Unless you have the need and capacity to maintain a *clean room*
environment (i.e., certain computer centers, computer chip manufacturing
facilities, etc.) a HEPA filter should be more than adequate.
 
If people and ventilation ducts enter the *clean* space it will no longer
be clean.  Mold spores are always with us; control is largely a matter of
maintaining temperature and relative humidity below their activation level.
 
The standard recommendation of approx. 70 degrees F and 50% RH is
adequate in most situations.
 
Jack C. Thompson
Thompson Conservation Lab
Portland, OR
 
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