NEBOSH Physical Hazards 4 — Questions and Answers
Question 1: Noise-induced hearing loss (NIHL) has what characteristics?
- It is temporary and fully reversible with treatment
- It is permanent, irreversible, typically affects higher frequencies first (4 kHz dip), and develops gradually over years of exposure (Correct answer)
- It only affects one ear
- It can be cured by removing the person from noise exposure
Correct answer: It is permanent, irreversible, typically affects higher frequencies first (4 kHz dip), and develops gradually over years of exposure
NIHL is permanent and irreversible — damaged sensory hair cells in the cochlea do not regenerate. It typically begins with a characteristic dip at 4 kHz (the frequency most susceptible to noise damage) before spreading to affect speech frequencies. It develops gradually and often goes unnoticed until significant damage has occurred, which is why health surveillance (audiometry) is essential for early detection.
Question 2: What control measures can reduce hand-arm vibration exposure in the workplace?
- Wearing thicker gloves is the only effective measure
- Selecting low-vibration equipment, maintaining tools in good condition, limiting daily exposure duration, job rotation, keeping warm, and using anti-vibration gloves as a supplement (Correct answer)
- Working faster to reduce the total time using vibrating tools
- Increasing the grip force on the tool to reduce vibration transmission
Correct answer: Selecting low-vibration equipment, maintaining tools in good condition, limiting daily exposure duration, job rotation, keeping warm, and using anti-vibration gloves as a supplement
HAV control measures include: selecting tools with the lowest vibration emission, regular maintenance (sharp cutting tools, balanced rotating parts), limiting daily exposure time with job rotation, using jigs or fixtures to reduce grip force, keeping hands warm (cold worsens vascular symptoms), anti-vibration gloves (limited benefit but supplementary), and health surveillance for early detection of HAVS.
Question 3: What are the health effects of working in extreme cold environments?
- Cold environments only cause discomfort, not health effects
- Hypothermia, frostbite, reduced manual dexterity leading to accidents, chilblains, and trench foot (non-freezing cold injury) (Correct answer)
- Only frostbite on exposed skin
- Cold environments improve worker productivity
Correct answer: Hypothermia, frostbite, reduced manual dexterity leading to accidents, chilblains, and trench foot (non-freezing cold injury)
Extreme cold exposure can cause: hypothermia (core body temperature below 35°C — confusion, loss of consciousness, cardiac arrest), frostbite (freezing of tissue, usually extremities), non-freezing cold injury/trench foot (prolonged cold-wet exposure), chilblains, and significantly reduced manual dexterity increasing accident risk. Cold also exacerbates Raynaud's phenomenon and HAVS symptoms.
Question 4: Under the Electricity at Work Regulations 1989, what is the duty regarding the strength and capability of electrical equipment?
- Equipment must be the most expensive available
- All systems and equipment must be of sufficient strength and capability for the purpose for which they are used (Correct answer)
- Only equipment manufactured in the UK meets the requirement
- The regulations do not specify strength requirements
Correct answer: All systems and equipment must be of sufficient strength and capability for the purpose for which they are used
Regulation 5 requires that all electrical equipment, including conductors, must be of such construction as to be suitable for the purpose and conditions of use, and of sufficient strength and capability. This means equipment must be rated for the voltages, currents, and environmental conditions it will encounter, including fault conditions.
Question 5: What does 'proving dead' mean in the context of safe electrical isolation?
- Testing the equipment after repair to ensure it works
- Using a voltage indicator to confirm that the conductors are at zero voltage after isolation, having first proved the indicator works on a known live source (Correct answer)
- Visually checking that cables are disconnected
- Switching the equipment off at the plug
Correct answer: Using a voltage indicator to confirm that the conductors are at zero voltage after isolation, having first proved the indicator works on a known live source
Proving dead is a critical step in safe isolation: (1) test the voltage indicator on a known live source to prove it works, (2) use it to test the isolated conductors to confirm they are dead (zero voltage), (3) re-test the indicator on the known live source to confirm it is still working. This three-step process ensures the test result is reliable. GS38 guidance covers suitable test equipment.
Question 6: What is the recommended workplace temperature for sedentary work under the Workplace (Health, Safety and Welfare) Regulations 1992?
- A minimum of 13°C
- A minimum of 16°C during working hours (Correct answer)
- A minimum of 20°C
- There is no legal requirement for temperature
Correct answer: A minimum of 16°C during working hours
The Approved Code of Practice to the Workplace Regulations suggests a minimum temperature of 16°C for sedentary work (offices) and 13°C where work involves severe physical effort. There is no maximum temperature specified in law, but the employer must provide a 'reasonable' working temperature. The HSE considers thermal comfort factors including air temperature, radiant temperature, humidity, and air movement.
NEBOSH Physical Hazards 4
Noise-induced hearing loss (NIHL) has what characteristics?