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Physiological responses to the wearing of protective equipment and respirators: effects of hot, humid inspired air on work of breathing, final report.

Turner NL
NIOSH; :1-32
The physiological effects of breathing cool/dry, cool/humid, hot/dry, and hot/humid air were observed during rest, and during light and moderate intensity exercise on a cycle ergometer. Nine male volunteers, 18 to 35 years old, took part in four 50 minute submaximal exercise tests under the four different inspired air conditions. The results demonstrated several positive effects of hot air breathing on lung mechanics. Dynamic lung compliance was increased with both hot/dry and hot/humid air breathing during rest and exercise. These increases in compliance implied a decrease in the inspiratory work of breathing, although no statistically significant decreases were demonstrated. Frequency of breathing was decreased and tidal volume increased with hot air, allowing a more efficient breathing pattern. These results lent support to the current inspired air temperature criteria for SCBA certification, as set forth in 30 CFR, Part 11 and proposed 42 CFR, Part 84. The authors suggest that future research in this area include a study in which both inspired air and ambient air temperatures are varied. The possibility of interactions between hot inspired air and hot ambient air should be explored as closed circuit respirators used in both fire fighting and hazardous waste operations may be used under hot ambient conditions.
NIOSH-Author; Physical-exercise; Temperature-effects; Humidity; Respiratory-protection; Lung-function; Pulmonary-function-tests; Work-environment; Personal-protective-equipment; Respirators; Physiological-response;
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Injury Prevention Research Branch, NIOSH, Cincinnati, Ohio, 32 pages, 27 references
Page last reviewed: September 4, 2020
Content source: National Institute for Occupational Safety and Health Education and Information Division