COSHH assessment for construction

The injuries that make the news on construction sites are the falls and the collapses. The ones that quietly do the most harm are often the substances: the silica dust from cutting a paving slab, the fumes from a diesel generator, the isocyanates in some sprayed coatings. A COSHH assessment is how a site controls those risks, and it is a document a principal contractor will expect alongside the RAMS for any task that creates or uses a hazardous substance. This guide explains what a construction COSHH assessment should cover.

What a COSHH assessment for construction needs to cover

COSHH, the Control of Substances Hazardous to Health Regulations 2002, asks you to identify the hazardous substances a task involves, assess who could be exposed and how, and put controls in place that adequately prevent or reduce that exposure. On a construction site the substances split into two groups: products you bring on, such as adhesives, resins, solvents and cements, and hazards the work itself creates, such as silica dust, wood dust and welding fume. Both need assessing, and the process generated hazards are often the more serious.

The main COSHH hazards on a construction site

• Respirable crystalline silica from cutting, grinding or drilling concrete, stone, brick and screed. A major cause of long term lung disease.
• Wood dust from cutting and sanding, especially hardwoods and manufactured boards.
• General construction dust from demolition, chasing and clearing.
• Cement and wet concrete, which can cause burns and dermatitis.
• Solvents, resins, adhesives and coatings, including isocyanates in some two pack products.
• Fumes: welding fume, diesel engine exhaust, and fumes from hot works.
• Naturally occurring and site specific hazards such as lead in old paint and possible contamination in the ground.

Asbestos is controlled separately under its own regulations and is not managed through a general COSHH assessment.

The control hierarchy a reviewer expects

COSHH controls follow an order. Work down it, do not jump to protective equipment first.

• Eliminate or substitute: avoid the substance or use a less hazardous one, for example a lower silica material or a ready mixed product.
• Change the process: cut fewer pieces, order materials pre cut, or use a method that makes less dust.
• Control at source: water suppression and on-tool extraction for dust, local exhaust ventilation for fume, kept in good order and tested where required.
• Organisational controls: keep others out of the dust or fume zone, limit exposure time, and good housekeeping instead of dry sweeping.
• Respiratory and personal protection last: suitable RPE with the right protection factor, face fit tested for tight fitting masks, plus gloves and eye protection, backing up the controls above rather than replacing them.

How to record and use a COSHH assessment

1. List the substances the task involves, both supplied products and process generated hazards.
2. Gather the information: safety data sheets for products, HSE guidance for dust and fume.
3. Assess who is exposed, how, and for how long, including nearby trades and the public.
4. Set the controls in hierarchy order and record them against each substance.
5. Add health surveillance and exposure monitoring where the assessment shows it is needed.
6. Brief the team through a toolbox talk, so the controls are understood on the tools.
7. Review it when the material, the method or the guidance changes.

Where COSHH assessments go wrong on site

• Relying on a supplier safety data sheet as if it were the assessment. The sheet is information, not the assessment of your task.
• Missing the process generated dust and fume because there is no product sheet for it.
• Going straight to a mask without source control such as water or extraction.
• Tight fitting masks issued without face fit testing.
• No plan for people working nearby who did not create the dust but breathe it.

Frequently asked questions

What does COSHH stand for?

Control of Substances Hazardous to Health. The COSHH Regulations 2002 require employers to assess the risk from hazardous substances at work, prevent or adequately control exposure, and keep the controls working. On construction sites that covers dusts, fumes, chemicals and some naturally occurring hazards.

Does COSHH cover construction dust?

Yes. Respirable crystalline silica from cutting or grinding concrete, stone and brick, along with wood dust and general construction dust, are among the most serious COSHH risks on site because the harm builds up over years. Water suppression, on-tool extraction and suitable respiratory protection are common controls.

Where do I find the information for a COSHH assessment?

For supplied products, start with the safety data sheet, which lists the hazards and handling advice. For process generated hazards such as silica dust or welding fume, use HSE guidance. The safety data sheet is a source of information, not the assessment itself.

Is this legal advice?

No. This is a plain-English working summary to support site teams. For the detail see the COSHH Regulations 2002 and HSE guidance, including the construction dust guidance.

Related guides: RAMS for working at height, permit to work, and the CDM 2015 regulations explained pillar.