What is a common way divers can monitor their oxygen exposure during a dive?

Divers can effectively monitor their oxygen exposure during a dive by using dive computers that are specifically programmed for Enriched Air Nitrox (EANx) mixtures. These dive computers calculate the partial pressure of oxygen based on the specific gas mix being used, the depth of the dive, and the duration of the dive, allowing divers to keep track of their oxygen exposure in real-time. This capability is crucial because excessive oxygen exposure can lead to oxygen toxicity, which poses serious health risks.

Other methods mentioned, such as counting breaths or estimating exposure based solely on depth, are not reliable for monitoring oxygen levels. Counting breaths does not provide any information about the quantity of oxygen being breathed, and depending solely on depth ignores the complexities of varying gas mixtures and the impact of time spent at different depths. Checking a buddy's gas supply is important for safety but does not relate directly to monitoring one's own oxygen exposure. The use of a dive computer designed for EANx mixtures is the most accurate and effective means to track oxygen exposure during a dive.