As summer approaches, homeowner complaints about corroded copper air conditioner coils and the smell of rotten eggs in their homes—two symptoms of tainted Chinese drywall—could soar with the mercury, some in the industry predict.

“When the summer gets hotter and the air gets moister, it wouldn’t surprise me at all if we see a lot more reports from homeowners [about] their drywall,” says Miami attorney David Lichter, whose firm Higer Lichter & Givner has filed a class-action lawsuit on behalf of Florida homeowners against a Florida developer and drywall supplier, and another against the German parent of a Chinese drywall manufacturer.

The complaints began in hot, humid south Florida, where hundreds of homeowners who bought houses between 2004 and 2007 have reported smelling sulfur and dealing with corroded copper air-conditioning parts and plumbing pipes, malfunctioning TVs and appliances, and blackened mirrors, jewelry, and tea kettles. In addition, they say they suffer from headaches, difficulty breathing, nosebleeds, sore throats, and other health problems.

The culprit, say the growing number of lawsuits against builders, drywall subs, suppliers, and manufacturers, is a giant batch of drywall imported from China during a shortage of U.S.-made product caused by a nationwide building boom and a flurry of post-Katrina construction. 

The Florida Department of Health found traces of strontium sulfide, which can emit corrosive gases when it contacts moist air and a foul smell when it gets hot, in drywall samples from a dozen Florida homes.

By early this year, homeowners in at least 14 states, mostly in the South and Southwest, reported similar trouble, and the U.S. Consumer Product Safety Commission and a handful of state and federal agencies began investigating. The Florida Attorney General’s office is considering whether to charge two companies at the center of the controversy—Knauf Plasterboard Tianjin and L&W Supply Corp.—with committing deceptive sales or marketing practices.

Some builders, like Lennar Homes, which says its subs used Chinese drywall without the firm’s knowledge, are ripping the drywall out of Florida homes and paying for the homeowners to stay elsewhere while it does the repairs. Homeowners say some other builders have refused to step up or simply have replaced the corroded air conditioner coils while leaving the offending drywall in place—triggering a barrage of lawsuits.

“If the developer starts to remediate, that will go a long way to providing the relief [the owners] seek,” says Lichter, whose lawsuit does not involve Lennar. “Our goal is to get people back into their homes.”

Lennar took action after dealing with an unusually high number of callbacks on air conditioners, whose coils were black and corroded. It hired Environ International to conduct tests in the homes, and found three sulfide gases—carbon disulfide, carbonyl sulfide, and dimethyl sulfide—in the air, according to a statement by the builder. It found another, hydrogen sulfide, in the Chinese-made drywall itself. Gypsum drywall does not normally emit sulfur gases or smells.

The Lennar tests and a report from Knauf both say the gases given off by the drywall pose no health threat.

But toxicologist Dr. David Krause of the Florida Department of Health says he isn’t so sure. “We have not yet identified any concerns that chemicals in the drywall are at a level that would pose a significant health risk,” he said after the department’s initial testing. “That’s not to say we’re saying it’s safe.”

Krause called for more studies and said the next round of tests should determine whether the gases are contaminating indoor air—a process that he said could take some time. “This won’t happen overnight,” Krause said. “Gypsum drywall is not a simple product. It’s like unbaking a cake.”

Also, the Florida Department of Environmental Protection is testing the drywall to see if it is safe to dispose of it in landfills.

In the meantime, Lennar has filed its own lawsuit—against 12 installers the company says used imported drywall without its permission, and a supplier and two manufacturers, whom they allege sold the “defective gypsum.”

Lennar declined a request by EcoHome for an interview. 

Other builders are filing suits as observers estimate that up to 100,000 American homes, including more than 30,000 in Florida, may have been built with the tainted drywall. An analysis by The Associated Press estimates that China exported more than 540 million pounds of plasterboard to the United States from 2004 to 2008.

In the meantime, Congress is considering legislation that would temporarily ban Chinese-made drywall. The proposals come just two years after China tightened restrictions on exports after its manufacturers sent defective or dangerous cough syrup, pet food, and toys to the United States. 

As the problem gets more attention, homeowners from as far north as Ohio and even Toronto are reporting drywall dilemmas. Washington, D.C.-based research group America’s Watchdog says it has heard from homeowners in California, Arizona, Ohio, Texas, Louisiana, Nevada, North and South Carolina, Georgia, Mississippi, and Virginia.

Lichter advises builders whose customers have complaints to remedy the problem by tearing out all the drywall. “The only way to stop the corrosion is to remove the drywall,” he says. “It’s a huge expense, but changing the air conditioner coils is only a Band-Aid. It’s only a matter of time before the copper corrodes.”