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What is Black Mold?

Posted in: Health Risks of Mold, Science of Mold by Bay Area Mold Services on December 12, 2011 | No Comments

What is Mold?

Mold, or mould in other parts of the world, is a common kind of fungus that grows naturally anywhere there is moisture and some kind of organic material on which the mold can feed. Mold decomposes dead biological matter, like fallen leaves. Mold spreads from one place to another by releasing tiny seeds, called spores, which float in the air and land on other places that might serve as a new home. If mold is in your basement, bathroom or any other part of your house, it can cause a visual blight, a musty odor, and put contaminants in the air. People who inhale mold can suffer from mold allergies (sore throat, itchy eyes, coughing, wheezing, and sneezing) and people with asthma can experience sudden asthma attacks.

What is Black Mold?

Black mold, or toxic mold, refers to Stachybotrys chartarum or Stachybotrys atra. The name “black mold” can be confusing because many different kinds of mold are black in color and sometimes Stachybotrys looks green, grey, or white. Also, according to the Centers for Disease Control, Stachybotrys mold is technically “toxigenic.” The fact remains, however, that Stachybotrys (black mold) is very harmful to a person’s health. If you are exposed to black mold, you could suffer from a variety of upper respiratory tract problems, even pulmonary hemorrhaging (bleeding of the lungs). When you inhale the black mold spores floating in the air, they can infect the lungs and make you gravely ill. In San Francisco black mold removal is of the utmost importance. If you allow black mold to grow in your home, you will inhale the mycotoxin-containing spores of black mold, and you may fall ill to “black mold sickness” or “sick building syndrome.”

Are All Black Mold Toxic?

Just a few years ago, many Americans, including the well-educated in the San Francisco Bay Area, had no idea what black mold was. The term “black mold” didn’t enter the national consciousness until the late 1990s and early 2000s, when reports began surfacing about the health problems children developed as a result of black mold exposure. Since that time, “black mold” and “toxic mold” have been discussed at length in the media. Most people know that black mold can be bad for your health. Yet many people are uninformed about the specifics pertaining to this household hazard. Can you tell what black mold or toxic mold is just by looking at it? Are all mold and mildew varieties toxic? What is involved in the safe removal of mold?  As with any potential danger, the first step to protecting yourself is understanding exactly what you’re dealing with.

When it comes to mold varieties, there’s good news and bad news. The good news is that the vast majority of mold types are perfectly harmless. In fact, mold has probably been much more helpful than harmful to life on this planet. As a simple multicellular fungi, mold has existed long before other life forms on this planet, including humans. Mold’s main purpose is biodegradation, the breaking down of organic material. Mold grows on tree branches that fall on the ground, helping to decompose them and eventually return their minerals to the soil. Certain kinds of molds, called yeasts, help us make cheese, bread, and beer. During the regular course of the day, while walking through a park, opening your refrigerator, or working in an office building, you encounter numerous kinds of molds, and none of them cause any harmful health effects. Without realizing it, you’ve probably eaten many slices of bread that contained small, unnoticeable growths of mold, and look—you’re still here!

But before you start singing the praises of mold and all of its contributions to your health and comfort, you should hear the bad news. The bad news about mold in San Francisco is that some varieties are, in fact, dangerous to your health. The worst part is that the most dangerous molds can grow inside your home. Estimates about the number of mold species on Earth range from about 400,000 to over 3,000,000. The vast majority of mold varieties have yet to be named or catalogued. Only about 1,000 kinds of molds live inside homes, and of those, only about a dozen are considered dangerous.

So-called “black mold” is actually one of two species of mold, either Stachybotrys chartarum (also known as Stachybotrys atra) or Stachybotrys chlorohalonata. Although it is commonly dark in color, Stachybotrys is at first white, and can sometimes look greenish or brown as it grows. This kind of mold is particularly bad for humans because of the kind of spores it produces. Spores are tiny, almost invisible particles of mold that detach from the mold site, float through the air, and land on other potential host sites. Stachybotrys is considered a toxigenic mold, or “toxic mold,” because it releases spores that contain a mycotoxin metabolite. While most molds do release spores into the air, only the rare kinds of molds that release mycotoxins are dangerous for people to inhale. The list of indoor “toxic molds” that produce mycotixins includes: Alternaria, Aspergillus (flavus, Fumigates, niger, ochraceus, cf. ustus, versicolor), Chaetomium globosum, Memnoniella echinata, Penicillium (brevicompactum, chrysogenum, expansum,  polonicum), and Trichoderma.

Toxic black mold growing on wall in San Francsico building

When mycotixin spores enter a person’s lungs, they can cause a multitude of health problems. The most common symptoms of black mold exposure include flu and allergy-like symptoms: irritated eyes, wheezing, coughing, sneezing, headaches, asthma attacks, and drowsiness. People with respiratory problems or immune weaknesses (such as people with bad seasonal allergies or asthma) are particularly susceptible and can experience the most severe reactions. Infants and the elderly can develop symptoms easily, as well. Repeated exposure to high concentrations of mycotoxin mold spores has been linked to long-term respiratory problems, which may become fatal to humans or animals. Black mold and toxic mold spores are dangerous for anyone to breathe.

Many San Franciscans have a vague knowledge of what constitutes a dangerous variety of mold, much like their understanding of poisonous plants and spiders. Just because a shrub has three leaves, it’s not necessarily poison oak. Just because a spider is black, it isn’t necessarily a black widow. The same kind of reasoning is true for black mold. Many thousands of kinds of molds can be black in color, but that doesn’t necessarily mean that the fungus you’re looking at is toxic black mold. As mentioned earlier, Stachybotrys can be a number of different colors, so the fact that a mold is greenish cannot eliminate the possibility that it is in fact Stachybotrys.

One distinguishing feature of Stachybotrys is that it grows on cellulose-rich surfaces. This would include wood products—such as drywall and floor paneling—but would all but exclude surfaces made of tile and plastic. For instance, many people have a black mold growing on their shower curtain. Should you be worried? Most likely the mold in your shower is not the toxic mold people ought to be concerned about, but rather one of the many garden-variety molds that are simply a blight to look at. If mold is the result of a larger moisture control issue in your home, however, it may be cause for concern. Since the varieties of mold that are bad for you can look like the kinds of molds that are mostly harmless, it’s impossible to detect black mold with a mere visual inspection. So how can you know for sure what kind of mold is in your home? How can you tell a toxic mold from a harmless mold?

The only way to know for certain whether black mold is present in your home is to get professional surface and air testing done, with the results analyzed by a third party lab. The U.S. Environmental Protection Agency’s pamphlet A Brief Guide to Mold, Moisture and Your Home states that “sampling for mold should be conducted by professionals who have specific experience in designing mold sampling protocols, sampling methods, and interpreting results. Sample analysis should follow analytical methods recommended by the American Industrial Hygiene Association (AIHA), the American Conference of Governmental Industrial Hygienists (ACGIH), or other professional organizations.” The EPA advises that homeowners hire mold testing professionals if they feel as though the mold problem is a serious concern or if they suspect that it is affecting their health. Additionally, some mold infestations may be hidden, perhaps growing behind a wall or in a crawlspace. According to the EPA, “if you believe that you may have a hidden mold problem, consider hiring an experienced professional.”

If you have any suspicion that the mold you’re dealing with is harmful, you should not attempt the removal of mold yourself. Disturbing areas of mold growth by scrubbing or removing building materials around the mold can cause the area to release even more spores into the air. Certified professionals can be hired to conduct a safe mold removal procedure, called mold remediation. The process of mold remediation includes the use of personal safety equipment and the installation of containment chambers, which will keep mold spores from traveling to other areas of the building. Any removal of mold that goes beyond the surface should be conducted by a professional.

Of course, it’s always best to keep mold—black mold especially—from growing in your home in the first place. The most important thing to remember is that mold requires only three things to grow—moisture, organic material, and time. Given a little dust, some humidity, and 24 hours, mold can begin growing on practically any surface. Since you can’t stop time, and your home is made of organic material, the best way to stop mold growth is by limiting the amount of moisture in your residence.  This can be as simple as common sense maintenance: Keep the most humid parts of your home—such as your kitchen, bathroom and laundry room—well ventilated. Don’t let leaks go unrepaired. Quickly dry any areas where flooding has occurred. Other times it may become necessary to have a professional moisture reading done with an infrared moisture reader.

Even though mold is common, and most molds are generally not toxigenic, there are times when you should be concerned about the presence of mold. Stachybotrys, otherwise known as toxic mold or black mold, should be taken seriously and dealt with by trained, professional San Francisco mold technicians.