NEBOSH Physical Hazards 4

Question 1

Noise-induced hearing loss (NIHL) has what characteristics?

Accepted Answer

It is permanent, irreversible, typically affects higher frequencies first (4 kHz dip), and develops gradually over years of exposure

Answer

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?

Accepted 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

Answer

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?

Accepted Answer

Hypothermia, frostbite, reduced manual dexterity leading to accidents, chilblains, and trench foot (non-freezing cold injury)

Answer

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?

Accepted Answer

All systems and equipment must be of sufficient strength and capability for the purpose for which they are used

Answer

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?

Accepted 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

Answer

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.

NEBOSH IGC Practice Test

NEBOSH IGC Practice Test

NEBOSH Physical Hazards 4