This fall, officials delayed the opening of Cedarbrook Middle School in Cheltenham because of mold, a chronic condition dating at least to 2003.
Now, parents want the building torn down. Another option: a $26.3 million renovation.
Even if mold is only in the basement, students can be exposed. "We like to think of buildings as compartmentalized," said Richard J. Shaughnessy, an indoor-air expert at the University of Tulsa. "But it's not true. Spores quickly disseminate into the air."
Although the public frenzy - some would say hysteria - over "toxic mold" and "black mold" a decade ago has waned, mold is far from benign.
It is one of the most common allergens in the Mid-Atlantic, along with pollen, cat dander, and dust mites. Some people have a genetic predisposition to mold allergies. Also, allergies can develop, and worsen, with repeated exposure.
On the low end of the scale, someone who is allergic might get a runny nose, a sore throat, or a headache. But in an asthmatic, mold sensitivity could trigger an attack. It could exacerbate other pulmonary conditions, and those with compromised immune systems are at risk for mold infections.
In recent years, studies have shown that infants who live in moldy homes are three times more likely to develop asthma by age 7.
In schools, where one in every 10 children has asthma, mold can lead to increased absenteeism. The U.S. Environmental Protection Agency says mold causes 13 million missed school days a year.
If your child is sensitive to it, and his or her school has a mold issue, "one plus one equals two," said Reynold A. Panettieri Jr., director of the asthma program at the University of Pennsylvania.
"That's going to create an environment where the kids aren't going to be at their best, and their learning is going to suffer," said Drexel University School of Public Health's Hernando Rafael Perez, who a decade ago chaired a state committee on mold.
Even so, public health officials have devised no exposure limits. "It's impossible to come up with standards," said Perez. There are too many species of mold, and people's sensitivity varies.
We've come a long way from the case of Texas homeowner Melinda Ballard, who won a multimillion-dollar judgment against her insurance company. She blamed the company's mishandling of a water-damage claim for an explosion of mold that made her 12,000-square-foot mansion uninhabitable.
Many other lucrative mold cases, for litigants and lawyers alike, followed, prompting one lawyer to ask in a 2003 paper, "Mold is gold, but will it be the next asbestos?"
Not quite. Many insurers have altered their policies, refusing to cover mold claims, or covering them only in the case of storms or other unexpected events, said Glenn Fellman, executive director of the Indoor Air Quality Association, a nonprofit industry group.
If the mold was a result of a building owner's ignoring a leaking roof, cleanup wouldn't be paid for.
In any building, although mold is the problem, water is the culprit. It seeps in, often unseen and unknown, but making the spores already there grow out of control.
Or it flows into the building in a big gusher of floodwater. If you don't dry everything out in 48 to 72 hours, "you're going to have a problem. After that point," said Tulsa's Shaughnessy, "it's an uphill battle. The mold has already set in."
That happened to many Jersey Shore homes after Hurricane Sandy, prompting the state health department to launch a campaign urging people with sodden walls or rugs: "When in doubt, throw it out."
Mold is so worrisome that it's one of the first things energy auditors and other home inspectors look for. It's a sign of a building's air flow and its overall health.
All too often, they find it, said Jeffrey Lane, president of Star Energy Solutions, a Fort Washington energy-assessment company. Older homes have notoriously soggy nether regions. Even new homes are not immune; some were built in floodplains.
Indeed, today's tighter homes - their cracks and leaks sealed for better energy efficiency - may be part of the problem.
"When water comes in," said Lane, "it doesn't evaporate as quickly."
Cristina Schulingkamp, an air-quality expert in the EPA's Philadelphia office, said keeping humidity below 60 percent was key.
A dehumidifier can help - as long as you don't forget to empty the reservoir.
Some homeowners can treat small areas with bleach, but generally, dousing a large area of porous material with the stuff is akin to "putting a Band-Aid on heart surgery," said Frank Vodraska, a board member of the New Jersey Association of Licensed Professional Home Inspectors.
When his own Shore-area home in Toms River took in 15 inches of floodwater during Sandy, he paid a professional $15,000 to gut and treat it.
Officials in Pennsylvania and New Jersey also do not regulate mold-remediation contractors stringently enough, experts say. So the area is ripe for unscrupulous contractors. "Do your homework," officials advise. Check references.