People with healthy lungs should have a blood oxygen level of 80-100 mm Hg, or 95-100%, when measured with a pulse oximeter. For people with lung diseases, a doctor should determine the optimal levels.
What are blood oxygen levels?
Your blood oxygen level is a measure of how much oxygen your red blood cells are carrying. Your body closely regulates your blood oxygen level. Maintaining the precise balance of oxygen-saturated blood is vital to your health.
Most children and adults don’t need to monitor their blood oxygen level. In fact, many doctors won’t check it unless you’re showing signs of a problem, like shortness of breath or chest pain.
However, people with chronic health conditions may need to monitor their blood oxygen level. This includes asthma, heart disease, and chronic obstructive pulmonary disease (COPD).
In these cases, monitoring your blood oxygen level can help determine if treatments are working, or if they should be adjusted.
Keep reading to learn where your blood oxygen level should be, what symptoms you may experience if your level is off, and what happens next.
How your blood oxygen level is measured
Your blood oxygen level can be measured with two different tests:
Arterial blood gas
An arterial blood gas (ABG) test is a blood test. It measures your blood’s oxygen level. It also can detect the level of other gases in your blood, as well as the pH (acid/base level). An ABG is very accurate, but it’s invasive.
To get an ABG measurement, your doctor will draw blood from an artery rather than a vein. Unlike veins, arteries have a pulse that can be felt. Also, blood drawn from arteries is oxygenated. Blood in your veins isn’t.
The artery in your wrist is used because it’s easily felt compared to others in your body.
The wrist is a sensitive area, making a blood draw there more uncomfortable compared to a vein near your elbow. Arteries are also deeper than veins, adding to the discomfort.
A pulse oximeter (pulse ox) is a noninvasive device that estimates the amount of oxygen in your blood. It does so by sending infrared light into capillaries in your finger, toe, or earlobe. Then it measures how much light is reflected off the gases.
A reading indicates what percentage of your blood is saturated, known as the SpO2 level. This test has a 2 percent error window. That means the reading may be as much as 2 percent higher or lower than your actual blood oxygen level.
This test may be slightly less accurate, but it’s very easy for doctors to perform. So doctors rely on it for fast readings.
Things like dark nail polish or cold extremities can cause the pulse ox to read lower than normal. Your doctor may remove any polish from your nails before using the machine or if your reading seems abnormally low.
Because a pulse ox is noninvasive, you can perform this test yourself. You can purchase pulse ox devices online or at most stores that carry health-related products. Talk to your doctor before using a home device so you understand how to interpret the results.
What is a good blood oxygen level?
A measurement of your blood oxygen is called your oxygen saturation level. In medical shorthand, you may hear it called a PaO2 when using a blood gas and an O2 sat (SpO2) when using a pulse ox. These guidelines will help you understand what your result might mean:
Normal blood oxygen level
A normal ABG oxygen level for healthy lungs falls between 80 and 100 millimeters of mercury (mm Hg). If a pulse ox measured your blood oxygen level (SpO2), a normal reading is typically between 95 and 100 percent.
However, in COPD or other lung diseases, these ranges may not apply. Your doctor will let you know what’s normal for your specific condition. For example, it isn’t uncommon for people with severe COPD to maintain their pulse ox levels (SpO2) between 88 to 92 percentTrusted Source.
Low blood oxygen level
A below-normal blood oxygen level is called hypoxemia. Hypoxemia is often cause for concern. The lower the oxygen level, the more severe the hypoxemia. This can lead to complications in body tissue and organs.
Normally, a PaO2 reading below 80 mm Hg or a pulse ox (SpO2) below 95 percent is considered low. It’s important to know what’s normal for you, especially if you have a chronic lung condition.
Your doctor can provide recommendations as to what ranges of oxygen levels are acceptable for you.
High blood oxygen level
If your breathing is unassisted, it’s difficult for your oxygen levels to be too high. In most cases, high oxygen levels occur in people who use supplemental oxygen. This can be detected on an ABG.
What happens if your blood oxygen level is too low
When your blood oxygen level goes outside the typical range, you may begin experiencing symptoms.
- shortness of breath
- chest pain
- rapid heartbeat
If you continue to have low blood oxygen levels, you may show symptoms of cyanosis. The hallmark sign of this condition is a blue discoloration of your nail beds, skin, and mucus membranes.
Cyanosis is considered an emergency. If you’re experiencing symptoms, you should seek immediate medical attention. Cyanosis can lead to respiratory failure, which can be life threatening.
How to increase blood oxygen levels
There are several ways to increase your blood oxygen levels naturally.
Breathing exercises can help bring fresh oxygen to the body. Here are two useful breathing exercises you can try:
pursed lip breathing: Breathe in through your nose, and then breathe out through your lips while they are in a pursed position, for twice as long.
belly breathing: Start by breathing in through your nose, using your hand to feel your belly filling up with air. Then, breathe out through your mouth for two to three times the length of your inhale.
Taking a walk outside, allowing fresh air into your house, or adding houseplants can also help increase your oxygen levels.
Additionally, you can make lifestyle changes such as quitting smoking, avoiding secondhand smoke, exercising regularly, and eating a well-balanced diet.
If your blood oxygen level is too low, you may need to boost your oxygen saturation. This is often done with supplemental oxygen.
Home supplemental oxygen is considered a medication, and your doctor must prescribe it. It’s important to follow your doctor’s specific advice on how home oxygen should be used to avoid complications. Your health insurance may cover the expense.
What causes blood oxygen levels to be low
Conditions that can negatively affect your blood oxygen level include:
- COPD, including chronic bronchitis and emphysema
- acute respiratory distress syndrome
- collapsed lung
- congenital heart defects
- heart disease
- pulmonary embolism
These conditions may prevent your lungs from adequately inhaling oxygen-containing air and exhaling carbon dioxide. Likewise, blood disorders and problems with your circulatory system may prevent your blood from picking up oxygen and transporting it throughout your body.
Any of these problems or disorders can lead to declining oxygen saturation levels. As your oxygen levels fall, you may begin experiencing symptoms of hypoxemia.
People who smoke may have an inaccurately high pulse ox reading. Smoking causes carbon monoxide to build up in your blood. A pulse ox can’t tell the difference between this other type of gas and oxygen.
If you smoke and need to know your blood oxygen level, an ABG may be the only way to receive an accurate reading.