[Robert A Cook PE]

When did the "rules" come in to effect, and over what time frame did they actually occur?

(You can write a law in 78 to begin phasing chemicals in 79, but not see a change in actual output until 92, for example.)

[cogitator]

History of the Montreal Protocol

"By September 1987, progress in negotiations offered the prospect of consensus on control measures. On September 16, 1987, the Montreal Protocol on Substances that Deplete the Ozone Layer was signed by 24 countries."

"On January 1, 1989, the Protocol came into effect. Parties agreed to freeze their production and consumption of CFCs and halons within seven months of the Protocol’s entry into force, and to reduce consumption of CFC by 50% within 10 years. Developing countries were accorded a period of grace of 10 years."