| From the World Health Organization: > "Although aircraft cabins are pressurized, cabin air pressure at cruising altitude is lower than air pressure at sea level. At typical cruising altitudes in the range 11 000–12 200 m (36 000–40 000 feet), air pressure in the cabin is equivalent to the outside air pressure at 1800–2400 m (6000–8000 feet) above sea level. As a consequence, less oxygen is taken up by the blood (hypoxia) and gases within the body expand. The effects of reduced cabin air pressure are usually well tolerated by healthy passengers." http://www.who.int/ith/mode_of_travel/cab/en/ While the NY Times blog link earlier in this chain of comments had a recommendation about reducing cabin air pressure to 6,000 ft, I question how useful that is, since for those susceptible to altitude sickness, 6,000 feet is going to be enough to trigger symptoms for many. These next two articles are not devoted to airline travel per se, but about high altitude related sickness. From "Preparing for Safe Travel to High Altitude", by Paul Anderson, M.D. > "High Altitude Illnesses (HAI) include Acute Mountain Sickness (AMS), High-Altitude Pulmonary Edema (HAPE), and High-Altitude Cerebral Edema (HACE). The symptoms of AMS are typically felt by most people when they arrive at a new altitude, but the symptoms are usually self limiting (e.g. 1st 3-5 days at high altitude). The exact mechanisms of AMS remain unclear, however symptoms tend to be the most prevalent 1-2 days after arrival at elevation. The most common symptoms include a headache, gastrointestinal upset, feelings of fatigue, dizziness, and sleep disruption. ..." http://www.mayo.edu/research/documents/preparing-for-safe-tr... From "Altitude-Related Illnesses", Mayo Clinic Preceedings: > "... An estimated 30 million people are at risk for altitude related illnesses in the western United States annually. Many cases are unrecognized by the victims and by their physicians who may attribute symptoms to viral illness, “hangover,” or fatigue. In addition, commercial airline travel exposes passengers to a cabin pressure equivalent of 2,500 m and allows them to travel rapidly to high altitude destinations such as Aspen or Steamboat Springs, Colorado, where they may be exposed to even greater altitudes. ... The rate of ascent and a prior history of altitude illness are the major determinants of a person's susceptibility to altitude illness. Aerobic fitness does not correlate with the likelihood of acquiring AMS." (See especially the symptoms of Acute Mountain Sickness in this article.) http://www.mayoclinicproceedings.org/article/S0025-6196(11)6... |