Too long is when someone gets the bends. I am referring to the chambers that go over 1.3 ATA, this is probably why in the USA they don't legalize chambers that go over 1.3 ATA. People compress the air so high that too much oxygen gets into the cells and most people aren't "burning" it. Many people just lay down in the chamber and let the chamber do the work for them. I have the same type of issue with oxygen concentrators. So many people over do it. They hear about "Exercise With Oxygen Therapy" EWOT and buy the concentrator without a prescription and end up hurting themselves. So, getting a chamber that goes over 1.3 ATA if the person doesn't know what they are doing can have negative results instead of people thinking the more the oxygen in the body the better.
If people really know how to use their chamber and they have an oxygen concentrator, there is so much people can do with them that they never do. Some people buy a chamber just to build 3 to 5 lbs of aerobic bacteria in their gut. Many people with health issues get a chamber and never do this. If trying to build an aerobic bacteria lining in the intestines, there are protocols to take in order to do this. Having a large amount of aerobic bacteria in my gut has been a game changer in my life.
I urge people to know someone or talk to someone that really knows how to use hyperbaric chambers at 1.3 ATA, 1.4 ATA and 1.5 ATA as each of these concentration levels can affect the body differently especially when staying in for long times and sleeping in the chamber. Someone can really ruin their lungs if using hyperbaric chamber therapy in the wrong way. I have doctors that own hyperbaric treatment centers on call if there is ever a question I can't answer. They can answer questions that manufacturer will not answer as they are not a medical doctor and is not ethical to give medical advice.
Contact me on my contact page for any questions about hyperbaric oxygen therapy and the reason needing a chamber.