Carbon Monoxide Diffuses Across Gypsum Wallboard
CO diffuses across single-layer, double-layer, painted double-layer drywall
WEDNESDAY, Aug. 21 (HealthDay News) -- Carbon monoxide (CO) diffuses across single-layer, double-layer, and painted double-layer gypsum wallboard, according to a research letter published in the Aug. 21 issue of the Journal of the American Medical Association.
Neil B. Hampson, M.D., from the Virginia Mason Medical Center in Seattle, and colleagues assessed whether CO diffuses across drywall using a Plexiglas chamber divided by various configurations of gypsum wallboard (single layer 0.25- and 0.5- inch thick wallboard; double layer 0.5-inch thick wallboard; and double-layer 0.5-inch thick wallboard painted on one side). CO test gas (3,000 parts per million [ppm]) was infused into one chamber to a concentration of 500 to 600 ppm and concentrations were measured with monitors in each chamber for 24 hours.
The researchers found that CO diffused across single-layer, double-layer, and painted double-layer wallboard. The concentration of CO reached 500 ppm in the infused chamber within seven minutes of infusion. The concentration in the non-infused chamber increased rapidly, reaching 100 ppm (considered toxic to humans) at 17 to 96 minutes after infusion stopped. In all configurations, by 12 hours, the concentrations of CO were less than 5 percent different between the two chambers.
"The ability of CO to diffuse across gypsum wallboard may explain at least some instances of CO poisoning in contiguous residences," the authors write. "Exempting residences without internal CO sources from the legislation mandating CO alarms may put people in multifamily dwellings at risk for unintentional CO poisoning."
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