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..
Guinness World Records recognized NASA's X-43A scramjet with a new world speed record for a jet-powered aircraft - Mach 9.6, or nearly 7,000 mph. Answer The fastest speed wasâ¦ recorded by an unmanned aircraft called X-43. It can reach the speed of almost 7460 miles per hour. The fastest manned aircraft is X-15. Its top speed is 5115 miles per hour. This is very, very fast. Different ways of flight propulsion must have different categories as fastest in their method of power, to allow for this question to be answered properly. However, the overall fastest flight reached is Mach 9.8, which is about 12,144 km/h.