DSEAR 2002
DSEAR explained: explosive atmospheres and safety
Updated 2026
DSEAR — the Dangerous Substances and Explosive Atmospheres Regulations 2002 — requires employers to assess and control the risks from substances that can cause fire, explosion or corrosion. This includes classifying areas into hazardous zones and controlling ignition sources. Knowing who is in each classified zone, in real time, is a practical control that supports a DSEAR safe system of work.
- 1. DSEAR 2002 / ATEX 137
- 2. HSE
- 3. DSEAR 2002
What DSEAR covers
DSEAR applies wherever dangerous substances are present — flammable gases, vapours, mists and combustible dusts. Employers must identify these substances, assess the risks, and put control and mitigation measures in place.
Where an explosive atmosphere may occur, the area is classified into zones (0, 1, 2 for gases; 20, 21, 22 for dusts) according to how often and how long an explosive atmosphere is present.
Controlling access to classified zones
A core DSEAR control is limiting who enters a classified zone and ensuring only inducted, authorised and correctly equipped people do so. Ignition sources — including some electronic devices — must be controlled.
Real-time zone awareness makes this enforceable: the system knows when an un-inducted worker crosses a threshold and can raise an alert immediately, rather than relying on signage and supervision alone.
Intrinsically safe tags
Tags used inside classified zones must themselves be safe. Intrinsically safe, ATEX-rated tags are designed so they cannot release enough energy to ignite an explosive atmosphere, allowing personnel tracking to extend into Zone 0/1 areas.
The Salvus Safety Desk
HSE research & compliance team
The Salvus Safety Desk is our in-house health, safety and compliance team, drawing on frontline experience across COMAH, DSEAR and CDM sites to translate regulation into practical, real-time controls.
Frequently asked questions
How does DSEAR relate to ATEX?+
DSEAR implements the ATEX 137 workplace directive in Great Britain. ATEX also governs the equipment used in explosive atmospheres. Together they cover the workplace and the equipment within it.
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