A hazardous substance can be anything, whether natural or artificial, solid, liquid or powder, that can potentially harm the health of employees and other persons, including unborn children, at work. A more formal definition is provided in the regulations.

Most workplaces will use hazardous substances in one form or another, and any one workplace may use many different hazardous substances. The "use" of hazardous substances includes the production, handling, storage, transport or disposal of the substance.

Examples of hazardous substances include:

• industrial chemicals

• cleaning products

• pesticides

• paints

• glues

• pool chemicals

• garden chemicals

• hair products

• synthetic mineral fibres, eg: fibreglass.