Every year, thousands of students excitedly migrate from their campus-owned dorms to apartments of their own. They pick out their own couches, buy their own groceries, choose their own WiFi password. It’s an experience familiar to many — along with another common first-apartment feature: mold, mildew, and fungi.

It covers many surfaces. It’s most frequently spotted near bathroom showers, in sinks or along window panes, but it can be found just about anywhere.

Mold is particularly pervasive in Berkeley and the greater Bay Area, but this isn’t necessarily random. We know that the physical conditions, more specifically a moderate temperature and high moisture level, are ideal for harboring the growth of certain fungi, but there’s a bigger question that still remains: Are the same factors that contribute to Berkeley’s massive housing crisis also fueling the city’s mold problem?

Not everyone agrees on the answer.

Fungi growth can be perpetuated by a few different physical conditions, but chief among them is high moisture level. Areas that tend to accumulate water and rarely have the opportunity to dry out are the most likely to be moldy. In a functioning home, that’s usually limited to kitchens, bathrooms and windows. But plumbing or roof leaks, which can often go unnoticed by tenants, are open invitations for mold to grow just about anywhere.

Professor John Taylor, a UC Berkeley faculty member in the Plant and Microbial Biology department who studies fungi, points primarily to structural issues such as leaks as the major culprit.

“You can’t say it enough — it’s a roof problem, a window problem, a plumbing problem, or a subterranean problem, or a condensation problem,” said Taylor.

Angel Sindayen, an active housing supervisor for the City of Berkeley who regularly inspects Berkeley homes for code violations, doesn’t see these same issues at the heart of the mold problem. If tenants were consistent in basic cleaning and maintenance, he argues, this would clear up the unwelcome fungi.

“If they don’t do their housekeeping or they don’t do their sanitary issues — let’s say, for example, younger people who are more active they sweat a lot. They go to the gym, they exercise, they sweat a lot and next you know they put their sweaty clothes in the closet. That’s more moisture right there, and that will propagate the mold — that’s food for the mold,” said Sindayen. “The mold will not grow as long as you take care of it.”

According to Taylor, that’s exactly “what a landlord would say.” Poor housekeeping can definitely contribute to growth, but “a lot of private student housing is poorly maintained,” and it’s far more likely that washing and drying your sweaty gym shorts will only melt the tip of the iceberg.

The city of Berkeley has an incredibly high student population that has in turn lead to a serious housing crisis. Residents face the near-impossible challenge of finding reasonably-priced space among the old, often structurally flawed homes and apartment units.

Perhaps unexpectedly, this may play a critical role in fungi growth.

Alan Cohen’s “A History of Berkeley, From The Ground Up” indicates that the majority of apartment complexes or homes in Berkeley are several decades old. A quick walking tour of Berkeley’s neighborhoods will make it clear that while some have been remodeled, many remain just as they were originally constructed — which means terrible insulation and few fans.

Without insulation, warmth and moisture are trapped inside, an issue only exacerbated by the lack of fans in bathrooms that might alleviate some of the condensation build-up along shower walls. Similar, Sindayen explains, a single-pane window — common in older homes — is a poor insulator against condensation. And even worse, older apartments may lack accessible windows, which limits air circulation that can aid in evaporating water clinging to the walls.

In addition, there are more people in need of housing than there is space for them — so they’re often packed into complexes meant to hold half as many people. An article by The Bold Italic about San Francisco’s mold issues claims that using up every extra bit of space limits the amount of “airing out” options for moisture produced from cooking or showering. With nowhere else to go, water clings and serves as the ideal breeding ground for mold.

Is there any validity to these claims? Yes and no. As Sindayen explains it, the number of people present in a home has nothing to do with mold creation as long as every resident is taking care of their sanitary issues. But Taylor points out that high population density can play a role, if only because there’s simply more water being produced per square foot of space.

“They’re going to cook more; they’re going to take more showers. It’s going to increase the amount of water in the air, and in the building, and have the exterior wall problem. It would exacerbate it,” explained Taylor.

It begs the question of just exactly how mold grows — and more specifically, how it spreads. Much like a spider that hatches thousands of eggs at once and whose babies are immediately carried off into the wind, mold particles launch spores, which are carried through the air and frequently inhaled by humans. It clings to just about any surface, including the human body.

Most of the time, this isn’t a big deal. We inhale mold particles all of the time, indoors and outdoors. But as mold continues to accumulate in a home, so do the quantity of spores, which can then build up in the lungs.

According to Taylor, the health consequences related to fungi issues aren’t yet well-understood. Links between fungi and asthma instances have yet to be thoroughly established, mostly due to a lack of funding for adequate research.

“We do know some fungi cause disease. We know that they’re not that common indoors. We know that some fungi make toxins. Those fungi can be common indoors,” notes Taylor. “But the estimates of how much you would have to acquire to get a toxin indicated would be a lot.”

Fortunately, should you be living in a mold-infested home, it doesn’t have to stay that way.

According to the City of Berkeley’s website, mold is one of many housing conditions that can violate the “implied warranty of habitability,” meaning that landlords are under legal obligation to address it properly. This is particularly true when mold issues can be traced back to leaking pipes or roofs. There’s plenty who get away with doing nothing at all, either by slipping a clause into their housing contracts or, more commonly, by luck. Most tenants simply don’t know that they have any kind of legal backing to demand protection from the health hazards caused by mold.

Sindayen speaks more directly to Berkeley’s specific mold-related policies. Berkeley falls under the jurisdiction of California Senate Bill 655. Under this policy, active housing supervisors like Sindayen are only able to take legal action against mold that is majorly visible and located on surfaces other than those “that can accumulate moisture as part of their properly functioning or intended use.”

“Windows, where the moisture is there because of the condensation and all that, we can’t write that,” said Sindayen. “Definitely not the bathroom or the bathroom area. Once you close the door and somebody takes a shower, moisture is all over the place, and therefore we can’t write up that mold.”

Evidently, this law has a fairly limited scope that hardly encompasses the majority of mold issues in an apartment — ones that are invisible, such as located behind a wall, and those occurring in kitchens, bathrooms or near windows.

“That is by definition missing the problem,” said Taylor upon hearing of the city’s policy.

So, why isn’t the City of Berkeley looking to tackle the root of its residents’ mold troubles?

For one, it’s expensive — especially if the report proves to be a false alarm. If you tear out an entire wall, a process Sindayen describes as “very invasive,” and don’t find any mold, you can lose a considerable amount of money repairing it. But even if a resident pays for an outside entity to test for invisible mold, the City of Berkeley cannot use the test results when considering whether they need to take legal action against a landlord.

There are still a few options for mold prevention and elimination that don’t involve large investment. Sindayen recommends making air circulation a top priority, while Taylor emphasizes a high-quality fan and a light switch that controls both the bathroom light as well as the fan, so that tenants are more likely to make a habit of using it.

But if mold in your home is related to an infrastructural issue that allows water into the home, such as leaks, no amount of cleaning or regular maintenance will permanently keep the fungi at bay. Many companies make cleaning products designed to kill mold, but Taylor says that the majority are volatile — meaning they’ll quickly vaporize — and the fungi will return.

“Fungal spores are everywhere. There’s nothing you can do about that. Buildings are made out of products that fungi eat. There’s nothing you can do about that,” said Taylor. “The only thing you can do is keep the water out.”