Setting aside the fact that this source is a random person blogging and quoting a pilot (his job is flying, not dealing with air-con), the fact that airplane air "isn't as disgusting as you think" doesn't mean it isn't more disgusting now than it was when smoking was allowed.

I don't have a source and am too lazy to find one, but it was stated on QI which is a show with a team of good researchers, they can on occasion be wrong (and have corrected themselves for mistakes in previous shows in the past), but they won't put a fact into a show without getting good sources for it, so if they say that air gets recycled less now than when smoking was allowed, I believe them.

That's not what you claimed - you claimed that it was a) recirculated less and as a direct result b) more airborne germs are prevalent and c) cost is saved.

Sorry - it's my fault for not giving more background on Mr. Smith - Patrick Smith has been a Delta Air Lines pilot for about 10 years, written two books on airlines, before that flying cargo, and I've met him more than once, so I'll trust him and the other pilots I've met when they tell me how their airplanes work.

Here's more of his articles on the subject: http://www.salon.com/2009/09/25/askthepilot335/ http://www.askthepilot.com/questions-and-answers/#cX-q9

and another article here: http://airlinesafety.com/articles/FSFCabinAir.htm

I'll allow that it's certainly possible that manufacturers have tweaked the circulation post-smoking, but even if so, it wasn't done with some nefarious intent or to the detriment of passengers. The air we breathe (as I'm about to get on a flight) is incredibly clean, cleaner than in my office.

That's not what I claimed because I didn't claim anything at all.

Your sources are all (I think?) about the fact that the way they deal with air is good, and you may well be right that it's cleaner than in your office. That doesn't mean that it's not less clean than when smoking was allowed - it may well be that in order to get rid of the smell of smoke they needed to clean the air way more than technically necessary, and that therefore after the smoking ban it could be lowered without being "some nefarious intent".

Except the recirculation systems started well before the smoking ban...

I'n sorry, you're right. I confused you with the OP, please accept my apology.

From the transcript (http://sites.google.com/site/qitranscripts/transcripts/1x10) - just the tidbit about 6% savings in fuel cost just by reducing airflow sounds completely implausible:

"Stephen Well, the question is . . . It was almost certainly a bad idea, erm . . . It was a lousy idea, in fact, 'cause when smoking was allowed, the cabin air was completely replaced with fresh air every three minutes, and now, the airlines save money . . . they save up to 6% of their fuel bills by using a mixture of fresh and recycled air--

Julia And SARS.

Peter Ohh.

Stephen --yeah . . . using under half the amount of fresh air needed for comfort; increasing the amount of carbon dioxide in the cabin; causing dizziness, and nausea, and allowing viruses to thrive. Passengers think that, because they can't smell smoke, the air is fresher. This is not so. Apart from anything else, it has dramatically increased the number of air rage incidents. One of the earliest reported incidents of air rage involved a passenger in first class, probably trying to take his mind, erm, off cigarettes, by drinking too much, and he was refused another drink, and so he decided to lodge his displeasure, and shat on top of the food trolley. "

While Patrick Smith may not be an air conditioning expert, as a pilot he's required to know how the AC systems work and how to operate them, and if there was a widespread modification to AC systems or pilot procedures after the smoking ban, I'd expect him to know about it and mention it in the article.