COSHH Explained: Controlling Hazardous Substances at Work.

Every year, thousands of workers across the UK suffer injuries and ill health due to exposure to hazardous substances. From cleaning chemicals in offices to industrial solvents in manufacturing, hazardous substances are present in almost every workplace.

What Does COSHH Stand For?

COSHH stands for Control of Substances Hazardous to Health. These regulations, formally known as the Control of Substances Hazardous to Health Regulations 2002, form the cornerstone of UK workplace safety legislation for managing dangerous substances.

The COSHH regulations require employers to control exposure to hazardous substances in the workplace to prevent ill health. This includes protecting not just employees, but also contractors, visitors and anyone else who might be affected by work activities.

What is COSHH and Why Does It Matter?

The COSHH meaning represents a comprehensive framework for protecting human health in the workplace. The regulations cover any substance that could cause harm to health, whether through immediate effects (like chemical burns) or long-term exposure (such as respiratory diseases).

The Human Cost

The latest HSE statistics (2023/24) paint a clear picture of workplace health impacts:

• 1.7 million workers suffering from work-related ill health.

• 12,000 lung disease deaths estimated to be linked to past occupational exposures.

• 2,218 mesothelioma deaths in 2023 due to past asbestos exposures.

• 33.7 million working days lost due to work-related ill health and injury.

  
  

The Business Impact

Poor COSHH management damages businesses through:

• Increased insurance premiums.

• Legal costs and unlimited fines under the Health and Safety at Work etc. Act 1974.

• Lost productivity and absenteeism.

• Recruitment and training costs for replacement staff.

• Damage to company reputation.

• Enforcement action by the Health and Safety Executive.

  
  

What Substances Does COSHH Cover?

COSHH regulations apply to a wide range of hazardous substances found in workplaces, including:

Chemical Substances

• Cleaning products – bleach, disinfectants or degreasers.

• Solvents – paint thinners, adhesives or printing inks.

• Acids and alkalis – battery acid or caustic soda.

• Paints and coatings – primers, varnishes or spray paints.

• Pesticides and herbicides

  
  

Physical Forms

• Dusts – wood dust, cement dust or flour dust.

• Fumes – welding fumes or exhaust emissions.

• Vapours – from heated chemicals or solvents.

• Mists – from spray painting or machining.

• Gases – carbon monoxide or hydrogen sulfide.

• Fibres – mineral wool or synthetic fibres.

• Nano-particles – engineered nanoparticles.

  
  

Biological Agents

• Fungi – moulds or yeasts.

• Parasites

• Breath or Urine

  
  

What COSHH Doesn't Cover

Importantly, COSHH legislation doesn't cover:

• Asbestos (covered by the Control of Asbestos Regulations 2012)

• Lead (has specific regulations under the Control of Lead at Work Regulations 2002)

• Radioactive substances (covered by separate HSE radiation guidance)

  
  

COSHH Risk Assessment: The Foundation of Safety

A COSHH assessment an important step in managing workplace hazards. Under Regulation 6 of the COSHH regulations, employers must conduct "suitable and sufficient" risk assessments before work with hazardous substances begins. More serious and complex risks require greater consideration to meet this requirement, simpler and lower risk situations will require less.

The 5-Stage COSHH Assessment Framework

According to HSE guidance, COSHH assessment follows a systematic five-stage process:

1. Identify the Hazards

• Read product labels and safety data sheets (SDS).

• Contact suppliers if in doubt.

• Consider harmful substances produced by your processes (wood dust from sanding, silica dust from tile cutting or welding fumes).

• Look for processes that emit dust, fume, vapour, mist or gas.

• Consider skin contact with liquids, pastes and dusts.

• Check for substances with workplace exposure limits (WELs).

  
  

2. Assess the Risks

• Decide who might be harmed and how.

• Consider how workers might be exposed (inhalation, skin contact or ingestion).

• Evaluate how often people work with the substance and for how long.

• Think about others who could be exposed (maintenance workers, contractors, visitors or public).

• Review what you're already doing to control risks.

• Identify what further action is needed.

  
  

3. Control the Risks

Follow the hierarchy of control:

• Elimination: Can you avoid using the substance or find a safer alternative?

• Changing the process: Reduce temperature to minimise vapour or use pellets instead of powders.

• Containment: Enclose processes, use closed transfer systems or implement local exhaust ventilation (LEV).

• Systems of work: Restrict access, plan storage and disposal and ensure proper labelling.

• Cleaning: Plan for easy cleaning, have spillage procedures and use dust-free methods.

• Personal protective equipment: Only when other measures are insufficient.

4. Information and Training

• Explain the assessment outcomes to workers.

• Communicate hazards, risks and workplace exposure limits.

• Train workers on correct use of controls and PPE.

• Share monitoring results and health surveillance findings.

• Prepare emergency procedures.

• Brief contractors on workplace risks.

  
  

5. Record Your Findings

• Record assessment if you have 5 or more employees (recommended for all).

• Document steps taken to identify risks.

• List actions taken to control risks.

• Keep records up to date.

  
  

6. Review Your Controls

• Review risk assessments regularly.

• Check controls are working effectively.

• Update when there are changes to staff, processes, substances or equipment.

• Review after accidents, near misses or worker concerns.

• Update assessment records with any changes.

  
  

Real-World COSHH Assessment Example

Scenario: Hair Salon

A hair salon uses various chemicals including:

• Hair dyes containing ammonia and hydrogen peroxide.

• Bleaching agents with sodium persulfate.

• Nail products with formaldehyde.

• Cleaning products with sodium hypochlorite.

  
  

Assessment findings:

• Who's at risk: Stylists, clients and cleaning staff.

• Exposure routes: Skin contact and inhalation of vapours.

• Health effects: Skin irritation, respiratory sensitisation and dermatitis.

  
  

Control measures implemented:

• Improved ventilation systems.

• Protective gloves and aprons.

• Client skin patch testing.

• Safe storage in locked cabinets.

• Staff training on proper mixing techniques.

  
  

Understanding COSHH Symbols and Signs

Modern COSHH symbols follow the globally harmonised system (GHS) with distinctive diamond-shaped pictograms:

Key Hazard Symbols

• Skull and Crossbones (Toxic) - Substances that can cause death or serious harm at low doses. Examples: Pesticides, mercury compounds or cyanide.

• Flame (Flammable) - Substances that catch fire easily. Examples: Petrol, acetone or many solvents.

• Corrosion - Substances that can destroy living tissue and materials. Examples: Strong acids, caustic soda or bleach.

• Exclamation Mark (Irritant) - Substances causing skin, eye or respiratory irritation. Examples: Mild acids, detergents or some glues.

• Health Hazard - Substances causing serious long-term health effects. Examples: Carcinogens or substances affecting fertility.

• Gas Cylinder - Pressurised gases. Examples: Compressed air, welding gases or aerosols.

• Exploding Bomb - Explosive substances. Examples: Some peroxides or certain chemicals when mixed.

• Flame Over Circle (Oxidising) - Substances that intensify fire. Examples: Hydrogen peroxide or bleaching powder.

• Environment - Substances dangerous to aquatic life or environment. Examples: Certain pesticides or heavy metals

Workplace Exposure Limits (WELs)

The UK Health and Safety Executive sets Workplace Exposure Limits for many hazardous substances. These represent concentrations in air that most workers can be exposed to day after day without adverse health effects. The annual publication EH40 "Workplace exposure limits" contains the complete list of current exposure limits.

Types of Exposure Limits

Long-term Exposure Limit (LTEL) - 8-hour time-weighted average exposure

Short-term Exposure Limit (STEL) - 15-minute time-weighted average exposure

Example: Toluene (common solvent)

• LTEL: 50 ppm (191 mg/m³)

• STEL: 100 ppm (384 mg/m³)

COSHH Training Requirements

Effective COSHH training should cover:

For All Employees

• COSHH meaning and importance

• Hazard identification techniques

• Safe handling procedures

• Emergency procedures

• Proper PPE use

• Reporting requirements

  
  

For Supervisors and Managers

• COSHH risk assessment techniques

• Control measure selection

• Monitoring and review procedures

• Legal responsibilities

• Incident investigation

  
  

Common COSHH Compliance Mistakes

1. Inadequate Risk Assessments

• Using generic assessments instead of workplace-specific ones.

• Failing to consider combination effects of multiple substances.

• Not updating assessments when processes change.

  
  

2. Poor Control Implementation

• Relying too heavily on PPE instead of eliminating risks.

• Inadequate maintenance of control systems.

• Insufficient monitoring of control effectiveness.

  
  

3. Training Gaps

• One-off training without refreshers.

• Failing to train temporary workers.

• Not providing role-specific training.

  
  

4. Documentation Failures

• Poor record keeping.

• Missing safety data sheets.

• Inadequate incident reporting.

  
  

Health Surveillance Under COSHH

For certain substances and exposure scenarios, COSHH requires health surveillance to detect early signs of work-related ill health.

When Health Surveillance is Required

• Work with substances known to cause specific diseases (listed in Schedule 6 of COSHH).

• Exposure levels that may cause harm despite controls.

  
  

Types of Health Surveillance

• Questionnaires for respiratory symptoms.

• Skin examinations for dermatitis.

• Lung function tests for respiratory sensitisers.

• Blood tests for lead exposure.

• Audiometry for hearing damage from noise and ototoxic substances.

  
  

Emergency Procedures

Spillage: Contain immediately, clean safely, dispose correctly, report incident.

Exposure: First aid, emergency shower/eyewash, seek medical attention, document.

Equipment: Spill kits, emergency showers, ventilation controls, communication systems.

Essential Documentation

Safety Data Sheets: 16-section chemical information documents.

Assessment Records: Substances, hazards, who's at risk, controls, and monitoring.

Other Records: Training logs, health surveillance, incidents or equipment maintenance.

Review documentation immediately if: assessments are no longer valid, work circumstances have changed, control system are defect, work-related illness have been reported or new hazard evidence emerges.

Getting Professional Help

Effective COSHH assessments require expertise in both hazardous substance control and health and safety principles. Many businesses benefit from professional support to ensure their assessments are comprehensive, compliant and practical.

We at DuoDynamic Safety Solutions specialise in COSHH assessments and providing health and safety advice for businesses across most sectors. We can help you create documentation that protects your workers and meets all regulatory requirements.