Abstract: A multilayer filter assembly for use inside an electronic enclosure, such as a hard disk drive enclosure containing a rotating disk, is disclosed. The filter assembly provides filtration of air entering the enclosure, as well as air circulating within the enclosure. The filter assembly is generally a single-piece unit that can be formed without a rigid frame, thus allowing the filter assembly to be produced at a reduced cost. In one implementation of the invention, the multilayer filter assembly contains at least two particulate removal layers covering, enclosing, and dividing at least two adsorbent regions. One of the adsorbent regions is configured to be placed flush against an interior wall of the electronic enclosure to allow air to flow in and out of the enclosure, while the other adsorbent region is configured to be placed in an upright position in the enclosure with exposed surfaces that allow airflow through this portion of the filter assembly.