27/08/2026
ATEX studies (from the French ATmosphères EXplosives) are one of the most important tools in managing industrial risks. Although traditionally associated with sectors like petrochemicals or oil and gas, its application is much broader and covers a wide variety of industries where gases, steam, or combustible dust are handled.
Industrial explosions are among the most destructive accidents that can occur at any production facility. In addition to the consequences for people, they can cause very significant material damage, interrupt activity for long periods of time, result in economic loss, and be the source of reputational problems for the companies affected. In many cases, these accidents have a common origin: the presence of an explosive atmosphere that encounters an ignition source capable of triggering the explosion.
What is an explosive atmosphere?
An explosive atmosphere is a mixture of air and flammable substances in the form of gases, vapors, fogs, or combustible dust particles that, once combustion starts, allows it to spread rapidly throughout the entire mixture.
For an explosion to occur, several factors must coincide. A combustible substance must be present in the atmosphere; there must be sufficient oxygen to sustain the combustion, and an ignition source with enough energy to set off the reaction must be present too. In the case of combustible dust, the degree of particle distribution in the air is also relevant.
Although the risk is usually associated with hydrocarbons or chemicals, numerous everyday materials have explosive capacities: in certain concentrations, flour dust, sugar, cereal, wood, aluminum, or coal dust can produce extremely dangerous explosions.
What is an ATEX study?
An ATEX study is a systematic evaluation that aims to identify those areas where an explosive atmosphere may form, and define the necessary measures to prevent its ignition or reduce its consequences.
ATEX studies are not used solely to comply with regulatory requirements. Their true value lies in understanding how the industrial process behaves, identifying loss scenarios, and establishing prevention and protection measures in accordance with the existing level of risk.
The analysis considers the substances present in the installation, operating conditions, ventilation, possible leak points, installed equipment, and the different ignition sources that could be present during normal operation or during anomalous situations.
Classification of ATEX zones
One of the main results of the study is the so-called classification or zoning of areas.
In facilities where flammable gases or flammable vapors exist, zones 0, 1, and 2 are defined.
- Zone 0 corresponds to places where the explosive atmosphere is present continuously or for long periods.
- Zone 1 identifies areas where an explosive atmosphere could occasionally appear during the normal operation of the facility.
- Zone 2 refers to areas where the presence of explosive atmospheric elements is unlikely, and if they are present, it is only for a short period.
When the risk is associated with combustible dust, the classification is carried out using zones 20, 21, and 22 following an equivalent logic.
This classification is essential because it determines what type of equipment can be installed at each location and what additional measures must be implemented to ensure an adequate level of security.
Explosion risk assessment
The classification of zones is only part of the work. A full ATEX study must include an explosion risk assessment that facilitates understanding the probability and consequences of an event.
The first step is to identify the flammable substances present and assess their relevant physical properties, such as explosive limits, self-ignition temperature, or the minimum energy required to cause ignition.
Possible ignition sources are then analyzed. Among the most common are defective electrical equipment, hot surfaces, mechanical sparks produced by friction, static electricity, cutting and welding work, and certain maintenance operations.
Finally, the potential consequences of the accident are evaluated. An isolated or confined explosion in a small piece of equipment isn’t the same as an event capable of compromising a whole factory or a production-critical installation.
Industrial sectors that are particularly exposed
The application of ATEX studies is common in the chemical, petrochemical and oil and gas industries. However, there are numerous sectors where this risk has traditionally been underestimated.
Cereal storage silos are one of the best-known examples. The continuous movement of products generates large amounts of combustible dust that can accumulate and disperse under certain circumstances. Similar situations arise in flour mills, sugar plants, or feed factories.
ATEX risks are also common in metal dust handling systems, especially aluminum, magnesium, or titanium. In recent years, the development of new energy technologies has equally increased the importance of hydrogen-related installations, whose flammability properties require special attention during design and operation.
Likewise, the facilities that store or use natural gas, LPG, flammable solvents, or liquid fuels continue to be classic scenarios where the ATEX assessment is essential.
The importance of designing with ATEX in mind
One of the most common errors is to do the ATEX assessment once the facility has been built. From a risk engineering point of view, the best time to carry out these studies is during the conceptual design phase and the detailed engineering phase, when it’s still possible to modify the location of equipment, optimize ventilation systems, reduce potential leakage points, and minimize the extent of classified areas.
The solutions implemented during the design phase usually turn out to be much more effective and economical than the modifications made once the plant is operational.
Main preventive measures
The corrective measures resulting from an ATEX study are usually aimed at three areas:
- Avoiding the formation of explosive atmospheres
- Eliminating ignition sources
- Limiting the consequences of a possible explosion
In practice, this can translate into ventilation improvements, closed process systems, inertization with nitrogen, leak control, installation of certified equipment for classified areas, or grounding systems to prevent static electricity accumulations.
When the residual risk remains significant, additional protective measures can be incorporated such as vent panels, explosion suppression systems, equipment isolation, or the installation of barriers to prevent propagation of the pressure wave.
How Europe stacks up against the United States
In Europe, the management of explosive atmospheres is fundamentally regulated by Directive 2014/34/EU, which establishes the requirements for protective equipment and systems intended for potentially explosive atmospheres, and by Directive 1999/92/EC, aimed at protecting workers exposed to this type of risk.
In the United States the focus is different, where there is no equivalent ATEX framework. The main reference is the National Electrical Code (NEC), contained in the National Fire Protection Association (NFPA) 70 standard, which classifies hazardous locations using class systems, divisions, and substance groups.
Although the methodologies present differences, the objective is essentially the same: to identify the areas where an explosive atmosphere may exist and ensure that the installed equipment doesn’t act as an ignition source.
In other countries like Colombia or Mexico, where there are no regulations requiring the carrying out of these types of studies, applying the European directive or the NFPA standard is the recommended course of action.
The risk engineer’s perspective and the insurance interest
From an insurance perspective, ATEX studies are extremely valuable because they help control one of the most severe loss scenarios that an industrial facility can suffer.
A significant explosion can destroy critical equipment, affect entire buildings, and cause business interruptions lasting several months. That’s why during risk inspections special attention is paid to the quality of the ATEX analysis, the correct implementation of mitigation measures, and the maintenance of the design conditions initially considered.
Experience shows that having an ATEX study done isn’t enough – what really matters is that its conclusions are translated into concrete and verifiable actions within the plant.
Numerous industrial accidents that have occurred over the last few decades have shown that the risks associated with combustible gases and dust are usually related to known deficiencies: accumulations of dust, unevaluated modifications, inadequate equipment for classified areas, or insufficient control of ignition sources.
This is why ATEX studies must be considered living documents. Whenever there is a process modification, a change in equipment, an expansion of installations, or the incorporation of new flammable substances, it’s essential to review the evaluation initially carried out.
Furthermore, although the regulations don’t generally establish a fixed updating frequency, the accepted best practice is to conduct a comprehensive review approximately every five years to verify that the initial assumptions remain valid.
Conclusion
ATEX studies are much more than a regulatory obligation: they function as an engineering tool that identifies explosion scenarios, prioritizes investments, and reduces risks that could compromise both the safety of people and the economic viability of a facility.
From a risk engineering perspective, their true value is appreciated when they are integrated from the outset of the design of a plant or installation, kept up to date, and used as a basis for operational decision-making. In an increasingly complex industrial environment, ATEX studies remain one of the most effective defenses against one of the risks of greatest potential severity.
Author of the article:
Borja de la Rica, Risk Engineer at Mapfre Global Risks.
