Deficiencies in the existing INES have emerged through comparisons between the 1986 Chernobyl disaster, which had severe and widespread consequences to humans and the environment, and the 2011 Fukushima Daiichi nuclear accident, which caused no fatalities and comparatively small (10%) release of radiological material into the environment. The Fukushima Daiichi nuclear accident was originally rated as INES 5, but then upgraded to INES 7 (the highest level) when the events of units 1, 2 and 3 were combined into a single event and the combined release of radiological material was the determining factor for the INES rating.