Page 171 - New Medley 3 Semester 2

 Carbon dioxide gets into the air when living things breathe out. It also comes

from burning fuel and other things.

 When green plants make their food, they give

out oxygen. is oxygen mixes with air.
 In the sun, the water from the rivers, oceans,

lakes, etc., changes into water vapour and mixes
with air. Clothes drying in air

 When we clean the objects lying in our houses

and sweep the oors, dust rises and mixes with air.
 Germs from open garbage mix with air.

 Smoke from the vehicles, factories, burning
garbage, etc., mixes with air. Water changes into water vapour

Smoke from factory, vehicles and burning garbage

e harmful things like smoke, dust and germs make air dirty. Dirty air is harmful

and can spread diseases.

Green plants clean the dirty air and make it fresh. We must grow as many plants
as we can.

How air is useful
 All living things such as plants and animals

need air to breathe.

 Plants also need air (carbon dioxide gas) to
make their food.

 Moving air helps in drying clothes and wet

surfaces.

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