Mold Allergy

According to a recent Quest Diagnostics Study, allergies are on the rise. Especially in regards to two environmental allergens: ragweed and mold. Over the four year period, sensitization to common ragweed grew 15% nationally while mold grew 12%. By comparison, sensitization to the 11 allergens combined (including two house dust mites, cats and dogs, and five foods) increased 5.8%. 
Allergic responses to mold are quite common, the symptoms are hay fever-type: sneezing, runny nose, red eyes and skin rush. 

In US, mold allergies can appear any time. Mold is a precipitation-affected aeroallergen, it may increase in prevalence with a warmer climate. The southern part of United states faces the longest mold allergy season as warmer weather last for a longer time. Mold allergy season here normally begins in the month of June and continues up to the month of August, but it can start earlier and last longer. Mold allergy is especially bad in the coastal area due to the presence of humidity which results in wet summers. In the North, The map shows a snapshot of mold allergies in continental USA. Hawaii is not shown, but its climate is very favorable to mold growth. Midwest and Great Plains, mold allergy fluctuates throughout the year and can appear any time. 

Mold spores usually land on wet surfaces and need water or moisture to grow. There are many types of mold. Cladosporium is one of the most common indoor and outdoor varieties. This fungi appear olive-green, brown and black and are usually found on living and dead plant material. In May, it was observed in Washington, DC, Delaware, Florida, Idaho and many other states. 


Basidiosporus is another cosmopolitan mold. It can cause brown rot, grow and destroy the structural wood in buildings. It can cause type I allergies (hay fever-like, asthma) and type III hypersensitivity pneumonitis. 


Smuts can be found on cereal crops, grasses and other flowering plants. They usually do not grow indoors and cause type I allergy symptoms. In May they were identified in Idaho and other states. 


Ascospores are among the most variable fungi in appearance ranging from transparent and colorless to opaque black. They are very abundant in outdoor air on rainy days, often appearing when the first warm rains occur after winter.
Although generally considered "outdoor" spores, some Ascomycetes producing ascospores grow well indoors on wet materials. In May this type of fungi were identified in Florida and other states.


Alternaria - known as major plant pathogens - stimulates sensitization in the lower airways, grow on skin and mucous membranes, including on the eyeballs, not only within the respiratory tract. Many human health disorders  - related to alternariosis and alternariatoxicosis - can be caused by these fungi, although serious infections are rare.

All fungi can produce some kind of allergens, but the most common ones are less likely to cause symptoms. Cladosporium, Alternaria, Bipolaris, Curvularia, Pithomyces and Stachybotrys contain allergens reacting to the IgE, but Epicoccum, Fusarium, and Spegazzinia apparently do not. Besides, personal exposure to airborne fungi could significantly vary even in exactly the same conditions. Thus personal spore traps may be a better measure of exposure than stationary air sampling equipment.