What conservative approach is suggested for tracking oxygen exposure for dives with a ppO2 of 0.5 and less?

The conservative approach suggested for tracking oxygen exposure for dives with a partial pressure of oxygen (ppO2) of 0.5 and less recommends treating them as if they are equal to 0.6. This approach provides a margin of safety and helps divers stay within recommended oxygen exposure limits.

When you encounter ppO2 levels near the threshold of 0.6, it is prudent to assume that you are closer to that value. This allows divers to account for any variations in actual oxygen exposure that could occur. By considering dives at or below 0.5 ppO2 as equivalent to 0.6, it guards against the risks associated with elevated oxygen levels and mitigates the potential for oxygen toxicity.

In contrast, assessing these dives as equal to 36% or 32% does not align with the physiological effects of oxygen exposure and does not adequately account for the associated risks of higher partial pressures. Additionally, treating dives as equal to 0.7 would unnecessarily increase risk by overshooting the conservative estimates. Thus, treating them as equal to 0.6 is the most responsible and prudent method for monitoring oxygen exposure in those dive conditions.