What is the recommended ATA range for breaching 100% O2 to minimize toxicity risks during diving?

The recommended ATA range for breaching 100% oxygen to minimize toxicity risks during diving is 1.3-1.6 ATA. Within this range, the partial pressure of oxygen is high enough to be beneficial for certain therapeutic purposes, such as treating decompression sickness or carbon monoxide poisoning, while still being low enough to mitigate the risk of oxygen toxicity that can occur at higher pressures.

Oxygen toxicity can manifest in two forms: central nervous system (CNS) toxicity and pulmonary toxicity. CNS toxicity is a concern at pressures exceeding 1.6 ATA, which can lead to symptoms such as convulsions and other severe neurological effects. By keeping the pressure within the 1.3-1.6 ATA range, divers can achieve the therapeutic benefits of high oxygen levels without entering the risk zone for CNS toxicity.

In contrast, the other options represent higher partial pressures of oxygen that may significantly increase the risk of toxicity. Hence, staying within the 1.3-1.6 ATA range is critical for safety in diving operations involving high concentrations of oxygen.