History Mario

History Mario Molina and Frank Sherwood Roland were the first to bring to the CFCs as those responsible for ozone depletion had been observed in 1974. The inert nature of them had made them very attractive for many applications. However, in the upper atmosphere, these substances are most affected by solar UV radiation present thus dissociate and radicals (atoms of chlorine and bromine) released, attack the ozone. At first it was believed that these gases could not reach the upper layers of the atmosphere as they are denser than air. However, they have a very long half-life (75 to 120) and atmospheric air currents that CFCs can reach heights that would not be unlikely to moving air. The Molina and Rowland's argument was based on a similar proposal by Paul J. Crutzen and Harold Johnston, who had shown such as nitrous oxide could act as a catalyst in ozone destruction.Although other scientists have independently proposed that chlorine could catalyze ozone losses (Ralph Cicerone, Richard Stolarski, Michael McElroy and Steven Wofsy), Molina and Rowland were the first to identify the CFC as a huge source of atmospheric chlorine. Crutzen. Rowland and Molina received the Nobel Prize in Chemistry in 1995 for his work on ozone. Ozone plays a key role in absorbing most of the UV-B radiation (UV-B) preventing them from reaching the surface of the planet. Depletion of the ozone layer by CFCs would result in increased UV-B radiation incident on the surface with a powerful environmental effect affecting crops, marine phytoplankton and sharply increasing the risk of skin cancer. After the publication of this work in 1974, Rowland and Molina had to testify before a hearing of the House of Representatives of the United States in December 1974.From there, many funds were allocated to study the problem and verify the initial results. The National Academy of Sciences of the USA published a report in 1976 that validated the results and gave credence to the hypothesis by Molina and Rowland. In 1985, Farman, Gardiner and Shanklin, who worked for the British Antarctic Survey, rocked the international community when they published results of a study in the journal Nature that showed a "hole" in ozone, a decrease in ozone levels in the polar area much larger than anyone had anticipated. That same year, 20 countries, including most of the major producers of CFCs, signed the Vienna Convention which established the framework for negotiating international regulations on ozone depleting substances.During the 1980s, the company DuPont, the world's largest producer of CFCs, tried to convince the government of the United States of America, and the general public, that they were responsible for depleting the ozone layer. 2