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's midtier fare, Blue Plus, includes one complimentary checked bag. A second bag is $35, which JetBlue again notes is a reduction from the previous $50 fee for a second bag.JetBlue says Blue Plus fares will vary by route and by demand, but that they'll generally be about $15 more than the more-basic Blue fares.ustomers choosing to check a bag can do so for $20 if they pay to check the bag online or at an airport kiosk. The fee rises to $25 if done at a check-in counter. A second bag is $35, which JetBlue notes is a reduction from the previous $50 fee for a second bag.