Final answer:
The 'no venting' rule for CFCs and HCFCs went into effect in 1995, following the international agreement of the Montreal Protocol ratified in 1987. This protocol aimed to protect the ozone layer by phasing out the production and emission of these and other harmful substances.
Step-by-step explanation:
The ban on venting chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) is a point of international environmental policy stemming from the Montreal Protocol on Substances that Deplete the Ozone Layer. This rule was officially applied worldwide starting in 1995, following the Protocol's ratification in 1987. It aimed to control the production and emission of 96 chemicals that significantly damage the ozone layer. Substances like HCFC-22, HCFC-123, and HCFC-124, among others, were phased out under the Protocol due to their ozone-depleting potential. The initial action against CFCs began earlier, in 1978, with the United States and most Scandinavian countries banning their use of aerosol sprays. Nonetheless, the comprehensive efforts to cease their emission were solidified with the international agreement of the Montreal Protocol, ensuring that both developed and developing countries would critically reduce their production and consumption of these harmful substances.