The ISPE Good Practice Guide: HVAC and Process Equipment Air Filters aims to be a valuable reference on the selection, application, specification, testing, and operation and maintenance of filters in the pharmaceutical industry. This Guide is intended to be used as supplement to the ISPE Good Practice Guide: Heating, Ventilation, and Air Conditioning (HVAC), providing detailed information into the subject of air filters in HVAC and process equipment applications. This Guide describes current technologies and their application as it relates to the current guidance. This Guide also explains the principles and objectives of filter testing conducted during manufacturing and after installation, and includes a suggested approach for evaluating the impact of lifecycle costs in filter selection.