On mountain-tops about 8000 ft. above from the sea level, one has difficulty in breathing due to considerable decrease in the oxygen in the air. Consequently, the alveolar pO2 reduces and oxygen cannot be diffused into the blood. Thus, the process of oxygenation of blood progressively gets decreased to such an extent that the person develops mountain sickness. It produces a number of symptoms like breathlessness, headache, dizziness, nausea, vomiting and a bluishness of skin, nails and lips. This is because of lack of adequate oxygen. People suffering from heart ailment or blood pressure should not go to such a height.
