Quick Answer
Dehydration occurs faster at high altitudes due to decreased atmospheric pressure and lower humidity, which increases the rate of water loss from the body.
Lower Humidity and Evaporation
At high altitudes, the lower air pressure reduces the relative humidity, allowing water to evaporate more quickly from the skin and respiratory system. This increased evaporation rate accelerates dehydration, as the body loses water at a faster rate than it can replenish it. To combat this, drink at least 3-4 liters of water per day, and aim for electrolyte-rich beverages to replace lost salts.
Decreased Atmospheric Pressure and Blood Concentration
The lower atmospheric pressure at high altitudes also causes blood to become more concentrated, with a higher concentration of red blood cells and plasma proteins. This increased blood concentration raises the osmotic pressure, drawing water out of cells and tissues, further exacerbating dehydration. To mitigate this effect, drink at least 8-10 ounces of water per 1,000 feet of ascent to maintain proper hydration levels.
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