It’s in the tastiest cheeses and used to make soy sauce. It’s even the source of our most effective antibiotics. It breaks down decaying matter and our ecosystem wouldn’t be the same without it. It’s mold, and it’s everywhere.
But when most people think of mold, they’re not thinking of the tasty green ribbon in a wheel of Gorgonzola. They’re thinking about the creeping growths that pop up around windowsills, on bathroom ceilings, and in dank basements. Earlier this year, I moved out of a cold, damp, ground-level apartment, and when we lifted up the couch, we discovered that the legs and underside were totally covered with mold, as were the wall and floor. No wonder I’d been sneezing and coughing for months.
Mold exists to break down organic matter, and there’s thousands of species specializing in different niches. Mold is found both indoors and out, in almost every area of the world. Mold spores can be found in dirt, in household dust, and in the air we breathe. The spores exist everywhere, but they need moisture in order to grow. When a mold spore, transported by the air, lands in a hot, dry climate or house, it remains dormant. However, if it lands on a cool patch of dampness, it can begin to thrive and reproduce.
Good Mold, Bad Mold
Most molds themselves aren’t dangerous, but as molds grow and digest their food, they produce metabolites, just like humans exhale carbon dioxide. Some of those byproducts are good, like the antibiotic produced by Penicillium chrysogenum or the delicious Penicillium roqueforti, which is in Roquefort cheese. A few molds, though, give off allergens, irritants, and even harmful compounds called mycotoxins, and these are what cause problems for humans. Scientists think that the mycotoxins are intended to interfere with the growth of other mold species, and humans are caught in the crossfire.
Indoor molds tend to congregate in the dampest parts of the house, like showers, kitchens, basements, or other areas with inadequate ventilation. They can also accumulate underneath wallpaper, in ductwork, near damp areas around pipes or cabinets, or behind drywall. Mold spores sometimes find their way onto food, too. According to the CDC, the most common indoor molds are species from the Cladosporium, Alternaria, Penicillium, and Aspergillus genera.
Exposure to mold can cause typical allergy symptoms, such as itchy eyes, sneezing, and nasal congestion, both for people with allergies and those without. It can also cause flu-like symptoms including lethargy, headaches, and digestive troubles. Mold also has the potential to exacerbate asthma, especially in people who already have pulmonary diseases. People who are severely allergic to mold or have compromised immune systems can even develop severe side effects like infections in the lungs.
Although it’s well-documented that mold can trigger allergies, the case for the so-called “toxic mold syndrome” is far from conclusive. Despite some people’s claims that exposure to mold causes pulmonary hemorrhages, chronic fatigue syndrome, cancer, hair loss, or other serious side effects, there’s little evidence to prove their veracity, and scientists and doctors consider “toxic mold syndrome” to be a specious and controversial diagnosis. Many people are mildly or moderately affected by mold, but it’s doubtful that mold has the potential to cause the serious diseases that some people claim it does.
One strain of mold that gets a particularly bad rap is Stachybotrys chartarum, commonly cited as the dreaded “toxic” or “black” mold, but the CDC has found no definitive link between this type of mold and severe health problems. According to the CDC and EPA, it’s no more serious than any other type of mold. Regardless of the species, the only people at real risk for serious or life-threatening mold-related illnesses are those who are already sick, and therefore more susceptible to infection.
Keep Your House Healthy
The EPA recommends eradicating any indoor mold colony, regardless of the kind or color. Unfortunately, mold can be incredibly frustrating to get rid of, and besides simply cleaning up the existing mold, the most important step is fixing the existing moisture problem that allowed the mold to grow. Cleaning mold without fixing the underlying cause will only enable the mold to return.
Mold is easy to clean from hard surfaces using a mild bleach solution, but when it infests porous surfaces like walls, carpets, upholstery, or insulation, total removal and replacement is usually required. Houses or buildings with extreme mold problems may have to replace all the drywall or the HVAC unit to be sure that the entire mold is gone. For large areas of mold or total house infestations, professional help is probably necessary.
To reduce moisture that could foster mold growth, the EPA recommends keeping the humidity level between 30 and 50 percent using an air conditioner or a dehumidifier. Less ambient humidity means that the mold spores won’t have the chance to grow. Water spills, condensation, or leaks should be cleaned up and fixed immediately, and you should run exhaust fans or open a window whenever using the shower or cooking in the kitchen. Even if you don’t see mold around your house, you should be on the look out if you live in an area with high humidity, experience regular flooding, have cracked or peeling paint, live in a home with poor ventilation, or have a damp basement or crawl space. If you don’t see any mold but smell the characteristic musty odor, there’s a good chance that hidden mold is lurking behind the walls or in unseen areas, and you may want to consider hiring a professional for abatement. If you suspect that your workplace or school has a problem with mold growth, the EPA’s booklet on mold remediation  can help.
While there’s no proof that mold is the “silent killer” it’s sometimes portrayed as in the media, it’s still not an ideal houseguest. Whether it’s under your carpet, in your grouting, or on your bread, it’s best to eradicate it quickly and thoroughly, keeping your home high and dry.