This guide is maintained as a current resource for September 2026 and covers only the laws of England and Wales. Information is for general guidance, not legal advice. Consult a qualified solicitor for advice specific to your situation.
Discover how employers in England and Wales must handle hazardous substances under COSHH and health and safety law, including risk assessments, control measures, training, emergency planning and legal consequences of non‑compliance.
Employers in England and Wales have specific legal duties when work involves hazardous substances. These duties stem from the Control of Substances Hazardous to Health Regulations 2002 (COSHH) and the broader health and safety framework under the Health and Safety at Work etc. Act 1974. The purpose of these laws is to prevent ill‑health, injury and chronic disease caused by exposure to harmful chemicals, dusts, fumes, biological agents and other dangerous materials. Breach of these duties can lead to enforcement action by the Health and Safety Executive (HSE), civil claims for compensation, and criminal penalties. This article explains how hazardous substances must be managed in practice and what employers need to do to meet their legal obligations.
What Is a Hazardous Substance?
A hazardous substance under COSHH is any chemical or material that can cause harm to health if inhaled, ingested, absorbed through the skin, or otherwise encountered in the workplace. This includes:
- chemical products and preparations
- gases, vapours, dust and mists
- biological agents such as bacteria and viruses
- substances that carry hazard symbols for toxicity, corrosion, irritation and other risks
Some materials such as asbestos or lead are regulated separately, but COSHH covers the majority of harmful workplace substances.
Legal Framework Governing Hazardous Substances
COSHH Regulations
The Control of Substances Hazardous to Health Regulations 2002 require employers to plan, manage and monitor work with hazardous substances. These regulations sit within the wider health and safety regime created by the Health and Safety at Work etc. Act 1974, which imposes a general duty to ensure, so far as is reasonably practicable, the health, safety and welfare of employees and others affected by work activities.
COSHH applies to substances used deliberately and to those generated during work (such as welding fume or dust). Employers must not start work that could expose employees to hazardous substances unless they have complied with the regulations.
Step‑by‑Step: Handling Hazardous Substances
1. Identify Hazardous Substances
The first obligation is to identify all hazardous substances present in the workplace. This includes substances that may be created by a process or brought in by contractors. Employers should consult Safety Data Sheets (SDS) supplied with chemicals to understand hazards and ensure relevant materials are included in assessments.
2. Carry Out COSHH Risk Assessments
A COSHH risk assessment is the core legal duty employers must complete before any work involving hazardous substances begins. The assessment should:
- locate and list hazardous substances in use
- evaluate how people might be exposed (inhalation, skin contact, ingestion)
- assess the likelihood and severity of harm
- determine what control measures are necessary to prevent or control exposure
Suitable and sufficient assessments must be carried out by someone with the appropriate knowledge and experience and, where there are five or more employees, significant findings must be recorded in writing.
3. Prevent or Control Exposure
COSHH requires employers to prevent exposure to hazardous substances wherever reasonably practicable. Where elimination is not possible, employers must implement adequate controls to reduce exposure to acceptable levels. This might include:
- using less hazardous substances where possible
- modifying processes to minimise generation of harmful materials
- installing local exhaust ventilation to capture dust, fumes or vapours at source
- segregating work areas where harmful substances are used
Only where such measures do not provide sufficient protection should employers rely on personal protective equipment (PPE), such as respirators, gloves or eye protection.
4. Provide Information, Instruction and Training
Employers must give workers clear and relevant training and information about:
- the properties and health risks of substances they work with
- the control measures in place
- correct use of PPE and engineering controls
- emergency procedures for spills or exposures
Training should be tailored to the specific substances and work practices in the workplace and revisited whenever risks change.
5. Maintain and Review Control Measures
Control measures cannot be “set and forget”. Employers must ensure that ventilation systems, PPE, safety barriers and other controls are maintained, examined and tested at appropriate intervals. COSHH also calls for monitoring and health surveillance where assessments indicate it is necessary, such as where exposure could lead to long‑term health effects.
6. Prepare for Emergencies
Handling hazardous substances carries the risk of accidents – for example, spills, leaks or unplanned exposures. Employers must have emergency plans that cover:
- spill containment and clean‑up procedures
- first‑aid arrangements for exposure
- safe evacuation in the event of a release
- reporting and investigation protocols for incidents
Training and drills ensure that employees know how to respond if something goes wrong.
Employer and Employee Responsibilities
While employers carry the primary legal duties under COSHH, employees also have responsibilities. Workers must:
- use control measures and PPE provided by the employer correctly
- follow safety procedures and instructions
- report defective equipment or emerging hazards
- participate in training and health surveillance where required
This cooperative approach helps maintain compliance and supports a safer workplace.
Enforcement and Legal Consequences
Failure to comply with COSHH and associated health and safety law is a criminal offence. The HSE can take enforcement action including:
- improvement notices requiring remedial action
- prohibition notices stopping unsafe work
- prosecution in the courts, with potential unlimited fines and custodial sentences for serious breaches
A COSHH breach that results in injury or disease may also expose employers to civil claims for compensation. Serious failings that contribute to fatalities or grave illness can attract custodial sentences under broader offences in the Health and Safety at Work etc. Act 1974.
Common Questions
Is COSHH compliance mandatory?
Yes. Employers must comply with the Control of Substances Hazardous to Health Regulations whenever work involves hazardous substances. Non‑compliance is a criminal offence.
How often should COSHH risk assessments be reviewed?
There's no fixed timeframe, but assessments should be reviewed whenever there are changes to substances, processes, equipment or work practices, and after incidents.
Do employers have to monitor employee health?
Where risk assessments identify significant health risks, employers must provide health surveillance appropriate to the hazard.
Key Takeaways
Handling hazardous substances in the workplace requires careful planning and strict compliance with COSHH and broader health and safety law in England and Wales. Employers must identify hazardous materials, carry out risk assessments, prevent or control exposure, provide training and information, maintain control measures, and prepare for emergencies. Employees also have duties to use controls and report hazards. Effective management of hazardous substances reduces the risk of illness and injury, supports legal compliance, and protects both workers and employers from enforcement action and compensation claims.
