Hey!
I’m using UE4.8.3 and I created snow GPU particle system with collision.
So I have a problem with the collision, it isn’t collide with the enviorment.
Why it isn’t working?
Thanks for help! 
Someone?
Hi YoniBE -
GPU Particle Systems use Scene Depth to determine scene collision which means that items at extreme edges of your scene’s camera frustum (view cone) will not have any apparent depth. This is why GPU Particles can often fall through roofs above a character’s location or at seams between meshes which don’t met at true edges.
You will also want to make sure that you have your Engine Scalability Settings set to EPIC and are not running in Mobile Preview Mode.
If you can post a video of the collision issue I can better guide you if the above steps do not help.
Thank You
Eric Ketchum
Thanks! It works!