AMS-Explained

Early AMS
The earliest known account of mountain sickness can be traced back to the first few decades of the first century A.D. One account from the period reads, “The travellers have to climb over Mount Greater Headache, Mount Lesser Headache, and the Fever Hill, where they will develop a fever, turn pallid, feel a headache, and vomit." (Ward 1975)
In 1590 in Peru, a Spanish priest wrote of the ill effects of altitude while crossing the Andes and concluded, “the element of the air is so subtle and delicate, as it is not proportional with the breathing of man, which requires a more gross and temperate air.” (Heath and Williams 1981)
Theories of mountain sickness advanced rapidly with the popularity of ballooning in the eighteenth century and alpine climbing in the nineteenth century.
As man continued to push his physical boundaries by venturing higher and higher, he occasionally paid the ultimate price. In 1875, the flight of the Zenith from Paris resulted in the deaths of two balloonists, Sivel and Croce-Spinelli. However, this did not deter the early pioneers. This century's leap into aviation and space travel has brought with it a deeper understanding of human ability to function at altitude.

Onset of AMS
The incidence and severity of AMS depend on the rate of ascent and the altitude attained as well as the length of altitude exposure, the level of exertion and inherent physiological susceptibility.
The main symptoms of AMS are headache, fatigue, dizziness and anorexia with nausea also being common – in fact the initial symptoms are very similar to that of an alcohol hangover.

Where and at what altitude does AMS occur?
High Altitude is classed as 1500 to 3500m – AMS is common with rapid ascent above 2500m but does not tend to occur below this.
Very High Altitude is 3500 to 5500m – this is the most common range for severe AMS.
Extreme Altitude is over 5500m – any ascent without supplementary oxygen invites severe AMS. There is no human habitation above 5500m.