The phase-out of CFCs means that nitrous oxide (N 2O), which is not covered by the Montreal Protocol, has become the most highly emitted ozone-depleting substance and is expected to remain so throughout the 21st century.
Pembatasan CFC berarti pula bahwa dinitrogen oksida (N2O), yang tidak tercakup dalam Protokol Montreal, telah menjadi bahan perusak ozon yang paling banyak dipancarkan dan diperkirakan akan tetap demikian sepanjang abad ke-21.