What is considered the most dangerous sign of O2 toxicity in divers?

Convulsions are considered the most dangerous sign of oxygen toxicity in divers because they represent a severe physiological response to elevated levels of oxygen. While other symptoms like chest pain, nausea, and fatigue can indicate issues related to oxygen exposure, convulsions can lead to immediate and life-threatening situations underwater.

During a convulsion, a diver may lose consciousness and control of their body, which can result in drowning if they are in the water. This risk emphasizes the critical nature of recognizing convulsions as a red flag for oxygen toxicity. It indicates that the diver's central nervous system is severely affected, requiring immediate action to mitigate further injury or potential fatality.

Understanding the risks associated with oxygen toxicity ensures that divers can respond effectively to early signs and prevent progression to more severe symptoms, such as convulsions.