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Normal Blood Oxygen Levels

Normal blood oxygen level

Oxygen saturation is the fraction of oxygen-saturated haemoglobin relative to total haemoglobin (unsaturated + saturated) in the blood. The level of oxygen in the blood must be precisely balanced to meet the needs of the human body.  Normal arterial blood oxygen saturation levels in humans are 97–100%. If the level is below 90%, it is considered low and called hypoxemia. Arterial blood oxygen levels below 80%  should be promptly addressed as it might compromise organ function, such as the heart and brain. Continued low oxygen levels might lead to cardiac or respiratory arrest. 

Maintaining a blood oxygen level of 95–100% is vital for healthy kidneys, brain and heart. Most people don’t need to monitor their blood oxygen levels regularly, however, if you have a health condition that might cause low oxygen states, measuring your levels with pulse oximetry is quick and noninvasive.

What should be the normal Oxygen Level?

The measure of how much oxygen your red blood cells are carrying is your blood oxygen level. Most adults and children do not need to monitor their blood oxygen levels. Most doctors won’t check it unless you are showing signs of problems like chest pain or shortness of breath or having a procedure done. Blood oxygen levels may need to be monitored in people with certain medical disorders to assess if treatments are effective or whether they need to be changed. These conditions may include:

  • Cystic fibrosis
  • COPD (Chronic obstructive pulmonary disease)
  • Heart disease
  • Asthma

Blood oxygen levels can be measured through 2 types of tests: ABG (arterial blood gas) and pulse oximeter. The method adopted to monitor your blood oxygen levels might have an impact on your findings. 

A pulse oximeter reading indicates the SpO2 level (the percentage of your blood which is saturated). It is the most common type of test because it provides quick readings and is noninvasive. A normal, healthy reading is 95-100%. A doctor might recommend you get an ABG if your SpO2 level is less than 92%.

An ABG measurement will determine the PaO2 (the partial pressure of oxygen in your blood). For healthy lungs, a typical ABG oxygen level ranges from 75 to 100 millimetres of mercury (mm Hg). This test is more invasive but very accurate. 

Smokers may additionally require an ABG test as they may have an unreliable high pulse oximetry value. Carbon monoxide builds up in your blood due to smoking. A pulse ox can’t tell the difference between oxygen and this type of gas. 

ABG (Arterial blood gas) Pulse oximeter
Healthy level 75–100 mm Hg 95–100%
When to get medical help less than 74 mm Hg less than 95%

These ranges may differ for people with lung diseases or COPD. Discuss your levels with your doctor if you are living with a lung condition as they can help you identify what a normal range will look like for you. 

What are the symptoms of Low Blood Oxygen Levels?

You’re at risk of hypoxemia when your blood oxygen level goes below 95%. The medical term for low blood oxygen levels is hypoxemia. 

It is a cause for concern often and might lead to complications that affect the heart, kidneys and brain. You could notice any of the following indicators:

  • Rapid heartbeat
  • Headache
  • Confusion
  • Wheezing or coughing 
  • Chest pain
  • Shortness of breath

Cognitive and visual changes might start to develop if your blood oxygen level falls below 80–85%. 

You are at risk of developing symptoms of cyanosis at 67%. The hallmark sign of this is a blue discolouration of your mucus membranes, skin and nail beds. This might also lead to respiratory failure, which can be life-threatening. If you have symptoms, get medical help right away. 

It is crucial to know what your regular oxygen level is, particularly if you have a chronic lung condition. Regarding the range of oxygen levels that are suitable for you, a doctor may provide advice.

What are the reasons why Blood Oxygen Levels are Low?

Some particular health conditions might cause hypoxemia by affecting your lung function, which includes:

  • Pulmonary embolism
  • Heart disease
  • Congenital heart defects
  • Anaemia
  • Pneumonia
  • Collapsed lung
  • Asthma
  • Acute respiratory distress syndrome
  • COPD, including emphysema and chronic bronchitis

Problems and blood disorders with your circulatory system might also prevent your blood from picking up oxygen and transporting it throughout your body.

How these disorders and conditions lower your blood oxygen levels can be classified in 5 different ways:

  • Low environmental oxygen (usually happens at high altitudes)
  • Hypoventilation
  • Diffusion impairment
  • Shunt
  • V/Q (ventilation/perfusion) mismatch 

How can we increase Blood Oxygen Levels?

There are numerous ways to increase your blood oxygen levels at home naturally, like:

  • Eating a well-balanced diet
  • Exercising regularly
  • Avoiding secondhand smoke or quitting smoking 
  • Having houseplants
  • Allowing fresh air into your home
  • Walking outside
  • Belly breathing
  • Pursed lip breathing

You might need supplemental oxygen to boost your oxygen saturation if your blood oxygen level is too low. Home oxygen supplementation is a drug that needs a doctor’s prescription. It is important to follow their advice on how home oxygen should be used to avoid complications.


Blood oxygen levels are an indicator of the amount of oxygen in your blood. If your levels are critically low, then it is advisable to seek medical help from an experienced pulmonologist. Timely care and help can ensure long-term balanced oxygen levels in your blood. 

At the CK Birla Hospital, we ensure patients get holistic medical support which includes treatment in a compassionate environment. This patient-centric approach not only helps patients heal better but also ensures they are aware of the preventive measures as well. In case you need to consult a pulmonologist, reach out to us, or book a direct appointment with pulmonologist at the CK Birla Hospital.

FAQs about Normal Blood Oxygen level

What is a Good Oxygen Level?

A healthy blood oxygen level is 95–100% in most people. Anything below 95% might put you at risk of hypoxemia and is considered low.People with specific conditions, such as COPD, might need to maintain their blood oxygen at a different level. Speak with a doctor to determine the realistic or ideal level for you.

What is a Dangerously low Oxygen Level?

A blood oxygen level below 95% is considered low and might increase the risk of hypoxemia. If you are experiencing some symptoms like chest pain, shortness of breath and rapid heartbeat, then you should get immediate medical attention.

How can I increase my Oxygen level?

You can increase your oxygen level by doing certain things like walking outside, allowing fresh air into your home, exercising regularly, eating a well-balanced diet and quitting smoking. 

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