Aerosol penetration through respirator exhalation valves.
Am Ind Hyg Assoc J 1990 Oct; 51(10):555-560
The nature and extent of exhalation valve leakage (back leakage of outside air through the exhalation valve as it closes and seals during inhalation) was investigated. An MSA Comfo-II half face mask respirator sealed to a manikin and a dual piston mechanical breathing machine were used for aerosol penetration tests. Aerosol particle sizes tested were 0.5, 2, 4, and 8 micrometers. Copper wires of known thickness were placed in contact with the exhalation valve seat to simulate valve defects. Thicknesses of 0.03, 0.08, their exterior surface were also tested. Introduction of a 0.25 millimeter wire increased aerosol penetration by 100 to 1000 fold. Aerosol particle penetration was strongly dependent on particle size. Penetration for wire induced exhalation valve leaks was as high as 1.1%. The effect of paint and/or dust accumulation on a valve was comparable to that of wire induced leaks, 0.2% to 0.6%. The authors conclude that proper inspection of all respirator components is a necessary component of a respiratory protection program.
NIOSH-Publication; NIOSH-Grant; Respirators; Training; Safety-practices; Safety-equipment; Respiratory-protective-equipment; Personal-protective-equipment
Inst of Safety & Systems Mgmt University of California University Park Los Angeles, Calif 90089-0021
American Industrial Hygiene Association Journal
University of Southern California, Los Angeles, California