The invention relates to an apparatus for decontaminating premises by the atomisation of a liquid treatment product (3) in the volume thereof, comprising a receiving tank (2) for said product (3), means (4) capable of generating fine droplets of the product (3) in an area of the surface thereof, means (6) capable of . generating an air flow for driving said fine droplets while mixing with them, and means (10, 12) adapted for injecting into the premises the mist thus formed. The apparatus is characterised in that the air flow flows through a convergent tubing (18) having an axis (xx") identical with that of the air flow, the tubing opening in the vicinity of the surface of the liquid product (3) and being inclined at an angle (3) relative thereto.
