((Just to clarify things a bit, the maintenance and shuttle rooms were pressurized at a lovely 100kPa. The hangar was below 0.5kPa (less than Mars). For purposes of calculation, we can assume this is 0. When the hangar airlock opened, I assumed it went from fully closed to fully open instantaneously to simplify things further (I don't really feel like busting out Bernoulli); net result being that the two rooms reached an equilibrium very quickly. If the hangar were equal in volume to the maintenance room, they'd equalize at 50kPa. This wouldn't really result in much harm unless you're standing in the doorway when the equalization occurs (see: Felicia Hasting). I mean, the explosive decompression is dangerous for your ear drums and lungs, but we hand-wave that because she rolled relatively well (a 6 -- much lower and burst lungs and ear drums are a real possibility)
Simply halving the air pressure isn't enough to cause significant problems for most people: it's equal to flying in an unpressurized aircraft cabin at 5,000 meters. Of course, the hangar is much larger than the maintenance room, so we're not dealing with the air pressure just being halved. If it's low enough that you guys have trouble breathing, but high enough that your eye fluids aren't boiling off, then it needs to be above the
Armstrong limit i.e., 6.3kPa. Pressures that low would definitely result in some decompression sickness, but the shuttle has independent life support systems, so there's no reason you couldn't jury rig it into a hyperbaric chamber if someone starts to get the bends (extremely unlikely, but I wouldn't rule it out entirely
).
tl;dr: You don't know what pressure the maintenance and hangar are at right now. It's definitely above 6.3kPa and definitely below 50kPa. If you spontaneously open the shuttle (which is at about 100kPa), the pressure will equalize very rapidly (cover your ears), and unless you've got internals you're gonna risk passing out every turn until you get it repressurized. Who's to say that's the only solution, though?))