This is one of the times where Ilya being from the past is going to cost him dearly. He slams chunks of the wall into the canisters, which if they were grenades would diffuse most of the power of the explosion and keep it in one area. Gas grenades, which were not in use during his era, just release all their gas, and he brings down a piece of the ceiling onto them in a really impulsive attempt to contain it.

This means the entire ceiling is now cracked and structurally unsound, but his healing factor keeps him from being incapacitated; he can still see clearly enough through the tears and breathes fine. It's the panic that's pushing him into 'kill or be killed' mode.

A thought flutters through his head like a butterfly: if he could survive a train crash, he could survive bringing a room down on anyone who came in.