Final answer:
The Clean Air Act addresses the phase-out of CFC/HCFC production and prohibits the use, release, and trade of these substances in various products and systems, with the correct answer being all of the options listed. The Montreal Protocol has been crucial in reducing the use of CFCs to protect the ozone layer.
Step-by-step explanation:
The Clean Air Act calls for the phase-out of CFC/HCFC production and prohibits a few activities. It specifically prohibits 1) the use of certain substances in aerosols and foam products, 2) the release of certain substances in refrigeration and air conditioning systems, and 3) the import and export of certain substances. Thus, the correct answer is 4) all of the above.
Chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) have been widely used in applications such as refrigerants and propellants due to their stability. However, these compounds have been found to contribute significantly to ozone layer depletion. The Montreal Protocol, established in 1987, has played a critical role in phasing out these substances globally.
While there has been progress in reducing emissions and signs of ozone layer recovery, continued efforts are needed, especially given the challenges posed by existing 'banks' of CFCs in older equipment and the development of alternative substances like hydrofluorocarbons (HFCs) that, despite having less impact on the ozone layer, still possess their own environmental problems.