MadSci Network: General Biology

Re: About how many gallons of air does the human body inhale in one day?

Date: Fri Oct 8 17:21:36 1999
Posted By: Dian Dooley, , Associate Professor, Food Science and Human Nutrition, University of Hawaii at Manoa
Area of science: General Biology
ID: 938570883.Gb

Aloha, Christa,

Let me show you how I figured out the answer to this question...just so you can see all the pieces involved. It is an interesting question, too; I think you might just be surprised at the final answer.

First, I had to look up in a physiology test what was an average number of times a person at rest breathes in/out. For a normal person at rest, that is about 12-16 times a minute. Each time a person breathes in/out in a normal/gentle way, about 1/2 liter (500 ml) of air moves back/forth. Of course, the air coming into the lungs has more oxygen; the air leaving the lungs has %-wise more CO2 (Do you know why?)

The next piece of the puzzle is to figure out that about 6-8 liters of gases move in/out each minute (How did I know that?)

Then, I had to figure out how many minutes there are in a day. Does 60 x 24 seem right? Yes, there are 1440 minutes in each 24-hour day. This allows me to estimate that between (1440 x 6) to (1440 x 8) liters of gases pass in/out of the lungs every day. A liter is about a quart, and you asked for an answer in gallons. Since there are 4 quarts (liters) to a gallon, the answer above has to be divided by 4, right?

Therefore the answer is 2160-2880 gallons!!! of gases pass in/out of the lungs each day. The answer seems like a lot, but I think the math is correct. Check it out.

Admin note: If you want to make your calculation more accurate, consider that 1 quart = 943.3 milliters.

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