Indoor fungi and fungi-like bacteria produce spores. However, the most common spores in indoor air are mold spores. Other fungal spores (such as yeasts spores) and bacteria spores can also be found indoors.
Mold spores are recognized allergens. It’s the outer wall of the mold spores that is believed to elicit allergic reactions. Hyphal fragments can be allergenic as well.
Mold is a problem in wet or damp indoor environments. Mold is often found growing on water-damaged building materials and furniture. Mold can also be found growing on walls where warm moist air condenses on cooler wall surfaces, such as inside cold exterior walls, behind dressers, headboards, and in closets where articles are stored against walls. Mold often grows in areas with both high water usage and humidity, such as kitchens, bathrooms, laundry rooms, and basements.
Molds are potentially a health hazard. Molds produce allergens, irritants, and in some cases, potentially toxic substances (mycotoxins). Inhaling or touching mold or mold spores may cause allergic reactions in sensitive individuals. Allergic responses include hay fever-type symptoms, such as sneezing, runny nose, red eyes, and skin rash (dermatitis). Allergic reactions to mold are common. These reactions can be immediate or delayed. Molds can also cause asthma attacks in individuals with asthma who are allergic to mold. In addition, mold exposure can irritate the eyes, skin, nose, throat, and lungs of both mold-allergic and non-allergic people.