Take a look at the attached file,
SHALLOW-WATER NITROX DIVING, THE NASA EXPERIENCE.
NASA uses EAN46 in its Neutral Buoyancy Lab, a huge 12m deep pool for training astronauts. The attached paper gives a summary of their dive lengths and depths and notes they have had no oxygen toxicity events.
CONCLUSIONS: The suit configuration produces a maximum equivalent air depth of 7 meters, essentially eliminating the risk of DCS. Based on average run depth and time, approximately 17% of the training runs exceeded the NOAA oxygen maximum single exposure limits, with no resulting oxygen toxicity. The NBL suited training protocols are safe and time tested. Consideration should be given to reevaluate the NOAA oxygen exposure limits for PO2 levels at or below 1 ATA.
Here's the graph of all of their dives of 6+ hours duration. Blue diamonds represent actual dives. The axes are time and average PO2 for the dive. The NOAA single exposure recommended limit is the red line.
SHALLOW-WATER NITROX DIVING, THE NASA EXPERIENCE.
NASA uses EAN46 in its Neutral Buoyancy Lab, a huge 12m deep pool for training astronauts. The attached paper gives a summary of their dive lengths and depths and notes they have had no oxygen toxicity events.
CONCLUSIONS: The suit configuration produces a maximum equivalent air depth of 7 meters, essentially eliminating the risk of DCS. Based on average run depth and time, approximately 17% of the training runs exceeded the NOAA oxygen maximum single exposure limits, with no resulting oxygen toxicity. The NBL suited training protocols are safe and time tested. Consideration should be given to reevaluate the NOAA oxygen exposure limits for PO2 levels at or below 1 ATA.
Here's the graph of all of their dives of 6+ hours duration. Blue diamonds represent actual dives. The axes are time and average PO2 for the dive. The NOAA single exposure recommended limit is the red line.