The steady state metabolic demands for each of the individual work tasks used in man testing of self contained breathing apparatus (SCBA) and the use of continuous monitoring of physiological responses in short duration man tests were evaluated. Subjects' expired air, oxygen, and carbon-dioxide concentrations were measured during performance of walking, running, carrying, and ladder climbing tasks and during the following pulley and overcast tasks to determine steady state responses. Pulmonary ventilation rate, oxygen rate, and carbon-dioxide elimination rate were measured on laboratory instruments during four short duration man tests and were then computed and recorded at 0.2 minute intervals. Equations were derived to predict the oxygen cost during walking, oxygen rate during pulling, total oxygen cost during performance of overcast tasks, and oxygen rate during laddermill tasks. Values were computed for total oxygen costs of some tasks. The pulmonary ventilation and oxygen uptake were smaller during the transient experiments than predicted using the values calculated from the steady state analysis. The continuous monitoring tests showed that pulmonary ventilation drops off as almost a first order exponential function of time with a rate constant of 0.93 per minute or with a half time of about 45 seconds when there is a sudden drop in work rate from one level to another, demonstrating the need to take measurements as close to the end of the task as possible in order to obtain accurate values. Data from these tests were used to develop a new set of tables for use in testing of self contained breathing apparatus.
Papers from the NIOSH International Respirator Research Workshop, September 9-11, 1980, Division of Safety Research, NIOSH, Morgantown, WV