When less is more: Study tracks down lingering source of carbon tetrachloride emissions

Carbon tetrachloride (CCl4) was once commonly used as a cleaning agent and remains an important compound in chemical industry. CCl4 is responsible for that sickly sweet smell associated with dry cleaning solvents from decades ago. It's a known air toxin and it eats away at the ozone layer—the gas accounts for about 10-15 percent of the ozone-depleting chemicals in the atmosphere today. As a result, production across the globe has been banned for many years for uses that result in CCl4 esca