There are many substances that can form an explosive atmosphere; for example, gases (natural gas, butane, propane, acetylene, etc.), liquids (propellants, solvents, oils, paints, etc.) and solids (wood, coal, cereal grains, metal powder) and therefore many installations and activities that must be evaluated according to regulations.
Directive 99/92/CE provides that the employer must take the appropriate measures to prevent the formation of explosive atmospheres or, where the nature of the activity does not allow that, to prevent the ignition of explosive atmospheres, and mitigate the adverse effects of an explosion so as to ensure the health and safety of workers.
To classify the areas, you must follow and take into account the international standards (UNE/IEC 60079-10) and the physical and chemical parameters of the substances liable to cause explosive atmospheres. It is therefore possible to identify the site based on the characteristics of the substances in the facility.