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COSHH 2002 — Control of Substances Hazardous to Health
Almost every workplace handles substances covered by COSHH. The regulations don't ban hazardous substances — they require you to understand the risk and control it before exposure happens. The structure of the regulations follows the same logical sequence every time: identify, assess, prevent, control, monitor, train, review.
What counts as a hazardous substance
Anything classified as hazardous under the GB CLP regulation, anything with a Workplace Exposure Limit, biological agents, and any dust at concentrations above the action level. That sweeps in cleaning chemicals, paints, solvents, fuels, welding fume, wood dust, flour, cement and most lab reagents.
Workplace Exposure Limits (WELs)
WELs are concentrations of substances in the air that must not be exceeded. They're published by HSE in document EH40, updated annually. Two main types: Long-Term Exposure Limit (8-hour time-weighted average) and Short-Term Exposure Limit (15-minute reference period).
Prevention before control
COSHH requires you to prevent exposure where reasonably practicable — by substitution, process change, or enclosure — before defaulting to control measures like ventilation or PPE. The hierarchy is fixed:
- Eliminate the substance entirely.
- Substitute with a less hazardous alternative.
- Enclose the process or substance.
- Local Exhaust Ventilation (LEV) at source.
- Administrative controls — procedures, rotation, training.
- Personal Protective Equipment, including Respiratory Protective Equipment (RPE).
RPE face-fit testing
Where tight-fitting RPE is used, face-fit testing is mandatory for every wearer, of every mask type they use. A face-fit test is invalidated by facial hair, significant weight change or facial injury. Records must be kept and the test repeated whenever the user, mask or condition changes.
LEV thorough examination
Local Exhaust Ventilation must be thoroughly examined and tested at least every 14 months by a competent person — a P601 qualified engineer is the recognised standard. Records of the examination must be kept for at least 5 years.
Health surveillance
Where exposure to certain substances remains foreseeable after controls (sensitisers, carcinogens, lead, asbestos, isocyanates, silica), health surveillance by an Occupational Health provider is required. The aim is early detection of harm so controls can be improved.