COSHH Hazards Explained: 7 Hazardous Substances Every Employer Must Know

The Control of Substances Hazardous to Health (COSHH) Regulations 2002 are a key part of UK workplace health and safety law, helping to protect employees from the risks associated with hazardous substances. The regulations place a legal duty on employers to assess risks, prevent or adequately control exposure, and provide appropriate training and supervision. You can view the full legislation here: Control of Substances Hazardous to Health Regulations 2002.

For practical guidance on complying with COSHH requirements, employers can also refer to the Health and Safety Executive’s official COSHH guidance.

From cleaning chemicals and solvents to dust, fumes, vapours, and biological agents, employers must identify hazardous substances in the workplace and implement effective control measures to protect employee health and safety.

Despite the importance of COSHH compliance, many businesses remain unsure about who is responsible for implementing COSHH procedures, conducting risk assessments, and ensuring ongoing compliance with health and safety regulations. While the ultimate responsibility for COSHH management rests with the employer, employees also have legal responsibilities to follow safe working practices and use control measures correctly.

To achieve effective COSHH compliance, everyone within an organisation must understand their roles and responsibilities. In this guide, the occupational safety specialists at SafetyBuyer.com explain the hazardous substances covered by COSHH, how to identify and assess workplace hazards, the meaning of COSHH hazard symbols, and the three essential COSHH control methods every employer should implement to create a safer working environment.

What are COSHH Hazards?

COSHH hazards are substances that can cause harm to human health if they are inhaled, ingested, absorbed through the skin, or otherwise encountered in the workplace. Under the Control of Substances Hazardous to Health (COSHH) Regulations 2002, employers must identify hazardous substances, assess the risks they pose, and implement suitable control measures to protect employees.

COSHH Hazard vs COSHH Risk

A COSHH hazard is the substance itself and its potential to cause harm. A COSHH risk is the likelihood that exposure to the substance will cause harm.

The 7 COSHH Hazards Found in the Workplace

The Control of Substances Hazardous to Health (COSHH) Regulations apply to a wide range of hazardous substances that can pose risks to employee health and workplace safety. Employers are legally required to identify these substances, assess the risks they present, and implement appropriate control measures to minimise exposure.

The seven main categories of hazardous substances covered by COSHH include:

• Chemicals (and products containing chemicals)
• Fumes
• Dust
• Vapours
• Mists
• Gases
• Germs

Understanding which hazardous substances are present in the workplace is the first step in conducting a thorough COSHH risk assessment. By identifying hazards and implementing effective COSHH control measures, employers can reduce exposure risks, protect employee health, and maintain compliance with UK health and safety legislation.

COSHH hazard symbols

Hazard labels play a vital role in workplace safety by helping employees quickly identify the risks associated with hazardous substances. Under the Control of Substances Hazardous to Health (COSHH) Regulations, hazardous materials must be clearly labelled so that appropriate handling, storage, and emergency procedures can be followed.

Many hazardous substances are classified according to internationally recognised danger categories. Common examples include:

• Explosive
• Flammable
• Oxidising
• Gas Under Pressure
• Corrosive
• Acute Toxicity
• Serious Health Hazard
• Irritant/Harmful
• Environmental Hazard

Understanding hazard symbols and classifications is an essential part of COSHH training, risk assessments, and workplace safety management. Employers must ensure that hazardous substances are correctly labelled, supported by up-to-date Safety Data Sheets (SDS), and accompanied by suitable control measures to minimise employee exposure and maintain COSHH compliance.

Employees should always check hazard labels before handling chemicals or other hazardous materials and follow the recommended safety precautions to reduce the risk of accidents, injuries, and occupational illnesses.

To learn more about COSHH symbols and their meanings, read our guide on the importance of COSHH training in the workplace.

The three COSHH control methods that every employer should be aware of

The employer must ensure that three major compliance requirements must be met at the workplace, which includes:

1. Control Measures for Hazardous Substances

COSHH control measures are physical or technical solutions designed to prevent or reduce employee exposure to hazardous substances. Employers should always prioritise engineering controls and containment systems before relying on personal protective equipment (PPE).

Examples of COSHH control measures include:

• Local exhaust ventilation (LEV) systems
• Enclosed processes and equipment
• Safe storage and containment systems
• Spill control procedures and readily available spill kits
• Automated handling processes

Spill kits should be suitable for the hazardous substances being used and easily accessible in areas where spills are most likely to occur. Employees must receive training on spill response procedures and the correct use of spill control equipment.

Spill incidents can expose employees to hazardous substances and increase the risk of injury, contamination and environmental damage. Having appropriate spill control measures in place is an important part of COSHH compliance and workplace safety. To learn more about preparing for and responding to workplace spills, read our guide on Spills in the Workplace: Is Your Business Prepared?.

Regular inspection, testing, maintenance, and monitoring of control measures are essential to ensure continued effectiveness and compliance with COSHH regulations.

2. Safe Working Methods and COSHH Procedures

Safe working methods form a critical part of any COSHH risk assessment. These procedures help minimise exposure to hazardous substances by ensuring employees handle, store, transport, and dispose of materials safely.

Examples of safe working methods include:

• Following documented COSHH risk assessments and procedures
• Using the correct equipment and tools for the task
• Minimising the quantity of hazardous substances used
• Safe handling, transfer, and disposal of hazardous materials
• Implementing cleaning and decontamination procedures
• Reporting spills, leaks, and defects promptly

Employers should provide clear instructions, supervision, and regular COSHH training to ensure safe working methods are understood and consistently followed across the organisation.

3. Workplace Behaviour and Employee Responsibility

Employee behaviour is a key factor in maintaining a safe workplace and achieving ongoing COSHH compliance. Even where effective control measures and procedures are in place, poor workplace behaviour can increase the risk of exposure to hazardous substances.

Examples of good workplace behaviour include:

• Using control measures and PPE correctly
• Following COSHH procedures and training instructions
• Maintaining good personal hygiene, including washing hands after handling hazardous substances
• Avoiding eating, drinking, or smoking in areas where hazardous substances are present
• Keeping work areas clean and free from contamination
• Reporting hazards, incidents, near misses, and health concerns promptly

Regular supervision, COSHH refresher training, and workplace monitoring can help reinforce safe behaviours and support a positive health and safety culture.

Why these COSHH control methods matter

By combining effective control measures, safe working practices, and responsible employee behaviour, employers can significantly reduce the risks associated with hazardous substances. Implementing these three COSHH control methods helps businesses meet their legal obligations, protect employee health, and create a safer working environment.

Conducting a COSHH Risk Assessment

A COSHH risk assessment is a legal requirement for employers whose employees may be exposed to hazardous substances in the workplace. The purpose of the assessment is to identify potential health risks, determine who may be affected, and implement suitable control measures to prevent or reduce exposure.

Follow these seven key steps when conducting a COSHH risk assessment:

1. Identify Hazardous Substances

Begin by identifying all hazardous substances used, stored, handled, or generated in the workplace. This may include chemicals, cleaning products, solvents, dusts, fumes, vapours, gases, mists, and biological agents.

Review product labels, warning symbols, and Safety Data Sheets (SDS) to understand the hazards associated with each substance.

2. Determine Who May Be Harmed

Consider which employees, contractors, visitors, or members of the public may be exposed to hazardous substances. Particular attention should be given to vulnerable individuals, such as young workers, pregnant employees, and those with existing health conditions.

3. Assess the Level of Risk

Evaluate how exposure could occur and the likelihood of harm. Consider:

• The quantity of substance being used or stored
• The duration and frequency of exposure
• The route of exposure (inhalation, skin contact, ingestion, or injection)
• The working environment and ventilation arrangements
• Existing control measures already in place

4. Implement Appropriate Control Measures

Where risks are identified, employers must take steps to eliminate or adequately control exposure. Suitable control measures may include:

• Substituting hazardous substances with safer alternatives
• Installing local exhaust ventilation (LEV) systems
• Using enclosed processes and containment systems
• Providing spill kits and emergency response equipment
• Supplying appropriate personal protective equipment (PPE)
• Implementing safe working procedures and training

5. Record Your Findings

Employers should document their COSHH assessment findings, including identified hazards, affected persons, control measures, and actions required to reduce risks.

Maintaining accurate records demonstrates compliance and helps ensure consistent risk management.

6. Provide Information, Instruction and Training

Employees must understand the hazards they may encounter and the precautions required to work safely. COSHH training should cover:

• The hazardous substances present in the workplace
• Safe handling, storage, and disposal procedures
• Emergency response procedures
• The correct use of PPE and control measures
• How to report incidents, spills, or defects

7. Review and Update the Assessment

A COSHH risk assessment should be reviewed regularly and whenever significant changes occur, such as the introduction of new substances, changes to work processes, workplace incidents, or updated safety information.

Regular reviews help ensure that control measures remain effective and that the organisation continues to comply with COSHH regulations.