The Montreal Protocol categorizes which of the following substances in two classes based on their ozone-depleting potential?

The Montreal Protocol is an international treaty designed to phase out substances that deplete the ozone layer. In this context, chlorofluorocarbons (CFCs) and halons are specifically classified due to their significant ozone-depleting potential. CFCs are commonly used as refrigerants, propellants, and solvents, while halons are primarily utilized in fire extinguishing systems. Both classes of substances have been scientifically shown to release chlorine and bromine upon breakdown in the stratosphere, which then catalyze the destruction of ozone molecules.

The focus of the Montreal Protocol is on these substances due to their widespread use and high potential for harm to the ozone layer. As a result, the treaty sets the stage for global action aimed at reducing and ultimately banning their production and consumption to protect the environment and lessen the impact of ozone depletion.

The other options refer to substances that do not fit the criteria established by the Montreal Protocol. Carbon dioxide (CO2) and PAN, for instance, are primarily greenhouse gases and do not contribute to ozone depletion. Similarly, ozone-depleting greenhouse chemicals, while they may impact the ozone layer, are not specifically categorized by the protocol. Lastly, sulfur dioxide (SO2) and carbon monoxide