What is Mold?
Mold, also known as fungus, is a family of organisms that are found throughout nature. Unlike plants, mold need food and water sources in order to thrive. This food source is often in the form of a carbohydrate material, such as wood or cellulose.
Mold grows in units called mycelium and reproduce through the formation of spores. Spores frequently become airborne, and like pollen, can cause allergic disease.
What Types of Diseases Can Mold Cause?
Mold has well-known associations with human disease. People can develop fungal infections of various types, especially those with poorly functioning immune systems. Fungi are also known to produce toxins, which have been blamed for causing various diseases.
Molds can also cause severe immune reactions as a result of colonizing (living in, but not causing an actual infection) the lungs (hypersensitivity pneumonitis) and the sinuses. Molds are also well known to cause various allergic diseases, such as allergic rhinitis and allergic asthma.
Which Molds are Known to Cause Allergies?
There are thousands of types of mold, however, only a few of these are currently available for allergy testing. The following are the most likely causes of allergic disease based on the types of mold spores collected in the air:
•Alternaria. A common outdoor mold; allergy to this mold can be associated with severe asthma.
•Cladosporium. The most common airborne outdoor mold.
•Aspergillus. A common indoor and outdoor mold; also associated with allergic bronchopulmonary aspergillosis.
•Penicillium. A common indoor mold; allergy to which is not associated with antibiotic allergy.
•Helminthosporum. More commonly found in warmer climates.
•Epicoccum. Found in grassland and agricultural areas.
•Fusarium. Commonly found on rotting plants.
•Aureobasidium. Common outdoor mold, commonly found on paper, lumber, and painted surfaces.
•Phoma. An outdoor mold, especially common during wet periods.
•Smuts. Found in areas of agriculture.
•Rhizopus and Mucor. Commonly found on decaying leaves and damp indoor areas. Airborne forms of these molds are less common.
•Yeasts. Commonly found in the air during wet periods in agricultural areas. Allergic disease to Candida albicans is controversial, despite some people having positive allergy testing to this type of mold.
What Times of the Year Does Mold Allergy Occur?
In colder climates, molds can be found in the outdoor air starting in the late winter, and peaking in the late summer to early fall months (July to October). In warmer climates, mold spores may be found throughout the year, with the highest levels found in the late summer to early fall months.
While indoor molds can occur year round and are dependent on moisture levels in the home, indoor mold levels are higher when outdoor mold levels are higher. Therefore, a common source of indoor mold is from the outside environment, although can also be from indoor mold contamination.
What Measures Can Be Used to Decrease Indoor Mold Levels?
•Prevent outdoor molds from entering the home by keeping doors and windows closed and using air conditioning equipped with allergen-grade air filters
•Control indoor moisture with the use of dehumidifiers
•Fix water leaks in bathrooms, kitchens and basements
•Ensure adequate ventilation of moist areas
•Clean (or replace) contaminated surfaces with diluted a chlorine bleach solution (one part household bleach in nine parts water), while using proper protective gear (mask and goggles)
•Utilize HEPA filters on vacuums or as a stand-alone air filter
•Limit indoor houseplants, and ensure those that are present are free of mold on leaves and in potting soil
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Sources:
1.Bush RK, Portnoy JM. The Role And Abatement of Fungal Allergens In Allergic Disease. J Allergy Clin Immunol. 2001; 107:S430-40.
2.Eggleston PA, Bush RK. Environmental Allergen Avoidance: An Overview. J Allergy Clin Immunol. 2001; 107:S403-5.
Daniel More, MD, FACP is a board-certified allergist and clinical immunologist with a background in internal medicine. He is About.com's allergies guide.
DISCLAIMER: The information contained in this article is for educational purposes only, and should not be used as a substitute for personal care by a licensed physician. Please see your physician for diagnosis and treatment of any concerning symptoms or medical condition.
