ISO 29463-5:2011 specifies the reference test procedure for determining the efficiency of filters at their most penetrating particle size (MPPS). ISO 29463-5:2011 also gives guidelines for the testing and classification for filters with an MPPS of less than 0,1 µm and filters using media with (charged) synthetic fibres. ISO 29463-5:2011 is intended for use in conjunction with ISO 29463-1, ISO 29463-2, ISO 29463-3 and ISO 29463-4.