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Normal Oxygen Level

oxygen saturation, normal oxygen level, normal oxygen levels, pulse oximeterThe oxygen level in your blood can be precisely measured using a blood test known as an arterial blood gas (ABG) study. Although this test is the most accurate of testing methods, it is invasive, meaning it uses a needle to draw blood out of an artery, usually from your wrist and is therefore less preferable to many patients. A less accurate, but more common way to estimate oxygen saturation levels is with a pulse oximeter, a small, non-invasive device that attaches to the end of your finger. When measured by ABGs, normal oxygen levels are approximately 75-100 millimeters of mercury (mm Hg). When measured by pulse oximetry, normal oxygen levels are 95-100%.[1] In general, values below 55 mm Hg or 88% or less usually mean you need long-term oxygen therapy.[2] If your oxygen levels drop only during sleep or exercise, you may need supplemental oxygen during these specific time periods but not all the time.

What Causes Oxygen Levels to Drop?

Many health conditions can cause oxygen levels to drop including:

  • COPD
  • Pneumonia
  • Asthma
  • Acute respiratory distress syndrome (ARDS)
  • Collapsed lung
  • Fluid in the lungs
  • Blood clot in the lungs
  • Medications that slow breathing
  • Sleep apnea (a sleep condition that causes abrupt, frequent episodes of breathing cessation during sleep)

The Benefits of Supplemental Oxygen

When normal oxygen levels are compromised, supplemental oxygen can restore them to a healthy level. Besides improving oxygen levels in your blood, there are many benefits of using supplemental oxygen. They include:

  • Prolongs life – when used for more than 15 hours a day, supplemental oxygen improves survival in COPD patients with severe resting hypoxemia (low blood oxygen levels).[3]
  • Improves breathlessness – by far the most troubling symptom of COPD is progressively worsening dyspnea (breathlessness). Oxygen therapy has been found to decrease the sensation of dyspnea in COPD patients and reduce the rate of breathing when used during exercise as well.[4]
  • Improves quality of life – because oxygen therapy improves sleep and mood and increases mental alertness and stamina, it allows you to complete activities of daily living more easily, thus improving quality of life.[5]
  • Increases exercise tolerance – too often, people with COPD experience an intolerance to exercise. But regular exercise has been linked to increased exercise tolerance and improved quality of life in COPD. Using supplemental oxygen during exercise has many other benefits as well, including improving exercise performance and decreasing the sensation of breathlessness allowing you to exercise longer at higher levels of intensity.[6]
  • Improves your sex life – sexual impotence is a frequent occurrence for males with COPD who have low oxygen levels. Studies have found that using long-term oxygen therapy can help reverse sexual impotence in some COPD patients.[7]
  • Improves your social life – say goodbye to sitting at home tied to a home oxygen concentrator. With a lightweight, portable oxygen solution like the Inogen One G4, you have the freedom and independence to spend your days socializing anytime, anywhere.
  • Makes air travel safer and more comfortable – it’s common for people who don’t normally use oxygen to experience severe hypoxemia during air travel. Using supplemental oxygen during in-flight travel reduces the risk of severe hypoxemia. To find out if you qualify for in-flight oxygen therapy, talk to your primary health care provider before your next travel date.

Some people with COPD experience lower than normal oxygen levels, even while using supplemental oxygen. If you’re using oxygen therapy at home, it’s important to have a pulse oximeter on hand and keep a record of your oxygen saturation levels along with your oxygen flow rate and activity level at the time your oxygen saturation is measured. This way, your doctor can analyze the results to determine if there needs to be an adjustment in your oxygen flow rate. It’s also important to never increase or decrease your oxygen flow rate without first having a discussion with your doctor. Doing so can be hazardous to your health.


[1] Mayo Clinic. Hypoxemia (Low Blood Oxygen). Updated December 25, 2015.

American Thoracic Society. “Appropriate Candidates for Long-Term Oxygen Therapy. Updated 2015.

[3] From the Global Strategy for the Diagnosis, Management and Prevention of COPD, Global Initiative for Chronic Obstructive Lung Disease (GOLD) 2017. Available from: http://goldcopd.org.

[4] Christopher R. Swinburn, Hazel Mould, Timothy N. Stone, Paul A. Corris, and G. John Gibson “Symptomatic Benefit of Supplemental Oxygen in Hypoxemic Patients with Chronic Lung Disease”, American Review of Respiratory Disease, Vol. 143, No. 5_pt_1 (1991), pp. 913-915.

[5] American Lung Association. “Supplemental Oxygen”. Accessed August 16, 2015.

[6] Emtner, Margaret et. al. “Benefits of Supplemental Oxygen in Exercise Training in Nonhypoxemic Chronic Obstructive Pulmonary Disease Patients”. American Journal of Respiratory and Critical Care Medicine, Vol. 168, No. 9 (2003), pp. 1034-1042.

[7] Aasebo, U., et. al. “Reversal of sexual impotence in male patients with COPD and hypoxemia with LTOT”. J Steroid Biochem Mol Biol. 1993 Dec;46(6):799-803.


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