I was playing as Redeye hiding in smoke and was hit by an enemy concussion grenade at my feet. I was surprised to find that when it went off, it had no effect. Do you think this is a bug or by design?
Smoke cancels concussion?
Just tested it, and yes smoke appears to cancel flash AND concussion. I think it may be by design, but I’ll see if I can find out and clarify for you! 
It may potentially be by design because his IR goggles lessen the effect slightly (well make it easier to see while being flashed + concussed).
It could be another iteration of the bug where explosives don’t effect anybody standing directly on top of them, since concussions are treated as explosives.
I do know smoke functions like a wall if a concussion detonates on one side of it and you’re standing on the other side, but inside of it is an iffy point I haven’t been in a situation for yet.
That’s not how physics work. I mean, the flash, maybe, provided that the smoke is dense enough to be opaque enough. As for the EM and sound concussion, nope. But then again, that’s just a video game where a fat man can run with a full armor and a minigun, soooo, fuck physics 
It makes logical sense to an extent, not the EM part though. Redeye is old though, maybe his eyes are so bad he can’t really be affected by the flashbangs.
This happen to me before. But i never been able to test hit for sure. If it is a bug i hope they don’t fix it.
But i guess if you are in the radius of the nade you should get the concussion effect, but not the flash white screen effect.
Huh, I thought concussion would screw up your vision, let alone looking through smoke screwing up your vision even more and looking through infrared vision that literally adds up to being worse than blind.