NIOSH has updated the standard testing procedure for the determination of particulate filter efficiency for N95 series filters against solid particulates for non-powered, air-purifying respirators. According to the agency, these filters or filter cartridges may be integral to respirator construction; mounted individually or in sets of up to three; used in conjunction with cartridges and canisters for chin-style, front-mounted, and back-mounted gas masks; or used in combination with gas-and-vapor or atmosphere- supplying respirators. The purpose of the update is to establish the procedure for ensuring that the particulate filtering efficiency level of N95 series filters used on non-powered respirators submitted to NIOSH for approval or extension of approval meet minimum certification standards.  A PDF copy of the revised procedure, dated Oct. 31, 2019, is available from NIOSH. More information on standard respirator testing procedures is available from the NIOSH National Personal Protective Technology Laboratory website.