ISO 16890-4:2016 establishes a conditioning method to determine the minimum fractional test efficiency. It is intended for use in conjunction with ISO 16890‑1, ISO 16890‑2 and ISO 16890‑3, and provides the related test requirements for the test device and conditioning cabinet as well as the conditioning procedure to follow. The conditioning method described in this part of ISO 16890 is referring to a test device with a nominal face area of 610 mm × 610 mm (24 inch × 24 inch). ISO 16890 (all parts) refers to particulate air filter elements for general ventilation having an ePM1 efficiency less than or equal to 99 % and an ePM10 efficiency greater than 20 % when tested according to the procedures defined within ISO 16890 (all parts). NOTE The lower limit for this test procedure is set at a minimum ePM10 efficiency of 20 % since it will be very difficult for a test filter element below this level to meet the statistical validity requirements of this procedure. Air filter elements outside of this aerosol fraction are evaluated by other applicable test methods. See ISO 29463 (all parts). Filter elements used in portable room-air cleaners are excluded from the scope of this part of ISO 16890. The performance results obtained in accordance with ISO 16890 (all parts) cannot by themselves be quantitatively applied to predict performance in service with regard to efficiency and lifetime. The results from this part of ISO 16890 may also be used by other standards that define or classify the fractional efficiency in the size range of 0,3 μm to 10 μm when electrostatic removal mechanism is an important factor to consider, for example ISO 29461.