How well evaluate the face-seal leakage on RPD's : standard, artificial or in site methods ?

Development of safety requirements applicable to Respiratory Protective Devices (RPD) is tending towards definition of normative procedures representative of work situations. In this context, the present memorandum aims to explain the differences in respiratory mask performance characteristics measured in the field and obtained in the laboratory using a respiration machine. Usage limits have been established for this machine in its current form. Moreover, the aerosol detection principle retained for the tests turned out to play a leading part in evaluating respiratory mask performance. Toughening of respiratory flow conditions and consideration of the "occupational action" variable represent ways forward for normative testing; these emerged from both our laboratory and field tests. The method of quantifying face seal leakage by counting particles (CNC) was thus revealed to be suitable for intercomparing field fitting measurements and laboratory evaluations.