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Lung Capacity and Age *

Time Required Average (6-10 days)
Material Availability Bromothymol blue is a specialty chemical which can be ordered from an online vendor.
Cost Low ($20 - $50)
Safety Adult supervision is recommended. If using bromothymol blue, be careful not to ingest it. Any volunteer who feels light-headed after exhaling should stop immediately and not repeat the experiment.
*Note: This is an abbreviated Project Idea, without notes to start your background research, a specific list of materials, or a procedure for how to do the experiment. You can identify abbreviated Project Ideas by the asterisk at the end of the title. If you want a Project Idea with full instructions, please pick one without an asterisk.


Our metabolism changes as we get older, a sad fact of life that we cannot change. Old age affects our bodies in many ways. Changes in musculature, bone strength, energy, diet and breathing are some of the many ways we change as we age. You might notice that people often get out of breath when they are older and doing a physical activity. Why do some people feel out of breath, while others do not? Does this change correlate with age? Could this reflect a difference in lung capacity between the ages? You can test the lung capacity of several individuals using an empty soda bottle, some plastic tubing and a bucket of water. Partially fill a large bucket with water and use the water to fill a 2 liter soda bottle. Invert the bottle and immerse in the bucket of water, being careful not to spill out any of the water. Place one end of the tube into the opening of the bottle. Ask a volunteer to inhale, place their mouth on the other end of the tube and completely exhale into the tube. Watch as the water in the bottle becomes displaced by the exhaled air. When finished, carefully put the cap on the bottle and remove without spilling any of the remaining water. The lung capacity will be equal to the amount of water displaced by air in the bottle. You can also use a solution of bromothymol blue to measure the amount of carbon dioxide gas present when you exhale. Blow through a straw into the solution being careful not to suck up any liquid. The color of the solution will change according to the amount of carbon dioxide in solution, which will form carbonic acid and change the indicator from blue to yellow. How might respiration change before and after a physical activity? How does respiration compare between smokers and non-smokers? Adults and children? Dogs, cats and people? Good luck getting your cat to breath through a straw! (Dashefsky, 1995, 82-84;VanCleave, 1993, 177-182)

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Science Buddies Staff. "Lung Capacity and Age" Science Buddies. Science Buddies, 6 Oct. 2014. Web. 25 Oct. 2014 <http://www.sciencebuddies.org/science-fair-projects/project_ideas/HumBio_p003.shtml?from=Blog>

APA Style

Science Buddies Staff. (2014, October 6). Lung Capacity and Age. Retrieved October 25, 2014 from http://www.sciencebuddies.org/science-fair-projects/project_ideas/HumBio_p003.shtml?from=Blog

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Last edit date: 2014-10-06


  • Dashefsky, H.S. 1995. Zoology: 49 Science Fair Projects. New York, NY: McGraw-Hill, Inc.
  • VanCleave, J. 1993. Janice VanCleave's A+ Projects in Biology. New York, NY: John Wiley & Sons, Inc.

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I did this project I Did This Project! Please log in and let us know how things went.

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