Answer:
The respiratory system is directly connected to the external environment. More specifically, the gaseous environment around me can automatically find its way into the internal environment inside me.
The human respiratory system takes in air from the external environment. The purer the air is, the purer the content of its intake.
The system which keeps the lungs clean is found in the trachea which is lined with cells containing hair-like protrusions called cilia and also produces mucus and water droplets. The mucus and the cilia's activities combine to keep air passages hydrated and work together to trap dust, bacteria, and other foreign substances. An example of a foreign substance is heavy smoke from a building on fire. Other examples are cigarette smoke, heavy atmospheric dust such as is found in deserts. When these substances are inhaled, they can temporarily impede the efficiency of the cilia.
So it is important for one to avoid environments whose air is contaminated.
Because a contaminated environment translates to an impeded functioning of the respiratory system and a reduction in the quality of oxygen that reaches the bloodstream.
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