Why is it difficult to breathe in high altitudes?
At higher altitudes such as on top of a mountain, the air is less dense and this means that the partial pressure of oxygen is lower. Hence, the fall in atmospheric pressure at higher altitude decreases the partial pressure of inspired oxygen
At 12,500 feet the air becomes thinner and oxygen becomes lower making it difficult to breathe.
You will likely feel nauseous and lightheaded. You may vomit and have a headache. Different levels of altitude sickness have different symptoms: Symptoms of mild, short-term altitude sickness usually begin 12 to 24 hours after arriving at high altitude
High hemoglobin level is most often caused by low oxygen levels in the blood (hypoxia), present over a long period of time. Common reasons includes bone marrow disease that causes abnormal increase in red blood cells (polycythemia vera) Congenital heart disease and heavy smoking.
At high attitudes, hypoxia-induced erythropoietic drive results in erythrocytosis and an increase in hemoglobin concentration and hematocrit. Hence people with SCD should be careful and report abnormalities to the doctor immediately.