Control of Substances Hazardous to Health (COSHH)

A COSHH assessment identifies and evaluates the risks from hazardous substances used or created in your workplace. It looks at how employees might be exposed - whether by breathing in fumes, skin contact, or accidental ingestion - and determines what controls are needed to protect health. The aim is to prevent exposure wherever possible, or keep it to safe levels using a structured risk management approach.

Hazardous substances can cause serious health problems, including skin irritation, asthma, lung disease, and even long-term illnesses such as cancer. A proper COSHH assessment helps you identify these risks before they harm your team. It also ensures you comply with UK regulations, which require employers to protect employees from exposure to substances that could damage their health. Beyond compliance, good COSHH management creates a safer and healthier workplace, which can also improve productivity and staff wellbeing.

COSHH assessments should be reviewed regularly and updated whenever there are changes to your processes, equipment, or the substances you use. Even if nothing changes, it’s good practice to review assessments at least annually to ensure controls remain effective. If monitoring shows exposure levels are higher than expected, or if there are any incidents of ill health, the assessment should be reviewed immediately.

A COSHH assessment starts with identifying all hazardous substances in your workplace, including by-products such as dusts or fumes. The risk assessment process then looks at how these substances are used, who might be exposed, and how often. Once the risks are understood, control measures are designed using the hierarchy of control - starting with elimination or substitution of the substance where possible, and then applying engineering controls, safe working procedures, and personal protective equipment if needed. Good COSHH management also includes regular monitoring, maintenance of control measures, and clear information and training for staff.

Under the Control of Substances Hazardous to Health (COSHH) Regulations, employers must follow the hierarchy of control - starting with the most effective measures and only relying on personal protective equipment (PPE) as a last line of defence.

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The hierarchy is:

1. Eliminate the hazardous substance if possible.

2. Substitute it with a safer alternative or use a less hazardous form.

3. Use engineering controls such as Local Exhaust Ventilation (LEV) to remove contaminants at the source.

4. Apply administrative controls – like rotating staff, limiting exposure time, or improving work practices.

5. Provide PPE and Respiratory Protective Equipment (RPE) when other controls can’t fully remove the risk.

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Local Exhaust Ventilation (LEV)

LEV captures dust, fumes, and vapours at the source before they can be inhaled. Hoods must be correctly positioned, airflow kept within design limits, and systems maintained and tested at least every 14 months.

Respiratory Protective Equipment (RPE)

When other controls can’t fully reduce exposure, RPE provides extra protection. It must be suitable, face-fit tested for tight-fitting masks, and properly maintained.

Personal Protective Equipment (PPE)

Gloves, goggles, or protective clothing may be needed where there’s a risk of skin or eye contact. PPE should only be used after other controls and must be kept in good condition.

At Workplace Scientifics, we focus on how hazardous substances actually affect your people and your day-to-day operations. We look closely at your processes, talk to your team, and identify the real risks that matter to you. Our recommendations are practical and tailored to your workplace, so you can be confident that the controls we suggest will work in practice. We also explain everything clearly, giving you the support you need to protect your team and keep exposure under control.