Custodial Staff (Also Known as Janitors or Cleaners) Are the Unsung

Custodial staff (also known as janitors or cleaners) are the unsung heroes of the workplace. Going about their work while many of us are in bed, they deal with a whole host of situations that bring them into contact with a wide range of chemical and biological agents. They are exposed to residues left in the air and on surfaces from manufacturing processes, from service operations, and from human excretions (sweat, body oils, from sneezing, and so on) . While employees of the firms that they service receive training about specific chemical and biological hazards, the custodial staff are often unaware of some of the hazards that they may encounter.
-Custodial staff are exposed to aerosols through the cleaning products they use and as a by-product of mechanical and human activity at each workplace where they clean. What is the part of the respiratory system that is spiral shaped and could be protected from aerosols by wearing a face mask?

A) cilia
B) alveoli
C) turbinates
D) macrophages