Stachybotrys atra is a well known toxic mold which releases mycotoxins and has been blamed for numerous deaths, particularly several in Cleveland, Ohio.
Kimberly-Clark uses a test procedure was where samples were challenged with a biological aerosol of Staphylococcus aureus and the results employ a ratio of the bacterial challenge counts to sample effluent counts, to determine percent bacterial filtration efficiency (%BFE).