What should a diver do if they are uncertain about their EANx mix?

When a diver is uncertain about their EANx mix, the best course of action is to consult with a dive professional or instructor. This choice emphasizes the importance of safety and ensures that the diver receives accurate information regarding the specific gas mix. The risks associated with diving on an unknown or uncertain EANx mix can be significant, especially considering that the properties of the breathing gas can affect a diver's safety, bottom time, and risks of decompression sickness.

Consulting a dive professional allows for verification of the gas mixture, assessment of dive plans, and a better understanding of potential implications for the dive profile and equipment. A dive professional can provide critical insights on gas management, monitoring techniques, and safety procedures to follow, which reinforces safe diving practices.

The other choices could lead to unsafe situations. Proceeding with the dive without clarity on the gas mix can expose the diver to serious safety hazards. Using a different tank without verifying its contents may not resolve the uncertainty either. Assuming the EANx mix is correct can lead to catastrophic consequences, particularly if the mix is outside of safe operating limits for the planned dive.

Therefore, consulting with an experienced dive professional is vital to ensure a safe diving experience and make informed decisions regarding gas mixtures.