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ATEX potentially explosive atmospheres

Carrying out a risk explosion assessment is a requirement indroduced by ATEX Directive 99/92/CE and transposed to the domestic legislation in EU Member states, in particular via article R4227-46 of the Fair labour standards act.
The assessment and treatment of potentially explosive atmospheres is based on :
  • The probability of occurrence of an explosive atmosphere,
  • The probability of ignition of the explosive atmosphere,
  • The extent of the foreseeable consequences..


  • Risk explosion assessment is a requirement introduced by ATEX Directive 99/92/EC and transposed to domestic legislation in EU Member states, in particular via article R4227-46 of the Fair labour standards act.
  • In addition, the employer is held to subdivide into zones the areas in which explosive atmospheres can occur (article R4227-50 of the Fair labour standards act): These areas are defined in section 1 of the Decree of 8 July 2003 on the protection of workers exposed to explosion hazards:
    • Flammable gases and vapours: zones 0, 1 and 2
    • Combustible dust: zones 20, 21 and 22
  • As such, employers are obliged to formalise the assessment and classification of potentially explosive atmosphere areas (ATEX) in the document relating to protection against explosions (DRPE) (article R4227-52 of the Fair labour standards act)..

Our methodological approach

In order to assist you in setting up an explosion risk assessment initiative, the CNPP has developed the EVAREX®© method (a French acronym for explosion risk assessment), the principles and tools of which can be applied in order to obtain a structured, objective assessment of the explosion risks present within a plant. The method is implemented after the classification of the hazardous areas has been defined (commonly referred to as "ATEX zoning").
The method serves to :
  • Assess the explosion risks: the assessment is conducted for each risk of explosion, based on 5 parameters assessed using rating scales developed with reference to the regulation, recommendations, and feedback
  • Prioritise the explosion risks,
  • Develop corrective action and/or monitoring programmes to improve existing situations (probability, severity, penalizing factors, prevention, protection, etc.)
The EVAREX®© method is an application of the DIDERO®© occupational hazard assessment method (in response to article R.4121-1 of the Fair labour standards act) developed by the CNPP.

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It consists of consultants, engineers and auditors to assist you in your initiatives.

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