A few days ago a question was asked on Reddit whether or not a human could survive in space with "just enough" of a spacesuit to plug all the important holes, e.g. a face mask to plug the eyes, ears, nose and mouth, and some kind of special underwear that maintains pressure in the nethers. The astronaut would effectively be their own space suit.
The popular answer was that the astronaut's lungs would explode due to a lack of external pressure, however I'm struggling with the logic.
Based on everything I've read about how a human would cope in space with no spacesuit at all, e.g., their fluids wouldn't boil because the skin maintains an effective pressure barrier, and the fact that there must be some quantity of air in the thoracic cavity (i.e., outside the lungs but inside the chest), then supposing that this mask provides ~1 atm pressure, would it not be the case that they would be fine so long as their chest is sealed? In this scenario the pressure in the thoracic cavity would reach an equilibrium with the elasticity of the chest wall at somewhere less than 1 atm (Boyle's Law); if the astronaut is supplied air at roughly the equilibrium pressure then then my guess is that breathing shouldn't be a problem, but being off by too much would pop or collapse the lungs. As far as I know, the thoracic cavity is airtight, and this assumes the chest can withstand a ~1 atm pressure differential.
So is it possible to survive in space this way, at least in the scale of ~10-20 minutes? As in, the pressure differentials wouldn't cause your chest or lungs to explode, implode, or make it otherwise impossible to breathe?
This is of course ignoring all the other perils of being naked in space.
