Oxygen is very much necessary for one being to survive. The human body needs constant oxygen amounts in its blood for suitable functioning. However, low oxygen levels (or hypoxemia) can occur thanks to several conditions including lung disease, asthma and iron-deficiency anemia. Anxiety, disorientation, headaches, shortness of breath, bluish skin and high blood pressure are the common hypoxemia symptoms. Apart from blood transfusion, oxygen therapy and exercise and certain foods can help increase oxygen levels in your blood naturally.