What Supernova Distance Would Trigger Mass Extinction?

The deaths of massive stars results in one of the most beautiful and violent events in the universe: the supernova. They are so luminous we can see them here on Earth and historical records show that we can even see them into the day. But supernovas release deadly and violent radiation that could destroy our atmosphere. So how far away do these supernova have to be for humanity to be safe? And when will the next supernova occur