Mold grows in conditions of high humidity, direct wetting, and poor air circulation. Sometimes mold develops in a small, isolated area within a larger space served by a generally efficient HVAC system. In this case, a survey of the area will usually reveal inadequate air circulation. In some cases, a micro-environment such as an exhibit case can be conditioned to control humidity through means of a desiccant like silica gel, which absorbs moisture and thereby reduces humidity. This approach is only effective in an enclosed system.

Mites known as book lice can be a useful indicator of mold. These tiny grey/white insects inhabit the inner margins of damp books and feed on microscopic mold embedded in the paper. Hidden mold can also be detected with ultraviolet light, exposure to which causes the fungi to turn fluorescent. Mold can also be detected by the musty odor common to damp basements.

If mold is discovered, take immediate steps to discover the cause. Check for water infiltration (wet floors, ceiling, or walls). Is the HVAC functioning correctly? Does it provide the appropriate level of air flow, and are the pre-heat coil and misting unit working? Is there a structural problem causing rising damp or condensation?