Effect of facial-seal leaks on protection provided by half-mask respirators.
Appl Ind Hyg 1988 May; 3(5):158-164
The performances of half mask cartridge respirators for protection against aerosols were assessed using a predictive computer model based on quantitative fit test (QNFT) results, type of respiratory filter used, and exposure conditions of work rate of the wearer and size distribution of the exposure aerosol. Conditions were chosen to approximate those encountered in industrial environments. Measurement errors due to loss of particles in facial seal leaks were estimated to be less than 5 percent; change from high efficiency test filters to regular dust, fume, and mist (DFM) filters could significantly reduce protection. Overall protection factors were predicted for 33 industrial aerosol exposures based on assumed QNFT fit factors of 20 and 50; DFM respirators with a fit factor of 50 had predicted protection factors ranging from 21 to 2900 depending on aerosol size distribution. For an unknown aerosol size distribution and average respirator performance, a fit factor of 15 or more was necessary to ensure an overall protection factor of at least 10. For workers exposed to aerosols with mass median aerodynamic diameters greater than 1.0 micron, a fit factor of 11 was required to obtain a protection factor of 10. A protection factor of 50 with DFM filters required a fit factor of greater than 85 for aerosols with mass median aerodynamic diameter greater than 1.0 micron. Recommendations could not be made for disposable dust and mist respirators, but it was estimated that a facial seal leakage below 2 percent was necessary to obtain a protection factor of 5.
NIOSH-Publication; NIOSH-Grant; Respiratory-protection; Respiratory-protective-equipment; Computer-models; Equipment-design; Personal-protective-equipment; Aerosol-particles; Occupational-exposure; Industrial-safety
Environ and Nutritional Scis University of California 405 Hilgard Avenue Los Angeles, Calif 90024
Applied Industrial Hygiene
University of California Los Angeles, Los Angeles, California