The Twists and Turns of CFC Regulation around 1991

   There were twists and turns in the regulation of chlorofluorocarbons, but it was brought to the forefront of politics, industry, and technology in 1987 when the Montreal Protocol on Substances that Deplete the Ozone Layer was codified with the signatures of 32 countries.

　The Protocol included guidelines to reduce emissions to 50% or less by 1998, but it was later discovered that ozone depletion was progressing faster than expected and that the ozone hole was getting larger.

　Nevertheless, the total amount of CFCs released into the atmosphere over the past 70 years, even if limited to CFCs 11 and 12, is still about 18 million tons. It is estimated that more than 40% of this amount has not yet reached the stratosphere. (As of 1991)

　This is also the reason why regulations on ozone-depleting substances are expected to become more stringent in the future.