Mold spores stick to surfaces and, if conditions are sufficiently warm, moist and undisturbed, extrude tendrils which turn almost any surface into food — these form the fuzzy structures creeping out of the corner of the shower. Ceiling tiles, wood, paint, rubber, carpet, soil, dust; it’s all food to the mold, just add water.
How do you know when mold has arrived? That’s easy: you’ll smell the — how to put this? — the airborne end products of its digestive processes. That’s right, mold farts. “Every time you smell that musty odor, that mold smell, that’s what you’re breathing in,” said David Denning, principal investigator at the Manchester Fungal Infection Group and a professor at the University of Manchester, in England.
What effect does all this fungal activity have on health? Broadly speaking, we know there are two main ways mold can engage the immune system, and they depend on whether your system is underpowered or overactive.
If you’re going through chemotherapy or have had a recent organ transplant, your evolved immune system firepower may have been depleted. The fungus can colonize the lungs and begin treating you as it would ceiling tiles or wood paneling, said Matthew Fisher, an epidemiologist at Imperial College London. But this is more often a problem in hospitals, home infections are exceedingly rare.
You’re much more likely to have an overactive immune system that freaks out when confronted with the irritating proteins present in spores and mold filaments. Filaments land on the mucous membranes of our eyes, nose and mouth, causing eye-watering, itching, sneezing, coughing or asthma attacks.
For most, these stop when you leave the moldy room. But experts estimate that between 5 and 10 percent of the population are more sensitive than others. “In an environment that’s colonized by fungus, you’re also going to be inhaling those spores every day and you may potentially become sensitized to them,” said Elaine Bignell, Ph.D., who co-directs the Manchester Fungal Infection Group.
Sensitization means your body recognizes a substance and mounts an aggressive response to even the faintest traces of it. If you already have asthma, you might get a particularly severe “fungal asthma.”