At the end of Chapter 1, what problems does the author face?

At the end of Chapter One, Krakauer notices that the oxygen level in his supplemental tank is alarmingly low, creating a huge problem. Fifteen minutes into his descent, he reaches the Hillary Step, a notch in the ridge that requires rappelling. However, he sees more than a dozen climbers lined up at the bottom waiting to make their way up, and climbing-custom grants them the right of way. As he waits, he asks Andy Harris to turn off the valve on his tank in order to conserve oxygen, but Harris accidentally opens it to full flow. After a brief period of relief due to increased oxygen, Krakauer begins suffocating and realizes the mistake that Harris made.