Is a COSHH assessment a legal requirement?

Yes. The Control of Substances Hazardous to Health Regulations 2002 require employers to assess the risks from hazardous substances before work starts, and to prevent exposure or, where that is not reasonably practicable, adequately control it. Employers with five or more employees must record the significant findings.

Does construction dust need a COSHH assessment?

Yes, and it is one of the most commonly missed. Respirable crystalline silica from cutting or drilling concrete, stone and brick, along with wood dust and general construction dust, are substances hazardous to health under COSHH. They need assessing and controlling like any chemical product — typically through on-tool extraction or water suppression rather than PPE alone.

What is the difference between a COSHH assessment and a safety data sheet?

A safety data sheet is supplied by the manufacturer and describes the product in general. A COSHH assessment is yours, and describes how that substance is used on your job — the quantity, the method, the ventilation, who is exposed and for how long, and the controls you will apply. A safety data sheet is an input to a COSHH assessment, not a substitute for one.

How often should a COSHH assessment be reviewed?

Whenever it may no longer be valid — if the substance, the quantity, the method of work or the working environment changes, if monitoring or health surveillance suggests controls are not working, or after an incident. Many contractors also review annually as a matter of routine.

What Is a COSHH Assessment? UK Construction Guide

Q: What is a COSHH assessment?

A COSHH assessment is a written assessment of the substances hazardous to health that a job involves — what they are, how people could be exposed, the harm that could result, and the controls that prevent it. It is required by the Control of Substances Hazardous to Health Regulations 2002.

What COSHH actually requires

The Control of Substances Hazardous to Health Regulations 2002 (COSHH) require employers to assess the risks from hazardous substances before work starts, and then to prevent exposure or — where prevention is not reasonably practicable — adequately control it. Where five or more people are employed, the significant findings must be recorded.

“Substances hazardous to health” is broader than most people assume. It covers chemicals and products, but also dusts, fumes, vapours, mists, gases and biological agents generated by the work — not just things that arrive on site in a container with a label.

What an assessment must cover

The substance — what it is, its hazard classification, and the workplace exposure limit where one applies.
How people are exposed — inhalation, skin contact, ingestion or injection, and which of those routes actually applies to this task.
Who is exposed and for how long — including other trades working nearby, and anyone particularly at risk.
The controls — worked down the hierarchy: eliminate or substitute the substance first, then engineering controls such as on-tool extraction or water suppression, then working methods and limits on exposure time, and only then respiratory protection and other PPE.
Monitoring and health surveillance where the substance or the exposure warrants it.
Emergency arrangements — spills, first aid, and what to do if a control fails.
Instruction, training and information for the people doing the work.

The construction substances most often missed

Assessments tend to cover the obvious products and miss the substances the work itself generates:

Respirable crystalline silica — from cutting, grinding or drilling concrete, stone, brick and mortar. One of the most serious health risks in construction, and rarely controlled adequately by a mask alone.
Wood dust — hardwood and softwood, from sawing and sanding.
Cement and wet concrete — alkaline and abrasive; causes dermatitis and burns through prolonged skin contact.
Isocyanates — in some paints, foams and adhesives; a leading cause of occupational asthma.
Welding fume — now treated as a carcinogen, requiring extraction rather than natural ventilation.
Solvents and adhesives — particularly in enclosed or poorly ventilated spaces.

Asbestos and lead have their own regulations — the Control of Asbestos Regulations 2012 and the Control of Lead at Work Regulations 2002 — and are not covered by a COSHH assessment. If either may be present, that is a separate and more demanding process.

How COSHH fits with your RAMS

A RAMS covers the safe sequence of the job; a COSHH assessment covers the substances that job involves. On most sites the COSHH assessments are appended to the RAMS, and reviewers check that they match — if the method statement says a substance will be used, an assessment for it should exist. A missing COSHH appendix is a common reason for a RAMS to come back unapproved.

Getting them done

Complly Risk produces COSHH assessments alongside the RAMS they belong to, so the two cannot drift apart. Rodney draws on a substance library grounded in safety-data-sheet facts, and you can start an assessment by photographing a product label on site. As with every document, Rodney drafts and a competent person reviews and signs off before it is used.

Draft a COSHH assessment — free in Early Access

This guide is general information about UK construction health & safety practice, not legal advice. Your duties depend on the project and your role on it. Every document Complly produces is drafted by Rodney and must be reviewed and signed off by a competent person before it is used.