What’s a Normal Blood Oxygen Level? How To Test and Treat Low Levels

When it comes to health, finding out that your numbers are not normal can be frightening. Whether it’s blood pressure or the number of quality hours of sleep you get, abnormal numbers can indicate a variety of health issues. But, once you know what’s making your numbers abnormal, you can take steps to remedy the problem.

You may be wondering what a normal blood oxygen level is. Most people don’t pay much attention to this metric, but it’s a key tool used by doctors to get a picture of your overall health. For people who suffer from sleep disorders, heart disease and breathing issues such as asthma, sleep apnea and chronic obstructive pulmonary disease (COPD), tracking oxygen saturation levels can help in managing treatment plans.

Here, we’ll show you what constitutes a normal blood oxygen level and highlight what happens if your levels are low. We’ll go over how to measure your blood oxygen saturation level, symptoms, causes, and what you can do if your numbers are not normal.

What Is a Normal Blood Oxygen Level

Normal blood oxygen level: a pulse oximeter next to a heart shape

Blood oxygen saturation is a measure of how much oxygen is in your red blood cells. Within these red blood cells, iron attaches to oxygen atoms, transporting the oxygen to organs throughout the body. Oxygen is important to cellular health and low levels can cause symptoms ranging from dizziness to difficulty breathing.

Normal blood oxygen levels can vary from person to person, and factors like where you live can result in variations. Normal oxygen levels may be different for healthy individuals and those with chronic diseases.

People who live at high altitudes tend to have lower blood oxygen levels, which can be normal for that environment. That’s because there is less oxygen at high altitudes and less air pressure. People who live at sea level and travel to the mountains may experience a drop in blood oxygen saturation levels compared to their normal saturation levels. That’s because they are not used to the lower oxygen concentration in the air.

Finding your normal blood oxygen level takes some time. By testing your levels regularly, you’ll be able to see trends and if there are any dips in your baseline.

In general, there are three categories doctors use to determine whether your blood oxygen levels are normal. There are two different measurements depending on what type of test is used (more on that later). The basic guidelines are:

  • Normal: 75 to 100 millimeters of mercury (mm Hg) using an arterial blood gas test or 95% to 100% using a pulse oximeter.
  • Low: Less than 75 mm Hg or less than 95%.
  • High: High blood oxygen levels typically only occur if you’re using supplemental oxygen. If this occurs, a doctor will lower the amount of oxygen usage to get numbers back to a normal range.

Your normal numbers may be lower than these guidelines, particularly if you have a condition like COPD. Talk to a qualified healthcare professional to find out what is normal for you. If you suffer from an underlying health condition, a doctor can outline a normal range and help you identify when to take action if levels are too low.

How To Check Your Blood Oxygen Level

Normal blood oxygen level: a pulse oximeter on a person's finger

There are two main ways to measure your blood oxygen levels. The first test, known as an arterial blood gas test (ABG) can only be done by a doctor. The second test, a pulse oximetry test, can be done on your own at home. Here’s what to expect from each type of test.

Arterial Blood Gas Test

The ABG test measures for partial pressure of oxygen in the arteries, also known as PaO2. It tests for levels of oxygen as well as carbon dioxide and pH. These readings are conducted in measurements called millimeters of mercury, also known as mm Hg. During the ABG test, a doctor will draw a blood sample from an artery rather than a vein since arteries carry oxygen-rich blood cells. Doctors typically use the radial artery — located on your wrist — or the femoral artery, which is located in your groin. Results are usually ready within 15 minutes.

The ABG test can be uncomfortable and slightly painful. Because arteries are deeper than veins, larger needles are used to draw the blood. The pain is temporary and localized, and the benefit of this type of oxygen saturation test is that you’ll get a detailed analysis of your blood. You can also apply pressure to the injection site immediately following the blood draw to help reduce pain.

Pulse Oximetry

A pulse oximeter test is a non-invasive alternative to the ABG that can be done at home. A pulse oximeter is a small device that attaches to your fingertip, toe or earlobe. It uses infrared light to determine the oxygen levels in your red blood cells. You’ve probably seen this device before if you’ve ever visited a doctor’s office. Along with blood pressure cuffs, it’s a common tool nurses use to get a reading of your vital signs.

A pulse oximeter reading measures blood oxygen levels in percentages known as SpO2 or peripheral capillary oxygen saturation. The reading is a percentage that compares the amount of oxygen your blood is carrying to the maximum it can carry.

A pulse oximetry test is painless and easy, though it is slightly less accurate than the ABG test. To take the test, you’ll need a pulse oximeter device or a health tool like the Biostrap wearable. Both types of devices use infrared light to get a reading of your blood oxygen level. Blood that is rich with oxygen absorbs light differently than blood that doesn’t carry oxygen. This test reads those differences and gives you a percentage of your oxygen saturation levels.

All you do is put the wearable on your wrist or affix the pulse oximeter to your fingertip. Keep the pulse oximeter on until it gives you a reading. If you are using a pulse oximeter to test oxygen saturation during exercise, keep the device on until you are finished working out. When using a pulse oximeter, make sure to remove any dark-colored nail polish as it can interfere with the infrared light and result in incorrect readings.

Symptoms of Low Blood Oxygen Levels

An out of breath woman sitting on a bed

Low blood oxygen levels result in a condition called hypoxemia. It’s basically a condition where your body isn’t getting the proper amount of oxygen to function at optimal capacity. When your organs aren’t getting enough oxygen, you may develop some of the following symptoms:

  • Chest pain
  • Shortness of breath or difficulty breathing
  • Wheezing
  • Confusion
  • Headache
  • Dizziness
  • Rapid heartbeat
  • Increased stress and anxiety
  • Irregular pulse rate
  • High blood pressure
  • Changes in vision
  • Cyanosis, a medical condition that causes the skin to turn bluish

Why Your Blood Oxygen Level May Be Abnormal

There are many reasons why your blood oxygen level may drop below your normal numbers. As mentioned, changing elevation can cause drops in blood oxygen levels, particularly if you live at lower altitudes. Underlying health conditions can cause levels to be lower than normal and taking certain medications may also decrease blood oxygen levels. Here are some of the main culprits behind low oxygen levels in the blood.

  • High altitude
  • Air pollution
  • Smoking
  • Heart disease
  • Lung conditions including COPD, asthma, and acute respiratory distress syndrome (ARDS)
  • Sleep apnea
  • Influenza and coronavirus infections like COVID-19 that cause pneumonia
  • Emphysema
  • Pulmonary fibrosis, a lung disease that causes scarring
  • Medications, particularly pain pills
  • Carbon monoxide poisoning
  • Anemia

What To Do If Your Blood Oxygen Level Isn’t Normal

Normal blood oxygen level: a nurse administers supplemental oxygen

The best treatment plans start by identifying what’s causing low oxygen levels. To do this, you’ll need to start by measuring your blood oxygen levels. Talk to a doctor and explain your medical history, whether you’re taking any medications, and any lifestyle changes that may be contributing to the problem.

If your levels are low due to elevation gain, this can be easily remedied by returning to lower elevations. If you’re susceptible to oxygen level changes due to altitude, you can also try acclimatizing — a process where you slowly increase elevation while allowing your body to adjust to the changes over time.

If you find yourself over 8,000 feet above sea level and have difficulty breathing, develop blue or grayish skin, and experience difficulty walking, visit a doctor. These are signs of high altitude sickness which can be life-threatening if untreated.

For most other cases, low blood oxygen levels are treated with oxygen therapy or supplemental oxygen. Depending on your oxygen needs, you may receive short-term treatment or something more long-term — particularly if you suffer from a lung disease. You can get oxygen at the hospital or your doctor’s office for short-term treatment. For long-term oxygen therapy, you’ll need to get a doctor’s prescription to take an oxygen tank home with you. Talk to a doctor to determine the right level of oxygen and how often you should be using it.

People with respiratory conditions can take medications to help keep the disease in check. If you have asthma, taking long-term asthma control medications can help reduce flare-ups and the asthma attacks that drop oxygen levels.

Lifestyle Changes To Improve Your Health

A pilates ball, yoga mat, weights, jump rope, and exercise step

Low blood oxygen levels can indicate an underlying condition. Sometimes low levels are simply the result of the outside air quality, while other times they signal a more serious condition. Staying healthy is all about making healthy choices. To reduce the risk of developing low oxygen levels, exercise regularly and avoid smoking.

Monitoring your health is another great way to stay ahead of any issues. With the Biostrap health tracker, you can easily check your blood oxygen saturation levels, heart rate variability, and sleep patterns to ensure you get the rest you need to live a healthy life. The mobile app helps you track and monitor all your metrics, plus you’ll find workouts on everything from meditation to weight training to help you stay healthy and happy.

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