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Hazardous substances

COSHH that stays current

July 2026 · 7 min read

Ask a workshop owner whether they handle hazardous substances and the honest ones will often say no - then walk you past a shelf of degreaser, a tin of two-part adhesive, a box of welding consumables and a bag of cement dust on the way to prove it. COSHH-type control is not really about the substances with a skull on the label. It is about everything on that shelf, and most businesses that think they have none have a cupboard full.

Cleaning products, solvents, adhesives, paints and thinners, dusts thrown up by cutting wood or grinding metal, silica dust from block and stone, flour dust in a bakery, welding fume, exhaust fume in an enclosed bay, vapours from a print process - all of it counts. None of it needs to look dramatic to need assessing.

Where it shows up

The obvious setting is a factory floor, but the same duty reaches a much wider list of everyday businesses. A garage or MOT bay runs brake cleaner, degreaser and exhaust fume through a working day. A salon or barber's shop stores colour, developer, bleach and disinfectant behind the till. A cleaning or facilities contractor carries a van full of concentrates between sites. A print shop has solvent inks and cleaning fluids on the same bench as the press. In every case the substances are ordinary, the quantities are modest, and the assessment duty still applies.

The safety data sheet is the source of truth

Every hazardous substance a supplier sells arrives with a safety data sheet, and that sheet - not habit, not the label, not what the previous owner told you - is where the assessment starts. You classify and assess each substance from its own sheet, substance by substance, because two products that look similar on a shelf can carry very different hazards.

The sheet's hazard information section tells you what the substance is classified as. Its exposure-control and protective-equipment section tells you how it should be handled and what should stand between the substance and the person using it. You do not need to quote either section into your own paperwork - you need to read them, act on them, and keep the sheet on file so the next assessor, and any inspector, can trace your assessment back to its source. A substance with no safety data sheet on file is not a paperwork gap. It is a substance nobody has actually assessed.

Hazard classes and exposure routes, in plain English

The GHS and CLP hazard pictograms look like a small alphabet once you have seen them a few times, and it helps to know the plain-English shape of each class before you open a data sheet:

• Flammable - ignites easily, needs controlled storage away from ignition sources.
• Corrosive - damages skin, eyes or metal on contact.
• Acute toxic - causes serious harm from a single exposure.
• Harmful or irritant - lower-severity but still real skin, eye or respiratory effects.
• Health hazard - covers longer-term concerns such as carcinogens or respiratory sensitisers.
• Gas under pressure - stored gases with their own handling and storage rules.
• Oxidising - intensifies fire risk in other materials nearby.
• Environmental hazard - harmful if it reaches drains, soil or water.

Alongside the hazard class, note how a person actually encounters the substance - by inhalation, skin contact, ingestion, eye contact or injection. The same substance can reach someone by more than one route, and the route often decides which control matters most: a fume needs ventilation before it needs a glove.

Elimination beats PPE

It is tempting to jump straight to a glove and a mask, because PPE is visible, cheap and quick to issue. It is also the weakest control you have, and COSHH-style thinking asks you to work down a hierarchy rather than start at the bottom of it.

• Eliminate - stop using the substance at all, where a process change makes that possible.
• Substitute - swap it for a less hazardous product that does the same job.
• Enclose or extract - contain the process or fit local exhaust ventilation so the hazard never reaches the person.
• Administrate - limit exposure time, rotate tasks, train people in safe handling.
• PPE - gloves, respiratory protection or eyewear as the last line, once everything above it has been considered.

PPE is not the answer to a hazardous substance. It is what you fall back on once you have genuinely tried to remove, replace or contain it.

The part that fails first: review

A COSHH assessment does not usually fail because someone skipped it. It fails quietly, months after it was written, when the supplier reformulates a product, the process around it changes, or nobody has looked at it again since the day it was filed. None of those failures announce themselves. The assessment still sits in the folder looking finished, and it is wrong.

The fix is not more diligence - diligence fades. The fix is a review date that flags itself, so an assessment that is quietly going stale gets caught before someone relies on it. Set an interval when you assess a substance, and let the date do the watching rather than a person's memory.

A register, and a form

Two documents cover most of what a COSHH programme needs, and they do different jobs. The register is the overview - every substance in one place, its hazard class, its exposure route, whether its safety data sheet is on file, and its review status at a glance. The one-page assessment form is the detail - the substance, its use, who is exposed, the controls that apply, storage, emergency response and sign-off, all for a single substance in one place. The register tells you what needs attention this week. The form is what you hand to the person doing the work.