Explanation:

Montreal protocol aims to phase out several groups of halogenated hydrocarbons that have been shown to play a role in ozone depletion. All of these ozone depleting substances contain either chlorine or bromine (substances containing only fluorine do not harm the ozone layer). These include CFCs and HCFCs. HFCs replaced CFCs and HCFCs. HFCs pose no harm to the ozone layer because, unlike CFCs and HCFCs, they do not contain chlorine. The Montreal Protocol therefore does not address HFCs. But HFCs cause global warming. Dichloromethane is a new entry among gases that depletes ozone layer, but at present it has not been included under Montreal Protocol.