NEBOSH Physical Hazards 2 — Questions and Answers
Question 1: What is the upper exposure action value for noise under the Control of Noise at Work Regulations 2005?
- 80 dB(A)
- 85 dB(A) daily or weekly personal noise exposure (Correct answer)
- 87 dB(A)
- 90 dB(A)
Correct answer: 85 dB(A) daily or weekly personal noise exposure
The upper exposure action value is 85 dB(A) LEP,d or a peak sound pressure of 137 dB(C). At this level, the employer must: reduce exposure to as low as reasonably practicable, designate mandatory hearing protection zones with signage, ensure hearing protection is worn, and provide health surveillance (audiometry).
Question 2: What are the Exposure Action Value (EAV) and Exposure Limit Value (ELV) for hand-arm vibration?
- EAV 1.0 m/s², ELV 2.5 m/s²
- EAV 2.5 m/s² A(8), ELV 5 m/s² A(8) (Correct answer)
- EAV 5.0 m/s², ELV 10 m/s²
- EAV 0.5 m/s², ELV 1.15 m/s²
Correct answer: EAV 2.5 m/s² A(8), ELV 5 m/s² A(8)
The Control of Vibration at Work Regulations 2005 set the hand-arm vibration EAV at 2.5 m/s² A(8) (daily 8-hour normalised exposure) and the ELV at 5 m/s² A(8). At the EAV, employers must introduce a programme of controls. The ELV must not be exceeded. These values are based on the likelihood of developing HAVS at different exposure levels.
Question 3: What is a permit-to-work system in the context of electrical safety?
- A general work schedule for electricians
- A formal documented procedure that authorises specific persons to carry out specific work on specific equipment under controlled conditions, with defined safety precautions including isolation and proving dead (Correct answer)
- A licence issued by the local council
- An insurance certificate for electrical contractors
Correct answer: A formal documented procedure that authorises specific persons to carry out specific work on specific equipment under controlled conditions, with defined safety precautions including isolation and proving dead
A permit-to-work (PTW) for electrical work is a formal safety document that specifies: the exact equipment to be worked on, the hazards present, the safety precautions taken (isolation, locking off, proving dead, earthing), the persons authorised to carry out the work, the time limitations, and the procedure for returning equipment to service. It provides a systematic check and clear communication.
Question 4: What is the exposure limit value (ELV) for noise that must not be exceeded, taking into account hearing protection?
- 80 dB(A)
- 85 dB(A)
- 87 dB(A) daily or weekly personal noise exposure (Correct answer)
- 90 dB(A)
Correct answer: 87 dB(A) daily or weekly personal noise exposure
The exposure limit value of 87 dB(A) LEP,d or peak of 140 dB(C) must not be exceeded. Unlike the action values, the ELV takes into account the attenuation provided by hearing protection. If the ELV is exceeded even with hearing protection, the employer must take immediate action to reduce exposure below this level.
Question 5: What health effects are associated with prolonged exposure to whole-body vibration (WBV)?
- Vibration white finger
- Lower back pain, spinal degeneration, sciatica, and damage to the digestive system (Correct answer)
- Hearing loss
- Skin sensitisation
Correct answer: Lower back pain, spinal degeneration, sciatica, and damage to the digestive system
Whole-body vibration transmitted through the seat or standing platform primarily affects the lumbar spine, causing lower back pain, degenerative disc disease, herniated discs, and sciatica. Prolonged exposure may also affect the digestive system and circulatory system. Vehicle operators (forklift, tractor, HGV drivers) are most at risk.
Question 6: What factors determine the severity of an electric shock to a person?
- Only the voltage of the supply
- The magnitude of current flowing through the body, the path the current takes through the body, and the duration of contact (Correct answer)
- Only whether the person is wearing safety boots
- Only the type of electrical equipment involved
Correct answer: The magnitude of current flowing through the body, the path the current takes through the body, and the duration of contact
The severity of electric shock depends on: current magnitude (as little as 50mA AC can be fatal), current path through the body (hand-to-hand or hand-to-foot paths through the heart are most dangerous), duration of contact, frequency (AC at 50Hz is more dangerous than DC for the same current), and individual physiology. Voltage drives the current, but current through vital organs causes the harm.
NEBOSH Physical Hazards 2
What is the upper exposure action value for noise under the Control of Noise at Work Regulations 2005?