100% oxygen given to patient before induction of anesthesia (asleep) is the standard clinical care. However, studies using various methods have shown differences in terms of the optimal time, technique and number of breaths needed for efficient oxygenation. The only difference to the standard pre-anesthesia care is that we will record the time to raise patient oxygen to 90%. Age is recorded to ensure that the subjects fall within our inclusion criteria. The weight (W) in kilograms and height (H) in meters will be used to calculate the body mass index (BMI): BMI = W/H2. Alveolar oxygen uptake is dependent on respiratory rate, heart rate, blood pressure, temperature and hemoglobin level. These parameters are measured in order to identify factors that may affect the accuracy of the study. We will record the pulse oximetry value to note the initial oxygen saturation on room air and after the oxygenation.