HEPA filter packs effectively collect particulate contaminants from the exhaust airstream. HEPA filters are 99.999 percent effective at removing particulate 0.3 micron and larger. The filter pack's housing has a hinged access door with gaskets and spring latches for convenient filter change. Inlet and outlet plenums with duct connection collars are installed. The HEPA filter pack also can be paired with a carbon filter pack to remove chemical fumes and odors. The manufacturer recommends a minihelic or magnehelic gauge to monitor the airflow differential across the filter. The static pressure indicated would alert when to change filter.