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..
Boeing 777 reported at speeds of up to 745mph as it flies from New York to Heathrow in just 5 hours 16 minutes. The Boeing 777-200 jet reached a ground speed of 745mph as it rode winds of more than 200mph across the Atlantic Photo: Alamy. By Rob Crilly, New York. 5:14PM GMT 10 Jan 2015.