Respiratory demand in Individuals Performing Rigorous Physical Tasks in Chemical Protective Ensembles
Technical rept. Sep 2002
NAVAL AIR WARFARE CENTER AIRCRAFT DIV PATUXENT RIVER MD
Pagination or Media Count:
Protection afforded by a respiratory filter depends on chemical or biological agent and flow rate. Filtration mechanisms such as chemical adsorption depend on sufficient residence time for the filter media to extract noxious agents from the airstream. Consequently, filter efficiency is a function of inspiratory air velocities. Filter designs account for this by adjusting bed depth and cross-sectional area to anticipated flow rates. The NATO-standard military filter C2A1 and many commercial filters are designed and tested at 32 litersmin 1pm. The present study investigated respiratory demand while U.S. Marines n32 completed operationally relevant tasks in MOPP IV chemical protective ensembles including M-40 masks and C2Al filters. Respiratory demand greatly exceeded current test conditions during the most arduous tasks minute ventilation 96.4 - 18.9 1pm mean - SD with a maximum of 13l.7 1pm observed in one subject. Mean peak inspiratory flow rate PIF reached 238.7 - 34.0 1pm with maximum PIF often exceeding 300 1pm maximum observed value 356.3 1pm. The observed respiratory demand was consistent with data reported in previous laboratory studies imposing very heavy workloads. This study is among the few to report on respiratory demand while subject. perform occupationally relevant tasking in chemical protective ensembles. The results indicate that military and industrial filters will probably encounter higher flow rates than previously anticipated during heavy exertion.
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