Air is that which we breathe in and out. We can also notice air when we run or when we are riding down a hill on a bicycle.
If you look out of the window, you will notice that the leaves on the trees are moving. This movement of the leaves is due to air.


Clear your nostrils with a handkerchief or soft tissue paper. What do you notice?
These dirts are some dusts which are in the air and which was removed by the tiny hairs in our nostrils when we were taking in air.
If you breathe out on a mirror you will notice some tiny drops of water vapour. This is also part of the air. Apart from these two—dusts and vapour, air contains other things or gases. These are oxygen, carbon dioxide, nitrogen and some other minor gases.

When we breathe in, we are taking in oxygen and nitrogen

It is only oxygen which is useful in our body. It gives us life and without it death occurs. It helps to break down the food we eat and thus give us energy and power.
When we breathe out, we expel the air which we took in. this air, however, contains plenty of poisonous carbon dioxide and little oxygen since the body used it to live. The poisonous carbon dioxide that we breathe out is used by plants to manufacture their food during photosynthesis. When plants take in carbon dioxide, they produce oxygen which we breathe in. this is why we should always have flower bottles in our houses and in the classroom.


The main organ of breathing is called the lungs. It is made up of a right and left lungs. Each lung is a big bag with tiny air sacs.
From each lung arises a pipe. The two pipes (from the two lungs) join to form the windpipe. The windpipe opens into the back of the tongue.
Air usually enters the lungs through the nose. Occasionally during illness it can do so through the mouth. The nose has some hairs. These hairs filter and remove all dust before the air passes into the lungs.


When we breathe in, oxygen in the air enters the body through the nose. It then passes into the windpipe it gets into the two lungs.
The air sacs of the lung has very many tiny blood vessels in their thin walls. The oxygen, on getting into the lungs passes through the thin walls of the air sacs into the blood in the blood vessels. From here, the oxygen is carried round the body.
As the oxygen passes into the blood, carbon dioxide in the same blood from the body passes out into the air sacs of the lungs. When we breathe out, the carbon dioxide is expelled.
Hence, during breathing, oxygen is taken in while carbon dioxide is sent out of the body.


If you enter a house without windows, what happens to you?
You will feel uncomfortable, hot and will start to sweat. This is because the air in the room is stagnant or is standing still. Worse, the room itself will be warm or even hot. In such situations, you will want to get out of the room quickly.
To keep our houses and our rooms cool and allow air to pass through it, we always have windows. A good and well ventilated house, has windows at opposite sides of the house, so that air entering at one end, gets out through the other.

It is dangerous to live in poorly ventilated houses.

Some houses in the villages have no windows. This makes the house to be hot, dark, stuffy and wet. If there is a sick person in such house, then, it is likely that everybody in the house will be sick. This is because as he breathes out disease germs, the others will be taking them in since there is no window for the germs to be blown out.
Diseases that can attack persons living in poorly ventilated houses are tuberculosis, measles, chicken and smallpox, cough and common cold.
The practice in villages of keeping animals such as fowls, goats and sheep at night in the same badly ventilated rooms where people sleep, is bad. These animals will compete with people for the little oxygen there is in a room. Some of these animals may be sick and they can thus

spread germs that are harmful.

It is also bad to have wood or coal fire in the sleeping rooms at night. The smoke from the fire contains poisonous gases that can kill people. This is a warning to all villagers who make coal fires to warm themselves at night during the rainy season or during harmattan.

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Important topics related to the above article

1. Recognizing living things
2. Biology as an enquiry in science
3. Branches of biology
4. Processes of methods of science
5. Usefulness of science
6. Living and non-living things
7. Characteristics of living things
8. Differences between plants and animals
9. Organization of life
10. Complexity of organization in higher organisms
11. Kingdom monera
12. Kingdom Protista
13. Kingdom fungi
14. Kingdom Plantae
15. Kingdom Animalia
16. Cell as a living unit of an organism
17. Form in which living cells exist
18. Structures of plants and animal cells and functions of their components
19. Similarity and differences between plant and animal cell
20. Diffusion
21. Osmosis
22. Plasmolysis
23. Haemolysis
24. Turgidity
25. Faccidity
26. Nutrition
27. Feeding
28. Cellular respiration
29. Excretion
30. Growth
31. Cell reaction to its environment
types vertebrae and the vertebral column
32. Movement and responses
33. Reproduction
34. Skeleton
35. Type of skeleton
36. Bones of axial and appendicular skeleton
37. Joint
38. Functions of skeleton in man
39. Supporting tissues in plants
40. Mechanisms of supports in plants
41. Uses of fibres to plants
42. Functions of supporting tissues in plants
43. test for Food substances
44. Balanced diet and kwashiokor
food tests
45. Modes of nutrition
46. Feeding mechanisms in holozoic organisms
maintenance of teeth gum
47. Mammalian teeth
48. Dentition
49. Digestive enzymes
50. Meaning of ecology
causes of germs and diseases in humans
51. Local biotic communities or biomes in Nigeria
52. Major biomes of the world
53. Population studies
54. Ecological factors



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