reference to carbon dioxide (CO2) therapy, a type of psychotherapeutic treatment experimentally used in the 1950s which was said to help people overcome neurotic reactions. In one case, patients were made to breathe a mixture of 30 percent carbon dioxide and 70 percent oxygen until they lost consciousness; in another experimentation a single inhalation of a mixture of 70 percent carbon dioxide and 30 percent oxygen was taken which ususally produced a stupor. (A concentration of more than 5 percent of carbon dioxide canhave a harmful effect on people due to a lack of oxygen in the body.) —LCDH Approved Glossary