roughly 40% fewer oxygen molecules per breath. In order to oxygenate
the body effectively, breathing rate (even while at rest) has to be
increased. This extra ventilation increases the oxygen content in the
blood, but not sea level concentration. The fall in oxygenation of blood
produced the symptoms of mountain sickness. These symptoms include
breathlessness, headache, dizziness, nausea, vomiting, mental fatigue
and a bluish tinge on the skin, nails and lips.