A chemical substance used or present in the workplace that can cause harm to people due to its physical or chemical properties if not correctly controlled. Such substances include liquids, vapours, gases, and dust in the form of solid particles or fibrous materials that can form an explosive mixture with air. Examples include paints, solvents, reagents, varnishes, flammable gases, such as LPG, dusts and particulates from foodstuffs, machining and sanding operations that can cause harm through fire or explosion. In the UK, the DSEAR Regulations 2002 of the HSE (Health and Safety Executive) are intended to protect workers and members of the public from dangerous substances.