NCERT Book Class 8 EVS Estimation of particulate pollutants in air

4. Estimation of particulate pollutants in air

Background

Solid particles and liquid droplets present in air are called particulate matter. Their presence in air beyond a certain limit is one of the causes of air pollution. Dust particles, pollen grains, smoke, vehicular exhaust, fly ash, coal dust, cement and mist are some of the examples of particulate matter in air. Higher concentration of particulate matter in air prevents solar radiations from reaching the earth’s surface. At the same time they also prevent heat to escape from the earth’s surface. The net effect of these two phenomena is one of the causes of global warming. They absorb light and reduce visibility, and cause various respiratory diseases.

Methodology

1. Take six similar clean glass plates/slides. Mark them with numbers from one to six with a marker pen. The number should be written in a laterally reversed manner so that you can easily read it from the other side. Alternately, you can write the numbers on paper and paste them on slides.

2. Coat the other side of each slide with petroleum jelly. Project Book in Environmental Education 

3. Place the slides with coated side up at different places of your house, such as in open space (at the terrace), on the window sill, in different rooms, inside a table drawer, in the garden. Note the serial number of the slide kept at each site.

4. After one week, remove all the slides and place them on a sheet of white paper with coated side up.

5. Observe the slides with a magnifying glass or with a microscope to estimate the amount of particulate matter deposited.

6. Note down your observation in the form of a table given below.

Conclusion

Draw a conclusion on the basis of your observation. Did all the slides gather equal amount of particulate matter? Discuss with your teacher/ neighbour, the possible sources of particulate matter at your location. Prepare a report of your findings.

Follow-up

Repeat this activity in different seasons. You may also perform it in your school/market/factory/busy roads.

Please refer to attached file for NCERT Class 8 EVS Estimation of particulate pollutants in air