Toggle particles on trigger enter depending on physic material

Hello!

I have a problem with switching Particle emmiters ON/OFF depending on surface type they(not actually) collide with.

Let me describe the system. There's a road built from two meshes with dirt and snow physic materials,a box collider and two different particle emmiters(one emits dirt,other-snow) and what I want to happen is when the box (trigger) collides with part of a road which has snow physic material,then snow particle emitter is on,same with dirt,and when there's no collision - both of them are switched off.

I hope someone can find a solution,because I'm stuck with it :/