Following up on months of federal investigation into homeowner claims of harmful fumes and corrosion in homes caused by certain drywall products, the U.S. Consumer Product Safety Commission (CPSC) recently released the results of an indoor air quality study it commissioned of 51 homes in five states.
The study compared 41 homes in which owners had reported corrosion of wiring or piping (“complaint homes”) and 10 similar homes where the owners had not filed any complaints (“control homes”), comparing the indoor environments of each. This allowed the researchers to identify the differences in indoor air quality between complaint homes and control homes and to measure chemical interactions. Researchers also noted the surface area of Chinese-made drywall in each house, as well as each home’s air exchange rate, temperature, and relative humidity and then evaluated whether those conditions contributed to metal corrosion and health symptoms.
By exposing test strips of copper and silver in the homes, Environmental Health & Engineering (EH&E), the firm that conducted the study, determined that hydrogen sulfide gas is the component responsible for corrosion in the homes constructed with Chinese-made drywall. The gas reacted with the test strips to form copper and silver sulfides, and it created significantly higher rates of corrosion in complaint homes than in control homes, CPSC reports. By visually inspecting ground wires in homes, EH&E also found that complaint homes exhibited significantly greater corrosion in ground wires than control homes.
EH&E’s research also suggested that hydrogen sulfide in Chinese-made drywall and the formaldehyde and other chemical compounds typically found in new homes—though present in levels below those which would cause irritation individually—could be combining and reacting in a way that causes respiratory irritation and other health symptoms in homeowners.
Preliminary findings from two additional studies CPSC commissioned on corrosion safety issues that support the link between hydrogen sulfide and copper sulfide corrosion also were released. Both studies investigating home safety and the short and long-term effects of such corrosion are ongoing. One focuses on analyzing the condition of electrical components installed in homes built with Chinese drywall and the other is evaluating the condition of HVAC, gas distribution, and fire safety equipment installed in homes with Chinese drywall.
The CPSC-led Interagency Task Force has tapped a team of scientists and engineers to develop a cost-effective screening protocol that will help identify homes with drywall emitting hydrogen sulfide gas. Also, the task force has been working with U.S. Customs and Border Protection to monitor imports of drywall manufactured in China. According to the CPSC, no new Chinese drywall has entered the United States in 2009 and U.S. building materials suppliers who have inventories of Chinese-made drywall have been notified about the investigation and have indicated that the products will not be sold.
CPSC’s latest announcements and reports are available for download at www.drywallresponse.gov.
CUSTOM HOME covered CPSC’s earlier findings in November (read here).
