The Control Of Substances Hazardous to Health Regulations 2002 apply to a very wide range of substances and preparations mixtures of two or more substances - with the potential to cause harm if they are inhaled, ingested or come into contact with or are absorbed through the skin. These include individual chemical substances or preparations such as paints, cleaning materials, metals, pesticides, and insecticides. They can also be biological agents such as pathogens or cell cultures. Substances hazardous to health can occur in many forms, e.g. solids, liquids, vapours, gases, dusts, fibres, fumes, mist, and smoke.
The Health and Safety Executive publish information on workplace exposure limits and definitions of different types of dusts, and other substances. The document is EH40/2005 Workplace exposure limits.