The Lungs Have Their Own Emergency Defense Unit
Some cells in the lungs actually spray a natural biocide over bacteria and other microbes. This way, microbes and bacteria that enter through the respiratory tract and manage to reach the lungs alive are killed there.
Obviously, it's not possible for lung cells to recognize harmful substances, much less know to produce whatever's needed to neutralize them. Cells are devoid of abilities such as thinking, cognition, decision-making, or planning. These are all products of God, the One Who created it all in harmony and balance, and regulation with the heavens and the Earth. By making just one cell perform acts with such consciousness that dumbfounds human beings, God displays signs of His infinite knowledge and wisdom.
Cells in the lungs have their own defense system. Immediately identifying microbes that enter the body through the respiratory tract, they secrete a substance that neutralizes these microbes.
That a tiny cell invisible to the naked eye can distinguish between microbes and other substances is a great miracle, because if it makes the wrong decision, it could neutralize a substance the body actually needs.