In 1987, the original Montreal Protocol was signed as the first step by the international community to protect stratospheric ozone. The original agreement mandated that developed countries in 1993 begin phasing out chlorofluorocarbons or chemicals used in blowing agents that are also known to destroy the earth’s ozone layer. The agreement also called for these countries to achieve a 50 percent reduction in the use of CFCs relative to 1986 levels by 1998. However, after the agreement was signed, new data showed worse than expected ozone layer damage. What has followed subsequently is a series of amendments—including the London Amendment (1990), the Copenhagen Amendment (1992), the Montreal Amendment (1997), the Beijing Amendment (1999) and the Kigali Amendment (2016)—all aimed at controlling additional ozone depleting chemicals and finding mechanisms to enforce developing countries to comply.
Notably the Kigali Amendment extended controls to phase down the production and consumption of hydrofluorocarbons, another ingredient in older generation blowing agents which are commonly used in spray foam insulation and roofing systems, because they result in potent greenhouse gases which are detrimental to the Earth’s climate. At the time of the amendment ratification, U.S. President Obama and his administration strongly backed the effort.