😷 Respiratory Hazards — Dust, Fumes & Silica (COSHH)

1. What do the letters COSHH stand for?

1. Control of Substances Hazardous to Health
2. Control of Site Safety and Health Hazards
3. Codes of Safe Handling of Hazards
4. Construction Operatives' Safety and Health Handbook

COSHH stands for the Control of Substances Hazardous to Health Regulations, which govern how employers control exposure to hazardous substances such as dust and fumes. Source: COSHH 2002

2. Which of these is a substance hazardous to health that is covered by the COSHH Regulations?

1. Silica dust created by cutting concrete
2. A heavy load that must be lifted
3. Noise from a breaker
4. Vibration from a hand-held tool

COSHH covers airborne hazards such as dusts, fumes and vapours; manual handling, noise and vibration are dealt with under their own separate regulations. Source: COSHH 2002

3. Before work starts with a hazardous substance, what must your employer carry out under COSHH?

1. A COSHH assessment of the risks and the controls needed
2. An insurance valuation of the materials
3. A noise survey of the area
4. A first-aid needs assessment only

COSHH requires a suitable and sufficient assessment of the health risks before work begins, identifying the controls needed to prevent or adequately control exposure. Source: COSHH 2002

4. Where would you usually find information about the hazards of a product such as a sealant or solvent so it can be used in a COSHH assessment?

1. On the safety data sheet supplied with the product
2. On the delivery note for the order
3. In the site sign-in book
4. On the manufacturer's advertising poster

The safety data sheet provides the hazard information needed to complete a COSHH assessment and decide on suitable controls. Source: COSHH 2002

5. In the COSHH hierarchy of control, what should be considered FIRST when trying to reduce exposure to a hazardous dust?

1. Eliminate or substitute the substance or process
2. Issue respiratory protective equipment (RPE)
3. Reduce the time workers spend in the area
4. Provide barrier cream for the skin

COSHH requires elimination or substitution to be considered first, with RPE only used as a last line of defence once other controls have been applied. Source: COSHH 2002 control hierarchy

6. Under the COSHH control hierarchy, where does respiratory protective equipment (RPE) sit?

1. It is the last line of defence, used after other controls
2. It is the first and main control to rely on
3. It replaces the need for a COSHH assessment
4. It is only required for outdoor work

RPE is the last resort under COSHH; engineering controls such as extraction and water suppression must be used first to reduce the dust at source. Source: COSHH 2002 control hierarchy

7. You are about to use a product you have never used before and there is no COSHH assessment available for the task. What should you do?

1. Stop and report it to your supervisor before using the product
2. Use the product carefully and write the assessment afterwards
3. Carry on but open the windows for extra ventilation
4. Read the label and decide the controls for yourself

Work with hazardous substances must not start until a COSHH assessment is in place; you should stop and report the missing assessment to your supervisor. Source: COSHH 2002

8. What is the main health risk from breathing in respirable crystalline silica (RCS) over time?

1. Serious and irreversible lung diseases such as silicosis
2. Temporary watering of the eyes only
3. A mild skin rash that quickly clears
4. Short-term ringing in the ears

Fine respirable crystalline silica penetrates deep into the lungs and can cause silicosis, lung cancer and other serious irreversible lung diseases. Source: COSHH 2002; HSE guidance on silica

9. Which common construction tasks are most likely to release dangerous silica dust?

1. Cutting, grinding or drilling concrete, stone and brick
2. Painting timber skirting boards
3. Fitting plasterboard with screws
4. Laying carpet tiles indoors

Silica is found in concrete, stone, brick and mortar, so cutting, grinding and drilling these materials releases respirable crystalline silica dust. Source: HSE guidance on silica

10. The workplace exposure limit (WEL) for respirable crystalline silica is an 8-hour time-weighted average. What does staying below the WEL mean?

1. Average airborne exposure should be kept below the legal limit, and still reduced so far as is reasonably practicable
2. The substance is completely safe at any level below it
3. No controls are needed if you are below it
4. It applies only to work lasting longer than one day

The WEL for respirable crystalline silica is the maximum permitted 8-hour average airborne concentration of 0.1 mg/m3; exposure must be controlled below it, and employers must still reduce exposure so far as is reasonably practicable. Source: COSHH 2002 workplace exposure limits

11. A workmate says the dusty job 'only takes ten minutes so a mask isn't needed'. What is the best response?

1. Even short tasks can give a harmful dose, so the COSHH controls must still be used
2. Agree, because short tasks are exempt from COSHH
3. Tell them to hold their breath while cutting
4. Suggest they simply work faster to finish sooner

Harmful exposure to silica can occur in minutes, so the controls set out in the COSHH assessment must be used even for short tasks. Source: COSHH 2002; HSE guidance on silica

12. Under COSHH, when an employer's monitoring or assessment shows workers may be exposed to a substance that can damage the lungs, what may also be required?

1. Health surveillance for the workers exposed
2. A daily fire drill for the whole site
3. A new manual handling assessment
4. A reduction in the site's electricity supply

COSHH requires health surveillance where workers are exposed to substances linked to identifiable disease, such as lung conditions from respirable dust. Source: COSHH 2002 health surveillance

13. Why is dry sweeping up of silica dust a bad way to clean up after cutting blocks?

1. It throws fine dust back into the air where it can be breathed in
2. It uses too much water
3. It makes the floor slippery
4. It is too slow compared with a brush

Dry sweeping disturbs settled dust and makes it airborne again; an H-class vacuum or wet cleaning methods should be used instead. Source: HSE guidance on silica; COSHH 2002

14. You find a container of liquid on site with no label and you do not know what it is. Under COSHH, what should you do?

1. Do not use it and report it to your supervisor
2. Smell it carefully to identify the contents
3. Pour a small amount away to see how it behaves
4. Use it only if it looks like a product you recognise

Unlabelled substances must not be used because their hazards are unknown; they should be reported so they can be identified and controlled. Source: COSHH 2002

15. What does LEV stand for in dust control?

1. Local exhaust ventilation
2. Low energy ventilator
3. Large extraction vacuum
4. Light extraction valve

LEV stands for local exhaust ventilation, an engineering control that captures dust or fume at source before it can be breathed in. Source: COSHH 2002; HSE guidance on LEV

16. What are the two main 'on-tool' methods used to control dust when cutting or grinding masonry?

1. Water suppression and on-tool dust extraction (LEV)
2. Extra lighting and a longer break
3. A louder warning alarm and signage
4. Barrier tape and a banksman

Water suppression damps down the dust at source and on-tool extraction (LEV) captures it, both being engineering controls preferred over RPE. Source: COSHH 2002; HSE guidance on silica

17. How does water suppression reduce the dust when cutting concrete or stone?

1. The water damps down the dust so less becomes airborne
2. The water cools the worker's hands
3. The water makes the blade cut faster
4. The water cleans the finished surface

Feeding water to the cutting point keeps the dust damp so far fewer fine particles become airborne and can be breathed in. Source: HSE guidance on silica

18. How does on-tool extraction (LEV) control dust at the cutting or grinding point?

1. It draws the dust away at source into a filtered vacuum unit
2. It blows the dust away from the worker into the open air
3. It traps the dust inside the cutting blade
4. It dissolves the dust using a chemical spray

On-tool LEV captures dust at the point it is created and draws it into a suitable filtered extraction unit, stopping it reaching the breathing zone. Source: HSE guidance on LEV; COSHH 2002

19. You are about to cut paving with a cut-off saw fitted with water suppression, but the water bottle is empty. What should you do?

1. Stop and refill the water before cutting
2. Cut anyway as it is only a short job
3. Cut slowly to make less dust
4. Wet the slab once at the start and then carry on dry

Water suppression must run continuously during cutting to keep dust down; cutting dry, even briefly, releases large amounts of harmful silica dust. Source: HSE guidance on silica; COSHH 2002

20. Why should engineering controls such as LEV and water suppression be used in preference to relying on a dust mask?

1. They reduce the dust at source and protect everyone nearby, not just the wearer
2. They are cheaper to throw away after use
3. They remove the need for any COSHH assessment
4. They make the tool easier to carry

Controls at source reduce the dust everyone is exposed to, whereas a mask only protects the individual wearing it and only if it fits and is worn correctly. Source: COSHH 2002 control hierarchy

21. How often must an LEV (local exhaust ventilation) system normally be thoroughly examined and tested under COSHH?

1. At least once every 14 months
2. Only when it stops working
3. Once every five years
4. Only at the start of each project

COSHH requires LEV systems to be thoroughly examined and tested at suitable intervals, normally at least every 14 months, to confirm they still control exposure effectively. Source: COSHH 2002 regulation 9

22. Even with water suppression working well on a cut-off saw, why might you still be told to wear suitable RPE?

1. Engineering controls may not remove all the dust, so RPE gives added protection
2. Because RPE replaces the need for water suppression
3. Because the law bans the use of cut-off saws without a full mask in all cases
4. Because RPE keeps the saw cooler

Engineering controls reduce but do not always eliminate exposure, so suitable RPE is used together with them when the assessment shows residual risk. Source: COSHH 2002 control hierarchy; HSE guidance on silica

23. You notice the on-tool extraction unit's hose is split and dust is escaping during grinding. What is the correct action?

1. Stop work and report the fault so it can be repaired or replaced
2. Tape over the split loosely and keep grinding
3. Carry on because the vacuum is still making a noise
4. Remove the extraction unit and work without it

A damaged extraction system is no longer controlling the dust effectively, so work should stop and the fault be reported and put right before continuing. Source: COSHH 2002; HSE guidance on LEV

24. When emptying or maintaining a dust extraction unit used for silica, what precaution helps prevent breathing in the captured dust?

1. Follow the safe procedure and wear suitable RPE to avoid releasing the dust
2. Tip the dust out quickly in the open and walk away
3. Blow the filter clean with an airline indoors
4. Empty it next to where other people are working

Captured silica dust is still hazardous, so maintenance must follow a safe procedure with suitable RPE to avoid making the fine dust airborne again. Source: COSHH 2002; HSE guidance on silica

25. Which type of vacuum cleaner is suitable for clearing up hazardous silica dust?

1. A specially designed H- or M-class dust extraction vacuum
2. A standard domestic vacuum cleaner
3. A garden leaf blower set to suck
4. Any vacuum, as long as the bag is new

Only a vacuum with the correct high-efficiency filtration (such as an M- or H-class unit) will safely capture fine silica dust; ordinary vacuums can blow it back into the air. Source: HSE guidance on silica; COSHH 2002

26. A colleague is dry-cutting blocks indoors with no water and no extraction, creating a cloud of dust. What is the best thing to do?

1. Ask them to stop and use water suppression or extraction before continuing
2. Open a door so the dust drifts outside and let them carry on
3. Lend them your own mask so they can keep cutting dry
4. Ignore it because they are the one being exposed, not you

Dry cutting without controls exposes the worker and everyone nearby to harmful silica dust, so the work should stop until water suppression or extraction is in use. Source: COSHH 2002; HSE guidance on silica

27. Which serious lung disease is caused by breathing in respirable crystalline silica dust over time?

1. Silicosis
2. Sunburn of the airways
3. Tennis elbow
4. Hay fever

Silicosis is an irreversible, disabling lung disease caused by inhaling fine respirable crystalline silica (RCS) dust. Source: COSHH 2002 / HSE guidance

28. Crystalline silica is commonly found in which of these construction materials?

1. Concrete, mortar, sandstone and brick
2. Plasterboard only
3. Soft timber only
4. Mineral wool insulation only

Silica is a natural mineral present in large amounts in materials such as concrete, mortar, sandstone, sand and brick, so cutting or grinding them releases RCS. Source: HSE guidance (Construction dust)

29. Why is respirable crystalline silica dust so dangerous to the lungs?

1. It is fine enough to be breathed deep into the lungs where it causes scarring
2. It is too large to enter the nose
3. It only irritates the eyes
4. It dissolves harmlessly in the bloodstream

Respirable particles are so fine they reach deep into the lungs and cause permanent scarring (fibrosis), which leads to silicosis. Source: HSE guidance (Construction dust)

30. Under COSHH, what is the workplace exposure limit (WEL) for respirable crystalline silica as an 8-hour time-weighted average?

1. 0.1 mg/m³
2. 10 mg/m³
3. 5 mg/m³
4. 100 mg/m³

The COSHH workplace exposure limit for respirable crystalline silica is 0.1 mg/m³ averaged over an 8-hour shift. Source: COSHH 2002 (Workplace Exposure Limits, EH40)

31. You are about to dry-cut paving blocks with a disc cutter, creating a cloud of dust. Under the COSHH control hierarchy, what should be done first before relying on a mask?

1. Use water suppression or on-tool extraction to stop the dust at source
2. Put on a basic nuisance dust mask and start cutting
3. Cut faster so the job finishes sooner
4. Open a window nearby

COSHH requires controlling dust at source (water suppression or LEV/on-tool extraction) before RPE, which is the last line of defence. Source: COSHH 2002 (control hierarchy)

32. A colleague is sweeping up dry silica dust with a brush, sending clouds into the air. What is the better method?

1. Use a suitable H-class (Type H) vacuum or wet cleaning methods
2. Use a leaf blower to clear it faster
3. Sweep harder so it settles quickly
4. Leave it; the dust is harmless once on the floor

Dry sweeping makes settled silica airborne again; an H-class vacuum or wet methods prevent it being re-inhaled. Source: HSE guidance (Construction dust) / COSHH 2002

33. Silicosis can increase a worker's risk of developing which other serious condition?

1. Lung cancer
2. Improved lung capacity
3. Better night vision
4. A faster heartbeat that is harmless

Long-term exposure to RCS is linked not only to silicosis but also to lung cancer, COPD and other chronic lung diseases. Source: HSE guidance / COSHH 2002

34. Why can damage from breathing silica dust be especially dangerous over a working lifetime?

1. The harm builds up slowly and symptoms may not appear for years
2. It causes instant pain that warns you immediately
3. It clears completely overnight
4. Your body filters out all silica naturally

Silicosis develops gradually and symptoms can take years to appear, so workers may be seriously harmed before they notice anything is wrong. Source: HSE guidance (Construction dust)

35. Your employer arranges regular lung function checks and questionnaires for workers exposed to silica dust. What is this called?

1. Health surveillance
2. A performance review
3. A toolbox talk
4. A method statement

Where exposure to a substance hazardous to health may cause disease, COSHH requires appropriate health surveillance to detect early signs of harm. Source: COSHH 2002 (health surveillance)