How low can your oxygen level go before you die Dangerously low oxygen levels, known as hypoxemia, can lead to severe complications or even be fatal. Generally, oxygen saturation below 90% is concerning. Prolonged levels below 80% can lead to organ damage, while levels below 75% are life-threatening. However, individual tolerance varies. If you suspect low oxygen levels, seek immediate medical attention. This information is not a substitute for professional medical advice.