Effect of dust loading on the performance of half-mask respirators.
Appl Occup Environ Hyg 1994 Oct; 9(10):700-706
The effect of dust loading on the protection provided by three types of respirators were characterized. Types of respirators included: dust and mist (DM); dust, fume and mist (DFM); and dust, fume, mist and radionuclide (DFMR). Using a breathing machine and a dust chamber, respirator filters were loaded with AC Fine Test Dust to six successive loading conditions at approximately 0, 100, 200, 400, 800, and 1,600 milligrams. Penetration and resistance measurements were made at seven flow rates for each loading condition. Penetration was monitored at 12 particle sizes, ranging from 0.14 to 3.6 micrometers. A respirator performance predictive model was used to evaluate the influence of changes in resistance and penetration. For DM and DFM respirators, there was an increase in protection which was noted until a loading of 200 to 400 milligrams was reached and then decreased gradually. Where fit factors exceeded 100, loading was beneficial in terms of protection factor for DM and DFM respirators, at least until more than 1 gram of dust was collected on the filters. The protection provided by respiratory using high efficiency DFMR filters was decreased with conditions of loading. The authors conclude that the change in protection factor is not likely to exceed a factor of three under usual conditions of use.
NIOSH-Publication; NIOSH-Grant; Respirators; Personal-protective-equipment; Respiratory-protection; Dust-exposure; Inhalants; Airborne-particles; Airborne-dusts
Environ and Nutritional Scis University of California 405 Hilgard Avenue Los Angeles, Calif 90024
Applied Occupational and Environmental Hygiene
University of California Los Angeles, Los Angeles, California