With roughly 200 different species and varieties, Aspergillus mold grows in humid conditions on anything from leather and fabric to food and grains and leaves. Its coloring can range from yellow-green to gold and red brown. A highly toxic mold, Aspergillus produces a mycotoxin called aflatoxin, which is a carcinogen.

Aspergillus is extremely common and its mold spores are present both indoors and outdoors. Most people will breathe them in every day, and in a healthy person they will usually go unnoticed. However, in a person who is immune compromised, Aspergillus can cause serious respiratory issues.

Aspergillus mold spores are so microscopic that, when inhaled, 70% of them are able to penetrate the trachea and bronchi and one percent are small enough to enter the alveoli, causing respiratory ailments and distress. Aspergillosis of the lungs is a serious disease that can afflict animals and humans.

Generally, aspergillosis only afflicts those with lowered immunity (cancer, AIDs, organ transplant, etc) or prior respiratory distress, like asthma or cystic fibrosis. It presents in several forms, including an allergic pulmonary reaction, a fungal growth in areas of past lung disease or scarring, and invasive pulmonary infection with pneumonia, sometimes spreading to other parts of the body.