Review of methods to collect settled dust and isolate culturable microorganisms.

Examination of settled dust is often included in investigations of indoor environments to identify the types and concentrations of particles to which building occupants may be exposed. Fungi and bacteria are among the many components in dust that have been studied. Isolation by culture is an established method that is used widely to quantify and identify microorganisms in environmental samples. However, no standard procedures for culturing fungi or bacteria from dust have been adopted widely to ensure the validity of comparing findings from different studies. This paper reviews methods various researchers have used to study surface particles and to isolate culturable microorganisms from dust. Factors that were found to differ included the method of sample collection, the ways dust was prepared for inoculation onto growth media, and the culture media chosen for specific categories of agents. The need for reference methods in environmental microbiology for use in the assessment of indoor environmental quality is discussed.