# Air Pollution Detective STEM Challenge

Take a deep breath.  Along with that life-giving oxygen, you are inhaling, there are quite a few other things mixed into the air you breathe.  Let’s start with the gasses.  Air (on Earth, anyway) is made up of 78% nitrogen and only 21% oxygen.  Your lungs take up the oxygen and just breathe the nitrogen back out.  If you were paying attention to the math there, you noticed that it doesn’t quite add up to 100%.  You’re right!  The remaining 1% includes gasses such as argon, carbon dioxide, and others.

Aside from the gasses, there are other things in the air we breathe.  Solids called particulates can be suspended in the air.  They come from many different sources, depending on location.  A home may have pet dander or dust.  A busy street corner will have auto emissions and dirt.  A field of flowers will have pollen, depending on the season.  When any of these sources become a hazard to health, they are classified as pollution.

## How to do the Air Pollution Detective STEM Challenge?

The Challenge: Compare the amount of particulates in the air in different locations.

Materials: Index card, scissors, hole punch, clear packing tape, string or yarn, marker, magnifying glass, or microscope

Challenge Criteria: Cut a square out of the center of each index card.  Make sure the square is the same on each card, and that it isn’t larger than the width of the packing tape. Place packing tape over the square hole, being careful not to get anything on the sticky side in the process – this is what will be collecting particulates from the air!  Punch a hole in the corner of each card and run string or yarn through it so you can hang it up.  Choose indoor and outdoor locations for each card and hang them up.  Label each card with its location.  Decide how long you will leave them up (more than 24 hours is best).

## Reflection

Use the magnifying glass or microscope if you have one to compare the amount and type of particulates found in each location.  How do they look different from each other?  Did any of the results surprise you?

## Challenge Extension

Try the experiment again, but place cards on a flat surface (sticky-side up) to see if you get different results.