Coughing is the way in which the lungs dislodge anything that blocks the air passages. Usually these are only minor blockages caused by a build-up of mucus when you have a cold or chest infection. When you cough, your vocal cords press together to seal off the air passages. At the same time your chest muscles become tense, raising the pressure in your lungs. When you release the air it rushes out, carrying the obstruction with it.
The delicate alveoli inside the lungs can be damaged by many different things, thus causing us to cough. One is tobacco smoke, which clogs the alveoli and airways with thick tar. Others are the polluting gases that hover in the air of many big cities, coming from vehicle exhausts as well as factory and power-plant chimneys. Some types of industrial dust and particles floating in the air, such as asbestos or coal-mine dust can cause considerable damage to the lungs.
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Fact File: It can be quite hard to breathe when you are at the top of a mountain. At high altitudes the air is thinner so there is not so much oxygen in it. This means that you will breathe heavily if you exert yourself by climbing. |
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