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Normal Blood Oxygen Levels: What Is Safe & What Is Low?

What is Meant by Blood Oxygen Level?

The quantity or level of oxygen that is circulating in the blood is known as Blood Oxygen Level(1). Red blood cells are the main carriers of oxygen where they collect the oxygen from the lungs and transport it to all over the body(9, 10). Our body keeps a close watch on the blood oxygen levels and tries to keep it in a specific range to ensure sufficient amount of oxygen is present to fulfill the requirements of every cell in the body.

An individual’s blood oxygen level indicates how well the oxygen distribution is from the lungs to different parts and cells of the body and it is very crucial for the health of a person that it remains in the desired parameters.

Normal Blood Oxygen Levels: What Is Safe & What Is Low?

Measurement of Blood Oxygen Levels

ABG Test: For monitoring blood oxygen levels, ABG test or arterial blood gas test is the most effective way to go(6). For ABG test, an arterial blood sample is taken, often from the wrist, for testing the levels of blood oxygen.

Pulse Oximeter: A pulse oximeter is the common method used to measure the blood oxygen levels(1, 4). A pulse oximeter looks like a small clip, which is commonly put over the finger; however, this device can also be put over the toe or ear(4). A pulse oximeter measures the oxygen in the blood indirectly by mild absorption through the patient’s pulse. A pulse oximeter is easily available online in a variety of easy-to-use devices for home use(3).

Which is More Accurate for Measuring Blood Oxygen Levels?

ABG test is more accurate than the pulse oximeter test; however, the latter is quicker, easier and painless(4, 5). There are various factors that influence the result of pulse oximeter, such as nail polish, dirty fingers, bright lights and reduced circulation to the extremities(7, 8); and all this makes ABG test more accurate than the pulse oximeter test; albeit with a little bit of pain and requiring time.

What are Safe and Low Blood Oxygen Levels?

Safe or Normal Blood Oxygen Level: The level of normal blood oxygen is between 75 and 100 mm Hg(1).

Low Blood Oxygen Level: The level of blood oxygen is considered low when it drops below 80 mm Hg and may need oxygen supplementation, depending on the patient and what the doctor decides(11).

If a person is having low blood oxygen levels then it is indicative of hypoxemia, which is a condition where the body has difficulty in transporting oxygen to different parts of the body including the organs, tissues and cells.

What are the Causes of Low Blood Oxygen Levels?(11)

Common causes of Low Blood Oxygen Levels or Hypoxemia are:

Lung Problems: When a person’s lungs are not able to inhale and transport the oxygen to the rest of the body.

Atmosphere: When there is insufficient oxygen in the air.

Circulation Problems: When there is a problem with the bloodstream and its circulation and the blood is not able to collect the oxygen from the lungs and transport it to all over the body.

Factors Contributing to Low Blood Oxygen Levels(11)

Other conditions that contribute to Low Blood Oxygen Levels are:

What are the Symptoms of Low Blood Oxygen Levels?(1, 11)

When a person is having low levels of blood oxygen, then it causes disruption in the blood, which produces the following symptoms in the patient: shortness of breath, restlessness, rapid heartbeat, headache, rapid breathing, dizziness, chest pain, lack of coordination, hypertension, visual problems and a sense of euphoria.

Serious Symptoms of Low Blood Oxygen Levels That Need Immediate Medical Attention:

  • Sudden and severe shortness of breath.
  • Shortness of breath at rest.
  • Waking up at night with a choking sensation or shortness of breath.
  • Severe shortness of breath worsening with physical activity or exercise.
  • When at high altitude and suffering from acute shortness of breath, with a rapid heartbeat, cough and fluid retention.

What is the Treatment for Low Blood Oxygen Levels?(11)

Treatment of low blood oxygen levels mainly consists of supplemental oxygen being given to the patient. Home treatment for low blood oxygen levels with supplemental oxygen is known as home oxygen therapy (HOT).(3)

To improve low blood oxygen levels, it is important to quit smoking and also avoid places where other people are smoking.

A variety of devices are available for monitoring and delivering home oxygen therapy (HOT); however, a few of them need a prescription.(3)

Lifestyle Changes for Low Blood Oxygen Levels

Some lifestyle modifications go a long way to reduce the symptoms of Low Blood Oxygen Levels and improve the patient’s quality of life. Measures that are important to undertake in order to normalize your blood oxygen levels are: quitting smoking, eating a healthy diet, avoiding passive smoking and daily exercise.

What is the Prognosis of a Patient with Low Blood Oxygen Levels?(11)

Having low blood oxygen levels is not necessarily a fatal condition and people suffering from this condition can recover completely depending on its cause and treatment. Healthy people also suffer from low blood oxygen levels when they are at high altitude and they don’t need to monitor their levels of blood oxygen regularly.

Patients suffering from chronic lung diseases, such as pulmonary fibrosis, COPD/ emphysema can have low levels of blood oxygen due to their disease and may need regular monitoring of their blood oxygen levels(2).

Lifestyle changes that include: quitting smoking, following a healthy diet and regular exercise along with supplemental oxygen gives a good prognosis for people suffering from low blood oxygen levels.


Pramod Kerkar, M.D., FFARCSI, DA
Pramod Kerkar, M.D., FFARCSI, DA
Written, Edited or Reviewed By: Pramod Kerkar, M.D., FFARCSI, DA Pain Assist Inc. This article does not provide medical advice. See disclaimer
Last Modified On:July 20, 2021

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