PO2 Max - Why 1.4/1.6?

[Twoblues]

You're right that oxygen toxicity limits are still relevant in other applications, it's just that one of the possible symptoms (convulsions) is much more dangerous when diving than in, say, a decompression chamber, or even hard hat surface supply.

Not because convulsions are necessarily harmful in themselves, just that it will likely result in drowning as the regulator falls from the mouth.

My least favorable thing in the sea would be experiencing convulsions/death from exceeding a ppo of 1.6