But this does not mean Fukushima is now on a par with Chernobyl. Indeed, as Bloomberg notes, the data so far suggests that Fukushima has released only one-tenth as much radioactive material as Chernobyl did.

It's also important to note that the upgrading does not mean that the situation is getting worse. Rather, it is a reassessment of what has already happened. The largest releases of radioactive material occurred in the first days after the earthquake, and the amount released every day has generally been decreasing as various leaks have been plugged.