When diving underwater, oxygen is typically considered toxic at a partial pressure of 1.4. However, hyperbaric chamber treatment tables regularly require taking patients up to 60fsw on 100% O2, which translates to a partial pressure of 2.81. Why is the same amount of oxygen more toxic underwater than in the chamber, if the pressure exerted on both the body and the gas are the same in both scenarios? What variable when we’re “dry” allows us to tolerate more than double the amount of oxygen than when we’re “wet”?
In: Biology
Oxygen under water is more toxic than in a very large room for several reasons. The water in the environment affects how the body absorbs and uses oxygen. In a hyperbaric chamber, air exchange is most effective under dry conditions. Increased downstream pressure can increase the production of reactive oxygen species (ROS), resulting in significant toxicity. In addition, divers are exposed to high levels of oxygen for extended periods of time, increasing the risk of toxicity.
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