Why is there less oxygen at Higher Altitudes?

If a person who lived in a location like Hawaii moved to Denver, Colorado what would be the positive and negative implications to his health and well-being. Why does a location’s altitude affect an individuals living capacity. Today’s question stems from the environmental properties of air and how it may affect an individual facing an environment at high altitudes.


Mount Everest from outer space

First it is important to note why there is less oxygen at higher altitudes. According to health awareness webstie Altitude.org, we must think of the atmosphere “as a huge ocean of air” that is constantly applying pressure on our bodies equivalent to about 10 meters of sea level. At sea level, oxygen levels in the air are the highest and individuals are unaffected by the direct levels of oxygen existing around them. Because air is compressible, the air at the surface level is denser and compresses around us at the surface. However as you rise higher into the sky the air becomes less compressed and is therefore thinner in the upper portions of the atmosphere. This leads to not only oxygen but the entire composition of air like nitrogen and carbon dioxide to thin out in the higher levels of the atmosphere.

Now that we’ve analyzed why less oxygen exists in the upper levels of the atmosphere, what are the some of the dangers that exist due to overexposure in these conditions?

At higher altitudes, the atmosphere is significantly different than that at sea-level and there are certain dangers that exist. The atmosphere for one is thinner and usually much colder at higher altitudes and if someone is exposed too long under these conditions he or she may be susceptible to a condition known as altitude sickness.


Oxygen levels at varying altitudes

Altitude sickness has three different forms.

  1. Acute Mountain Sickness (AMS) – Occurs at altitudes up to 2,500 meters. Feels quite similar to a hangover as symptoms include headache, nausea, and fatigue. Very common as some are affected more than others but should be used as a warning sign.
  2.  High Altitude Pulmonary Oedema (HAPE) – Usually occurs after 2-3 days above 2,500 meters above sea-level. HAPE is the “excess fluid on the lungs” and can cause breathlessness when resting. Can also cause high fever and coughing.
  3. High Altitude Cerebral Oedema (HACE) – A severe form of mountain sickness occurring in about 1% of people who ascend 3000 meters above sea-level. HACE is a build-up of fluid in the brain and requires urgent medical action as it is life threatening.

I hope you are more aware of why the atmospheres differ between altitudes and certain conditions that may occur due to thin atmospheric over-exposure.

Thanks for the read!

-Sammy Lee

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