International Chernobyl Disaster Remembrance Day is observed worldwide on April 26 each year. This day was established by the United Nations General Assembly in 2016 to commemorate the victims of the Chernobyl nuclear accident, which occurred on April 26, 1986, when Reactor No. 4 at the Chernobyl Nuclear Power Plant in Ukraine was destroyed by an explosion. The disaster resulted in significant radioactive contamination affecting large areas of Ukraine, Belarus, and Russia, with over 8 million people exposed to radiation. In Ukraine, the day is marked by memorial ceremonies and special lessons in schools, emphasizing the need to remember the consequences of the disaster and to consolidate efforts to address them. The observance also aligns with ongoing initiatives for sustainable development in the affected territories, initiated by the International Chernobyl Research and Information Network launched in 2009.