This is interesting. Though we understand Green Lantern Alan Scott's ring not to work against wood and other plant material today, in the Golden Age, it was sometimes taken to mean it didn't work on "non-metallic" objects, like here, concrete. So did that include people? He does use his fists a lot, but what keep him in the air? Or do we have just enough iron in our blood to count? Wait, if so, what about spinach?
We need a continuity expert to go back in time and fix this!