Since 31 March 2015, credits issued in respect of emission reductions occurring during the first commitment period of the Kyoto Protocol (so-called "CP1 credits") can no longer be exchanged in the EU ETS.
Alates 31. märtsist 2015 ei saa Kyoto protokolli esimesel kohustusperioodil tekkinud heite vähendamise eest saadud ühikuid enam ELi HKSis vahetada.