A coated porous sheet material comprising a gas permeable sheet material selected from the group consisting of flash spun plexifilamentary nonwoven sheet, spunbonded-film-spunbonded composite sheet, spun-laced polyester/wood pulp composite sheet and paper and a polymeric coating on at least one side thereof, wherein the permeability of the coated sheet material is substantially equivalent to the permeability of an equivalent sheet material without the coating. The coated porous sheet material is suitable for use in heat sealable packages.