Workplace Breathing Rates: Defining Anticipated Values and Ranges for Respirator Certification Testing
OAK RIDGE INST OF NUCLEAR STUDIES TN
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Test methods currently used by the National Institute for Occupational Safety and Health NIOSH are designed to assure that respirators meet a minimum level of efficacy when tested under standard laboratory protocols. For air-purifying respirators APRs, the primary performance tests most affected by airflow rate are filter gas-life capacity, particulate filter efficiency, and respirator breathing resistances. Presently, NIOSH measures all three parameters using constant-rate airflow conditions. An analysis of the measured and estimated minute volumes contained in the literature indicated a range from about 8 to 162 L minexp -1 for unencumbered ventilation and work activities that spanned from mild to exhaustive. Based on an empirical relationship between minute volume and peak inspiratory flow PIF, peak flows between 72 minexp-1 and 183 L min exp -1 would be expected for the mean minute volume for 38.5 L minexp -1. The anticipated range of PIF rates for the 95th percentile minute volume is between 182 L minexp -1 and 295 minexp -1. The results of this literature review suggest an increases in cyclic flow rates used for respirator certification testing should be considered to better represent ventilation rates found in the workplace.
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