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Operational Details of the Air Transportation System
Published in Steven J. Landry, Handbook of Human Factors in Air Transportation Systems, 2017
Climbout is the portion of flight that transitions the aircraft from the immediate vicinity of the airport to high-altitude cruise flight. For small general aviation aircraft, high-altitude may be a few thousand feet; for commercial aircraft, cruise flight typically occurs between 29,000 and 41,000 feet. (Some small business jets can fly at slightly higher altitude, and the now-defunct supersonic Concorde would cruise at up to 60,000 feet.)
Toxic and Asphyxiating Hazards in Confined Spaces
Published in Neil McManus, Safety and Health in Confined Spaces, 2018
The zone of high altitude begins at 8,000 ft (2,440 m). The latter is generally regarded as the threshold above which altitude-related illness occurs. At this altitude, the arterial partial pressure of oxygen is 60 mmHg. Corresponding hemoglobin saturation relative to sea level is 92%. At higher altitudes, hemoglobin saturation decreases rapidly. At 14,000 ft (4,270 m), arterial partial pressure is 46 mmHg; arterial oxygen saturation is 82%.
Military optoelectronics
Published in P. Dakin John, G. W. Brown Robert, Handbook of Optoelectronics, 2017
At sea, the horizon and weather limit lines of sight. In the air, cloud and terrain normally limit the line of sight at low altitude. At medium and high altitude (above 5000 m) and in space, air-toair lines of sight are very long, limited only by the earth’s curvature. At high altitude, the atmosphere is thinner and atmospheric absorption becomes less significant. Air-to-ground visibility is (obviously) affected by cloud cover.
Circulating markers of intestinal barrier injury and inflammation following exertion in hypobaric hypoxia
Published in European Journal of Sport Science, 2023
Zachary J. McKenna, Bryanne N. Bellovary, Jeremy B. Ducharme, Michael R. Deyhle, Andrew D. Wells, Zachary J. Fennel, Jonathan W. Specht, Jonathan M. Houck, Trevor J. Mayschak, Christine M. Mermier
Each year, more than 40 million people visit high altitude areas (> 2500 m), and an estimated 140 million people have a permanent residence above 2500 m (Tremblay & Ainslie, 2021). The decreased barometric pressure and reductions in the partial pressures of inspired oxygen at high altitudes can have a host of physiological consequences including significant impacts on morbidity and mortality (Burtscher, 2014). High altitude illnesses vary from mild to life-threatening and often present in the form of acute mountain sickness (AMS), high-altitude cerebral edema (HACE), and high-altitude pulmonary edema (HAPE). The most common of these is AMS which has an estimated prevalence between 20% and 60% for those traveling to high altitudes (Meier et al., 2017). AMS develops following rapid high-altitude ascent and includes a variety of nonspecific symptoms such as headache, nausea, dizziness, fatigue, and insomnia. In addition, gastrointestinal (GI) distress (e.g. anorexia, nausea, diarrhea, or vomiting) is one of the most commonly reported AMS symptoms with an estimated incidence of 80% amongst people suffering from the illness (Anand et al., 2006). The pathophysiology of AMS is currently unknown, though one prevailing theory is related to dysfunction within the central nervous system (Imray et al., 2010). However, given the high incidence of GI symptoms associated with high altitude exposures, we speculate that the GI system may contribute to the development of AMS as well as other high-altitude associated GI complications (i.e. peptic ulcers (Fruehauf et al., 2020) and GI bleeding (Wu et al., 2007)).
Measured moisture accumulation in aircraft walls during simulated commercial flights
Published in Science and Technology for the Built Environment, 2018
Tengfei (tim) Zhang, Guohui Li, Chao-Hsin Lin, Zhigang (daniel) Wei, Shugang Wang
Modern commercial airplanes cruise at a high altitude, at which both the atmospheric pressure and the temperature are extremely low. To sustain human life, aircraft cabins are pressurized, and the cabin air pressure is commonly set at 80% of that at sea level. The aircraft shell is covered with insulation blankets to resist the extreme outside temperature. When an airplane is cruising, large temperature gradients across the insulation blankets cause a net migration of water vapor toward the aircraft shell. Subject to the cabin humidity and thus the dew point temperature, the water vapor may condense into liquid water or freeze directly into ice. At times, the liquid water may evaporate, and the ice may thaw or sublime. In the course of these moisture phase changes, heat release or absorption occurs. The moisture transfer is further complicated by cabin air pressurization or depressurization during flights. Hence, cabin air pressure, relative humidity, and temperature gradients across the insulation blankets may affect moisture accumulation within aircraft walls.
Risk management of free radicals involved in air travel syndromes by antioxidants
Published in Journal of Toxicology and Environmental Health, Part B, 2018
Hypoxia occurs in aircraft cabins at high altitude when cabin air pressure is relatively low, and the amount of oxygen carried in the blood is reduced compared with that at sea level (WHO 2018). High altitude sickness associated with hypoxia includes headache, lassitude, dizziness, nausea, cerebral edema, decreased consciousness, and pulmonary edema (Luks, Swenson, and Bärtsch 2017). In addition, hypoxia at high altitude may play an important role in producing inflammation, gastric ulcer or bleeding, and inflammatory bowel disease (IBD) (Anand, Sashindran, and Mohan 2006; Vavricka, Rogler, and Biedermann 2016). Therefore, air travelers with heart and lung diseases and blood disorders (e.g., sickle-cell anemia), may require additional oxygen supply during flight (WHO 2018). To predict the need for supplemental oxygen during airline flight in patients with chronic pulmonary disease, 16 published equations were applied (Bradi et al. 2009). However, the test results showed that most of them were inaccurate and only one equation showed a positive predictive value of the partial pressure of arterial oxygen (PaO2) obtained during altitude simulation.