CHEMICAL & SUBSTANCE GOVERNANCE

COSHH Assessments for ContractorsManaging hazardous substances under UK health & safety law.

A practical operational guide to managing chemicals, gases, fumes, and hazardous substances under the Control of Substances Hazardous to Health Regulations 2002 for UK commercial contractors.

7 min read•Updated 2026• UK Commercial FM Standard

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Executive Summary

An SDS is not a COSHH assessment. A valid COSHH evaluation details how a substance is stored, diluted, applied, ventilated, and contained in real site conditions.

Authoritative UK facilities management guidance. Non-legal operational standard.

01 // STATUTORY OBLIGATION

Understanding the 8 Core Principles of COSHH

Under the Control of Substances Hazardous to Health Regulations 2002, contractors must systematically assess and control exposure to all hazardous materials. The Health and Safety Executive (HSE) outlines an 8-step approach:

Assess the Risks

Identify all substances used or generated (e.g. welding fumes, silica dust, refrigerants).

Decide What Precautions Are Needed

Can the chemical be eliminated or substituted for a safer alternative?

Prevent or Adequately Control Exposure

Prioritise Local Exhaust Ventilation (LEV), closed transfer systems, and dilution.

Ensure Control Measures Are Maintained

Verify LEV testing (every 14 months under Regulation 9), check seals and containers.

Monitor Exposure

Measure airborne concentrations where WELs exist in EH40 or where required.

Carry Out Health Surveillance

Mandatory for operatives exposed to isocyanates, respiratory sensitisers, or skin irritants.

Prepare Emergency & Spill Procedures

Eyewash stations, chemical spill kits, neutralising agents, and evacuation routes.

Inform, Instruct & Train Operatives

Ensure technicians understand GHS hazard pictograms, SDS sheets, and PPE donning/doffing.

02 // EXPOSURE MECHANISMS

The Four Primary Routes of Chemical Exposure

1. Inhalation (Breathing)

Most common industrial route. Fumes, mists, dusts, and gases enter the lungs and bloodstream (e.g. solvent vapours, welding fumes, refrigerant asphyxiation).

2. Skin Contact / Absorption

Direct contact leading to occupational dermatitis, chemical burns, or systemic poisoning absorbed through broken skin (e.g. coil acid cleaners, epoxy resins).

3. Eye Contact / Splashing

Splashes or airborne corrosive aerosols causing permanent corneal damage or blindness. Requires EN 166 chemical splash goggles and nearby eyewash.

4. Ingestion (Swallowing)

Chemical transfer from contaminated hands during eating, drinking, or smoking on site. Strict site hygiene and hand-washing mandatory.

QUESTIONS & ANSWERS

COSHH Assessment FAQs for Contractors

Key guidance on Safety Data Sheets, exposure limits, and FM supply chain compliance.

What is COSHH?↓

COSHH stands for the Control of Substances Hazardous to Health Regulations 2002 (as amended). It is the UK statutory framework requiring employers and contractors to prevent or reduce workers' exposure to hazardous substances (including chemicals, fumes, dusts, vapours, gases, and biological agents).

What is the difference between a Safety Data Sheet (SDS) and a COSHH Assessment?↓

A Safety Data Sheet (SDS) is provided by the chemical manufacturer and describes the substance's properties, hazards, and first aid measures in the bottle. A COSHH Assessment is written by the contractor and evaluates how that substance will actually be used on site (e.g. quantity, dilution, ventilation, application method, operative exposure duration, and emergency controls). Having an SDS is NOT the same as conducting a COSHH assessment.

Which trades require COSHH assessments?↓

Almost every trade works with hazardous substances: Cleaners (detergents, descalers, bleach, sanitiser); HVAC/Refrigeration engineers (refrigerant gases, coil cleaners, compressor oils); Plumbers (flux, solder, solvent cement, drain acids); Electricians (cable pulling lubricants, solvent cleaners, resin jointing kits); Fabric/Decorating contractors (paints, solvents, adhesives, fillers, wood dust).

What are Workplace Exposure Limits (WELs)?↓

Workplace Exposure Limits (set out in HSE publication EH40) are legal maximum concentrations of airborne hazardous substances averaged over an 8-hour Time Weighted Average (TWA) or 15-minute Short-Term Exposure Limit (STEL). COSHH assessments must demonstrate that controls keep operative exposure well below these statutory limits.

KNOWLEDGE ECOSYSTEM