Compounded by ever more stringent energy conservation measures which can limit the ventilation in these spaces, the air we breathe indoors can pose threats to us now undreamt of in the days of draftier buildings.
Sources can be external or internal, biological or chemical in nature.
External biological contaminants can come from standing water which promotes mold growth. To view the list of sources, please see the List of References . Last updated December 31, 1995.