CCl4 Emissions (IMAGE) University of Colorado at Boulder Caption Based on measurements made at sites indicated by the symbols, researchers derived US emissions of the ozone-depleting chemical carbon tetrachloride (CCl4). Emission rates were highest in three regions: The Gulf Coast, Denver, and San Francisco areas. Credit CIRES/NOAA Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.