Abstract: A modular chemical/biological headgear system includes a helmet liner of a resilient shock absorbing material that conforms generally to the shape of a wearer's head, provides a cavity for removable installation of one or more modular filters in the back, and a duct to convey filtered air from the one or more modular filters to a face mask. The helmet liner may be equipped and configured with a variety of interchangeable modular components including hardened outer shells, communications modules, enhanced chemical biological filters, and the like, to meet a wide variety of operational needs.

Abstract: Airflow is improved for multi-agent chemical biological air-purifying apparatus by providing a filter module that has multiple filter elements contained within a substantially sealed housing. The housing secures the filter elements in a spaced relation such that the top and bottom faces of each filter element are exposed to the flow of air and provides an air path within the housing adapted to channel air through the multiple filter elements in a parallel flow. The filter module may be made from a flexible and resilient plastic material and may be contoured to conform to the shape of a helmet liner or similar headgear.