What is mild HBOT? Mild HBOT is hyperbaric oxygen therapy at low pressures, typically at 1.3 ATA – 1.5 ATA. Mild HBOT is available in portable hyperbaric chambers at 1.3 ATA – 1.5 ATA with compressed room air. Please log in to rate this. 0 people found this helpful. ← What is mild HBOT?