Which of the following statements is true?

a. Fog and mist are considered water vapor.
b. Medical aerosols are much smaller than molecules of water.
c. Medical aerosols range from 0.2 ?m to 50 ?m.
d. All of the above are true.

ANS: C
Medical aerosol must deposit anywhere from the upper airways to the lower airways; therefore, it must be the appropriate size for the target site, with a range of 0.2 ?m to 50 ?m. Fog and mist are considered aerosols, not water vapor. Medical aerosols need to be larger than water vapor mole-cules—otherwise they would be too stable to deposit at their target site.