[Stratoscope]

Of course there were smoking and non-smoking sections on airplanes. The same air recirculated through the entire airplane, and the non-smoking section began the very next row after the smoking section.

[RobotToaster]

Fun fact, the air quality on aeroplanes got worse after they banned smoking, because they could cut costs by re-circulating the same air for longer.

[7jjjjjjj]

Recirculated air is still a thousand times cleaner than air with cigarette smoke in it.

[IAmBroom]

You are naively assuming the only really dangerous part of recirculated air is nicotine byproducts.

Bacteria and virus loads are far more dangerous. Cigarettes take longer than a couple weeks to kill.

[kortilla]

Air isn’t recirculated on an airplane. It’s continually brought in from outside the aircraft

[helloplanets]

50% is recirculated, 50% is from the outside. Before the 80's it was 100% from the outside, though.

[ses1984]

That statistic doesn’t mean much.

The question is how long does it take for all the air in the plane to be replaced.