This year the National Ozone Unit (NOU) of Ministry of Environment of Cambodia celebrated the International Day for the Preservation of the Ozone Layer, 16 September 2020 and marks the 35th anniversary of the Vienna Convention for the Protection of the Ozone Layer and the marks the 33rd anniversary of the Montreal Protocol on the Substances that deplete the Ozone Layer under the theme of “Ozone for Life: 35 years of Ozone Protection”. NOU, Department of Air Quality and Noise Management, General Department of Environmental Protection of Ministry of Environment of Cambodia organized many programmes to mark the day. The programme included round table discussion, the awareness workshop on the implementation of Montreal Protocol and the process toward the ratification of Kigali Amendment of which the workshop was participated by provincial government officials, students from the university and youth association.