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Lung Capacity and Age

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Areas of Science
Time Required
Average (6-10 days)
Material Availability
Bromothymol blue is a specialty chemical which can be ordered from an online vendor.
Low ($20 - $50)
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: For this science project you will need to develop your own experimental procedure. Use the information in the summary tab as a starting place. If you would like to discuss your ideas or need help troubleshooting, use the Ask An Expert forum. Our Experts won't do the work for you, but they will make suggestions and offer guidance if you come to them with specific questions.

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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)


  • 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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Global Connections

The United Nations Sustainable Development Goals (UNSDGs) are a blueprint to achieve a better and more sustainable future for all.
This project explores topics key to Good Health and Well-Being: Ensure healthy lives and promote well-being for all at all ages.


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Science Buddies Staff. "Lung Capacity and Age." Science Buddies, 20 Nov. 2020, https://www.sciencebuddies.org/science-fair-projects/project-ideas/HumBio_p003/human-biology-health/lung-capacity-and-age. Accessed 30 Nov. 2023.

APA Style

Science Buddies Staff. (2020, November 20). Lung Capacity and Age. Retrieved from https://www.sciencebuddies.org/science-fair-projects/project-ideas/HumBio_p003/human-biology-health/lung-capacity-and-age

Last edit date: 2020-11-20
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