The effects of deterioration become marked after 4 or 5 days and unless trapped by weather it is advisable not to stay much above 7000m for longer periods. There is little to be gained from attempting to set an altitude duration record by waiting for several days for weather to clear, because it is unlikely that you will have the energy in reserve to make use of it. Recovery from high altitude deterioration is a gradual process which can only take place at altitudes well below 6000m. Base camp should be below or as near 5000m as possible. Illnesses at extreme altitude Any illness at extreme altitude tends to be much more serious than at sea level.
Sore throats are common, a product of the dry air and cold, and notoriously difficult to treat.
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.