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Where Does Black Mold Grow?

by Amanda Demsky
black mold symptoms

A concern one may have when encountering mold in their environment or food is that most molds appear black in color to the naked eye. This leaves one to wonder if they’ve come in contact with one of the most toxic molds and if they should be worried about serious health concerns. Another dilemma this possibility raises is the fact that, if it is black mold, clean up may have to be accomplished by a professional mold remediation team instead of a DIY project—for added safety precautions. Therefore, it is perfectly reasonable to ask, “Where does black mold grow?”


What is Black Mold?

Stachybotrys chartarum (sometimes Stachybotrys atra)—commonly known otherwise as “black mold”—is a greenish-black mold usually accompanied by a distinctive odor.

The scent of black mold is described as “musty,” “earthy,” and often likened to sweaty, dirty gym socks. It generally has a more intense smell than other molds, which, in turn, gives it the capacity to make individuals gag, throw up, and/or develop an immediate headache because of it.

Is Black Mold Dangerous?

Black mold is one of the most toxic molds that can be found in homes because it produces toxic secondary metabolites called mycotoxins, which are capable of causing severe, chronic, and life-threatening health problems in both mankind and animalkind.

Symptoms of Black Mold

Black mold symptoms in humans depend entirely on the amount of exposure, as well as the health of the individual(s) being affected.

First-time/temporary exposure to black mold symptoms:

• a long, painful headache
• a tightening in the chest
• burning sensations in airways
• cough
• difficulty breathing
• fever
• fits of sneezing
• nose bleeds
• skin irritation
• stuffy nose
• watery or itchy eyes
• wheezing

Long-term exposure to black mold symptoms:

• asthma
• autoimmune disease
• cold and flu
• emphysema-like disease
• fatigue
• memory loss
• migraine-like headaches
• muscle aches
• nosebleeds
• pulmonary hemorrhage
• rashes and dermatitis
• sore throat
• vomiting and diarrhea

High-concentration levels and long-term exposure to black mold symptoms:

• cancers (still under debate, but the possible connection between black mold and liver cancer is currently under investigation)
• death
• fungal arthritis
• myocarditis
• organ damage/failure
• sepsis

Note: The idea of black mold having the capacity to set in motion cancer in various parts of the body is not that far-fetched. Even if the mycotoxins of black mold merely serve to indirectly instigate a susceptibility to cancer by lowering the body’s immune defense, black mold would still be considered an early onset culprit to cancer. In fact, Aspergillus molds that produce aflatoxins are well-known for causing liver and hematologic cancers. More and more research is uncovering the grand scope of toxic molds’ effects on the body and the sad truth is that some incidents of cancer are likely the result of high-concentration levels and long-term exposure to toxic molds.

What Causes Black Mold?

Like all mold, black mold growth begins as an airborne mold spore. Mold spores are microscopic reproductive units (think: “seeds”) that established and fully-developed colonies of mold releases into the air for purposes of colonizing other areas. Not only do spores cause the fungus to spread, but they can also trigger a wide range of allergic reactions when inhaled or after making contact with mucous membranes, such as the eyes.

Mold spores travel by air currents and settle on the walls, floors, ceilings, furniture, and other surfaces of a home. When the proper conditions are present, the spore is activated and mold growth begins. Because mold spores teem in the millions or more when a fully-developed colony is nearby, it is nearly impossible to prevent them access from one room to the next. And, because black mold spores are exceptionally hardy, even the most extreme circumstances will have a hard time extinguishing their proclivity toward persistent survival.

That said, all molds require certain conditions for growth. While the mold spore may find an undisturbed surface for possible growth, it’s still in need of a food source, plenty of moisture, and adequate oxygen levels. Another important growth factor is a setting with little to no light.

The food source for mold is organic decaying material—preferably substances with high amounts of cellulose (processed cellulose in particular). Paper materials are a favorite, but mold can also grow incredibly well on wood, cardboard, particleboard, straw, and drywall. Even lint and dust can stand as sufficient food sources for black mold due to their cellulose content.

As long as there is a food source, molds can grow on any surface. This means furniture, clothing, books, carpet, tile, ceilings, walls, and so much more can provide a platform for a colony of mold.

While MoldBlogger readers are encouraged to air out rooms infected with mold, mold still requires some oxygen in order to grow. Depriving a mold colony of oxygen will not kill it, though, because it is capable of lying dormant until oxygen levels improve.

The last and most important catalyst of mold growth is moisture. Often, this means water damage to organic materials the mold spore has settled on, such as leaky pipes, spills, flooding, etc. Other times, this simply means high humidity levels within the space, which is why humid climates experience more cases of mold than dry climates, despite the same availability of food sources.

But, what about black mold? Does it grow in more specific environments than other molds?

Where Does Black Mold Grow?

Unfortunately—and, as you may have already guessed—black mold can grow just about anywhere. It is one of the hardiest molds in existence, which means it can sustain itself in some of the harshest environments. It can also lie dormant for a very long time between droughts and famines. Just because an environment’s moisture level is reduced and there is a long period wherein the mold lacks access to material on which it can feed, doesn’t mean the mold is dead—it simply means it is not capable of further growth. Once conditions become more hospitable, black mold can suddenly flourish again and spread out in no time.

So, while its needs don’t differ from that of other molds, there are a few places that black mold is more likely to grow:

• basements
• bathrooms
• crawl spaces
• kitchens
• laundry rooms

These spaces are generally high in moisture and organic decaying food sources (wood, dust, etc.), and they commonly lack proper and consistent maintenance to stave off water damage and the build-up of food sources.

How to Prevent Black Mold Growth


Prevention will always involve regular cleaning and maintenance of these spaces, as well as consistent evaluations of the status and durability of various parts of the home’s structure, such as the roof and plumbing. Because encountering mold spores is unavoidable, the best any home owner or renter can do is prevent the spore’s chances of establishing permanent residence. That means the goal of prevention will be to reduce the perfect conditions for mold growth.

Reduce moisture: Repair that leaky roof, fix that faulty plumbing—don’t give black mold a chance. The EPA suggests maintaining or reducing home humidity levels to 30-60% (ideally 30-50%) to prevent mold growth. Also, it’s important to note that condensation on or around windows can be an indication that the home’s moisture levels are too high. Two ways a homeowner or renter can decrease the humidity in their home is by increasing ventilation and buying a dehumidifier.

Keep the home cool: Mold grows optimally in warmer conditions—absolutely flourishing between 77 and 86 °F (25 to 30 °C). This is why it is optimal to open the windows when it’s cooler outside and run the A/C when it’s hotter outside.

Avoid filth and decaying materials: Keep all spaces of the home clear of the build-up of debris—dust, lint, crumbs, etc. Keep surfaces, pieces of furniture, or items from acquiring water damage so that they don’t present themselves as food sources to mold spores.


Where does black mold grow? Anywhere you let it. So, don’t.

For more information regarding mold, mold prevention, and mold solutions, please check out the rest of MoldBlogger.com.

Have you encountered black mold growth in your home? Where was the weirdest and most unexpected mold growth spot you’ve ever encountered? We’d love to read your stories in the comments below!

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