Abstract: A disposable cover for an air flow grille of the type permitting air flow through a plurality of air flow openings in a predefined array of said openings, each said air flow opening having a forward inlet aperture and a passage wall extending from said forward opening to a discharge aperture on a downstream side of said air flow grille, said disposable cover being made from a thin walled mouldable plastics material having passage means corresponding to the predefined array of said openings in said air grille and being engageable therein during use of the disposable cover, said disposable cover, in use, covering at least forward facing regions of said air flow grille and at least a portion of each of the passage walls extending towards the discharge aperture on the downstream side of said air flow grille.