Suffering from Altitude Sickness in Crested Butte?

It is Caused By A Decrease In Oxygen Levels at Higher Altitudes:

Oxygen at Sea Level: 0 Feet
Oxygen in Denver, CO: 5,280 Feet Above Sea Level
Oxygen in the town of Crested Butte: 8,885 feet above Sea Level
Oxygen at the Summit of Mt. Crested Butte: 12,162 feet above Sea Level