Chronic mountain illness (CMS) is a disease wherein the percentage of blood volume this is occupied by using red blood cells will increase (polycythaemia) and there may be an abnormally low stage of oxygen within the blood (hypoxemia). CMS normally develops after extended time dwelling at excessive altitude. Acute mountain illness is due to reduced air strain and decrease oxygen degrees at excessive altitudes. The quicker you climb to an excessive altitude, the much more likely you may get acute mountain illness. The excellent way to prevent altitude infection is to ascend steadily.