This Part of this European Standard specifies requirements for non-filtration aspects of breathing system filters (BSFs) intended for the filtration of respired gases in humans when used with a breathing system. It addresses connection ports, leakage, resistance to flow, packaging, marking and information supplied. It is not intended for other types of filter e.g. those designed to protect vacuum sources or gas sample lines, to filter compressed gases, to protect test equipment used for physiological respiratory measurements.