NEBOSH CC Construction Site Hazards 2 — Questions and Answers
Question 1: What is the most significant health risk from exposure to construction dust containing crystalline silica?
- Silicosis (progressive fibrosis of the lungs) (Correct answer)
- Skin irritation
- Eye inflammation
- Temporary coughing
Correct answer: Silicosis (progressive fibrosis of the lungs)
Respirable crystalline silica (RCS) causes silicosis, an irreversible and progressive fibrotic lung disease. Construction activities such as cutting concrete, sandstone, granite, and mortar generate RCS dust. The UK workplace exposure limit is 0.1 mg/m3 (8-hour TWA). Silica exposure is also associated with lung cancer.
Question 2: A delivery lorry is reversing on a construction site. What is the most effective measure to prevent pedestrian being struck?
- Segregation of vehicle and pedestrian routes with physical barriers (Correct answer)
- Relying on the vehicle's reversing alarm only
- High-visibility clothing for all pedestrians
- Verbal warnings from the driver
Correct answer: Segregation of vehicle and pedestrian routes with physical barriers
Physical segregation of vehicle and pedestrian routes is the most effective control measure, applying the hierarchy of control (engineering control). While reversing alarms, banksmen, cameras, and hi-vis clothing all help, they are lower-order controls that depend on human behaviour and can fail.
Question 3: Under the Electricity at Work Regulations 1989, what is the primary control measure to protect workers from contact with underground cables during excavation?
- Use cable avoidance tools (CAT) and signal generator, plus safe digging practices (Correct answer)
- Wearing rubber gloves during excavation
- Digging quickly to minimise exposure time
- Assuming there are no cables if plans show none
Correct answer: Use cable avoidance tools (CAT) and signal generator, plus safe digging practices
HSG47 guidance requires using cable avoidance tools (CAT scanner) and signal generators to locate underground services before excavation. Safe digging practices (hand digging within 500mm of detected services, no mechanical excavation near cables) must follow. Plans alone are unreliable as cables may have been diverted.
Question 4: A worker on a construction site develops occupational dermatitis from cement exposure. Which component of cement is primarily responsible for causing allergic contact dermatitis?
- Hexavalent chromium (chromium VI) (Correct answer)
- Calcium oxide
- Silicon dioxide
- Iron oxide
Correct answer: Hexavalent chromium (chromium VI)
Hexavalent chromium (Cr VI) in cement is the primary sensitiser causing allergic contact dermatitis. EU regulations limit Cr VI content in cement to 2 ppm (2 mg/kg). Cement also causes irritant contact dermatitis due to its high alkalinity (pH 12-13). Controls include reduced-chromate cement, gloves, and barrier creams.
Question 5: What is the purpose of a traffic management plan on a construction site?
- To manage the safe movement of vehicles and pedestrians, minimising the risk of collisions (Correct answer)
- To schedule deliveries for cost efficiency
- To ensure vehicles are taxed and insured
- To manage parking for site visitors only
Correct answer: To manage the safe movement of vehicles and pedestrians, minimising the risk of collisions
A traffic management plan (TMP) manages the safe movement of all vehicles and pedestrians on site. It should include designated routes, speed limits, one-way systems, turning areas, segregation of pedestrians, signage, banksmen requirements, and loading/unloading arrangements. It is a key requirement under CDM 2015.
Question 6: What is the maximum noise exposure level (daily or weekly average) above which an employer must provide hearing protection zones on a construction site under the Control of Noise at Work Regulations 2005?
- 85 dB(A) — the upper exposure action value (Correct answer)
- 80 dB(A) — the lower exposure action value
- 87 dB(A) — the exposure limit value
- 70 dB(A)
Correct answer: 85 dB(A) — the upper exposure action value
At the upper exposure action value of 85 dB(A), employers must establish hearing protection zones, ensure hearing protection is worn, and implement a programme of noise reduction measures. At 80 dB(A) (lower action value), hearing protection must be made available. The exposure limit of 87 dB(A) must never be exceeded (measured at the ear, taking account of hearing protection).
NEBOSH CC Construction Site Hazards 2
What is the most significant health risk from exposure to construction dust containing crystalline silica?