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WORKING DRAFT 9.15.92—Performance Evaluation of DM and DFM Filter Respirators
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  In 1987, Hinds and Kraske published filter leakage results for the 3M 8710 single-use, DM-filter respirator and MSA Type S DFM filters for aerosol size midpoints ranging from 0.14 to 11.3 μm and flow rates of 2 to 150 L/min/mask.[1] At 50 L/min/mask and against aerosol sizes about 0.2 um diameter, they reported leak- ages through the 8710 DM filter of about 14 to 18% and about 4 to 5% leakage through MSA DFM filters. /&7

In 1989, Stevens and Moyer reported filter leakage results for four DM filters and four DFM filter challenged against 0.03 to 0.24 um CMD (GSD of 1.4 to 1.6) NaCl aerosols at flow rates of 32 to 170 L/min/mask.’® For flow rates in the range 32 to 85 L/min/mask, they reported maximum-leakage results of 11% to 29% for DFM filters and 1% to 6% for DFM filters./4?

NIOSH concludes that for over two decades data have been available to indicate that substantial leakage can be expected to occur through some models of NIOSH. certified DM and DFM filters. There have been numerous reports of this filter leak- age occurring when these filters were used against contaminant sizes ranging from about 0.05 to 0.40 micrometers (um) (count median diameter).

Experts in the field of respiratory protection have cautioned that filter-protection

limitations must be considered when determining aasigned protection factors. In 1976, Hyatt cautioned:

The [assigned] protection factor can only be applied when a comprehensive respirator program is being carried out and the respirator approval limitations are considered. Also, other factors must be considered, such as. . . the efficiency of a particulate-filter element for removal of specific types of aerosols!”

Hyatt also observed with regard to respirator-performance test results on dust filters using sodium chloride aerosol (0.6 Hm MMAD):


bid.

Stevens, G.A. and E. S. Moyer: “Worst Case” Aerosol Testing Parameters: I. Sodium Chloride and Dioctyl Phthalate Aerosol Filter Efficiency as a Function of Particle Size and Flow Rate, Am. Ind. Hyg. Assoc. J., 50(5):257-264 (1989).

7bid., Table Il, p. 262.

‘Hyatt E.C.: Respirator Protection Factors. Los Alamos Scientific Laboratory, Informal Report No.

LA-6084—MS (1976), pet,

  1. ↑ Hinds, W. C. and G. Kraske: Performance of Dust Respirators with Facial Seal Leaks: I. Experimental, Am. Ind. Hyg. Assoc. J., 48(10):836-841 (1987), Figures 6 and 6, pp. 839-840.
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