As a respiratory physiologist, I can tell you that the amount of oxygen needed for an individual to survive can vary based on several factors, including age, health, activity level, and the environment. However, I can provide a general guideline based on the information you've given. The human body requires a continuous supply of oxygen to function properly. Oxygen is essential for cellular respiration, which is the process by which cells produce energy. In a healthy adult at rest, the average oxygen consumption rate is about 250 to 300 milliliters per minute. This rate can increase significantly with physical activity. Using the information you've provided, if we consider that the air we inhale is approximately 20-percent oxygen and the exhaled air is about 15-percent oxygen, it means that approximately 5-percent of the oxygen in the inhaled air is utilized by the body. To calculate the amount of pure oxygen needed per day, we can use the following calculation: If a person uses about 550 liters of air per day and 5-percent of that is oxygen, then the amount of pure oxygen consumed would be: 550 liters of air * 5% = 27.5 liters of pure oxygen However, this calculation is based on the assumption that the air is at standard atmospheric pressure and the individual is at rest. It's important to note that the actual amount of oxygen needed can be influenced by various factors, and the body's oxygen requirements can change throughout the day based on activity levels. read more >>

The air that is inhaled is about 20-percent oxygen, and the air that is exhaled is about 15-percent oxygen, so about 5-percent of the volume of air is consumed in each breath and converted to carbon dioxide. Therefore, a human being uses about 550 liters of pure oxygen (19 cubic feet) per day.read more >>