Dirty Air

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Author: Alexa Bach McElrone


When we look around, we do not typically see ‘air’ so it is easy to assume that our air is clean. In reality, our atmosphere is made up of mostly invisible gases. Additionally, most air pollutants are invisible as well. Some particles are so small that we do not usually see them floating by while others are gases without color. Given this, how do we know if the air we breathe is clean or polluted? Scientists use complex sensors to detect the presence and quantity of specific gases in the air. In this experiment, we will make a sensor to detect particulate matter in our air – any objects floating through on the wind.


  • A piece of white or clear plastic (salad plate size)
  • Petroleum jelly
  • Duct tape
  • A wood block or brick
  • Blank white paper 

​Experimental Procedure:

  1. Coat the top of the white or clear plastic with petroleum jelly.
  2. Secure the plastic to a wood block, brick, or other weighted object using duct tape.
  3. Identify an outdoor location that is mostly open with decent air circulation (on a fence is preferable to on the ground). (Tip: Take a photograph to include in your presentation.)
  4. Let the plastic/block sit for at least 24 hours (weather permitting).
  5. At the end of your experimental time, collect the plastic/block and bring it inside. If you are using a clear piece of plastic, place it on a white piece of paper or light-colored surface.
  6. Examine the top of the plastic for any particles collected. (Tip: Take a photograph to include in your presentation.) Make a list of these particles.
  7. OPTIONAL: Create two air pollution sensors and place them in different locations – at home/at school, indoor/outdoor. Then compare the pollution collected by each.


Clean Air Kids:

U.S. Environmental Protection Agency Clean Air:

AirNow Air Quality Games:

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