Very few people with allergies are allergic only to mold: many react to other allergens created by molds.

Molds grown on almost all organic substances – foods, but also books, textiles and wallpaper, if they’re damp enough. Advances in building technology, such as better soundproofing and insulation, have led to increased humidity in many interiors, and thus to an ideal breeding ground for molds. Molds can be spread through a building via the air conditioning system. The concentration of mold spores is generally lower indoors than outdoors.  The highest concentration of mold spores in the air comes in late summer.

The allergens are either released by the molds into the air and end up in household dust, or the mold spores themselves end up in the air, and then are inhaled. Molds live from animal and plant by-products, and live symbiotically with mites.  

Molds and mildews are found especially in:

• Summer houses closed all winter
• Damp cellars
• Poorly ventilated bathrooms
• Wallpaper on cold, damp walls
• Window frames with frequent condensation
• Moist clothing
• Food products