Today marks the first ever UN Chernobyl Disaster Remembrance Day.

The world’s worst nuclear accident struck the Ukrainian city 31 years ago and over one million children are still living in the radioactive zone.

The official recognition for the day comes after Adi Roche, founder and CEO of Chernobyl Children International, gave a speech to the UN General Assembly last year.

She says that it’s important that we never forget the tragedy.