Oxygen concentrations in commercial aircraft flights.

Measurements of ambient oxygen concentrations were made in 22 commercial flights (707 and DC-9 aircraft) starting at an altitude of 1,500 meters (5,000 feet) with two oxygen analyzers, one calibrated at sea level (158.8 torr) and a second for Denver's altitude. Peak "pressurized cabin" altitudes ranged between 6,050 and 8,450 feet when "cruising altitudes" varied between 29,000 and 37,000 feet. In the former analyzer, the lowest oxygen concentrations noted were about 15.2% (15.5 torr), while in the latter, they were 17.6% (133.7 torr). The possible dangers of temporary hypoxia to patients with cardiac, pulmonary, and hematologic diseases, while flying under these circumstances, are discussed.