The effects of hypoxia begin immediately upon exposure to any altitude above sea level. Below 3,500 m (about 11,000 ft), the performance decrements are minimal and normally go unnoticed.

At what oxygen level does hypoxia occur?

Oxygen saturation levels should be between 92% and 98% for an adult without an underlying respiratory condition. Lower than 92% is considered hypoxic. For patients with COPD, oxygen saturation levels may range from 88% to 92%. Lower than 88% is considered hypoxic.

What is the first symptom of hypoxia?

Causes of Hypoxia

Hypoxia can also result from lung damage due to trauma. Other things can cause hypoxia include: Lung diseases such as chronic obstructive pulmonary disease (COPD), emphysema, bronchitis, pneumonia, and pulmonary edema (fluid in the lungs)