A multi-layer film (22) covers an aperture (21) in a rigid container (10) to provide a filtered venting system (C) for the container. The film includes a porous filter layer (36,36') of a material such as polytetrafluoroethylene foam which filters bioburden from air as it enters the container during the dispensing of a fluid from a nozzle (14) in the container. The film also includes a barrier layer (34,34') of an impermeable material that prevents air from entering the container during transit and storage and prevents blockage of the porous layer with dried fluid. Before dispensing, the film is stretched, thereby destroying the integrity of the barrier layer and allowing air to enter through the porous layer.