Filtering device for air conditioners, in particular for vehicles, and reducing the propagation of fire

Filtration device intended to equip an aeration and/or heating and/or air conditioning apparatus, in particular for a motor vehicle, of the type comprising at least one filter media and a grid: the grid comprises a mineral filler intended to reduce the speed of propagation of a flame, such as for example an alkaline earth metal silicate, better a magnesium silicate, advantageously a natural magnesium silicate or talc; the quantity of mineral filler is between 10 and 40% by weight, better between 20 and 30% by weight.