Health and Safety
Executive / Commission
Fire and explosion
Flammable substances can be grouped into four categories:
Liquids (such as petrol and other fuels) and solvents in industrial products (such as paint, ink, adhesives and cleaning fluids) give off flammable vapour which, when mixed with air, can ignite or explode. Flammable liquids are classed as:
Liquids which have a flash point lower than 0°C and a boiling point (or, in the case of a boiling range, the initial boiling point) lower than or equal to 35°C.
Liquids which have a flash point below 21°C but which are not extremely flammable.
Dusts can be produced from many everyday materials such as coal, wood, grain, sugar, certain metals and synthetic organic chemicals. A cloud of combustible dust in the air can explode violently if ignited.
Gases such as liquefied petroleum gas or methane. These are usually stored under pressure in cylinders and bulk containers. Uncontrolled releases can readily ignite or cause the cylinder to become a missile.
Solids include materials such as plastic foam, packaging, and textiles which can burn fiercely and give off dense black smoke, sometimes poisonous.
HSE and local authorities are responsible for enforcing those workplaces covered by the legislation on working in potentially explosive atmospheres. These are covered in the following list:
Details of HSE priced publications, free leaflets, research and useful links.
At some sites, the amount of substance present may be so large that the site has to comply with the following legislation to control the potential major accident hazards.
Substances manufactured intentionally as explosives are not covered on this page, for information on this topic or these industries please visit the HSE Explosives website.