Abstract: The invention relates to a ventilated enclosure for the treatment of workpieces, particularly an elongated enclosure for painting workpieces, comprising a treatment space situated between a ceiling through which the supply of new air takes place and a floor, said ceiling comprising, particularly from upstream to downstream following the path of the air, a filter and a diffuser, said enclosure being furthermore equipped with air injectors. These injectors are arranged and disposed so as to deliver jets or sheets of air in one or more free spaces situated in the ceiling between the filter and the diffuser.