Which hazardous substance is most commonly encountered when chasing walls or cutting concrete on a construction site?

Chasing walls and cutting concrete, brick, block, or mortar releases respirable crystalline silica (RCS) dust. Silica is a major component of these materials, and the cutting/grinding process creates very fine dust particles that can penetrate deep into the lungs, causing silicosis and increasing the risk of lung cancer.

Polychlorinated biphenyls (PCBs)

Respirable crystalline silica (RCS) dust

What hazardous substance is an electrician most likely exposed to when soldering copper pipe joints or cable terminations?

Soldering traditionally uses tin-lead alloy solder and rosin-based flux. This creates lead fume and rosin (colophony) fume. Lead is toxic to the nervous system, kidneys, and reproductive system. Colophony fume is a respiratory sensitiser and a known cause of occupational asthma. Lead-free solder is now preferred where possible.

Silica dust from the soldered joint

Asbestos fibres from the cable insulation

Lead and rosin (colophony) fumes from solder and flux

Isocyanate vapour from the flux

What type of hazardous substance can be released when drilling into painted surfaces in buildings constructed before 1980?

Lead-based paints were widely used in UK buildings until the late 1970s. Drilling, sanding, or scraping these painted surfaces can generate lead-containing dust. Electricians frequently drill into walls and ceilings in older buildings, making lead paint dust a significant occupational hazard that requires assessment under COSHH.

Asbestos fibres from the paint binder

Mercury vapour from the pigment

Carbon monoxide from the drill motor

Free mock exam

Hazardous Substances on Site — COSHH Practice

Free topic-focused mock exam: 15 random questions from a pool of 40 on Hazardous Substances on Site, drawn from the wider COSHH bank. 20-minute timer, 70% to pass, worked explanation on every question. Use this when you've taken the full mock once and want to drill the topics you got wrong.

Questions: 15
Time limit: 20
Pass mark: 70%
Bank size: 40

Free · no sign-up · timer can be ignored · retake as many times as you want

Sample questions

01Which hazardous substance is most commonly encountered when chasing walls or cutting concrete on a construction site?
- A.Respirable crystalline silica (RCS) dust
- B.Mercury vapour
- C.Polychlorinated biphenyls (PCBs)
- D.Carbon monoxide gas
Why: Chasing walls and cutting concrete, brick, block, or mortar releases respirable crystalline silica (RCS) dust. Silica is a major component of these materials, and the cutting/grinding process creates very fine dust particles that can penetrate deep into the lungs, causing silicosis and increasing the risk of lung cancer.
02What hazardous substance is an electrician most likely exposed to when soldering copper pipe joints or cable terminations?
- A.Silica dust from the soldered joint
- B.Asbestos fibres from the cable insulation
- C.Lead and rosin (colophony) fumes from solder and flux
- D.Isocyanate vapour from the flux
Why: Soldering traditionally uses tin-lead alloy solder and rosin-based flux. This creates lead fume and rosin (colophony) fume. Lead is toxic to the nervous system, kidneys, and reproductive system. Colophony fume is a respiratory sensitiser and a known cause of occupational asthma. Lead-free solder is now preferred where possible.
03What type of hazardous substance can be released when drilling into painted surfaces in buildings constructed before 1980?
- A.Lead-containing paint dust
- B.Mercury vapour from the pigment
- C.Asbestos fibres from the paint binder
- D.Carbon monoxide from the drill motor
Why: Lead-based paints were widely used in UK buildings until the late 1970s. Drilling, sanding, or scraping these painted surfaces can generate lead-containing dust. Electricians frequently drill into walls and ceilings in older buildings, making lead paint dust a significant occupational hazard that requires assessment under COSHH.

FAQ

Is the Hazardous Substances on Site mock exam free?

Yes — 100% free, no sign-up needed. Questions are pulled at random from a substantial bank, with a worked explanation on every question after you submit.

Can I retake the mock exam?

Yes. Every attempt picks a different random selection and reshuffles the options, so each retake gives you genuinely new questions. No limit on retakes.

Does this count towards the real qualification?

No — this is independent practice material. To gain the actual qualification you need to sit the official assessment through an approved provider.