Dry cleaning has long been a prime target on every environmentalist's hit list. Its main cleaning agent-perchlorethylene-is a volatile organic solvent whose toxic emissions cause headaches, dizziness, and nausea after short-term exposure and liver and kidney damage over the long term. In fact, all dry cleaners are required by law to protect employees from exposure to the chemicals.

The main approach so far toward meeting the regulations has been to install costly vapor-recovery systems and seal up the dry-cleaning machines to reduce perchlorethylene leaks. Now, however, Joseph DiSimone, a professor of chemical engineering at North Carolina State University, has developed a novel dry cleaning technology that completely eliminates perchlorethylene with one of the most common and innocuous substances on earth: carbon dioxide.