Yup. Me too.
I don't understand why they don't run/weave a 2.5 mile long O2 hose through the caves to the boys. A small diameter, high pressure hose, like the one we use to put air into our tires.
As the pressure of the atmosphere increases in the cave, the negative effects of the exhaled carbon dioxide also increases. It becomes a double edged sword.
Also, to be able to supply oxygen for that length would require a massive amount of PSI to overcome the friction in the hose. There may not be a pump that size available or an oxygen generator available.