Molds are parasitic, microscopic fungi without stems, roots or leaves. Because the spores are so small, they are also easily dispersed by the wind, and can invade the upper respiratory tract in the same way pollens do. Mold present outdoors and, equally significant, indoors, is a major contributor to allergy symptoms in patients. People allergic to molds can have symptoms from spring to late fall, and usually peak from July to late summer. Like pollens, mold spores are important allergens only if they are easily carried by wind or air currents.
Molds are prevalent in the Midwest, where they grow on grains such as corn, wheat, oat, and barley.
In the humid areas of the United States, however, molds thrive all year and can cause year-round allergic problems. Mold spores significantly decrease at high altitudes and in dry regions of the country. Indoor mold can cause perennial allergic rhinitis symptoms for allergy sufferers even in the coldest of climates. Damp basements, closets, and bathrooms are prime spots for indoor mold activity. For more information about allergies, click here.