COSHH for UK Trades — Hazardous Substances, Assessments and Staying Compliant (2026)

What COSHH Is — and What It Doesn't Cover

COSHH stands for the Control of Substances Hazardous to Health Regulations 2002. It is the law that requires employers (and self-employed people) to control exposure to hazardous substances to prevent ill health. It covers chemicals, products containing chemicals, fumes, dusts, vapours, mists, gases and biological agents (bacteria and other micro-organisms). If a substance has a hazard label, a workplace exposure limit, or simply produces dust or fumes that can harm health, COSHH almost certainly applies.

Crucially, COSHH does not cover everything. Some of the most dangerous materials tradespeople encounter have their own dedicated regulations and fall outside COSHH entirely:

• Asbestos — covered by the Control of Asbestos Regulations 2012
• Lead — covered by the Control of Lead at Work Regulations 2002
• Radioactive materials — covered by the Ionising Radiations Regulations 2017

COSHH also doesn't cover substances hazardous only because they are explosive, flammable, asphyxiating or at high pressure — those fall under separate fire and DSEAR rules. Knowing what sits inside and outside COSHH matters: assuming asbestos is "just a COSHH job" is one of the most dangerous mistakes a tradesperson can make.

The Hazardous Substances Tradespeople Meet Every Day

Most tradespeople think COSHH is about labelled bottles of chemicals. In reality, the biggest risks usually come from substances created by the work itself — dust and fumes that don't arrive in a container with a hazard symbol on the side. Here are the ones that matter most by trade.

Respirable crystalline silica (RCS)

Silica dust is the single biggest hidden killer on UK building sites. It's released when you cut, grind, drill or chase concrete, brick, block, stone, mortar, tiles or sand-based products. The respirable fraction — the part fine enough to reach deep into the lungs — causes silicosis, lung cancer and COPD. A single uncontrolled cut of a concrete slab can generate enough airborne silica to exceed the daily limit in minutes. Bricklayers, groundworkers, stonemasons, kitchen fitters working stone worktops and anyone using a cut-off saw are all in the firing line.

Wood dust

Sawing, sanding and routing timber produces wood dust, which is linked to occupational asthma and — in the case of hardwood dust — nasal cancer. Hardwood dust (oak, beech, MDF and similar) is treated as a carcinogen and carries a lower exposure limit than softwood. Carpenters, joiners, shopfitters and anyone running a workshop need to take it seriously, especially with MDF, which is bonded with formaldehyde-based resins.

Cement, wet concrete and mortar

Cement is highly alkaline. Wet concrete and mortar can cause irritant and allergic contact dermatitis, and prolonged skin contact — kneeling in wet screed, for example — can cause serious cement burns that reach the bone. Cement also contains hexavalent chromium, a skin sensitiser. Bricklayers, plasterers, renderers and concrete finishers are most at risk.

Isocyanates

Isocyanates are found in two-pack (2K) paints and lacquers, certain adhesives and expanding/spray polyurethane foam insulation. They are one of the leading causes of occupational asthma in the UK. Spray painters, vehicle refinishers and spray-foam installers face the highest exposures, and once someone becomes sensitised, even tiny future exposures can trigger a severe reaction.

Solvents, adhesives and welding fume

Solvents in paints, thinners, degreasers and adhesives can cause dizziness, headaches, dermatitis and longer-term nerve and organ damage. Welding fume — reclassified by the HSE as a carcinogen — affects fabricators and any tradesperson who welds, even occasionally. Mild steel welding fume now requires fume control regardless of duration.

The Core Duties — COSHH in Eight Steps

The HSE frames COSHH compliance as a set of core duties. Whatever the size of your business, you need to work through all of them:

• Assess the risks to health from hazardous substances used in or created by your work.
• Decide what precautions are needed — you cannot start work until you've worked out how to do it safely.
• Prevent or adequately control exposure, following the hierarchy of control (see below).
• Maintain control measures — keep extraction units serviced, RPE in good order and procedures followed.
• Monitor exposure where the assessment requires it, for example air sampling for silica or isocyanates.
• Carry out health surveillance where there is a recognised risk to health and a valid way of detecting harm.
• Plan for emergencies — spills, leaks and accidental releases.
• Train and inform your workers so they understand the risks and use the controls correctly.

How to Do a COSHH Assessment

A COSHH assessment is not a generic form you download once and forget. It is a practical look at the specific substances your work involves and the specific people exposed to them. The process is straightforward.

Start with the safety data sheet (SDS). Every hazardous product sold for trade use comes with a supplier safety data sheet — usually available on the manufacturer's website. Section 2 tells you the hazards, Section 8 lists exposure limits and recommended controls (including the right RPE), and Sections 4 and 6 cover first aid and spill handling. The SDS is the foundation of your assessment for any supplied product. For dusts and fumes created by the work — silica, wood dust, welding fume — there's no SDS, so you rely on HSE guidance instead.

Identify who is exposed and how. Think about the actual task: who is doing it, who is nearby, and by what route the substance gets in — breathing it in, skin contact, or swallowing. A labourer sweeping up dry silica dust at the end of the day may be more exposed than the person who cut the slab.

Decide the controls and write it down. Record what the substance is, the risk, who is exposed, the controls you'll use and the RPE required. Keep it proportionate — for a small job with a single product, a one-page assessment is fine. The point is that you've thought it through and the people on site know what to do. Keeping these assessments filed against each job, alongside your method statements and certificates, makes them easy to produce if an inspector or client ever asks — this is exactly the kind of record-keeping a tool like Trade2Base helps you keep organised rather than scattered across vans and inboxes.

The Hierarchy of Control

COSHH requires you to control exposure using a strict order of preference. You don't jump straight to a dust mask — that's the last line of defence, not the first.

• Eliminate or substitute. The best control is to avoid the substance entirely — order materials pre-cut to size, use a less hazardous product, or pick a water-based paint over a solvent one. No exposure means no risk.
• Engineering controls. Where you can't eliminate the hazard, control it at source. For silica, that means on-tool extraction (LEV) fitted to grinders and saws, or water suppression that damps down the dust as it's created. For welding, it means local exhaust ventilation drawing fume away from the breathing zone.
• RPE as a last line. Respiratory protective equipment supplements engineering controls — it does not replace them. For fine dusts like silica, an FFP3-rated mask or a powered respirator is the minimum, and tight-fitting masks legally require face-fit testing for each individual wearer. A mask that doesn't seal against the face offers almost no protection, and beards break the seal.

Don't forget skin protection. Gloves, barrier creams and good washing facilities are the controls for cement, solvents and adhesives — substances where the harm comes through the skin rather than the lungs.

Workplace Exposure Limits (WELs)

Many hazardous substances have a Workplace Exposure Limit — the maximum concentration of a substance in the air, averaged over a set period, that workers can be exposed to. WELs are published in the HSE document EH40. Respirable crystalline silica, for example, has a WEL of 0.1 mg/m³ averaged over 8 hours, and there is pressure to lower it further. You don't need to memorise the numbers, but where a WEL exists, your controls must keep exposure below it — and for the worst substances, as low as reasonably practicable below it.

Health Surveillance

Where workers are exposed to substances that can cause identifiable disease — silica, wood dust, isocyanates, substances causing dermatitis or asthma — and there's a reliable way to detect early signs of harm, you must provide health surveillance. In practice this means lung function tests (spirometry), skin checks, or questionnaires carried out by an occupational health provider, with records kept for up to 40 years. It catches problems early, before they become disabling, and the records also protect you as an employer if a claim is ever made.

Quick Reference: Common Substances by Trade

Record-Keeping and Training

COSHH requires you to keep your assessments, maintain records of any exposure monitoring and health surveillance, and provide information, instruction and training to your workers. LEV equipment must be examined and tested at least every 14 months (a TExT inspection), and you should keep those certificates. Workers need to know what they're exposed to, why the controls matter and how to use RPE properly — toolbox talks are a simple, documented way to deliver this.

Keeping all of this together — assessments, LEV certificates, face-fit records, training logs — against the right jobs and people is where many small firms come unstuck. Storing job records and compliance documents in one place rather than across paper folders and text messages makes it far easier to prove you did the right thing. Trade2Base is built around keeping that kind of job paperwork organised so it's there when you need it.

HSE Enforcement and Penalties

COSHH is enforced by the HSE (and local authorities for some sectors). Inspectors can issue improvement notices requiring you to put controls right, or prohibition notices that stop a dangerous activity immediately. Serious breaches lead to prosecution. Under the Health and Safety at Work etc. Act 1974, fines are unlimited in the Crown Court, and sentencing guidelines link penalties to turnover — meaning even a small firm can face a five- or six-figure fine. Individuals, including directors and sole traders, can also be prosecuted, and the HSE recovers its investigation costs from offenders through the Fee for Intervention scheme.

Beyond the legal risk, there's the human cost: an employee who develops silicosis or occupational asthma may be unable to work in the trade again, and civil claims often follow. COSHH compliance isn't about ticking a box for the HSE — it's about making sure the people doing the work, including you, are still healthy in twenty years' time.