How to do Radial Blur in UE4

Hi! I would like to have a radial blur which appears when certain events in the game occur, such as explosions and so forth.

a) I do not know how to add a radial blur. Would this be best done with a post-process material? I cannot see an obvious use for any of the basic post-processing effects on a post-processing volume for this effect.
b) How do I toggle a particular post-processing effect on and off from blueprints?

a) Ofcorse best would be postprocessing as you want to effect entire scene. You probably would need to use custom node in material editor (which im not sure if it works ihear there some problems with it), write HLSL code (or someone write for you ;p) which will do radial blur from grabbed scene output.

b) via material parameters

How would you do this using a material? Using the refraction node, or?

dont know, polay around, something tells me you would need to use some HLSL codeing