There is going to be an opportunity cost for purposely inducing a sweat in a sauna. With each degree of heat the body is raised, the oxygen consumption needed is raised. Many people have lots of fat under the skin and cellulite that restricts the blood vessels which for some people may want to consider doing whatever they can to open up these capillaries before the session and during the session.
Depending on the size of the infrared sauna and the breathing rate of the person and how long the person is in the sauna, about 85 to 100 liters of air is needed to have enough air in the sauna for the session. Most saunas have about 1400 to 2200+ liters of oxygen totally available
I do not like breathing in my own exhalation and don't like a muggy sauna. I prefer the larger saunas so this doesn't happen. Being crowded like in a phone booth sucks. The concentration of the oxygen in the smaller saunas is much lower than the larger ones. The goal is to increase the oxygen flow in the body when the capillaries expand but if their is low oxygen, then its harder to reach that goal. I strongly recommend and use an oxygen concentrator during my sessions. Almost everyone that uses the concentrator never goes back to not using it after doing a session with it. I do not recommend opening the door throughout the session to get in fresh air as this gets the heat out and slows the sweat process down especially with low fluence saunas. Many people get headaches and feel weak after a session without enough ventilation.
Getting a dome sauna might be the answer as it gives more ventilation but the neck, face, and shoulders don't get the far infrared heat. Using an oxygen concentrator takes the sauna session to the next level. It can be just as important as using the brine free salt to replace the salts lost in the session. The only thing that I don't like about the dome saunas is that the face has a lot of sweat glands and getting the infrared heat on my pores on my face clean.
Get discounts for taking the quiz before you call. Please call after 15 minutes after you take the quiz. Please refer to my rules of my site on my home page before you call and I will offer my standard discounted pricing. I will not discount saunas for those that do not follow my rules. My discounts that I have the privilege to offer are only available for those that take my quiz first and call 15 minutes afterwards.