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Learn About Blood Oxygen Levels

Your blood carries oxygen to the calls in your tissues and organs. Knowing how well oxygenated your blood is can help you understand your overall health.

Blood Oxygen Levels

Your blood oxygen level represents the percentage of the hemoglobin in your red blood cells that are carrying oxygen from your lungs to the rest of your body.


The vast majority of people have a blood oxygen level between 95-100%. However, some people live a normal life with levels below 95%.


Also known as oxygen saturation (SpO₂), blood oxygen levels are different from another oxygen-related health indicator called VO₂ max, which measures your body’s ability to use oxygen while you exercise.

Measuring Blood Oxygen Levels

The most precise way to measure blood oxygen levels is to draw blood in a lab. A method that’s nearly as precise, pain-free, and used in almost all hospitals is pulse oximetry. A pulse oximeter shines light through your skin and measures how the light changes as it interacts whit your blood. This indicates how well your blood is carrying oxygen. These measurements can vary from moment to moment.

What Can Make Blood Oxygen Levels Go Down?

There are two types of factors that decrease your blood oxygen level: changes in your environment and changes in your body.


Elevation is the most common environmental factor. In a high-elevation environment like the mountains or an airplane, there’s less oxygen in the air. So when you spend time in these environments, there’s also less oxygen for your blood to absorb from your lungs.


The most common physical factor that can cause a drop is holding your breath. Drops can also be caused by conditions such as:


. Respiratory/lung conditions

. Heart conditions

. Use of narcotics or anesthetics that slow breathing

. Sleeping and sleep apnea


If your blood oxygen level falls, there are some common symptoms:


. Elevated heart rate or blood pressure

. Shortness of breath, coughing, or wheezing


If your body is deprived of oxygen for long enough, you may experience more severe symptoms such as bluish skin, a headache, or confusion. Oxygen deprivation that goes on for too long can lead to a state called hypoxia, which can have life-threatening consequences.

Getting You Blood Oxygen Levels Back Up

The best way to reverse a drop in blood oxygen level depends on the cause. If it drops due to elevation, it should recover if you get closer to sea level or acclimate over several days. If it drops because of an illness, it should improve as you recover. If it’s due to a chronic condition, you may be able to manage it with the help of your doctor.


You should talk to a doctor immediately if you experience severe symptoms.

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