You'd last more than an hour in a sealed coffin before oxygen depletion caused you any significant problem
You'd have died of dehyrdation in a stuck tube train before you ran out of oxygen, even full of people. Remember you've got to use up the oxygen in the train, the whole length of the tunnel and every station on the line even ignoring all the vents to the surface. Gases diffuse from regions of high to regions of low concentration and they do so reasonably quickly. Certainly faster than load of passengers can use it up.

Jesus, sometimes I even bore myself. Sorry.
( the mighty badger Aphrodite, on a bar stool, by your side, Wed 7 Sep 2011, 14:58, 1 reply, 14 years ago)

Right, I know
still, it makes me unconfortable. Now I need to carry a bottle of water with me at all times.
(Aberracion Life's getting very complicated, but a lot of fun., Wed 7 Sep 2011, 15:00, Reply)