This experiment is a great introduction to air quality and particulate air pollution. Set-up is easy, and material cost is low- you can obtain everything you need for under $5 for a classroom of 30.

In this classroom experiment, you will use graph paper and petroleum jelly to "catch" particulate air pollutants for classroom observation. Each student group will be responsible for creating 3 Sample cards and placing them at various locations. At the end of the experiment period (24 hours) groups will collect the cards, observe, record, and analyze the pollutants collected.

Step 1: Materials

For this experiment, you will need the following materials (per group)

Graph Paper (x3)
Scissors
Solid backing for graph paper- we used index cards. Cardboard or even plywood can be a great choice for outdoor locations
Petroleum Jelly
Plastic knife
Binder Clips
Magnifying Glass

Step 2: Trim Graph Paper

First, you will want to trim the graph paper so that it fits on your backer card without overlapping the edges.

Depending upon the age of your students, you may choose to adjust what size graph paper you use in order to facilitate the math in obtaining averages. For our experiment we used 14x14 graph paper. For younger students, you may want to use larger 8x8 squares

Step 3: Mount Paper to Backer

Next, you will mount the graph paper to the backer card. If you're using thin cards, small binder clips work well to mount the paper. You want to ensure that the clips do not cover any of the squares of the graph paper.

On the back of each sample card, write the location of where the card will be placed as well as the name or group number of the students.

Step 4: Coat in Petroleum Jelly

Next you will want to cover the entire section of graph paper with a layer of petroleum jelly. You want this layer to be thick enough to catch pollutants without being so thick as to obscure the lines of the graph paper.

Step 5: Place Sample Cards

Now you will want your groups to determine where to place their cards. This experiment works best with a range of indoor and outdoor locations. You will catch the highest amount of particulate matter if you have access to a heavily traveled street or highway where you can mount some of the cards.

When mounting in outdoor areas with heavy traffic, we recommend using wood backers, and mounting in the ground with a dowel rod.

After mounting the sample cards, leave them undisturbed for 24 hours in order to collect particulate matter.

Step 6: Retrieve Sample Card and Analyze

After 24 hours, retrieve the sample cards. In groups, have the students observe the particulate pollutants trapped on the cards. Have them count the number of particulates in each square of the graph paper, and record them in a table laid out with the same number of squares as the graph paper.

After all particulates have been counted, have them calculate the average number of particulates per square to be used while comparing pollution with other groups.

After all groups are done recording data, have them discuss their findings.

Which areas had the highest pollution?
Are they surprised by any of the sample cards (more or less pollution than expected?)
Does the pollution outdoors look different than the pollution indoors?
What are some similarities between the indoor and outdoor cards?