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are reported only for lower volumetric flow rates (e.g., 28 or 32 L/min/filter), then the expected higher leakage values at 85 L/min/mask must be considered when evaluating a study depending on whether one or two filters are used per mask. All volumet- ric flow rate results reported and discussed in this evaluation have been converted to "as-used-on-mask" units (L/min/mask) when necessary.
  Refer to multiple flow-rate results reported by Hinds and Kraske,^[1] Liu and Fardi,^[2] or Stevens and Moyer 227 to gain an appreciation of the substantial effect of volumetric flow rate on DM and DFM filter leakage. Also refer to Figures VI through IX presented later in this evaluation.
  In order to evaluate what volumetric flow rates through filters are most relevant to actual workplace usage, one needs to know what volumetric flow rates are achieved by respirator users at various work rates. In 1990, this topic was commented on by Revoir as follows:

Breathing rates for healthy adult males determined by the late Dr. Leslie Silverman and his associates at Harvard University often are used to establish air-flow rates for performance test. ing of respirators. The breathing rates determined by Dr. Silverman and his associates that should be considered for respirator performance testing are listed as follows: Maximum Work Classification Work Rate (kg-m/min) Breaths per Minute volume Maximum Inspiratory Expiratory Rate minute (L/min) Rate (L/min) (L/min) Medium work 622-830 23-30 37-55 100-149 107-154 Heavy work 1107-1384 35-41 75-104 194-254 211-314 Maximum 1660 48 114 288 322 exertion The [volumetric] air-flow requirement for an open-circuit self-contained breathing apparatus listed in 30 CFR Part 11 is 200 liters/minute which means that if the activity of a wearer is that equivalent to heavy work, the wearer's peak inspiration rate may exceed the air-flow rate of the

227 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).