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.
jet blue checked-in baggage. Passengers can check items of luggage into the hold, with each bag measuring no more than 62 inches (157.48c m) in total dimensions and weighing no more than 50 lbs (22.68 kg). The first item of checked luggage is free of charge on Blue Plus and Blue Flex fares, but $20 online on Blue fares.