What is Stachybotrys? Stachybotrys is a greenish-black, slimy mold found only on cellulose products (such as wood or paper) that have remained wet for several days or more. Stachybotrys doesn't grow on concrete, linoleum or tile. According to the U.S. Centers for Disease Control and Prevention (CDC), all molds should be treated the same with respect to potential health risks and removal. All molds should be handled with caution. In 1994, the CDC investigated whether exposure to Stachybotrys might be related to pulmonary hemorrhage, also known as bleeding lungs, in infants in Cleveland, Ohio. They concluded that there was a strong association between Stachybotrys and bleeding lungs.

Because this conclusion was disputed by experts in the scientific community, the CDC organized a panel to review the study results. In the 10 March 1999 issue of Morbidity and Mortality Weekly Report, the expert panel concluded that an association between exposure to Stachybotrys and bleeding lungs in infants was not proven.

How does mold affect people?

Some people are sensitive to molds. For these people, exposure to molds can cause symptoms such as nasal stuffiness, eye irritation, wheezing, or skin irritation. Some people, such as those with serious allergies to molds, may have more severe reactions. Severe reactions may occur among workers exposed to large amounts of molds in occupational settings, such as farmers working around moldy hay. Severe reactions may include fever and shortness of breath. Some people with chronic lung illnesses, such as obstructive lung disease, may develop mold infections in their lungs.

How to Identify the Cause of a Mold and Mildew Problem

Mold and mildew are commonly found on the exterior wall surfaces of corner rooms in heating climate locations.  An exposed corner room is likely to be significantly colder than adjoining rooms, so that it has a higher relative humidity (RH) than other rooms at the same water vapor pressure.  If mold and mildew growth are found in a corner room, then relative humidity next to the room surfaces is above 70%.  However, is the RH above 70% at the surfaces because the room is too cold or because there is too much moisture present (high water vapor pressure)?

The amount of moisture in the room can be estimated by measuring both temperature and RH at the same location and at the same time.  Suppose there are two cases.  In the first case, assume that the RH is 30% and the temperature is 70oF in the middle of the room.  The low RH at that temperature indicates that the water vapor pressure (or absolute humidity) is low.  The high surface RH is probably due to room surfaces that are "too cold."  Temperature is the dominating factor, and control strategies should involve increasing the temperature at cold room surfaces.

In the second case, assume that the RH is 50% and the temperature is 70oF in the middle of the room.  The higher RH at that temperature indicates that the water vapor pressure is high and there is a relatively large amount of moisture in the air.  The high surface RH is probably due to air that is "too moist."  Humidity is the dominating factor, and control strategies should involve decreasing the moisture content of the indoor air.