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PROFESSOR: In Chapter 1,
we'll study the transfer

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of respiratory pathogens.

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Specifically, we'll consider
bacteria and virus, which

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originate in the lungs or
in the pharynx in the body

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and are transmitted
by forming droplets

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during the act of exhaling--
by breathing, or speaking,

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or other respiratory activities,

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and we'll study the
fate of those droplets.

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Will they shrink by evaporation?

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Will they fall and sediment
to different surfaces?

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Or will they be inhaled by an
susceptible person

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and thereby transmit
the infection?