Approximately how many liters of air does an average person breathe per day?

• A. 5,000 L
• B. 10,000 L
• C. 15,000 L
• D. 20,000 L

Answer: (C)

Think in terms of total daily ventilation—the amount of air moved in and out of the lungs, not the oxygen we use. A breath is about 0.5 liters, and a typical person takes roughly 12–20 breaths per minute. That gives a minute ventilation of about 6–10 liters per minute. Over a day (60 minutes × 24 hours), that totals roughly 9,000–14,000 liters. With everyday activity, many people breathe a bit more, bringing the estimate up toward about 15,000 liters per day. So, around 15,000 liters is a reasonable approximation for the average person.