For that, we need to know the overall air pressure, since more molecules in a certain volume means more pressure.

为此，我们需要知道整体气压，因为在一定体积中更多的分子意味着更大的压力。

With less protein in the blood the oncotic pressure falls, which lowers the overall osmotic pressure, which drives water out of the blood vessels and into the tissues, called edema.

血液中白蛋白越少，胶体渗透压下降，降低了总渗透压，使水从血管中渗出，进入组织中，称之为水肿。

The scientists also showed that the overall pressure (and so the risk of roof failure) could be reduced by increasing the proportion of oxygen in the artificial air used to fill the caverns.

科学家们还表明，可以通过增加用于填充洞穴的人造空气中的氧气比例来降低整体压力（以及屋顶破裂的风险）。