Wisconin Department of Health Service (DHS) - Position Statement Regarding the Impact of Mold on Health:
Molds grow abundantly in outdoor plant and soil materials. Molds produce spores that are normally found in both indoor and outdoor dust. Mold growth is familiar to most people when it is seen as a fuzzy patch or stain spreading across food or damp surfaces. It is known that many molds produce chemicals that can be toxic if eaten. Little if any of these chemicals are commonly found in indoor air and are not suspected to be a health hazard to the general public.
Mold exposure from breathing indoor or outdoor air can be irritating and can aggravate allergies and asthma. Health effects of mold can be a concern where exposures are very high, such as in sawmills, grain elevators, and agricultural settings. Where there are people with severely weakened immune systems, such as in hospital transplant units, mold infection can be a serious concern and exposures should be aggressively controlled. A physician should be seen whenever health effects are experienced.
It is not practical to expect a building to be completely free of mold, nor is it necessary. However, mold growth on indoor surfaces is a sign of moisture presence, the cause of which should be identified and corrected. Indoor mold growth should be removed regardless of mold type, using appropriate cleaning methods for small spots and careful attention to dust control, seeking professional assistance for larger amounts.