| You feel... | | | | impending trekking trip to Nepal, or ascent of a |
| You feel as if you have a bad hangover. Your head | | | | mountain in the Rockies. Don't be. You just need to |
| aches, you are a bit dizzy, you get short of breath | | | | know that mountain sickness is always caused by |
| with any exertion and you can't sleep. | | | | ascending too quickly. Prevention is better than cure, |
| If you're on a mountain and have risen to altitude too | | | | follow the rules and the guidance of people who |
| quickly, these are signs not of drunkenness, but of | | | | have more experience than you. One rule is to take |
| acute mountain sickness (AMS). | | | | several days climbing to 3,000 metres and thereafter, |
| Thin Air | | | | not to climb more than 300 metres in a day. |
| The higher you go above sea level, the thinner the | | | | Climb High - Sleep Low |
| air becomes. Barometric pressure decreases (although | | | | Mountaineers follow the rule: "climb high, sleep low". |
| the air still contains 21% oxygen). Every breath you | | | | This means they climb maybe 1,000 metres or a bit |
| take contains fewer molecules of oxygen. You find | | | | more in a day, but then come back down again to |
| yourself breathing faster and deeper in order to | | | | sleep at a lower altitude. You need to do this over |
| obtain oxygen, especially when you are doing | | | | several days, so that your body adapts gradually to |
| something strenuous, such as climbing or walking uphill. | | | | a higher altitude. Thus, your "zone of tolerance" |
| People usually do not experience difficulty when | | | | extends higher up the mountain each day. |
| ascending rapidly to modest altitudes, in, for example, | | | | Symptoms |
| a cable car or a train, some do, particularly the | | | | If you have not acclimatized properly, you may |
| elderly, babies and small children, those with lung or | | | | become ill. Look out for symptoms in yourself (as |
| heart conditions. You do not get altitude sickness in | | | | well as in others in your party, if you yourself feel |
| an aeroplane either, because the air within the craft is | | | | fine). Headaches, clouded judgement and confusion, |
| pressurised. | | | | swollen ankles, fatigue beyond what you would |
| Understanding What Happens | | | | normally feel on exertion, insomnia, "periodic |
| The trouble usually arises, if at all, above about 2,500 | | | | breathing" (involuntarily holding your breath), nausea |
| metres. It is not the decreased availability of oxygen | | | | and decreased frequency of urination are all |
| alone that causes acute altitude sickness, but the | | | | symptoms, which need to be attended to if you are |
| fact that carbon dioxide accumulates in your blood. | | | | to prevent rapid deterioration in your health. And |
| Your body may not recognize that you need to | | | | attended to immediately. Don't wait until daybreak: |
| increase your rate of breathing to dispose of it. An | | | | move down to a lower elevation straight away. This |
| excess of CO2 upsets your body's acid-alkali balance, | | | | is the only sure way to alleviate the symptoms and |
| which will in turn allow fluids to form in the wrong | | | | prevent further, more serious illness. Even moving |
| places. One serious consequence can be pulmonary | | | | down 500 metres may save the life of someone |
| oedema, or fluid on the lungs, which causes | | | | with AMS. At altitude, you become dehydrated, |
| breathlessness, may even lead to respiratory failure. | | | | drinking plenty of fluids is another measure both to |
| Another is cerebral oedema, when fluid collects in the | | | | prevent and to treat mild cases of mountain sickness. |
| skull, causing severe headaches and the risk of | | | | Precautions |
| permanent damage or death. | | | | Finally, there is a medication called acetazolamide |
| Can I Get Mountain Sickness? | | | | (trade name Diamox, not available everywhere, |
| Who can get acute mountain sickness? The answer | | | | however), which can prevent AMS, if taken before |
| is: anyone. It is no respecter of age, gender, physical | | | | an ascent or markedly decrease the symptoms if a |
| fitness or previous experience at altitude. Some | | | | bout of illness or headaches occur. |
| people get sick on one trip and not on another, even | | | | The message is: acclimatise slowly; but if you get |
| though the ascent and timings are the same. There is | | | | signs of sickness at altitude, don't be afraid to say |
| no way to predict who is likely to develop AMS. | | | | so. There is no shame in having AMS, but it is not OK |
| Need To Know | | | | to die from it. |
| Now you may be thoroughly frightened about that | | | | |