Science project

Testing the Ozone

Research Questions:

  • How can I test for ozone in the air?
  • Which locations have the most ozone?

Have you ever heard of an ozone alert? Ozone is a form of oxygen that can be harmful to humans when it enters our breathing space. You can test your surroundings to see which locations have the highest levels of ozone by creating your own ozone test strips.


  • Four cups
  • Distilled water
  • Glass pot (do not substitute a metal one!)
  • 1 ¼ teaspoons cornstarch
  • Stove
  • Wooden spoon
  • Potassium iodide
  • Coffee filter
  • Paintbrush
  • Scissors
  • Masking tape
  • Spray bottle

Experimental Procedure:

  1. Measure out four cups of distilled water and place it into a glass pot.
  2. Mix in 1 ¼ teaspoons of cornstarch
  3. Heat the mixture over a medium flame while stirring it with a wooden spoon. When the mixture thickens and becomes a bit see-through, remove it from the stove.
  4. Add ¼ teaspoon of potassium iodide, and stir. Let the mixture cool.
  5. Put a coffee filter on a ceramic plate, and brush both sides of the filter with the mixture. Try to make sure that the mixture is spread evenly on the whole filter. You have now created an ozone test paper.
  6. Use additional filters to make many more ozone test papers.
  7. Wash your hands with soap and warm water.
  8. Let the test papers dry in a dark place.
  9. Cut the test papers into strips.
  10. Spray a strip with distilled water and hang it in one of the locations that you would like to test.
  11. Spray and hang additional test strips in other areas. Consider hanging some strips inside and some outside, as well as hanging some in places that you think experience higher levels of pollution.
  12. Leave the strips for eight hours.
  13. Take down the strips and spray them with distilled water. The strips should change color based on how much ozone they were exposed to. The darker the purple color, the more ozone was in the air near their location.

Note: Do not place the strips in direct sunlight.

Terms/Concepts: Ozone; Which factors are likely to increase the ozone levels in the air?


First Place Science Fair Projects for Inquisitive Kids, by Elizabeth Snoke Harris. Pp. 110-112.

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