Microbial measurements taken from indoor air are relatively unreliable. This is especially true when structures have already been opened up, allowing contaminated air to flow inside. Indoor air microbial measurements may be necessary if the location of damage or microbial growth cannot be found, but indoor air quality issues or occupants’ symptoms in the building suggest a potential health hazard. Indoor air microbial samples can be used to assess whether the concentrations and species observed in indoor air typical results found in indoors or if they indicate microbial damage or another unusual microbial source in the building.
Individual indoor air measurements do not rule out the possibility of damage and should not be used to determine the building’s healthiness. When dealing with air samples, there must be additional evidence besides the microbial concentrations in the sample to establish microbial harm.
Indoor air measurements should not be conducted in the fall when outdoor microbial concentrations are at their highest.