What action should be taken if a diver exceeds the oxygen clock limits?

If a diver exceeds the oxygen clock limits, the appropriate action is to ascend immediately. The oxygen clock refers to the way that the body's exposure to elevated partial pressures of oxygen is monitored during a dive. Exceeding these limits can increase the risk of oxygen toxicity, which can lead to serious health issues, including seizures and other neurological impairments.

Ascending reduces the pressure experienced by the diver, which in turn decreases the partial pressure of oxygen in the breathing gas. This action is vital because it mitigates the risk associated with oxygen toxicity, promoting safety and preventing potentially life-threatening complications. The response to exceeding oxygen limits emphasizes the importance of adhering to safe diving practices and understanding the physiological impacts of increased oxygen exposure during dives.

Continuing the dive with caution, increasing depth, or taking a break at the bottom are not suitable responses since they could exacerbate the risk of oxygen toxicity rather than effectively address the problem.