Board Thread:Episodic and Issue Discussion/@comment-47881-20130213170533/@comment-5624498-20130214202453

Looking at the images again, I don't think Nightwing not being shown from the neck up has anything to do with him wearing an oxygen mask. If it did, then Captain Atom would be wearing one as well (notice the two images featuring Nightwing are from the same location).

The first one featuring Nightwing is definitely an odd choice for an image, though.