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..
The F-15 speed is mach 2.5, the Mig 25 is mach 3.2. The Concorde could fly around mach 2, but it's not in use any more. its not the concord. The SR-71 black bird(mach 3 or about 2100mph)is the fastest military jet and the NASA X-43 scramjet(mach 9-10 or about 6300-7000mph) is the fastes unmanned jet. The fastest TRUE JET is the SR-71. The key word is true JET! thats even a bit of strech for the blackbird.