In respiratory system, most of the dirt/ microbes in the air are trapped by

Cilia propel a liquid layer of mucus that covers the airways. The mucus layer traps pathogens (potentially infectious microorganisms) and other particles, preventing them from reaching the lungs.

mountains can affect the climate of nearby lands. in some areas, mountains block rain, so that one side of a mountain range may be rainy and the other side may be a desert. much of airborne moisture falls as rain on the windward side of mountains.

explanation:

check for the pregnancy rating of drug. if its class c or d see if other alternatives