The influence of a low air pressure environment on human metabolic rate during short-term (< 2 h) exposures.
Passengers in aircraft cabins are exposed to low-pressure environments. One of the missing links in the research on thermal comfort under cabin conditions is the influence of low air pressure on the metabolic rate. In this research, we simulated the cabin pressure regime in a chamber in which the pressure level could be controlled. Three pressure levels (101/85/70 kPa) were tested to investigate how metabolic rate changed at different pressure levels. The results show that as pressure decreased, the respiratory flow rate (RFR) at standard condition (STPD: 0°C, 101 kPa) significantly decreased. Yet the oxygen (O2) consumption and carbon dioxide (CO2) production significantly increased, as reflected in the larger concentration difference between inhaled and exhaled air. A significant increase in the respiratory quotient (RQ) was also observed. For metabolic rate, no significant increase (P > 0.05) was detected when pressure decreased from 101 kPa to 85 kPa; however, the increase associated with a pressure decrease from 85 kPa to 70kPa was significant (P < 0.05). Empirical equations describing the above parameters are provided, which can be helpful for thermal comfort assessment in short-haul flights.
Department of Building Science, School of Architecture, Tsinghua University, Beijing, China.
W
W
Cui
Department of Environment and Municipal Engineering, Qingdao Technological University, Qingdao, China.
H
H
Wang
Department of Building Science, School of Architecture, Tsinghua University, Beijing, China.
T
T
Wu
Department of Building Science, School of Architecture, Tsinghua University, Beijing, China.
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Q
Ouyang
Department of Environment and Municipal Engineering, Qingdao Technological University, Qingdao, China.
S
S
Hu
Department of Building Science, School of Architecture, Tsinghua University, Beijing, China.
Y
Y
Zhu
D000064:Acclimatization / Q000502:physiology*; D000399:Air Pressure; D000401:Aircraft; D002245:Carbon Dioxide / Q000032:analysis; D004781:Environmental Exposure / Q000009:adverse effects*; D005260:Female; D006801:Humans; D008297:Male; D010101:Oxygen Consumption / Q000502:physiology; D013997:Time Factors; D055815:Young Adult
D002245:Carbon Dioxide
CO2 production; Low-pressure environment; Metabolic rate; O2 consumption; Respiratory flow rate; Respiratory quotient