How Often Should you Review your ATEX/DSEAR?

Get in touch – you may need a DSEAR review if you answer “yes” to any of the following questions:

A DSEAR Risk Assessment must be regularly updated and assessed at proper intervals, just like any other risk assessment. When any potentially flammable or explosive materials are identified, a DSEAR Assessment should be completed. Ideally this should be achieved in the process design stage, but it’s far more common for DSEAR assessments to be undertaken when a process is already in place.

Businesses across all industries have made great strides in understanding and applying DSEAR regulations. However, many still overlook when a DSEAR review is actually needed, or whether their existing assessment remains valid. Undertaking regular reviews are essential to ensure ongoing compliance, especially in dynamic environments where processes and risks are constantly evolving.

This short blog will quickly outline the key parameters of an ATEX compliance assessment/DSEAR risk assessment. This will include flammable atmospheres, ignition sources and the ‘Basis of Safety’. We’ll dive into when it’s appropriate to conduct an ATEX/DSEAR review.

ATEX is the name given to the European Directives to ensure that all EU member states create appropriate legislation so that employees are protected from fires and explosions caused by work activity.

ATEX can be split into two main directives: 2014/34/EU, which applies to manufacturers of equipment used in explosive zones, and 1999/92/EC, which focuses on employer responsibilities in managing workplace explosion risks. 

Compliance of the ATEX directives are implemented in the UK through the Dangerous Substances and Explosive Atmospheres Regulations 2002 (DSEAR). 

Both of these assessments are systematic reviews of processing operations with respect to the industry handling dangerous substances in potentially explosive atmospheres. These risk assessments are used as a blueprint to prevent fires and explosions. 

Flammable atmospheres are the core hazards that the DSEAR and ATEX regulations have been designed for. 

A flammable atmosphere refers to an environment where flammable materials are present. This can include gases, vapours, mists, or dust. 

The ATEX directives define an explosive atmosphere as:

“Mixture with air, under atmospheric conditions, of flammable substances in the form of gases, vapours, mists or dust in which, after an ignition has occurred, combustion spreads to the entire unburned mixture.” (ATEX 114 – article 1.3 & ATEX 153 – article 2)

And a potentially explosive atmosphere as:

“An atmosphere that could become explosive due to local or operational conditions.” (ATEX 114 – article 1.3)

A flammable atmosphere is a key risk that DSEAR and ATEX reviews are designed to assess. These reviews ensure that areas where such atmospheres may exist are properly classified and managed, using appropriate equipment and safety practices to prevent explosions.

An ignition source is anything that can cause a flammable atmosphere to catch fire or explode. If an object, event, or condition can supply the necessary heat, spark, or flame with enough energy, it can ignite a flammable atmosphere.

Typically, there are thirteen effective ignition sources as stated in the standard EN1127.

Again, ignition sources a cornerstone Under DSEAR and ATEX because they are the trigger for explosions or fires in hazardous areas.  Your DSEAR/ATEX review should seek to: 

• Identify potential ignition sources 
• Control or eliminate these sources 
• Specify areas for the installation of ATEX-certified equipment

A ‘Basis of Safety’ is a primary method or strategy used to prevent fires and explosions. It will define how risk is controlled in a specific system or operation and will make up part of your DSEAR/ATEX documentation. 

As a concept or philosophy that usually comes in two layers (like most safety systems), a basis of safety will include primary and secondary layers, and will usually come in three different variations:

1) Avoidance of flammable atmospheres i.e. inertion

2) Avoidance of effective ignition sources i.e. control of ignition sources

3) Explosion protection i.e. suppression, venting and containment

As your ‘Basis of Safety’ will represent the underlying framework that instructs your decision-making, you will need to identify, justify, and verify your ‘Basis of Safety’ to ensure safety measures are effective and risks are managed properly during your DSEAR/ATEX review. 

The DSEAR risk assessment has been a compliance requirement within industry for many years, but many companies don’t undertake reviews frequently enough.

Businesses don’t change aspects of a process on a particular day every year, so why do we review our DSEAR compliance in the same way?

The HSE recommends that DSEAR is updated every 3–5 years depending upon the risk levels of the operations. A high-risk site will need to be revisited every 1–2 years and all other sites between 3–5 years. However, if there are alterations to a process, then a DSEAR may need to be reviewed sooner.

Much like a normal DSEAR/ATEX risk assessment, the review identifies fire and explosion risks, classifies hazardous areas into zones, and assesses the basis of safety for each process.

The review will also check that your equipment is appropriately ATEX-certified, ignition sources are controlled, and that staff are properly trained. 

At Sigma-HSE, we typically undertake two types of reviews. 

1) The conceptual study: this is usually undertaken during the design stage. In the UK, this is called a desktop DSEAR and its primary purpose is to give clients an idea of what type of equipment and zones should be accounted for.

2) The site verification DSEAR: this is typically completed independently and during commissioning and operations.

An ATEX/DSEAR review is a legal requirement undertaken to evaluate the risks of explosive atmospheres in a workplace to protect people and property.

A major reason why DSEAR reviews are required is that specific elements are often missed or overlooked in previous ATEX compliance checks or DSEAR assessments. 

Over time, changes to processes, equipment, or materials can introduce new risks that were not previously considered. 

By undertaking regular reviews, you can ensure that all hazards are identified, that your hazardous area classifications remain accurate, and that control measures and equipment still meet current standards. This helps maintain ongoing compliance and ensures that no critical safety gaps are left unaddressed.

Over the years, we have found that the below three areas are the most common areas that have triggered DSEAR/ATEX reviews:

• electrostatic hazards: low energy ignition risks, changes to the insulating/conducting properties of a material or poorly maintained earthing continuity.
• non-routine operations: including maintenance, cleaning, changes to a process, or the credibility of previous maintenance or inspections undertaken.
• change of personnel: including knowledge gaps, competence management and site contractor reviews (probably the cause of more incidents in industry than any other process risk)

A DSEAR review serves several important purposes beyond basic legal compliance. The review should also play a fundamental role in maintaining the overall safety and integrity of your facility. Below are some of the key reasons why conducting a thorough and up-to-date DSEAR/ATEX review is essential for both operational/process safety and business performance.

1) Ensuring the safe operation of a facility.

This must include general explosive atmosphere safety and control risks, process hazard risks and material hazard risks.

2) DSEAR reviews are a legal requirement for HSE compliance.

The equipment used in potentially flammable atmospheres must comply with the Equipment for Use in Potentially Explosive Atmospheres Regulations (EPS).

3) Aids in training and awareness for personnel at the facility.

This is especially true in regard to atmospheric explosions, hazardous substance identification and emergency preparedness. 

4) Insurance requirements may help in reducing premiums

From our experience speaking with clients, insurers are increasingly dissatisfied with inadequate DSEAR assessments as they often don’t cover a range of standard DSEAR risk assessment practices.

5) It compliments other process safety control measures and engineering packages for a facility

This may include risk assessments such as a HAZOP study, HAZID or a Layers of Protection Analysis (LOPA).

Unit operations are the individual steps or processes within your larger process. Examples can include mixing, distillation, filtration, drying, grinding, and heating.  

Each unit operation will involve specific equipment and conditions (e.g., temperature, pressure, material flow) and will pose unique risks.

In a DSEAR or ATEX review, each of your unit operations will be assessed to identify potential sources of flammable atmospheres and ignition sources. For example:

• Mixing volatile solvents may release flammable vapours.
• Drying combustible powders can create explosive dust clouds.
• Grinding can generate heat or sparks.

The review ensures that:

• Hazards are identified for each operation.
• Appropriate zoning and equipment selection (ATEX-rated) is applied.
• Control measures (ventilation, inerting, grounding, etc.) are in place.
• The basis of safety is clearly defined for each operation.

Unit operations, equipment, materials, and procedures can all change over time, and even seemingly minor modifications can significantly impact the validity of an existing DSEAR/ATEX assessment. 

A review must be triggered whenever change occurs, as they may alter your hazardous area classification, ‘Basis of Safety’, or the effectiveness of your existing control measures. The following are common types of change that require reassessment to ensure continued compliance and protection against fire and explosion risks:

1) The introduction of a new process(es), material(s) or equipment.

This can have many implications for DSEAR reviews as change may have consequences that will impact a hazardous area classification or a predefined basis of safety.

2) Degradation of existing equipment

You must think about equipment degradation. Not only can product efficiency degrade, but reaction times can too. Degradation regarding control valves reacting to alarm systems is a good example of this.

3) Changes to an existing process

If operating procedures have changed, which may include temperature or a move from automation over manual operations, then the extent or likelihood of a hazardous area being present alters.

4) Changes in Standard Operating Procedures (SOPs)

5) Changes in facility layout/ventilation characteristics

6) Changes to storage conditions

7) Changes in conveyance methods

When a change occurs, it can affect the size and extent of a flammable atmosphere. It could be as simple as the physical size of the explosive atmosphere increasing or decreasing. This in turn can affect the likelihood of an explosive atmosphere, which will impact your equipment and sources of ignition.

Management of Change (MoC) documentation and other checklists that have been completed must be sufficient to identify potential risks resulting from any change to your process. You can read more about the relationship between DSEAR and MOC here

Ultimately, a DSEAR assessment should always be reviewed if you believe that your current DSEAR may be invalid. 

The outcomes of a DSEAR review can vary depending on the specific circumstances and findings, but they should all focus on ensuring that all fire and explosion risks related to flammable substances are properly identified, assessed, and controlled. Your outcomes will help ensure legal compliance, protect personnel, and maintain safe operations. 

Key outcomes should include:

1) Hazard Identification

• Clear identification of all flammable gases, vapours, mists, or dusts present on site. 
• Recognition of processes or operations where explosive atmospheres may form.

2) Hazardous Area Classification

• Definition and zoning of areas where explosive atmospheres may occur (Zones 0, 1, 2 for gases; Zones 20, 21, 22 for dusts).

3) Confirmation or Update of Basis of Safety

• Establishing or re-confirming the primary method of explosion risk control (e.g., elimination of ignition sources, explosion venting, or inerting).

4) Equipment and Protection Review

• Assessment of whether existing equipment is suitably ATEX-rated for its location and zone classification.
• Recommendations for upgrades or changes where necessary.

5) Explosion Protection Document (EPD)

• Preparation or update of the EPD, which is a legal requirement under DSEAR to document the findings, zoning, and safety measures.

6) Risk Control Measures

• Identification and implementation of engineering and procedural controls, such as ventilation, grounding, and safe operating procedures.

7) Training and Awareness Needs

• Recommendations for personnel training related to explosive atmosphere risks and safe working practices.

Your DSEAR review must result in a clear understanding of explosion hazards, zoning of hazardous areas, confirmation of safety strategies, and recommendations to ensure safe equipment, procedures, and training.

However, there are some common outcomes and significant findings that you should be made aware of. We usually find the below may arise following a DSEAR review:

1) A revision of the ‘Basis of Safety’ to ensure validity

2) If your material has changed, then you must obtain updated flammability data to ensure your ‘Basis of Safety’ is achieved. 

• The question to ask is ‘Is my equipment suitably rated for my new materials?’

3) Ensure electrostatic hazards are removed or properly controlled

4) If an inerting system has changed, then you may need to conduct further Safety Integrity Level (SIL) studies

5) A change to the Standard Operating Procedures (SOPs) may need to be undertaken

6) A review of ventilation characteristics & facility layouts may be needed

Remember, multiple small changes that build up over time may lead to a completely different process – this is why you should undertake a thorough DSEAR assessment every 2-4 years.

By regularly reviewing your DSEAR you’re supporting your own legal compliance, improving your process safety, and providing assurance to both regulators and insurers that your site is operating to the highest safety standards.

Learn more about DSEAR reviews in our  FREE on-demand webinar.