A room to be sterilized, comprising: - a false ceiling for supplying treated or not treated air in said room to be sterilized, comprising: at least one protective tensioned fabric, blocking UVC, said protective tensioned fabric positioned on the underside and at a distance from the ceiling of the space to be sterilized, being fixed to the side walls of said space and arranged with an upper slab of the ceiling in order to delimit a so-called plenum space, at least one means for attaching said at least one protective tensioned fabric to the side walls of the space by means of at least one peripheral attachment profile comprising an air outlet slot giving onto at least one side wall of the space and allowing the passage of the air circulating between the plenum and said space to be sterilized, - at least one ventilation and/or air-conditioning means connected to said plenum via at least one air inlet air venting duct in said plenum, the blown air forming a horizontal unidirectional air circulation corridor over the entire length of the plenum, - an air return box able to be connected to ventilation and/or air conditioning means, as well as air suction openings located opposite said air outlet slot and allowing air to pass from inside the space to said air return box, and where said false ceiling includes a plurality of light sources arranged in the plenum over the entire length of said horizontal unidirectional air circulation corridor and where the distance between said plurality of UVC light sources and the ceiling on the one hand and the distance between said plurality of UVC light sources and said at least one stretched protective fabric on the other hand is at most 25 cm, characterized in that said plurality of light sources are UVC sources so as to sterilize the air flowing in the air circulation corridor before its passage through the air outlet slot and in that the walls of the plenum comprise means for reflecting the ultraviolet light emitted by said plurality of UVC light sources. - a false ceiling for supplying treated or not treated air in said room to be sterilized, comprising: at least one protective tensioned fabric, blocking UVC, said protective tensioned fabric positioned on the underside and at a distance from the ceiling of the space to be sterilized, being fixed to the side walls of said space and arranged with an upper slab of the ceiling in order to delimit a so-called plenum space, at least one means for attaching said at least one protective tensioned fabric to the side walls of the space by means of at least one peripheral attachment profile comprising an air outlet slot giving onto at least one side wall of the space and allowing the passage of the air circulating between the plenum and said space to be sterilized, at least one protective tensioned fabric, blocking UVC, said protective tensioned fabric positioned on the underside and at a distance from the ceiling of the space to be sterilized, being fixed to the side walls of said space and arranged with an upper slab of the ceiling in order to delimit a so-called plenum space, at least one means for attaching said at least one protective tensioned fabric to the side walls of the space by means of at least one peripheral attachment profile comprising an air outlet slot giving onto at least one side wall of the space and allowing the passage of the air circulating between the plenum and said space to be sterilized, - at least one ventilation and/or air-conditioning means connected to said plenum via at least one air inlet air venting duct in said plenum, the blown air forming a horizontal unidirectional air circulation corridor over the entire length of the plenum, - an air return box able to be connected to ventilation and/or air conditioning means, as well as air suction openings located opposite said air outlet slot and allowing air to pass from inside the space to said air return box, and where said false ceiling includes a plurality of light sources arranged in the plenum over the entire length of said horizontal unidirectional air circulation corridor and where the distance between said plurality of UVC light sources and the ceiling on the one hand and the distance between said plurality of UVC light sources and said at least one stretched protective fabric on the other hand is at most 25 cm, characterized in that said plurality of light sources are UVC sources so as to sterilize the air flowing in the air circulation corridor before its passage through the air outlet slot and in that the walls of the plenum comprise means for reflecting the ultraviolet light emitted by said plurality of UVC light sources.