Molds are a type of fungus and mold spores are their airborne particles that contribute to indoor air pollution. They need moisture to grow and are usually found in damp, poorly ventilated areas such as bathrooms. You cannot see the spores but you may be able to see molds–grey, green or black in color–growing on damp surfaces. Airborne mold spores can produce allergic reactions in sensitive people. People who experience allergic reaction to mold spores are also more likely to suffer from asthma.