[jamest (OP)]

Mark asks, 'Does the lack of oxygen in planes contribute to jet lag, and if it does, is it worse since the smoking ban? Also, do you get jet lag if you follow a time zone?'

[paul cotter]

Interesting question. Generally when one's oxygenation drops it is compensated for by increased breathing rate/depth. It would be an interesting experiment to try, ie use an oximeter on a flight- i'll do it on my next flight if I remember. I cannot see how the smoking ban could have aggravated the situation as smoking involves a certain amount of carbon monoxide inhalation which diminishes the blood's oxygen carrying capacity. Most people find a west bound flight easier to recover from than an east bound one- the west bound one following the time zone.

[alancalverd]

Airliners are pressurised to not more than 8000 ft effective altitude, which should not induce significant hypoxia - plenty of people live around 6 - 7000 ft in the USA. Many new planes work at 2500 ft.

Inhalation of tobacco smoke can induce hypoxia, so the smoking ban has made life better, not worse, for everyone.

Jet lag is entirely due to loss of synchrony between the traveller's circadian rhythms and the habits of the people at his destination. Some airlines try to compensate by serving the local-time-appropriate meal during the arrival phase. Flying north-south, i.e. in a single time zone, does not produce jet lag.

I'd be interested in Paul's findings. From my own limited experience of flying without oxygen at the statutory limit  (10,000 ft) I can certainly detect hypoxia symptoms above 8000 ft ("slightly intoxicated" and a general feeling of wellbeing) but get full recovery during the descent phase (around 15 minutes to approach altitude in the UK).

I just read an interesting note from a USAAF doctor who persuaded reluctant WW2 aircrew to use their oxygen masks by playing poker in a decompression chamber. The medics all wore oxy masks and "we made a lot of money and the aviators learned a vital lesson".

[Bored chemist]

The important fact about the smoking ban is that, since they introduced it, they are able to "get away with" fewer air changes per hour. That might well reduce the oxygen concentration.