In the preamble to the final Respiratory Protection Standard, OSHA discussed extensively its rationale for requiring that employees breathe air consisting of at least 19.5 percent oxygen. The following excerpt, taken from the preamble, explains the basis for this requirement: Human beings must breathe oxygen . . . to survive, and begin to suffer adverse health effects when the oxygen level of their breathing air drops below [19.5 percent oxygen].
- The Tu-144 supersonic transport was the fastest commercial jet plane at Mach 2.35 (1,555 mph, 2,503 km/h). It went into service in 1975, but soon stopped flying. The Mach 2 Concorde aircraft entered service in 1976 and flew for 27 years..
Some models of jets have been designed to reach much higher speeds than the average of 550 mph. Typically, these planes are designed for a limited number of passengers. One example is the Gulfstream G650 from Gulfstream Aerospace, which reaches speeds of up to 904 mph. Large passenger planes, such as the Boeing 747-8, can hold up to 700 passengers and reach cruising speeds of 649 miles per hour.