Allergic symptoms from fungus spores are most common from July to late summer. But with fungi growing in so many places, allergic reactions can occur year round. Although there are many types of molds, only a few dozen cause allergic reactions. Some common spores can be identified when viewed under a microscope. Some form recognizable growth or colonies.
Many molds grow on rotting logs and fallen leaves, in compost piles and on grasses and grains.
Unlike pollens, molds do not die with the first killing frost. Most outdoor molds become dormant during the winter. In the spring they grow on plants killed by the cold. Indoors, fungi grow in damp areas, particularly in the bathroom, kitchen or basement. It is common for people to get mold allergy if they or other family members are allergic to substances such as pollen or animal dander.