Study the Presence of Suspended Particulate Matter in Air at Two Widely Different Sites


To study the presence of suspended particulate matter in air at two widely different sites.

Material Required

  • Few freshly cut broad leaves
  • Vaseline
  • Laboratory balance
  • Weights
  • Brush
  • Paper clips
  • Twine thread


  1. Collect a few broad leaves from the nearby plants such as peepal.
  2. Wash the leaves to remove any dust particles and dry the surface of the leaves. 
  3. Trace the outline of the leaves on a graph paper to calculate the area of the leaf.
  4. Calculate the total number of full squares, ½ squares, ⅓ squares, ⅔ squares and individual small squares within the traced area.
  5. Calculate the total leaf area by adding all the squares.
  6. Multiply the obtained value with 2 to obtain the total area of both the surfaces.
  7. Take a 10 feet long twine thread and tie five leaves at a foot’s distance to each other.
  8. A thin layer of vaseline is applied on both the surfaces of the leaves and pack the leaves in polythene bags.
  9. Make two such bundles containing five leaves each.
  10. Measure the weight of each leaf bundle along with the polythene bags and mark them as A and B.
  11. Select any two spots (X and Y) near your area such that spot X has very heavy vehicular traffic and spot Y has very little vehicular traffic.
  12. Tie the two ends of the thread containing leaves in bundle A on a tree at a height of about 10 feet from the ground at spot X, such that all the leaves are exposed. Leave the leaves for two hours.
  13. After two hours, rebundle the leaves and place then in the polythene bag A. Record the readings in the observation table.
  14. Repeat the same process with the bundle B at another spot Y and record the readings.
  15. Reweigh each bundle of leaves along with their respective polythene bags.
  16. Calculate the amount of suspended particles in mg cm2  and compare the results of the two different spots.



Weight of leaves before exposure (W1)

Weight of leaves after exposure (W2)

Weight of suspended particles

Heavy Vehicular Traffic




Little Traffic





The weight of the suspended particles in the area with heavy vehicular traffic is greater than that in the area with very little traffic. This is because the air in the areas with heavy traffic is rich in smoke, dust and particulate matter when compared to the areas with little traffic.


The outer surface of the polythene bag containing the bundle of leaves should not have any vaseline sticking to it. 

Also Read: Air Pollution

Types of Pollution

For more information on Biology experiments for CBSE Class 12, keep visiting BYJU’S website or download BYJU’S app for further reference.

Leave a Comment

Your email address will not be published. Required fields are marked *