Dusty Air

Judith Brown
1991 Woodrow Wilson Biology Institute


At the end of this activity students will be able to:
  • Name three different types of particulate matter found in the air
  • Identify different types of solid particulate matter found in the air.


Particulate matter, or particles which can be found in the air, may be classified as solids, gases or aerosols. Some of the solid material may be soot, ash, soil or dust. Much of the solid material comes from the burning of trash, fires, dust storms and soil erosion. The most prevalent gases are carbon monoxide and sulfur dioxide. These come from imcomplete combustion of gasoline, natural gas, burning of sulfur-containing fuels , and smelting and refining or ores. Aerosols are insoluble particles suspended in a gas. The particles are too small to be pulled to the earth by gravity and remain suspended in the air. Many of the garden and household aerosols are potentially dangerous because, if they are not dispersed by a fan or the wind, they can cause respiratory illnesses.


  • petri dishes, graph paper cut into circles the size of the petri dishes, vasoline, tape


  1. Tape a circle of graph paper to the bottom of the petri dish so that the squares can be seen from the top of the dish.
  2. Cover the bottom of the plate with a thin film of vaseline.
  3. Have students place half of the dishes inside in various locations around the classroom and the other half outside sheltered from rain. (A screened porch is ideal.)
  4. Leave the plates for a week.

Activity: Detecting Number and Types of Particulates

1. Using a stereoscope, count the number of particulates you find in a small square of the graph paper . (Choose a square with lots of dark material in it to count.)

  • # of particles________
    # of different types of particles________
    List types of particles________________

  • Draw any pollen grains present on the plate. Pollen grains are often yellow and have a wide variety of shapes - some with spikes and long extended rays and others are notched oval or circular shapes.

  • Count all of the particles present on the small square you observed.

  • List ways you or your family could help reduce the amount of particulate matter in the air.

  • List ways different industries could reduce particulate matter and air pollution.

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