An “explosive atmosphere” is defined as a mixture with air, under atmospheric conditions, of flammable substances in the state of gases, vapors, mists or dusts in which, after ignition, combustion spreads to the unburned mixture as a whole (Art. 288, Legislative Decree. 81/08), it is sufficient that combustible and/or flammable substances mixed with air in the right proportions (mixing within the explosible range) are present in an activity during normal working conditions, or accidentally, to determine a possible presence of explosive atmospheres.

According to Article 289, in order to prevent explosions, the employer is obliged to take technical and organizational measures appropriate to the nature of the activity carried out on the basis of the risk assessment, which should consider the classification of areas with explosion hazards.

If the activity does not allow the prevention of the formation of explosive atmospheres, he shall:

• Avoid ignition of explosive atmospheres;
• Mitigate the detrimental effects of an explosion.

In fulfilling the obligations set forth in Article 290, the employer must prepare and keep up-to-date an “explosion protection document” (Article 294 of Legislative Decree 81/08), where it is specifically stated:

1. That explosion hazards have been identified and assessed;
2. That appropriate measures will be taken to achieve the objectives of Title XI of Legislative Decree 81/08;
3. Which places have been classified into the zones in Annex XLIX;
4. What are the places where the minimum requirements in Annex L apply;
5. That workplaces and equipment, including alarm devices, are designed, operated and maintained with due regard to safety;
6. That, in accordance with Title III of Legislative Decree 81/08, arrangements have been made for the safe use of work equipment.

The “explosion protection document” is to all intents and purposes an integral part of the risk assessment document referred to in Article 17 of Legislative Decree 81/08