What haemoglobin saturation is quoted at 19,000 feet compared with sea level?

1. A lower partial pressure of oxygen means fewer oxygen molecules are bound by haemoglobin. 2. At 19,000 feet above sea level, haemoglobin saturation is about 67 percent. 3. At sea level it reaches about 98 percent. 4. So the third option is correct, and the healthy sea level figure sits inside the usual 95 to 99 percent range. _Source: OpenStax Anatomy and Physiology (CC BY 4.0), Ch 22 "The Respiratory System", section 22.6 Modifications in Respiratory Functions_