Ambient air may be contaminated with or carry significant levels of a variety of potentially
harmful microorganisms. There are three major sources of such microbes: a) those arising
from microbial decomposition of various substrates associated with particular occupations
(eg," moldy" hay leading to hypersensitivity pneumonitis), b) those associated with certain
types of environments (eg, Legionnaires' bacteria in water supplies), and c) those stemming
from infective individuals harboring a particular pathogen (eg, tuberculosis). This�…