CITB Specialists Respiratory Hazards & COSHH 2 — Questions and Answers
Question 1: What is Local Exhaust Ventilation (LEV) and when is it used?
- An extraction system that captures dust, fume, or vapour at or near the source before it can spread into the working area (Correct answer)
- General ventilation provided by opening windows and doors
- The extraction system in a spray booth only
- Respiratory protection worn by the worker
Correct answer: An extraction system that captures dust, fume, or vapour at or near the source before it can spread into the working area
Local Exhaust Ventilation (LEV) is a fume or dust extraction system positioned at or close to the point of generation to capture contaminants before they can enter the worker's breathing zone or spread into the workplace.
Question 2: What does WEL (Workplace Exposure Limit) mean?
- The maximum concentration of a substance in air to which workers may be exposed averaged over an 8-hour shift (TWA) or short-term period (Correct answer)
- The maximum weight of a hazardous substance allowed on site
- The minimum ventilation rate required in a work area
- The legal limit for PPE replacement frequency
Correct answer: The maximum concentration of a substance in air to which workers may be exposed averaged over an 8-hour shift (TWA) or short-term period
A Workplace Exposure Limit (WEL) is the maximum concentration of an airborne substance (in mg/m³ or ppm) averaged over a reference period (8-hour Time Weighted Average or 15-minute short-term exposure limit) to which workers may legally be exposed.
Question 3: What is isocyanate and which specialist contractor is most exposed to it?
- A chemical in two-pack paints, lacquers, and spray foam insulation — highest exposure to specialist spray painters and insulators (Correct answer)
- A welding flux used by metal fabricators
- A solvent used by plumbers for plastic pipe jointing
- A preservative in treated timber used by carpenters
Correct answer: A chemical in two-pack paints, lacquers, and spray foam insulation — highest exposure to specialist spray painters and insulators
Isocyanates are highly reactive chemicals present in two-component polyurethane products including spray paints, adhesives, and spray foam insulation. They are a leading cause of occupational asthma. Spray painters and spray foam installers have the highest exposure.
Question 4: What health surveillance is required under COSHH for workers exposed to substances that can cause occupational asthma?
- Pre-employment and regular respiratory questionnaires with lung function testing (spirometry) by an occupational health professional (Correct answer)
- Only an annual GP appointment
- Only a pre-employment medical — no further monitoring
- No health surveillance is required unless the worker develops symptoms
Correct answer: Pre-employment and regular respiratory questionnaires with lung function testing (spirometry) by an occupational health professional
Workers exposed to respiratory sensitisers (like isocyanates, wood dust, or flour) that can cause occupational asthma require regular health surveillance including respiratory questionnaires and spirometry (lung function testing) to detect sensitisation early.
Question 5: What are the key components of a COSHH assessment?
- Identify substances, assess who is at risk, evaluate exposure, determine controls, record findings, and review regularly (Correct answer)
- Only list the chemicals and their suppliers
- Only state what PPE is needed
- Only note the disposal method for waste chemicals
Correct answer: Identify substances, assess who is at risk, evaluate exposure, determine controls, record findings, and review regularly
A full COSHH assessment identifies hazardous substances, determines who may be harmed, evaluates the level of exposure, determines appropriate control measures following the hierarchy, records the findings, and sets a review date. All elements are required.
Question 6: Under COSHH, what does 'adequate control' of a hazardous substance mean?
- Reducing exposure to below the WEL and as low as reasonably practicable using the control hierarchy (Correct answer)
- Providing PPE to all workers who may be exposed
- Only controlling exposure for workers directly using the substance
- Meeting the minimum legal limit without any further effort
Correct answer: Reducing exposure to below the WEL and as low as reasonably practicable using the control hierarchy
'Adequate control' under COSHH means reducing exposure to below the WEL and, for substances without a WEL (like sensitisers), reducing it as low as reasonably practicable. PPE alone does not constitute adequate control.
CITB Specialists Respiratory Hazards & COSHH 2
What is Local Exhaust Ventilation (LEV) and when is it used?