| MadSci Network: General Biology |
How much water do we exhale? This is a tough question to answer, since a lot of it depends upon other conditions. How big is the person breathing? What is the temperature outside? What is the humidity outside? How hydrated is the person? According to a web site I found (www.newton.dep.anl.gov/askasci/gen99/gen99801.htm) the average person’s breath is about 4% water by volume. According to their calculations, that amounts to about 20ml of water vapor per breath. If we average about 20 breaths per minute, and 8 hours of sleep, that would come to 20ml x 20 breaths per minute x 60 minutes per hour x 8 hours = 192 liters of water! What!? That doesn’t seem possible. Well, it isn’t exactly. Remember that you are also breathing in water vapor as you are breathing out. You should note that water vapor converts into a much lower volume of liquid water. So, what we really have is a potential volume of water that is circulating in and out during breathing.
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