Subsection 2: Ventilation.

The quality of the air in underground galleries and shafts must be compatible with the health and safety of workers.

When the natural ventilation of a gallery being excavated is insufficient, the atmosphere is purified by means of a mechanical ventilation system. This ventilation system ensures a minimum air flow of twenty-five litres per second per man at the working face. The air introduced is taken far from any source of pollution.

In underground galleries being excavated where explosives are used, ventilation is carried out under the following conditions: 1° At least 200 litres of air per second per square metre of the largest section of the ventilated gallery are introduced at the working face by means of a mechanical ventilation system. The air introduced is taken far from any source of pollution; 2° After each blast, suction is applied as close…

Where internal combustion engines are used or noxious fumes are emitted, the minimum quantities of air to be introduced under articles R. 4534-44 and R. 4534-45 are increased so that air quality remains compatible with the health and safety of workers.

When a gallery is drilled or a shaft is sunk in rock containing free silica, only water-injected foils or foils fitted with an effective dry dust collection device are used. Instructions indicate the workstations where it is necessary to reinforce collective protection measures through the use of appropriate respiratory equipment. This instruction also specifies, for each workstation, the maximum duration for which the apparatus must be worn and the conditions…

When explosives are used or when work is carried out in ground containing free silica, the spoil is watered.

In underground galleries and shafts where there is a risk of gas emanating and forming a detonating mixture with the air, the use of lamps or equipment burning naked flame is prohibited.