How Much Air Can Your Lungs Hold?

This week we discovered how much air our lungs can hold by building our own spirometer. We did this activity before I did any research about how much air lungs should hold, so I was little bit surprised by the results! Lungs can hold way more air than I suspected! The kids love this science experiment because they can figure out their lung capacity and learn about the respiratory system in a very hands-on manner.

I pulled this experiment from the First Encyclopedia of the Human Body, which is a must-have for families with young children. It has colorful pictures and simple text that make it easy to show kids what is going on inside of their body. Plus, it has instructions for easy experiments, like this one, and educational internet links the kids can go to to watch videos or play games online to reinforce what they learn in the book!

Total Time: 15 Minutes
Safety Concerns: None.

Materials You Need:
A plastic bottle (one that holds 2-3 liters is best) or a 1-gallon milk carton (3.8 liters)
A bendy straw
A large bowl filled about halfway with water

Directions:

  • Fill the plastic bottle with water all the way to the top. Screw the lid on.
  • Turn the bottle upside down in the bowl of water. Take the lid off while the mouth of the bottle is submerged in water, trying hard not to squeeze water out of the bottle while doing so.
  • Push one end of the straw into the neck of the bottle and hold onto the other end above the water.
  • Take a deep breath and blow gently into the straw until your lungs are empty. The air blows into the bottle and pushes water out into the bowl.
  • All the air you breathe out gets trapped at the top of the bottle. Make a mark at this point with a permanent marker so you can measure how much air your lungs hold.
  • To measure how much air you blew into the bottle: Fill the bottle with water up to the mark you made. Then dump this water into a measuring cup to see how much it is!
When I saw that my lungs could hold more than 2.5 liters of air I thought that sounded like a whole lot! I even attributed it to the fact that I grew up in the Rocky Mountains and that I am a distance runner. However, I looked it up later and found that average adult lungs can hold 4-6 liters so I guess I’m not all that special 🙂 Sometimes when we do these experiments I learn just as much, if not more, than the kids do.

Here is a fun fact for you: The lung capacity of freediver and world record holder Herbert Nitsch is measured to be 10 liters, which he can expand to 15 liters with a special technique called “buccal pumping”. This is the way amphibians inflate their lungs. Isn’t that cool?!

A study done in 1915 (I know, that’s forever ago) showed that lung capacity in children varies a whole lot and increases as the child grows. On average, a six-year-old’s lungs can hold about 1 liter of air, depending on how tall he or she is. A similar study in 1955 confirmed the results.

I love science + math, don’t you? I also love indoctrinating my son about the superiority of the metric system.

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