Federal investigators with the Consumer Product Safety Commission reported a strong association between Chinese drywall used during the housing boom and corrosion of metal parts and electrical problems in affected homes. The investigators also reported that hydrogen sulfide gas emitted from the drywall in combination with formaldehyde was a possible cause of respiratory problems.

More that 2,100 U.S. homeowners to date—most of them in Florida and Louisiana—have lodged complaints with the Consumer Product Safety Commission about a foul odor, failing appliances and electrical systems, and respiratory problems. The agency’s November 24 report noted that homes in the South are particularly subject to problems, due to the hydrogen sulfide in the drywall interacting with high humidity, warm temperatures and poor air circulation in air-conditioned homes.

An estimated 60,000 homes have been built with Chinese drywall. The investigation is the largest in the agency’s history, costing $3.5 million.

The commission is also exploring relief for homeowners, including ways to fix the problem and financial assistance. It has requested the Internal Revenue Service to allow deductions for related costs as casualty losses, for example.

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