A silk mask, worn as continuously as possible, warms and moistens the air. Inhalations of steam, with or without one of the many proprietary cough linctuses are extremely useful. Any chest infection is potentially dangerous and needs urgent treatment - by descent and antibiotics. A number of illnesses occur as a result of prolonged exposure to extreme altitude. High Altitude Cerebral Oedema and Pulmonary Oedema, though seen typically between 4000m and 5500m, during acclimatisation, do also occur suddenly at extreme altitudes in well acclimatised climbers.
Mental changes are frequent.
The feeling of apathy is coupled with mood changes, despair or undue elation and sometimes unreasonableness in argument. Recent memory is impaired above 7000m. It is most important to recognise these effects and to bear in mind that they may be made worse by many depressant drugs, such as sleeping pills - though these seem quite safe at lower altitudes. Cold, washing, defaecation, boots, frostbite, cooking The effects of cold are more pronounced at great heights for a variety of reasons. First, it is colder, with a summer night temperature of -25 C common at 7000m.