気管の耐圧性能　[Human Exposure to Vacuum]

Pressure

Human tolerances to atmospheric composition and pressure. From Living In Space by G. Harry Stine. Artwork by Rick Sternbach.

You can see why some spacecraft opt for an internal atmosphere with lower than Terra-normal pressure, increasing the percentage of oxygen to compensate. The lower the pressure, the slower the air will escape through a meteor hole. NASA uses Terra-normal pressure (14.7 psi) inside the Space Shuttle, but only 0.29 pressure (4.5 psi) with pure oxygen in the space suits. According to NASA, an astronaut wearing a Shuttle space suit can survive 22 minutes with a 1/8" hole.

>Human tolerances to partial pressure of oxygen. From Living In Space by G. Harry Stine. Artwork by Rick Sternbach.

This does raise a new problem. There is a chance that the high-oxygen atmosphere will allow a meteor to ignite a fire inside the suit. There isn't a lot of research on this, but NASA seems to think that the main hazard is a fire enlarging the diameter of the breach, not an astronaut-shaped ball of flame.

>Human tolerances to partial pressure of carbon dioxide. From Living In Space by G. Harry Stine. Artwork by Rick Sternbach.

The increased fire risk is one reason why NASA isn't fond of low-pressure/high oxygen atmospheres in the spacecraft proper. There are other problems as well, the impossibility of air-cooling electronic components and the risk of long-term health problems being two.Setting up the optimal breathable atmosphere is complicated.

A more annoying than serious problem with low pressure atmospheres is the fact that they preclude hot beverages and soups. It is impossible to heat water to a temperature higher than the local boiling point. And the lower the pressure, the lower the boiling point. You may have seen references to this in the directions on certain packaged foods, the "high altitude" directions. The temperature can be increased if one uses a pressure cooker, but safety inspectors might ask if it is worth having a potentially explosive device onboard a spacecraft just so you can have hot coffee.