In the 1970's, scientist Mario Molina set out to discover exactly what happened to the copious amounts of chloroflourocarbons (CFCs) that had been released into the atmosphere since their invention in the 1930's and especially after World War II where the popularity of CFC use skyrocketed. In 1973, a colleague of Molina's, F. Sherwood Rowland, suggested that Molina theorize what would happen if the chemicals had dispersed into the atmosphere. Molina hypothesized that if the CFCs were to get into the atmosphere, it would take so long for them to decompose that UV light from the sun would break them down with one of the byproducts, chlorine, reacting with ozone to cause ozone depletion.
Upon gathering data from the atmosphere, not only did Molina and Rowland find CFCs that had not broken down yet, but they found confirmation that after breaking down, the byproducts did react with ozone and had been contributing to the depletion of the ozone layer. After this discovery, other scientist were able to verify the accuracy of Molina's and Rowland's work as well as perform further research on CFCs and their role in causing ozone depletion. While it was confirmed in 1987 that chlorine was directly responsible for the deterioration of the ozone, it was not until 1996 that CFCs were officially named as a major contributor of the chlorine in the atmosphere.