Measuring blood oxygen levels, often through an SpO2 test, is crucial if an individual is experiencing sudden and severe physiological changes potentially related to low blood oxygen saturation. Common indications for an SpO2 test include: Difficulty breathing (dyspnea), Recent head or neck injury, Pneumonia, COVID-19, Carbon monoxide poisoning, Drug overdose. Furthermore, monitoring oxygen saturation levels can assist in assessing the stage or severity of chronic conditions, including: Asthma, COPD (Chronic Obstructive Pulmonary Disease), Cystic fibrosis, Heart disease.