Effects as a function of altitude. The human body can perform best at sea level, where the atmospheric pressure is 101,325 Pa or 1013.25 millibars (or 1 atm, by definition). The concentration of oxygen (O2) in sea-level air is 20.9%, so the partial pressure of O2 (pO2) is 21.136 kPa.
On Tuesday, the New York-based carrier rolled out a new three-tier structure for fares, giving the cheapest fares to passengers without checked bags. The airline's new fare types are labeled Blue, Blue Plus and Blue Flex, according to notices posted on JetBlue.com. Price differences between the tiers will vary, but Blue fares generally will be $15 cheaper than Blue Plus, and Blue Flex will be about $85 higher than that, according to JetBlue.
JetBlue passengers will have three options when buying tickets: Blue, Blue Plus and Blue Flex. It will cost fliers with a Blue fare $20 to check their first bag when checking-in online or at a kiosk. If they wait to check-in at the airport counter, the fee goes up to $25.A second checked bag flies for $35.Blue Plus tickets include the cost of a checked bag, while a second checked bag is $35. Blue Flex fares cover the cost of two checked bags.f they wait to check-in at the airport counter, the fee goes up to $25. A second checked bag flies for $35. Blue Plus tickets include the cost of a checked bag, while a second checked bag is $35.