Effect of external dead volume on performance while wearing a respirator

AIHAJ. 2000 Sep-Oct;61(5):678-84. doi: 10.1080/15298660008984577.


Respirator dead volume accumulates exhaled carbon dioxide and returns it to the respiratory system during subsequent inhalations. Because inhaled carbon dioxide is known to be a powerful respiratory stimulant and psychoactive gas, respirator dead volume would be expected to influence performance times while respirators are worn during work. This experiment was performed at intense levels of treadmill walking (80-85% VO2max) to demonstrate maximum sensitivity to respiratory stress. Six dead volume conditions (representing a range of 280 to 1,160 mL) were imposed on the subjects. Results show linear decreases in performance times and breathing apparatus comfort with increasing dead volumes. For each 350 mL of external dead volume, a 19% decrease of performance time and an 18% decrease in breathing apparatus comfort can be expected.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Acidosis, Respiratory / etiology
  • Acidosis, Respiratory / physiopathology*
  • Adult
  • Carbon Dioxide / adverse effects*
  • Carbon Dioxide / blood
  • Exercise Test
  • Female
  • Humans
  • Hydrogen-Ion Concentration
  • Lactic Acid / blood
  • Male
  • Oxygen / blood
  • Oxygen Consumption
  • Physical Exertion
  • Respiratory Protective Devices / adverse effects*


  • Carbon Dioxide
  • Lactic Acid
  • Oxygen