ATEX Zone Basics

Your equipment needs ATEX treatment if it is meant for use in a potentially explosive atmosphere and could ignite that atmosphere through its own ignition source. Protective systems, safety devices and components count as well. Not everything in scope needs a third-party certificate, though. A notified body certificate (EU-type examination) is required for category 1 and M1 equipment, for protective systems, and for electrical equipment and engines in category 2 or M2. Category 3 equipment is self-declared by the manufacturer. Non-electrical category 2 equipment is also self-declared, but the technical file must be lodged with a notified body.

Approach: The datasets don't hold the ATEX Equipment Directive 2014/34/EU, and EUR-Lex wouldn't open. So the article text below is quoted as reproduced in the European Commission's ATEX 2014/34/EU Guidelines, 6th edition (January 2026). The user-side rules come from the Irish S.I. 299/2007, the Swiss EKAS directive 2153 and the EU Machinery Regulation.

Four questions to work through

1. Is it meant for a potentially explosive atmosphere?

• An "explosive atmosphere" is a mixture with air, under atmospheric conditions, of flammable gases, vapours, mists or dusts in which combustion spreads to the entire unburned mixture once ignited (Art. 2(4)). A "potentially explosive atmosphere" is one that could become explosive due to local and operational conditions (Art. 2(5)) (Guidelines p. 60).
• If any of these elements is missing, the product is not covered. Examples are mixtures without air, oxidants other than air, or pressures and temperatures outside the atmospheric range. The Guidelines suggest −20 °C to 60 °C and 0.8 to 1.1 bar as a working basis for "atmospheric conditions" (p. 61).
• Equipment inside a vessel that holds an explosive atmosphere is itself in such an atmosphere and is covered (p. 60).

2. Is it one of the covered product types? (Art. 1(1), p. 31)

• Equipment. This means machines, apparatus, devices, controls and instrumentation that are "capable of causing an explosion through their own potential sources of ignition" (Art. 2(1), p. 47). The Guidelines call the own ignition source "a defining element".
  • Ignition sources include sparks, arcs, electrostatic discharges, hot surfaces, flames, mechanical sparks, optical radiation and compression (p. 48).
  • Non-electrical items are covered too, typically through hot surfaces or friction sparks. Examples: gears, fans, pumps, compressors, mixers, brakes (p. 49).
  • Not covered: slow-moving or very low-power mechanical items that cannot form an ignition source even under rare malfunction. Plastic items charged only by the process (containers, pipes, buckets) are also out. These must not carry ATEX marking (pp. 48-49).
• Protective systems.
• Safety, controlling or regulating devices placed outside the hazardous area that are needed for the safe functioning of ATEX equipment. An example is a motor overload or temperature trip. These carry the category in brackets, e.g. "II (2) G". Gas detectors that only sound an alarm and don't control the equipment, and fire water-spray systems, are outside this category (pp. 41-42).
• Components. These are not CE marked. They come with a written attestation of conformity instead (Art. 13(3), p. 91).

3. Is it excluded? (Art. 1(2), p. 43)

• Medical devices for use in a medical environment
• Products where the hazard comes only from explosives or unstable chemicals
• Domestic gas-leak-only situations
• PPE
• Seagoing vessels and mobile offshore units
• Most means of transport (vehicles meant for use in explosive atmospheres stay in scope)
• Military equipment under Art. 346 TFEU

4. Which category, and so which conformity route? The category follows the zone where the equipment is intended to be used. In Ireland, for example, the employer must use category 1 equipment in Zone 0/20, category 1 or 2 in Zone 1/21, and category 1, 2 or 3 in Zone 2/22 ^[2]. Zoning is the user's job under Directive 1999/92/EC. The manufacturer declares the intended use (p. 38, footnote 22).

Product	Route under Art. 13 (pp. 90-92)	Notified body?
Category M1 / 1 equipment	EU-type examination plus production QA or product verification; or unit verification	Yes
Protective systems	Same as category 1	Yes
Category M2 / 2, electrical or internal combustion engine	EU-type examination plus supervised product testing or product QA; or unit verification	Yes
Category M2 / 2, other (non-electrical)	Internal production control, with the technical documentation sent to a notified body, which keeps it	File is lodged; no certificate
Category 3	Internal production control (or unit verification)	No

Components follow the same routes but without CE marking or an EU declaration of conformity (Art. 13(3)).

Points that often change the answer

• Assemblies. If you combine ATEX-compliant items with no new ignition hazard, you can presume their conformity and issue one declaration without a notified body. If the combination adds an ignition hazard, or uses non-compliant parts, the whole assembly goes through the full procedure for its category (pp. 50-51).
• Used or modified equipment. The Directive applies again if the product is placed on the EU market for the first time, or is modified so much that it is in effect a new product (p. 32).
• Voluntary certificates don't count. The Commission states that only notified bodies may certify, and that "voluntary or other additional certificates are not a recognised means to prove compliance" (Commission ATEX page). That page links to NANDO for the list of ATEX notified bodies.
• Machinery. Under the EU Machinery Regulation 2023/1230, machinery must meet the specific Union explosion-protection legislation (i.e. ATEX) for explosion risk in a potentially explosive atmosphere, and must be marked accordingly ^[6].
• Switzerland. Work equipment used in hazardous areas must comply with the VGSEB (SR 734.6). Equipment outside the VGSEB may instead fall under the Machinery Directive 2006/42/EC ^[7][8].

I didn't check the GB (UKEX) rules. If you tell me the equipment type, where it will be installed and whether it is electrical, I can work through its category and route.

DSEAR (the Dangerous Substances and Explosive Atmospheres Regulations 2002, SI 2002/2776) is how Great Britain applies the ATEX workplace rules. Its zones and equipment categories are the same as the ones in my earlier answer. It puts duties on employers and the self-employed at workplaces in Great Britain where a dangerous substance is or could be present. It implements the safety parts of the Chemical Agents Directive 98/24/EC and the ATEX Workplace Directive 99/92/EC. On the equipment side, DSEAR points to the GB equipment rules (the EPS Regulations). Under those, you can place equipment on the GB market with either a CE or a UKCA mark.

Approach: The DSEAR text isn't in the datasets I can search; the GB COSHH ACOP L5 only refers to it. I couldn't open legislation.gov.uk this time, so the regulation text below comes from HSE's ACOP L138, 2nd edition (2013), which reproduces DSEAR with amendments up to mid-2013 only, plus HSE and GOV.UK pages.

What DSEAR covers (L138, pp. 10-16)

• Dangerous substance has three limbs:
  • substances meeting the criteria for explosive, oxidising, extremely flammable, highly flammable or flammable, whether or not they are classified;
  • substances that create a risk because of their physico-chemical properties and the way they are used;
  • any dust that can form an explosive mixture with air.
  • Examples given: petrol, LPG, paints, varnishes, solvents, and milling or sanding dusts.
• Fire and explosion risks only. Health effects fall under COSHH (L138 para 14). The COSHH ACOP says you can combine the COSHH assessment with the DSEAR regulation 5 assessment ^[9].
• "Explosive atmosphere" means a mixture with air under atmospheric conditions. For standardisation, L138 takes these as −20 °C to 40 °C and 0.8 to 1.1 bar. The EU ATEX Guidelines I quoted earlier suggest up to 60 °C, so the two differ. Below the lower explosive limit, or with an oxidant other than air, regulations 5(4)(c), 7 and 11 don't apply, but the rest of DSEAR still does (para 40).
• Exclusions from regulations 5(4)(c), 7 and 11 (reg 3(2)):
  • areas used for medical treatment of patients;
  • domestic-type gas appliances and domestic gas fittings;
  • explosives and chemically unstable substances;
  • mines, quarries, borehole sites and offshore installations;
  • certain means of transport.

Core duties

1. Risk assessment (reg 5). It must cover, among other things, how likely an explosive atmosphere is and how long it persists, ignition sources including static, the scale of effects, and connected places.
   • With five or more employees, you must record the significant findings.
   • Where an explosive atmosphere may occur, the record must also show the zoned places, the equipment needed for safe operation in hazardous places, the verification carried out, and the co-ordination arrangements (reg 5(4)(c)).
   • No new work activity may start until the assessment is done and the measures are in place (reg 5(5)) (pp. 25-26).
2. Eliminate or reduce risk (reg 6). Substitution comes first, then control and mitigation measures.
3. Places where explosive atmospheres may occur (reg 7) (pp. 73-74):
   • classify places as hazardous or non-hazardous, then sort hazardous places into zones (Schedule 2);
   • apply the Schedule 3 equipment rules;
   • mark entry points with signs where necessary (Schedule 4);
   • have overall explosion safety verified by a competent person before the workplace is used for the first time;
   • provide anti-static work clothing.
4. Emergency arrangements (reg 8), information and training (reg 9), co-ordination between employers (reg 11).

Zones and equipment

• Schedule 2 uses the same text as the Irish and EU wording: Zones 0, 1 and 2 for gas, vapour or mist, and Zones 20, 21 and 22 for dust clouds. It keeps both notes, on dust layers and on "normal operation" (pp. 74-75).
• Schedule 3 requires category 1 equipment in Zone 0/20, category 1 or 2 in Zone 1/21, and category 1, 2 or 3 in Zone 2/22 (p. 75).
  • Equipment must be selected to the EPS requirements "unless the risk assessment finds otherwise".
  • The 2013 reproduction cites the 1996 EPS Regulations. HSE's current ATEX page says selection is now under the 2016 EPS Regulations.
• The "unless the risk assessment finds otherwise" derogation must be justified and recorded, and must give equivalent safety. It covers cases such as:
  • equipment brought in temporarily, with other precautions in place;
  • workers excluded from the area;
  • no equipment of the required category being available.
  • It cannot be used to get around the duties of "responsible persons" under EPS (paras 374, 381-383).
• Making or importing equipment yourself. An employer who builds equipment for its own use, or imports it directly, becomes a "responsible person" under EPS and carries full compliance duties (para 383).
• Older equipment. Equipment in use before 30 June 2003 is exempt from Schedule 3. It still has to satisfy regulation 6 (paras 373, 404).
• Records and markings:
  • Record the hazardous area classification as plan and elevation drawings with supporting text (para 354).
  • Zones themselves don't need individual marking (para 386).
  • Check the Ex marking on equipment, for example "II 2 G" plus the T-class (para 376).

Product side in GB (UKEX)

• GOV.UK guidance (updated 24 March 2025) says the EPS Regulations 2016 recognise CE marking indefinitely for the GB market. UKCA marking applies where a UK Approved Body does the conformity assessment.
• Self-declared equipment may carry either mark. Equipment that needs third-party assessment carries CE (EU notified body) or UKCA (UK approved body). Both marks can appear together.
• Equipment for the EEA or Northern Ireland still needs CE marking.
• HSE is the market surveillance authority for equipment used at work.
• GOV.UK's CE/UKCA sector overview gives Group II category 3 equipment as an example of what can be self-declared.

Related GB rules

• Enforcement: DSEAR is enforced by HSE or local authority inspectors. Petroleum licensing authorities enforce it for refuelling at licensed premises.
• General fire safety: this sits under the Regulatory Reform (Fire Safety) Order 2005 in England and Wales, and the Fire (Scotland) Act 2005 in Scotland, and is enforced by fire and rescue authorities.
• Other regimes may also apply, notably COMAH and the carriage of dangerous goods rules (L138 paras 17-28).

I didn't check the Northern Ireland workplace equivalent of DSEAR, since DSEAR applies to Great Britain.