ATEX is an acronym of the French Atmospheriques Explosives. This European Directive amends and adds safety requirements for hazardous areas in the relevant national legislation in the member states of the European Union, bringing in a common standard. The purpose is to enable the sale of equipment across the European Union, without manufacturers having to satisfy different requirements for each national market.

Where equipment is to be used in potentially explosive atmospheres containing gas or combustible dust, it must comply with the ATEX directive.
Compliance with the ATEX Directive means reinforced safety aspects – safer design, more demanding testing procedures, and specific quality assurance measures for the design as well as the manufacturing process. It requires employers to protect both staff and local communities from the risk of an explosive atmosphere.

ATEX consists of two parts: ATEX 95, which concentrates on the duties of the manufacturers; and ATEX 137, which focuses on the end users’ obligations.
The ATEX 95 Directive is implemented into UK Law by the The Equipment and Protective Systems Intended for use in Potentially Explosive Atmospheres Regulations 1996 (EPS Regulations) making compliance with the ATEX directive mandatory from July 1st 2003.

The ATEX system depends on three key elements: Harmonised technical standards;Audits of the manufacturing facilities; and notification by the European Commission to recognise bodies and test laboratories known as Notified Bodies.

ATEX 100a

See ATEX 95. ATEX 100 originally covered the product directive until it was reclassified as ATEX 95 by the Treaty of Amsterdam.

ATEX 137

The “worker protection directive” 1999/92/EC, ATEX 137, describes the “minimum requirements” for improving the health and safety of workers potentially at risk. It classifies the environment into zones and outlines which category of equipment can be used in each zone.

The directive focuses on the analysis and description of the risks, the zone definitions, and the maintenance practices in relation to site safety. The safety of an installation in a hazardous area is the result of co-operation between the equipment manufacturer, the installer and the end user.

ATEX 137 concentrates on the duties of the end user. Workers should be trained on hazardous area issues by the employer. Authorisation should be given to each employee working in a hazardous area. Explosion protection measures should be taken and an explosion protection document (EPD) can be established (an EPD is not specifically required by the DSEAR Regulations, though verification of the explosion safety of an area is required before first use and sufficient documentation to show area classification, required equipment for safe working, and aims of coordination of measures to protect employees) . When equipment is repaired, the end user has the responsibility to select an appropriate repair shop (see Baseefa Certification Limited).

The Employers’ obligations in relation to ATEX include assessing the site’s Sources of Hazard and likely sources of ignition, classification of the area into zones and marking all points of entry, as well as producing and maintaining documentation. The main obligations relating to employers are:

  • Preparing an explosion protection document (EPD)
  • Classifying the workplace into Zones where applicable
  • Selecting ATEX 95 products according to Zone
  • Using warning signs to identify places where explosive atmospheres may occur

Essentially, the employer is required to take all reasonable measures to prevent the formation of an explosive atmosphere in the workplace. Where this is not possible, measures must be taken to avoid the ignition of any potentially explosive atmosphere. In addition, the effects of any explosion must be minimised in such a way that workers are not put at risk.


The product directive 94/9/EC, known as the ATEX 95 Directive, concentrates on the manufacturer’s duties, giving the safety requirements to be fulfilled by all equipment, both electrical and non-electrical, installed in hazardous areas within the European Union. It describes the Essential Healthy and Safety Requirements (EHSRs) of the products regarding their design, manufacturing process, testing, documentation and maintainability.

The requirements are divided into three categories: Technical requirements from harmonised European standards; health and safety aspects; and production quality requirements.

Voluntary since 1994, the requirements of the Directive will be mandatory from 1 July 2003. The Directive covers any electrical or mechanical product that contains or constitutes a potential ignition source and which requires a special design or installation procedure to prevent an explosion. Regulated equipment includes control and communication devices, monitoring and detection equipment. It also includes safety or control devices installed outside hazardous areas that have an explosion protection function, such as pressure-relief panels and fast-acting shutoff valves.