What gas law applies to oxygen toxicity?

Answer 1

The effects of oxygen are increased at depth so that the maximum PO2 in diving is 1.6 ATA, and this is achieved at 218 fsw breathing air, 132 fsw breathing 32% O2, and 20 fsw breathing 100% O2. This is due to the effects of Dalton's Law which states that on descent, the partial pressure of all component gases increase in the same ratio as the total pressure. this results in the creation of the elevated pO2 that causes the convulsions of O2 toxicity

(taken from http://Scuba-doc.com/o2tox.htm)