ATEX Workplace Directive (1999/92/EC)

While the Equipment Directive covers what goes into hazardous areas, Directive 1999/92/EC governs how those areas are managed to protect workers. Often called the "Workplace Directive" or "ATEX 137" (from its original Treaty basis), it establishes minimum requirements for worker safety in explosive atmospheres.

Legal Framework

The directive is the 15th individual directive under the Framework Directive 89/391/EEC on occupational safety and health. It was adopted on 16 December 1999 and Member States were required to transpose it into national law by 30 June 2003. Being a "minimum requirements" directive, Member States may maintain or introduce more stringent protective measures.

What It Covers

Article 1 defines the scope as workplaces where workers may be at risk from explosive atmospheres. Importantly, Article 1(2) lists exclusions: areas for medical treatment of patients, use of gas appliances under Directive 90/396/EEC, handling of explosives or chemically unstable substances, mineral-extracting industries (covered by separate mining directives), and transport by land, water, or air—though vehicles intended for use in explosive atmospheres are included.

Core Employer Obligations

The directive places substantial duties on employers, structured around a clear hierarchy of protective measures (Article 3):

• Primary: Prevent formation of explosive atmospheres
• Secondary: Where prevention isn't reasonably practicable, avoid ignition
• Tertiary: Mitigate the effects of any explosion to protect workers

These measures must be combined where necessary and reviewed regularly—particularly when significant changes occur. See Employer Duties Under ATEX for detailed coverage.

Risk Assessment (Article 4)

Employers must assess explosion risks considering: the likelihood that explosive atmospheres will occur and their persistence; the likelihood that ignition sources will be present, become active, and become effective; the installations, substances used, processes and their possible interactions; and the scale of anticipated effects. The directive emphasises that explosion risks must be assessed "overall"—not in isolation. See Risk Assessment Fundamentals.

Zone Classification (Article 7)

Employers must classify places where explosive atmospheres may occur into zones according to Annex I. The exact definitions from the directive are:

• Zone 0: Explosive gas/vapour/mist atmosphere present "continuously or for long periods or frequently"
• Zone 1: Explosive gas/vapour/mist atmosphere "likely to occur in normal operation occasionally"
• Zone 2: Explosive gas/vapour/mist atmosphere "not likely to occur in normal operation but, if it does occur, will persist for a short period only"
• Zone 20/21/22: Equivalent definitions for combustible dust clouds

The directive explicitly notes that dust layers, deposits and heaps must be considered as potential sources of explosive atmospheres. "Normal operation" means situations when installations are used within their design parameters.

The Explosion Protection Document (Article 8)

A centrepiece of the directive, the EPD must demonstrate that explosion risks have been assessed, adequate measures will be taken, zone classification has been completed, minimum requirements from Annex II will apply, and equipment is designed and maintained with safety in mind. The EPD must be prepared before work commences and revised following significant changes.

Minimum Requirements (Annex II)

Annex II sets out detailed organisational measures (training, written instructions, permits to work) and technical explosion protection measures. These include requirements for removing or diverting flammable releases, taking account of electrostatic discharges, ensuring equipment is safe before bringing into service, and providing warning systems where necessary. The annex distinguishes between equipment installed before and after 30 June 2003, with full ATEX marking requirements applying to the latter.

Coordination (Article 6)

When workers from several undertakings are present, the employer responsible for the workplace must coordinate safety measures and document this coordination in the EPD. Each employer remains individually responsible for matters under their control—coordination doesn't transfer or dilute those responsibilities.