There is considered to be a zero tolerance for the presence of Stachybotrys type of mold spores. This is based on the fact that Stachybotrys is rarely found in the natural outdoor environment; it is associated with water damaged building materials, and it has been associated with human health symptoms. Stachybotrys is a dark colored fungus that thrives on water damaged wallboard, wallpaper, and insulation. This fungus has the ability to produce very toxic chemicals, called mycotoxins. Exposure to these toxins can produce dermatitis, coughs, rhinitis, nosebleed, burning in the nasal passages as well as the throat and lungs, headache, sore throat, cold-like symptoms, intermittent local hair loss, general fatigue, and fever.

Additional information on Stachybotrys:
Bye Bye Mold's "Mold Glossary"
"Is Indoor Mold Contamination a Threat to Health?"
(By Harriet M. Ammann, Ph.D., D.A.B.T.)
Stachybotrys chartarum and its “New” Relatives
(From Aerotech Laboratories, Inc.)
Stachybotrys and Pulmonary Hemorrhages: Another Connection
(By Michael A. Pinto, Ph.D., CSP & Cherie Fennema.)

Additional papers by George Hatcher