Using supplemental oxygen during high altitude climbs is seen by some as cheating. However, our body is also at risk if oxygen levels are low. How far do we push ourselves before we push ourselves over the edge? We have decided to conduct research on it.
How high are we able to climb before getting oxygen depleted? The Death Zone is 26,000 feet (8,000 meters) and occurs when severe altitude sickness occurs without supplemental oxygen and sooner or later the body shuts down, resulting in death. Mild to moderate altitude sickness can even set in at lower altitudes of 8,000 to 12,000 feet (2,500 to 3,500 meters).
You need to consider more than the elevation of the mountain when deciding whether you will need oxygen for your climb. It is also important to consider other factors that could influence whether or not you suffer from altitude sickness.
When moderate altitude sickness sets in, you need oxygen
A standard practice is to use supplemental oxygen in the ‘Death Zone’ (approximately 26,000 feet), also known as the 8,000-meter mark. You should start using oxygen when you experience moderate altitude sickness, but altitude sickness can set it at a much lower altitude.
The reason you should include high altitude climbing in your routine is that it is based on experience. You might consider climbing a mountain below 8,000 feet (2,500 meters) if you’re planning on climbing a mountain above 12,000 feet (3,500 meters). This will test your altitude sickness susceptibility.

Altitude sickness can be mild to severe, depending on the individual and at what altitude. It is important to pay attention to your body’s condition and look out for signs of altitude sickness. T and all these symptoms worsen over time and even it may not respond to medication and often oxygen is required to alleviate them.
Acute Mountain Sickness (AMS) (also known as mild altitude sickness)
- Symptoms may include headaches, difficulty sleeping, nausea, dizziness, fatigue, shortness of breath, loss of appetite, and general fatigue.
- Within 12 to 24 hours of arriving at a high altitude, symptoms usually begin to appear.
- Often, mild forms of altitude sickness will disappear with rest after a few days as you adjust to the altitude, so giving yourself time to acclimatize before climbing is essential.
A moderate case of altitude sickness
- Symptoms are more severe and are not relieved by over-the-counter medications.
- Over time, fatigue, weakness, and shortness of breath worsen instead of getting better.
- An increasing headache, nausea and vomiting, and tightness in the chest are symptoms that can cause confusion, loss of coordination, difficulty walking, and a worsening headache that is not relieved by medicine. While it is difficult to perform normal activities, you can still walk by yourself (though you may stumble).
Having a severe case of altitude sickness
- There might be spit froth, coughing (with or without frothy spit), noisy breathing (rattling or gurgling sounds), and fever. There is an accumulation of fluid in the lungs due to High Altitude Pulmonary Edema (HAPE)
- There are confusion, extreme fatigue, inability to walk, severe headaches, vomiting, and lethargy. An example of this is High altitude cerebral edema (HACE), a swelling of the brain caused by the accumulation of fluid.
- The color of the lips, skin, or fingernails is gray, pale, or bluish.
- In case of severe altitude sickness, death can occur within hours. It is imperative that you are brought to a lower altitude as soon as possible.
The Causes of Altitude Sickness
High altitudes result in low oxygen levels in the body, which causes altitude sickness.

When you don’t have enough oxygen in your body, you suffer the following consequences:
- As your body tries to get more oxygen, your frequency of breathing increases
- Because your muscles aren’t getting enough oxygen, physical activities become more strenuous
- As your body redirects energy to other key functions instead of digestion, your appetite decreases. Also, food isn’t absorbed as well
- Further fatigue is caused by a lack of calories
- You are more likely to get frostbite on your fingers and toes because blood flows towards your vital organs
- Further fatigue is caused by difficulty sleeping
The cumulative negative effects eventually lead to severe altitude sickness and even death.
The factors that affect your ability to climb without oxygen
The lack of oxygen and the onset of altitude sickness are influenced by several factors.
Amount of time spent on acclimatization
An average concentration of oxygen is 20% at sea level and drops to 7% at 29,000 feet (9,000 meters). At a higher altitude, you are taking in less oxygen with each breath than you do at sea level.
A short-term compensatory action is for the body to breathe faster and harder.
On a longer term basis, your body will produce more red blood cells in order to carry more oxygen. The result of acclimatization is that your body produces more red blood cells to adapt to the lower oxygen levels in the air by taking more time.

Allowing yourself enough time to acclimatize will allow you to feel less affected by high altitude breathing. Acclimatization enables you to climb at higher altitudes before you require oxygen, and delays the onset of altitude sickness.
Allow your body to adapt by not ascending faster than 1,600 feet (500 meters) per day. If you climb above 10,000 feet (3,000 meters), you should only increase your altitude by 1,000 feet (300 meters) a day.
Typical environmental conditions in your area
Your body will naturally acclimatize to altitude if you live in a high altitude area.
Sherpas living in Nepal’s high altitudes are thus better suited to climbing Mount Everest. As they have lived at high altitudes, their bodies are used to operating at low oxygen levels (by producing more red blood cells) and altitude sickness is not a problem for them as it is for people at lower altitudes.
Genetics
Unfortunately, genetics have a role to play in a person’s susceptibility to altitude sickness and the person who is more prone to altitude sickness may not be able to adapt to high altitude quickly and efficiently.
Time spent at high altitudes
Acclimatizing at high altitudes is beneficial, but it might not always be the best option.
You should return to lower altitudes as soon as possible if you are already experiencing moderate altitude sickness.
Climbers have a motto that says “Climb High and Sleep Low”. Altitude sickness can be prevented if you return to sleep at a lower altitude after climbing more than 1,000 feet (300 meters) in a day.
Taking Preventive Medicines
Altitude sickness can be prevented with some medications. You should always seek the advice of your doctor before taking any medication or drug at high altitudes.

(Diamox) Acetazolamide
- The medication Acetazolamide allows you to breathe faster and minimizes the symptoms of low oxygen levels.
- By decreasing periodic breathing, it also improves sleep at high altitude.
Dexamethasone (a type of steroid)
- Dexamethasone reduces swelling in the brain and other parts of the body caused by altitude sickness.
What Is The Oxygen Level At High Altitudes
Above sea level, oxygen concentration drops from 20% to 29,000 feet (9,000 meters).
The following table shows the amount of oxygen at each level:
Altitude (feet) | Altitude (meters) | Effective Oxygen % | Altitude Category | Example |
0 | 0 | 20.9 | Low | Boston, MA |
1000 | 300 | 20.1 | Low | |
2000 | 600 | 19.4 | Low | |
3000 | 914 | 18.6 | Medium | |
4000 | 1219 | 17.9 | Medium | |
5000 | 1524 | 17.3 | Medium | Boulder, CO |
6000 | 1829 | 16.6 | Medium | Mt. Washington, NH |
7000 | 2134 | 16.0 | Medium | |
8000 | 2438 | 15.4 | High | Aspen, CO |
9000 | 2743 | 14.8 | High | |
10000 | 3048 | 14.3 | High | |
11000 | 3353 | 13.7 | High | |
12000 | 3658 | 13.2 | High | |
13000 | 3962 | 12.7 | Very High | |
14000 | 4267 | 12.3 | Very High | Pikes Peak |
15000 | 4572 | 11.8 | Very High | |
16000 | 4877 | 11.4 | Very High | Mont Blanc |
17000 | 5182 | 11.0 | Very High | |
18000 | 5486 | 10.5 | Extreme | |
19000 | 5791 | 10.1 | Extreme | Kilimanjaro |
20000 | 6096 | 9.7 | Extreme | Denali (McKinley) |
21000 | 6401 | 9.4 | Extreme | |
22000 | 6706 | 9.0 | Extreme | |
23000 | 7010 | 8.7 | Extreme | Aconcagua |
24000 | 7315 | 8.4 | Extreme | |
25000 | 7620 | 8.1 | Extreme | |
26000 | 7925 | 7.8 | Ultra | |
27000 | 8230 | 7.5 | Ultra | |
28000 | 8534 | 7.2 | Ultra | K2 |
29000 | 8839 | 6.9 | Ultra | Everest |
What Are The Benefits Of Oxygen In High Altitudes?
It is physiologically equivalent to lowering the altitude of a climb by using supplemental oxygen.

When a mountain is climbed with oxygen, it appears 5,000 feet (1,500 meters) lower than it actually is. The effect is about 15,000 feet (4,500 meters) lower at rest.
What Are the Chances of Climbing Mount Everest Without Oxygen?
They are, in short, racing against time to get to the top before their bodies give up. As a result of the reduced oxygen content in the air, their bodies are slowly dying and they risk permanent brain and body damage after ascent and descent.

Twenty-two percent of climbers who died at Mount Everest above 26,000 feet (8,000 meters) did not use supplemental oxygen.
Check Out This video to know more about it!
It doesn’t always make sense to do something because you can.
Frequently asked Questions (FAQs) :
What are need for ice climbing?
To know what are required for ice climbing, you need to check out this article written by us!
How high can you climb without oxygen?
The Death Zone is 26,000 feet (8,000 meters) and occurs when severe altitude sickness occurs without supplemental oxygen and sooner or later the body shuts down, resulting in death. Mild to moderate altitude sickness can even set in at lower altitudes of 8,000 to 12,000 feet (2,500 to 3,500 meters).
At what height do climbers need oxygen?
Climbers needs oxygen above 26,000 feet above. Even the sherpas starts using the oxygen from above 26,000 feet.
At what height you cannot breathe?
An altitude above which the amount of oxygen can sustain human life for long periods of time is considered high altitude. The height of this point is typically listed as 8,000 meters (26,000 feet, less than 356 millibars of atmospheric pressure).