand-arm vibration syndrome (HAVS) is a condition primarily caused by:
- Prolonged exposure to whole-body vibration from vehicles
- Regular use of vibrating hand tools such as grinders and jackhammers (Correct answer)
- High-frequency noise exposure above 4000 Hz
- Repetitive impact trauma without vibration
Correct answer: Regular use of vibrating hand tools such as grinders and jackhammers
HAVS results from chronic use of vibrating hand tools, causing vascular, neurological, and musculoskeletal damage to the hands and arms.
Question 2: Which of the following correctly describes the ALARA principle as it applies to ionizing radiation protection?
- Exposures must be kept at exactly the regulatory dose limit
- Exposures must be as low as reasonably achievable, economic and social factors considered (Correct answer)
- All radiation work must cease when dose approaches 50% of the annual limit
- Workers must always wear the maximum available shielding regardless of cost
Correct answer: Exposures must be as low as reasonably achievable, economic and social factors considered
ALARA (As Low As Reasonably Achievable) requires reducing radiation exposures below regulatory limits while considering economic and social factors.
Question 3: What is the primary difference between ionizing and non-ionizing radiation?
- Ionizing radiation only travels in straight lines; non-ionizing does not
- Ionizing radiation has sufficient energy to remove electrons from atoms; non-ionizing does not (Correct answer)
- Non-ionizing radiation penetrates tissue more deeply than ionizing radiation
- Ionizing radiation only includes visible light and UV
Correct answer: Ionizing radiation has sufficient energy to remove electrons from atoms; non-ionizing does not
Ionizing radiation carries enough energy to eject electrons from atoms, creating ions that can damage DNA and biological molecules.
Question 4: A worker is exposed to radiofrequency (RF) radiation from a radar antenna. What is the primary concern at high RF exposure levels?
- Ionization of cellular DNA
- Thermal heating of body tissues (Correct answer)
- Permanent hearing threshold shifts
- Induction of radioactivity in body tissues
Correct answer: Thermal heating of body tissues
High-level RF radiation exposure primarily causes tissue heating (dielectric and resistive heating), which can damage eyes and testes that have limited blood-cooling capacity.
Question 5: When calculating a time-weighted average (TWA) noise exposure, an IH uses a sound level meter to take area readings at 88, 92, and 96 dBA. Which tool is more appropriate for determining personal TWA?
- Dosimeter worn by the worker throughout the shift (Correct answer)
- Sound level meter readings logged manually every hour
- Octave-band analyzer positioned near machinery
- Integrating sound level meter placed at a fixed workstation
Correct answer: Dosimeter worn by the worker throughout the shift
A personal noise dosimeter worn by the worker captures actual exposure including all worker movement and activities, providing the most accurate personal TWA.
Question 6: Laser radiation hazards are classified primarily based on:
- Wavelength only
- Output power or energy and the potential to cause biological damage (Correct answer)
- Beam diameter at the aperture
- Pulse duration exclusively
Correct answer: Output power or energy and the potential to cause biological damage
The ANSI Z136 laser classification system categorizes lasers (Class 1 through Class 4) based on output power or energy and the associated risk of biological injury to the eye and skin.
Question 7: Which engineering control is most effective at reducing noise from a piece of rotating machinery?
- Posting warning signs on the machine
- Enclosing the machine with sound-absorbing panels (Correct answer)
- Scheduling maintenance during off-peak hours
- Providing ear muffs to nearby workers
Correct answer: Enclosing the machine with sound-absorbing panels
Enclosing the noise source with sound-absorbing or sound-isolating materials is an engineering control that reduces noise at the source before it reaches workers.
CIH Physical Agents: Noise and Radiation 5
Hand-arm vibration syndrome (HAVS) is a condition primarily caused by: