The Katsurao village official said about 337 square kilometers of land in seven Fukushima municipalities are deemed “difficult-to-return” zones. Of those, just 27 square kilometers in six of the same municipalities are specified reconstruction zones.
27 km² are the worst areas. The other 310km² are still “difficult-to-return”.
I think you misunderstood what was written:
27 km² are the worst areas. The other 310km² are still “difficult-to-return”.