Hazardous substances safety

The first step is to create an inventory of the harmful substances that are in your area of responsibility. Here are some suggestions to get you started.

Please use the inventory template (.xlsx) to record your inventory

• Walk around your workplace. What hazardous substances are there? Where are they? Think about chemicals, products or mixtures, fumes, dusts, vapours, mists, liquids, gases, and asphyxiating gases. Also consider biological agents and nanotechnology.
• Which tasks could lead to exposure? Include the intended use and by-products, storage, handling, transportation, waste disposal, cleaning, and maintenance in your task list. Think about the activities carried out, such as pouring, packing, weighing or dilution. Consider possible emergency situations, e.g., the accidental release of a substance or a spillage.
• Are there any areas of concern? Think about accidents or near misses involving hazardous substances.

Specialist advice

• COSHH (hse.gov.uk) - HSE industry-specific information and case studies.
• HSE direct advice sheets for tasks and processes in industry.

There are some hazardous substances that are covered by separate procedures so do not normally need to be included on the COSHH assessment. They are legionellalegionellalegionella, asbestosasbestosasbestos, and deliberate work with biological agentsbiological agentsbiological agents.

If you handle significant quantities of flammable substances, you may need to do a separate DSEAR assessmentDSEAR assessmentDSEAR assessment.

Once you have identified your substance you need to find out how it is harmful to health. If it is a chemical, the safety data sheet and hazard label provide information on the hazards and the handling, storage and emergency measures needed. They are provided by the supplier and must be up to date. Industry information will help in gathering information about biological agents or natural products like flour and wood dust.

The safety data sheet itself is not the COSHH assessment. The COSHH assessment is a product of the substance’s hazard information, how you are exposed and your control measures to reduce the risk.

Safety data sheets and labels have pictograms, signal words, hazard statements (phrases that describe the nature of the hazard) and precautionary statements (phrases that describe recommended measures to prevent harm) which follow a standard international labelling system.

• HSE guide to chemical classification
• HSE guide to labelling and packaging
• HSE guide to cleaning products and the corrosive pictogram

Understanding how people are exposed to the substance and how it enters the body can inform you on the range of control measures needed to reduce exposure. Hazardous substances can enter the body by:

• ingestion
• inhalation
• absorption through skin and eyes
• accidental injection

Once you know the routes of entry, consider the number and types of people who could be harmed through direct or indirect exposure. Direct exposure is when someone knowingly handles the substance or is aware that it's present as part of their work activity. Indirect exposure might happen when someone is exposed through an unrelated activity, such as cleaning, maintenance, responding to an emergency situation or working nearby.

In both cases, the nature of exposure needs to be assessed by establishing the likelihood and the frequency of exposure, along with the levels people are exposed to and for how long. Additional consideration must be made for people especially at riskpeople especially at riskpeople especially at risk. 

• HSE guide to workplace exposure limits

Now you know the risk posed by the substances in your workplace and the nature of exposure, choose control measures to prevent or adequately control exposure.

Control measures

When considering control measures, think about how you can reduce the likelihood of exposure and the harm and consequences if exposure occurs. Include control measures for emergency situations as well. You must consider control measures in order of priority and effectiveness.

• Eliminate the substance. If you do not need it, safely remove it from the workplace.
• Substance substitution. This is using alternative substances that are less hazardous or using another process that does not create a hazardous form.
• Engineering controls that enclose the process using full and partial enclosures.
• Extract emissions at source, for example, local exhaust ventilation (LEV). LEV needs periodic thorough examination and testing and records kept.
• Limit the number of people in harm’s way as much as possible. This can be authorised people only and permit to work procedures. 
• Provide personal protective equipment.
• Training for employees. The people at risk get the right information at the right time to stay safe. Some training courses may also require refresher training.

You will also need to consider what else is required to make sure your control measures are maintained, inspected and replaced when they are damaged or expired. In some cases, you will need to arrange for monitoring to be carried out to ensure your control measures are working well.

Health surveillance

Health surveillance involves ongoing health checks designed to detect ill-health effects from specific identified hazards. It is required when:

• there is a disease associated with the substance in use (e.g. Asthma, Dermatitis, cancers)
• it is possible to detect the disease or adverse change and reduce the risk of further harm
• the conditions in the workplace make it likely that the disease will appear.

If you use or create substances that are respiratory or skin sensitisers or potential carcinogens, health surveillance will be required unless control measures are robust enough to prevent exposure.

Your COSHH assessment should identify whether health surveillance is required. If you think you may need health surveillance for your hazardous substances, email Occupational Health for advice.

• HSE guidance of COSHH health surveillance