Dangerous substances and explosive atmospheres


The purpose of the Dangerous Substances and Explosive Atmospheres Regulations 2002 (DSEAR) is to protect workers from risk of fire and explosion linked to dangerous substances and potentially explosive atmospheres. The DSEAR regulations apply to workplaces where any substance or mixture of substances with the potential to create a risk from “energetic (energy-releasing) events”, such as fire and explosions, is present. Dangerous substances are substances or preparations that are explosive, oxidising, extremely flammable, highly flammable or flammable. They include any dust, whether in the form of solid particles or fibrous materials, petrol, liquefied petroleum gas, paints, varnishes and solvents. An explosive atmosphere is an accumulation of gas, mist, dust or vapour, mixed with air, which has the potential to catch fire or explode.



Employers must carry out a risk assessment whenever a dangerous substance is or may be present at the workplace (Regulation 5).



Employers must eliminate or reduce all risks, so far as reasonably practicable. Where risk is not eliminated, employers must apply measures to control the risk and mitigate any detrimental effects (Regulation 6).



Places where explosive atmospheres may occur must be classified as hazardous or non-hazardous (Regulation 7). Hazardous places must be classified into zones based on the frequency and duration of an “explosive atmosphere”. The regulations stipulate mandatory requirements for all equipment and protective systems for use in hazardous places. Hazardous places must be marked with signs at their points of entry.



Employers must make arrangements to deal with accidents, incidents and emergencies (Regulation 8). These include suitable warning and communication systems, escape facilities, emergency procedures, and equipment for personnel dealing with the incident and practice drills.



Employers must provide employees with precautionary information, instruction and training where a dangerous substance is present at the workplace (Regulation 9).



Containers and pipes used at work for dangerous substances must clearly identify their contents (Regulation 10). The storage of petroleum is covered by the DSEAR.



There are separate regulations on the manufacture and storage of explosives: the Manufacture and Storage of Explosives Regulations 2005 (MSER).



The Petroleum (Consolidation) Regulations 2014 replaced previous petrol storage legislation which was withdrawn. More information is available on the Petroleum page of the HSE website.



The Explosives Regulations 2014 and the Acetylene Safety (England and Wales and Scotland) Regulations 2014 apply to the explosives industry and those who manufacture and store compressed acetylene gas. They replaced the ACOP for the Manufacture and Storage of Explosives Regulations 2005, a number of legislative instruments and previous explosives guidance. This consolidation was one of the recommendations of the 2011 review of health and safety law undertaken by Professor Ragnar Löfstedt (see pages 21-23).



The Dangerous substances and explosive atmospheres ACOP and guidance are available to download from the HSE website, along with Safe handling of combustible dusts: precautions against explosions. A separate ACOP covers Unloading petrol from road tankers (L133).


HSE guidance on the Manufacture and Storage of Explosives Regulations is also available, as well as guidance to support the Explosives Regulations 2014 and guidance on working safely with acetylene.