What is ATEX?

ATEX is the European regulatory framework for explosive atmospheres, derived from the French "ATmosphères EXplosibles." It comprises two complementary directives that have protected workers and regulated equipment across the European Economic Area since the late 1990s, with the current Equipment Directive (2014/34/EU) replacing the original 94/9/EC in April 2016.

The Two ATEX Directives

The ATEX framework consists of two distinct but interconnected legal instruments:

• Directive 2014/34/EU (Equipment Directive): Applies to manufacturers, importers, and distributors placing equipment on the EU market. Equipment must meet Essential Health and Safety Requirements (EHSRs) in Annex II before carrying the CE marking with the distinctive hexagonal Ex symbol. Approximately 800,000 items of Ex equipment are certified annually under this directive.
• Directive 1999/92/EC (Workplace Directive): Applies to employers with workplaces where explosive atmospheres may occur. Requires zone classification, risk assessment, and preparation of an Explosion Protection Document (EPD). All EU countries now enforce these requirements.

Scope of the Equipment Directive

The Equipment Directive covers three categories of products. Equipment and protective systems include electrical items (motors, luminaires, control gear) and non-electrical items (pumps, gearboxes, conveyors) intended for explosive atmosphere use—approximately 70% of certified equipment is electrical. Safety, controlling, and regulating devices located outside hazardous areas but essential for safe operation are also covered, such as intrinsic safety barriers and control panels. Components essential for Ex equipment function but without autonomous function include certified Ex e terminals, cable glands, and display modules—these carry a 'U' suffix on their certificate numbers.

Industries Affected

ATEX requirements apply wherever flammable substances are processed, stored, or handled. Major sectors include oil and gas (refineries, platforms, terminals), chemical and petrochemical (90% of sites have classified areas), pharmaceutical (solvent handling, powder processing), food and beverage (grain handling, spray drying—responsible for approximately 30% of industrial dust explosions), surface coating (paint spray, powder coating), and waste treatment (biogas, landfill gas). The European Commission estimates over 4.3 million workers are potentially exposed to explosive atmospheres in the EU.

Equipment Groups and Categories

ATEX equipment is classified into groups and categories. Group I covers mining (firedamp and coal dust) with categories M1 (highest protection, can remain energised) and M2 (de-energised when explosive atmosphere detected). Group II covers all surface industries with Category 1 for Zone 0/20 (continuous hazard), Category 2 for Zone 1/21 (likely hazard), and Category 3 for Zone 2/22 (unlikely hazard). Approximately 15% of certified equipment is Category 1, 60% is Category 2, and 25% is Category 3.

ATEX Zones

One of the most practical aspects of the ATEX framework is zone classification—the system for categorising hazardous areas based on how frequently an explosive atmosphere is likely to be present. Zones determine which equipment category you need in each part of your facility.

For gases, vapours, and mists, the Workplace Directive defines three zones. Zone 0 is where an explosive atmosphere is present continuously or for long periods—typically inside tanks or vessels containing flammable liquids. Zone 1 is where an explosive atmosphere is likely to occur occasionally during normal operation, such as around pump seals, valve packings, or filling points. Zone 2 is where an explosive atmosphere is not likely during normal operation, but if it does occur it will persist for only a short period—often the wider area surrounding a Zone 1 location.

For combustible dusts, the equivalent zones are 20, 21, and 22, following the same logic of decreasing likelihood. The zone assigned to an area directly determines the minimum equipment category required: Zone 0/20 demands Category 1 equipment (the highest protection level), Zone 1/21 requires Category 2, and Zone 2/22 can use Category 3. Getting zone classification right is therefore the foundation of equipment selection—and getting it wrong means either spending too much on over-specified equipment, or far worse, installing equipment that isn't safe for the actual conditions.

Why ATEX Compliance Matters

Industrial explosions cause approximately 30 fatalities and 600 serious injuries annually in the EU. The ATEX framework creates a harmonised approach—equipment certified in any member state can be sold throughout the EEA without additional national approvals. For manufacturers, this single market access covers 450 million consumers. For employers, it provides clear legal obligations and practical guidance for worker protection, with penalties for non-compliance including fines up to €500,000 in some jurisdictions.

How This Wiki Works

This wiki is organised into 21 sections covering every aspect of ATEX compliance, from the fundamentals you've just read about through to specific equipment types, inspection requirements, and international certification systems. Across these sections, 98 articles guide you through the complete ATEX landscape.

If you're new to ATEX, the early sections cover the essentials: what makes an atmosphere explosive, how zones are classified, how equipment is grouped and categorised, and how temperature classes work. From there, you can explore protection types, marking requirements, and conformity assessment—the process of proving equipment meets safety requirements before it can be sold.

For employers, dedicated sections on workplace requirements, risk assessment, and inspection and maintenance walk you through your obligations under the Workplace Directive. Manufacturers will find guidance on their obligations, technical documentation, and working with notified bodies.

Every article links to related topics, so you can follow the connections that matter most to your situation. Whether you're an engineer selecting equipment for a classified zone, a safety manager preparing an Explosion Protection Document, or a manufacturer navigating certification—start anywhere that's relevant and explore from there.