COSHH Training Basics: What the Regulations Require on Site

COSHH is the set of rules that requires employers to prevent, or adequately control, workers' exposure to substances that can harm their health. The full name is the Control of Substances Hazardous to Health Regulations 2002. On a construction site that covers everyday materials such as cement, solvents, paints, adhesives and dust, not just obvious chemicals. This guide explains the basics in plain English, and the HSE page is the place to check the full duties.

Key takeaways

COSHH requires employers to prevent or adequately control exposure to hazardous substances, and prevention comes before control.
Hazardous substances include chemicals, fumes, dusts, vapours, mists and gases, and also biological agents, so a dusty task can fall under COSHH even when nothing is labelled.
Employers must assess the risk first, then choose, use and maintain controls that match what the assessment finds.
Personal protective equipment is the last line of defence, used after other controls have done what they can.
Workers must be given information, instruction and training about the substances they work with and the controls they must use.
Safety data sheets and product labels are the starting point for knowing what a substance can do and how to handle it.

What COSHH covers on a construction site

COSHH applies to substances that can cause harm to health when they are breathed in, swallowed, absorbed through the skin or splashed in the eyes. COSHH 2002 regulation 2(1) describes these as including chemicals, fumes, dusts, vapours, mists, gases and biological agents. It is about health effects, such as breathing problems, skin disease and poisoning, rather than injuries from accidents such as falls.

Typical site examples include:

Wet cement and concrete, which can harm the skin.
Dust from cutting, drilling or grinding masonry, concrete and tiles. The separate guide on silica dust and health on site covers one of the most serious dusts.
Solvents, thinners, paints, glues and resins.
Wood dust from cutting and sanding.
Fumes from welding and engine exhaust in poorly ventilated spaces.
Biological hazards such as contaminated water, or waste in an old building.

Some substances have their own separate regulations. Asbestos is the main example, and it is covered by its own regulations. Check the HSE COSHH page if you are unsure which rules apply to a particular substance.

What employers must do

The regulations place the main duties on the employer, but workers have a part to play too. COSHH sets out the steps an employer must follow. In plain English they are:

Assess the risk. Find out what the substance is, what harm it can do, who could be exposed and how.
Decide what precautions are needed. The assessment should lead to specific measures, not a general statement.
Prevent or adequately control exposure. Where possible, remove the hazard altogether. Where that cannot be done, control it.
Make sure the controls are used and kept working. A control that is switched off, blocked or left in a van is not a control.
Monitor exposure where it is needed. In some cases this means measuring what workers are breathing in.
Carry out health surveillance where it is appropriate. This means checking for early signs of harm in people whose work puts them at risk.
Plan for accidents, incidents and emergencies. Spills and exposures should have a prepared response.
Inform, instruct, train and supervise. People need to understand the risks and the controls before they start the task.

The order matters. The HSE page and the regulations both put preventing exposure ahead of controlling it, which is why the best answer to a dusty or harmful task is often to change the task or the product.

Controlling exposure: the order of preference

When exposure cannot be prevented, controls are chosen in a sensible order. The usual approach, which also follows the general principles of control, runs like this:

Remove the substance or stop the task being needed.
Substitute it for something less harmful.
Enclose the process or reduce the amount of substance released.
Use extraction or ventilation to take fumes and dust away from the breathing zone.
Set up safe working methods, for example limiting who is exposed and for how long.
Provide personal protective equipment and make sure it is the right type and fits.

Personal protective equipment, including gloves, eye protection and respirators, sits at the bottom of that list. It only protects the person wearing it, depends on being chosen well and used correctly, and does nothing for others nearby. That is why a supervisor who simply hands out masks has not finished the job.

Using and looking after controls

Workers have duties as well. You are expected to use the controls provided in the way you were shown, report any defect, and tell your supervisor if something is not working or you feel unwell after a task. Extraction units need their filters and bags dealt with as instructed. Respirators need to be stored clean and checked before use.

Labels and safety data sheets

Hazardous products carry a label with warning pictograms and wording. The employer must give workers information about the substances they work with (COSHH regulation 12(2)), and should hold the current sheets for the products in use.

You do not need to memorise a safety data sheet, but you should know what it is for. In general terms it tells you:

What the substance is and what its hazards are.
How to handle and store it safely.
What protective equipment and controls are suggested.
What to do in a spill, a fire or an exposure.
First aid measures.

Read the label and the sheet before a new product is used, not after something goes wrong. If the product name on site does not match the paperwork, ask your supervisor to check before you start.

COSHH checklist for your next task

Use this as a quick check before you start work with a substance or a dusty process.

Question to ask	What a good answer looks like
Do I know what the substance is?	The label is readable and the product matches the assessment.
Have I seen the safety data sheet or the task assessment?	You have been shown the relevant information, or know where it is kept.
Can the task be done a different way?	A less harmful product or a method that creates less dust or fume has been considered.
What control is in place?	Extraction, water suppression, ventilation or another named measure, not just "be careful".
Is the control working?	It has been switched on, checked and set up as intended.
What protective equipment do I need?	The type is named in the assessment and you have been shown how to fit and use it.
What do I do if something goes wrong?	You know the spill, first aid and reporting arrangements.

If any answer is unclear, stop and ask. Asking is part of the process, not a sign of weakness.

Practice check

These questions are original practice items written for this site. They are not official CITB questions and do not predict your result. This site is independent and not affiliated with CSCS or CITB. For the real format, see the operatives test format page.

Question 1. According to the order of preference in COSHH, which approach should an employer consider first?

A. Issue a respirator to everyone doing the task
B. Prevent exposure, for example by removing the substance or changing the method
C. Rely on workers to work quickly
D. Display a warning sign near the task

Correct answer: B. Prevention comes before control, and personal protective equipment sits at the bottom of the order because it protects only the wearer.

Question 2. Where would you look first to find out how a product should be handled and what to do after a spill?

A. The product's safety data sheet and label
B. The delivery note
C. The site notice board for visitors
D. A colleague's memory of the last similar job

Correct answer: A. The label and safety data sheet are written for this purpose, and a supervisor can help you find the right one.

FAQ

Does COSHH only apply to chemicals?

No. COSHH also covers dusts, fumes, vapours, mists, gases and biological agents. Cement dust or wood dust is a hazardous substance for COSHH purposes even though it is not sold as a chemical product.

Who is responsible for COSHH on site?

The employer carries the main legal duties, including assessing the risk and providing controls. Workers must use the controls as instructed and report problems. If you are unsure who holds the assessments on your site, ask your supervisor.

Is a face mask enough to comply with COSHH?

Usually not. Controls that prevent or reduce the release of the substance come first, and respiratory protection is the last line. If a mask is needed it must also be the right type for the substance and must fit properly.

Do I have to read the whole safety data sheet?

You do not need to memorise it, but you should know where to find the hazards, handling advice and emergency information. If a sheet or a label is missing or unclear, raise it with your supervisor before using the product.

Sources

Independent guide, not affiliated with, authorised by, approved by or endorsed by CSCS or CITB. Last updated 2026-10-08.