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- Anyone competent can carry out a DSEAR risk assessment. DSEAR and HSE's Approved Code of Practice, L138, name no qualification.
- Competence means enough training, experience and knowledge of your substances and of explosion risk on your site.
- You can use an employee who has that competence, and regulation 7(8) of the Management of Health and Safety at Work Regulations 1999 prefers them to an outsider.
- Hazardous area classification, and the verification of explosion safety under regulation 7(4) of DSEAR, need someone competent in explosion protection.
- The DSEAR duties stay with the employer, whoever carries out the assessment.
Anyone competent to do it can carry out a DSEAR risk assessment. The Dangerous Substances and Explosive Atmospheres Regulations 2002 (DSEAR) name no qualification, and HSE's Approved Code of Practice for them, L138, says only that "whoever carries out the assessment should be competent to do so". It can be someone in your business or an outside consultant. What decides it is whether they know enough about your substances and explosion risk to assess your particular site. One step has its own test: before a zoned area is first used, its explosion safety must be verified by someone competent in explosion protection.
DSEAR applies in England, Wales and Scotland. Northern Ireland has its own Dangerous Substances and Explosive Atmospheres Regulations (Northern Ireland) 2003.
What does "competent" mean for a DSEAR risk assessment?
The general test sits in regulation 7(5) of the Management of Health and Safety at Work Regulations 1999. A person is competent where they have "sufficient training and experience or knowledge and other qualities" to help you meet your duties. DSEAR adds no separate test for the assessment itself, so the practical question is what the work on your site demands.
Regulation 5(2) of DSEAR lists what the assessment has to consider. Each item asks something of the person doing it.
| What regulation 5(2) of DSEAR says the assessment must consider | What the assessor needs to bring |
|---|---|
| The hazardous properties of each substance, and the supplier's safety information, including the safety data sheet | The ability to read a safety data sheet for flammability, flash point and reactivity |
| The work processes, the amounts involved and substances in combination | Knowledge of how your site actually runs, including the jobs done once a year |
| Activities such as maintenance, where the risk can be high | An eye for hot work, cleaning and breakdowns, when controls may be off |
| The likelihood of an explosive atmosphere and how long it persists | Hazardous area classification into the zones set out in Schedule 2 of DSEAR |
| The likelihood of ignition sources, including electrostatic discharges | Electrical, mechanical and static ignition sources |
| The scale of the effects of a fire or explosion | The consequences for people on site and off it |
Competence is specific to the work. L138 gives an example for the verification step: someone competent to verify the explosion safety of a petrol station "may not be competent" to deal with combustible dust in a textile factory. Ask anyone who will assess your site the same question: have they assessed substances and processes like yours?
DSEAR deals with safety, meaning harm from fire, explosion and similar events. The health risks from the same products sit under the Control of Substances Hazardous to Health Regulations 2002 and need a COSHH assessment of their own.
Can you carry out your own DSEAR risk assessment?
Yes, if someone in your business has the competence. Regulation 7(8) of the Management of Health and Safety at Work Regulations 1999 goes further: where there is a competent person in your employment, you appoint them "in preference to a competent person not in his employment". The same applies to who acts as your competent person more generally. L138 also allows the DSEAR assessment to be carried out as part of the general risk assessment those 1999 Regulations require (paragraph 84 of L138).
The assessment scales with the risk. Where you hold small quantities with simple controls, the record may be brief. Where vapour, gas or combustible dust can form an explosive atmosphere, regulation 7 of DSEAR adds hazardous area classification: dividing those places into zones, marking them, and checking that the equipment in each zone meets Schedule 3 of DSEAR. That part takes specific training in hazardous area classification.
Whoever carries out the assessment, these duties stay with you as the employer:
- If you employ five or more people, record the significant findings as soon as practicable, under regulation 5(4) of DSEAR.
- Review the assessment regularly, and in particular after a significant change to the workplace, the work processes or how the work is organised, under regulation 5(3) of DSEAR.
- Start no new work involving a dangerous substance until the assessment has been made and the measures it requires are in place, under regulation 5(5) of DSEAR.
Who verifies explosion safety before a zoned area is used?
Regulation 7(4) of DSEAR sets its own test. Before a workplace containing hazardous places is used for the first time, the employer must ensure that "its overall explosion safety is verified by a person who is competent in the field of explosion protection as a result of his experience or any professional training or both".
L138 lets you do this in-house where the person is "impartial and sufficiently independent", and otherwise says to obtain external competent verification (paragraph 391 of L138). It describes independence as being separate from "the installation and operation of the work area involved", and notes that larger installations may need more than one person (paragraph 392 of L138). So the engineer who installed the equipment in a zone is the wrong person to sign it off.
When should you bring in an outside DSEAR assessor?
When nobody in your business has the competence for your substances and processes. Regulation 7 of the Management of Health and Safety at Work Regulations 1999 then lets you appoint someone from outside, and the DSEAR duties stay with you.
| Who carries it out | Where it fits | What to check first |
|---|---|---|
| An employee or manager | Small quantities of familiar substances with simple controls | Training in DSEAR and in your substances, and time to keep the assessment current |
| A health and safety consultant | Sites where DSEAR sits alongside COSHH, fire and the other duties | Whether they have assessed sites with your substances, and whether they zone hazardous areas themselves |
| A hazardous area or explosion protection specialist | Zoning, equipment selection and verification on larger or more complex sites | Experience with your type of atmosphere: gas, vapour or dust |
| A process safety engineer | Chemical processes and process plant | Experience matched to your plant and reactions |
Before you appoint anyone, ask:
- Which sites with substances like yours have you assessed?
- Will you classify and zone the hazardous areas, and provide zone drawings?
- What will we receive at the end?
- Who will verify explosion safety under regulation 7(4) of DSEAR, and how independent are they of the installation?
- How will the assessment be kept under review?
Opus Safety carries out DSEAR assessments and the hazardous area zoning that goes with them. That includes builders merchants that hold LPG and flammable stock, and petrol forecourts, where the tanker delivery area, the pumps and the underground tanks all sit inside hazardous zones. For what DSEAR covers and how it sits beside your fire risk assessment, read DSEAR explained.
Frequently asked questions
Does a DSEAR risk assessment have to be carried out by a qualified person? No qualification is named in DSEAR or in L138. The test is competence: enough training, experience and knowledge of the substances and explosion risk on your site.
Can the DSEAR risk assessment be part of my general risk assessment? Yes. L138 says the DSEAR risk assessment may be carried out as part of the assessment required by the Management of Health and Safety at Work Regulations 1999. Where it is not, a separate DSEAR assessment is required.
Does a DSEAR risk assessment have to be written down? Yes, if you employ five or more people. Regulation 5(4) of DSEAR requires the significant findings to be recorded as soon as practicable, including the zones and the verification of explosion safety where an explosive atmosphere may occur.
How often does a DSEAR risk assessment need reviewing? DSEAR sets no fixed interval. Regulation 5(3) of DSEAR requires the employer to review it regularly, and particularly where there is reason to suspect it is no longer valid or after a significant change.
Who can verify explosion safety under regulation 7(4) of DSEAR? Someone competent in explosion protection through experience, professional training or both. An employee can do it if they are impartial and independent of the installation and operation of the area. Otherwise, use an external verifier.
Does a DSEAR risk assessment cover the health risks of chemicals? No. DSEAR covers harm from fire, explosion and similar events. Health risks from the same substances need a COSHH assessment under the Control of Substances Hazardous to Health Regulations 2002.
Last updated
November 5, 2026
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