Have you ever experienced that moment of horror when you open a sour cream container in your fridge, only to find a patch of gray fuzz resting contentedly on top? If you’re like most people, your reactions to this discovery were probably unpleasant.
In fact, they were probably along the lines of gross. Most of us don’t appreciate finding mold in our refrigerators and bread bags. But what is this hairy organism? And why is it crucial to the survival of an ecosystem? In this article, we will learn more about mold and how it functions in our world.
What Is Mold?
Mold is a type of fungus that consists of small organisms found almost everywhere. In small amounts, mold spores are usually harmless, but when they land on a damp spot in your home, they can start to grow. When mold is growing on a surface, spores can be released into the air where they can be easily inhaled.
Mold is a living organism that belongs to the kingdom Fungi. Fungi are unique in that although some appear plant-like, they are neither plant nor animal. Mold is heterotrophic, meaning it cannot make its own food like plants do.
Mold must gain nutrients from other organic substances. Unlike animals, however, mold does not really ‘eat’ its food. It must absorb nutrition from other organisms. To do this, mold secretes enzymes that break down the food substance into smaller organic molecules that can then be absorbed.
If you’ve ever grabbed a piece of moldy fruit, you may have felt the soft and mushy area that has essentially been digested.
Mold is composed of thread-like filaments called hyphae. The hyphae then form a conglomerate, which is called mycelium.
You can think of this as a grassy lawn. Much like individual blades of grass make up a lawn, many hyphae make up a mycelium. This explains its ‘hairy’ appearance.
Although mold itself has no mobility, its hyphae can grow quite long. This is the primary mode used by the mold to spread more quickly to neighboring organisms. When you see a strawberry in a container that has been engulfed by mold, you can observe the hyphae reaching to the adjoining fruits.
Types of mold
Nobody knows how many kinds of mold there are, but experts estimate that there may be 300,000Trusted Sources or more different types. Some are more likely than others to appear in the home.
Common indoor molds include:
Alternaria: This occurs in damp places indoors, such as showers or under leaky sinks.
Aspergillus: This often grows indoors, on dust, powdery food items, and building materials, such as drywall.
Cladosporium: This can grow in either cool or warm areas. It tends to appear on fabrics and wood surfaces.
Penicillium: This tends to grow on materials with water damage. It often has a blue or green appearance.
Molds take a variety of forms and textures. They can be white, black, yellow, blue, or green and often look like discoloration or stain to a surface.
They can also have a velvety, fuzzy, or rough appearance, depending on the type of mold and where it is growing.
Mold Reactions: Who’s at Risk?
For people sensitive to mold, inhaling or touching mold spores can cause allergic reactions, including sneezing, runny nose, red eyes, and skin rash. People with serious mold allergies may have more severe reactions, including shortness of breath. In people with asthma who are allergic to mold, breathing in spores can also cause asthma attacks.
In addition to people with allergies and asthma, others who may be more sensitive to the effects of mold include:
- Infants and children
- The elderly
- People whose immune systems are compromised due to HIV infection, cancer, liver disease, or chemotherapy
- People with chronic lung disease
How do molds spread?
Molds spread by producing tiny reproductive cells called spores that waft through the air. Mold spores usually cannot be seen without magnification (ranging in size from 2-10 um) and are naturally present in both indoor and outdoor air. Some molds have spores that are easily disturbed and settle repeatedly with each disturbance. Other molds have sticky spores that will cling to surfaces and are dislodged by brushing against them or by other direct contacts.
Spores may remain able to grow for years after they are produced. In addition, whether or not the spores are alive, the allergens in and on them may remain allergenic for years.
How do molds affect people?
Exposure to damp and moldy environments may cause a variety of health effects or none at all. Some people are sensitive to molds. For these people, exposure to molds can lead to symptoms such as a stuffy nose, wheezing, red or itchy eyes, or skin.
Some people, such as those with allergies to molds or with asthma, may have more intense reactions. Severe reactions may occur among workers exposed to large amounts of molds in occupational settings, such as farmers working around moldy hay. Severe reactions may include fever and shortness of breath.
In 2004 the Institute of Medicine (IOM) found there was sufficient evidence to link indoor exposure to mold with upper respiratory tract symptoms, cough, and wheeze in otherwise healthy people; with asthma symptoms in people with asthma; and with hypersensitivity pneumonitis in individuals susceptible to that immune-mediated condition.
In 2009, the World Health Organization issued additional guidance. Other recent studies have suggested a potential link of early mold exposure to the development of asthma in some children, particularly among children who may be genetically susceptible to asthma development, and that selected interventions that improve housing conditions can reduce morbidity from asthma and respiratory allergies.
A link between other adverse health effects, such as acute idiopathic pulmonary hemorrhage among infants, memory loss, or lethargy, and molds, including the mold Stachybotrys chartarum has not been proven. Further studies are needed to find out what causes acute idiopathic hemorrhage and other adverse health effects.
There is no blood test for mold. Some physicians can do allergy testing for possible allergies to mold, but no clinically proven tests can pinpoint when or where a particular mold exposure took place.
How to Prevent Mold?
Clean up and dry out the building quickly (within 24 to 48 hours). Open doors and windows. Use fans to dry out the building. (Click on the following link for additional information on Reentering Your Flooded Home).
- When in doubt, take it out! Remove all porous items that have been wet for more than 48 hours and that cannot be thoroughly cleaned and dried. These items can remain a source of mold growth and should be removed from the home. Porous, non-cleanable items include carpeting and carpet padding, upholstery, wallpaper, drywall, floor and ceiling tiles, insulation material, some clothing, leather, paper, wood, and food. Removal and cleaning are important because even dead mold may cause allergic reactions in some people.
- To prevent mold growth, clean wet items and surfaces with detergent and water.
- Homeowners may want to temporarily store items outside of the home until insurance claims can be filed. See recommendations by the Federal Emergency Management Agency (FEMA).
- If you wish to disinfect, you can refer to the U.S. Environmental Protection Agency’s document, A Brief Guide to Mold and Moisture in Your Home.