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Performance Evaluation of DM and DFM Filter Respirators—WORKING DRAFT 9.15.92

Alamos Scientific Laboratory in the early 1970s.[1] Regarding the performance of fume (DFM) filters they stated:

Fume filters are designed to meet the criteria of an approval test involving a high load of lead oxide fume. . . . A comparison of the data of Table C-I for the half-mask facepiece respirators equipped with high efficiency filters with the data given in Table C-II indicates that the penetrations of the aerosols through the fume filters have a significant effect upon the determination of respirator protection factors.[2]

Regarding the performance of dust (DM) filters the ISEA Respirator Group stated:

Dust filters are designed to meet the requirements of an approval test involving a high load of relatively coarse silica dust... . Comparing the data given in Table C-I for the half-mask face- piece respirators equipped with high efficiency filters with the data given in Tables C-III & C-IV shows that the penetrations of NaC] aerosol through the dust filters have a significant effect upon the determination of respirator protection factors... .

A comparison of the protection factors given in Table D-I for respirators equipped with high efficiency filters and with the protection factors given in Tables D-II and D-III for respirators equipped with dust filters indicates that the dust filters Permitted significant aerosol penetra- tions.

In 1976, Douglas et al. at LASL reported on the effects of flow rates ranging from * 16 to 77 L/min/filter on leakage of a 0.6 um MMAD (GSD of 2.0, which is about 0.15 um CMD) NaCl aerosol through DM filters (both mechanical nonwoven and electrostatic-type filter materials).!™ At about 50 L/min/filter, they observed filter leakages ranging from about 3% to almost 20% for five different types of DM-filter material with two of the five DM-filter media exceeding about 13% leakage.!”*

During 1978, NIOSH conducted a multiphase investigation to compare filter leak- age results from test aerosols used in 30 CFR Part 11 and test aerosols that had been proposed by LASL several years earlier. The results of this investigation were


'™Thid., Section C, p. 12 and Section D, p. 17,

'SDougias, D. D. et al.: Respirator Studies for the National Institute for Occupational Safety and Health—July 1, 1974-~June 30, 1975, Loe Alamos Scientific Laboratory, Progress Report, No. LA-6386-PR (August 1976), pp. 13-14.

‘bid, Figure 7, p. 14.

  1. ↑ Wilcher, F. E.: ISEA Analysis of Supporting Test Data (OSHA Exhibit 38) Utilized by E. C. Hyatt to Develop Respirator Protection Factors, comments submitted by the ISEA to OSHA Docket SCP-1, Arlington, VA (October 1, 1975).
  2. ↑ Ibid., Section C, pp. 11-12.
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