Dangerous Substances and Explosive Atmospheres Regulations 2002

DSEAR, the Dangerous Substances and Explosive Atmospheres Regulations 2002, is the United Kingdom's implementation of the European Union-wide ATEX directive.

The intention of the Regulations is to reduce the risk of a fatality or serious injury resulting from a "dangerous substance" igniting and potentially exploding. Examples of a "dangerous substance", as defined by DSEAR, include sawdust, ethanol vapours, and hydrogen gas. The regulation is enforceable by the HSE or local authorities.

From June 2015, DSEAR incorporated changes in the EU Chemical Agents Directive and now also covers gases under pressure and substances that are corrosive to metals.