Abstract: A quantitative fit test (QNFT) system and method for assessing the biological fit factor (FF) performance of respiratory protective devices. The biological QNFT system includes the following three main elements: an aerosol generation system; an exposure chamber; and an aerosol sampling subsystem. The aerosol sampling subsystem includes an aerosol spectrometer that counts particles in discrete size units ranging from 0.5 to 20 micrometers (?m) making it possible to obtain several size-specific FF measurements from a single respirator fit test. A virtual impactor in the aerosol generation system increases the number of challenge particles in the primary target size of interest (1 to 5 ?m) and increases the sensitivity of the method allowing FF values of up to one million to be measured without the need to correct for in-mask background particles.

Abstract: A quantitative fit test (QNFT) system and method for assessing the biological fit factor (FF) performance of respiratory protective devices. The biological QNFT system includes the following three main elements: an aerosol generation system; an exposure chamber; and an aerosol sampling subsystem. The aerosol sampling subsystem includes an aerosol spectrometer that counts particles in discrete size units ranging from 0.5 to 20 micrometers (?m) making it possible to obtain several size-specific FF measurements from a single respirator fit test. A virtual impactor in the aerosol generation system increases the number of challenge particles in the primary target size of interest (1 to 5 ?m) and increases the sensitivity of the method allowing FF values of up to one million to be measured without the need to correct for in-mask background particles.

Abstract: An end-of-service-life-indicator for a multi-agent respirator filter that is safe, reliable, and easy to read and may be configured to cover a broad range of threats, including chemical warfare agents and toxic industrial chemicals, is achieved by positioning an array of chemically reactive calorimetric indicators substantially next to a sorbent bed behind a viewing window that may be integrated into the filter housing. Each colorimetric indicator in the array may be configured to produce a color change in responsive to a different target threat or threat category and may be calibrated to display easily identifiable colors, symbols or patterns to indicate an optimum time to exchange a filter.

Abstract: An air purifying respirator hood, or more particularly, an air purifying, rticulate respirator hood suitable for protection against biological hazards in military and civilian environments. The respirator hood includes an elastic fabric material which blocks the penetration of liquids and airborne particulate contaminants including biological aerosols, yet allows the transmission of moisture vapor and heat transfer to improve user comfort. It also includes at least one HEPA filter, at least one transparent lens, and a breathe-through airflow valve assembly.