From the French ATmosphère EXplosible (Explosive Atmospheres), ATEX refers to a set of European Union (EU) directives regulating explosion protection. To be able to manufacture, import and/or distribute Ex equipment within the EU, companies have to fulfill the ATEX requirements.  There is also a set of requirements for companies with Ex zones at their sites. ATEX certification in the EU is similar to, for example, KOSHA in South Korea and EAC in Russia.

There are two ATEX directives: the equipment directive 2014/34/EU (formerly known as ATEX 95, 94/9/EC) for manufacturers, and the workplace directive ATEX 137 (99/92/EC) for employers with Ex work areas.

For Ex equipment, the ATEX direct defines six different zones for explosion protection: three of gas and three for dust. For more information, see Ex Zone. Certified equipment must have the Ex logo, as below.

Ex logo for certified equipment

Designated areas are marked with either a generic danger sign as below, or with a zone-specific marker.

Ex Danger sign for all zone types