Well, since oxygen is so volatile, i'd put my oxygen tank in one corner of the room, cover it with the poisonous food so that its methane and poisonous acid would eat through the tank's surfaces, reacting with the tank's iron, which would create energy enough to light a spark inside of it, causing an explosion strong enough to tear down the wall. After that i just clear my way and head out with my bicycle.
It's not too hard when you think of it.
