I have often posted , supporting smokers [being one myself ] and to try and point out that smoking is not all negative and that there are things just as bad that don't seem to attract the same hysteria and hatred.
Came across this in The Weekly Telegraph , today , May 16th.
It's from a Julia Pickles , London S.W.1 ,

Sir ,
It is interesting to learn that low oxygen levels and not just cramped conditions in aircraft may cause deep vein thrombosis [Issue 719]. Not so long ago, when smoking was still permitted in designated areas , a good supply of oxygen was essential to avoid the entire cabin being enveloped in a fug of tobacco smoke. It worked well and the smoke was more or less confined to the smoking area at the rear of the plane.
DVT induced by long haul flights was unheard of and one was far less likely to disembark harbouring a respiratory infection contracted on board. Air rage was also unheard of :is there a connection between a ban on smoking and the rise of this phenomenon ?
It seems air travel was healthier and safer before the health-and-safety fascists took over our lives.
J.P.

Well , whoever you are , Ms. Pickles , thank you. I hope you're sitting in a Chelsea pub , enjoying a huge gin and tonic and a long cigarette and thinking rude things about the anti-smoking brigade.
Cheers !!

The question that comes to my mind is, why is there a lower level of oxygen in the cabin now than there was in the past? Are airlines now providing a worse airflow because there isn't any smoke in the air?

If so, why have they done it, and why have they been allowed to get away with it? It only takes common sense and a couple of years in school to know that there is less oxygen in the air you breathe out than there is in the air you breathe in.

I think the airlines ARE circulating less oxygen in the cabins and I think it saves them money. I vaguely remember reading something similar to Ms Pickles' point just after the smoking bans became effective.
In the same way , smoking bans save various companies a lot of money , not only through insurance , but also because they don't have to employ so many cleaners.
When it comes to money , the comfort , health and pleasure of the passengers comes very low on the list ; e.g. I would have thought a smoking section could be fairly easily sealed off from the rest of the plane , in that smoke couldn't penetrate from one cabin to another ? Smokers might even be willing to pay a bit extra to travel if the airlines could install the technology ? I can't remember being asked anything at all about it and I've flown pretty regularly since 1988.
Of course , even if the airlines did try to , "help" the smokers , there'd be such a hysterical outcry from the Health Lobby that they'd just roll over. Money and Telling You What's Good For You--------a very powerful combination !
As for changing the law on oxygen levels , since when has anyone been able to curb the arrogance and power of the airlines ? Travelling by 'plane gets more unpleasant , uncomfortable and inconvenient every year.To paraphrase , the Supermarkets , "Stack 'em high and treat 'em cheap !".