Stop Particle System Emmitting Light

Hi All,

I have a particle effect meant to represent a dust storm. I have set the colour to a grey colour, but when used in the real world (and when I turn down my sky light to make the overall world darker) the particles are very bright, almost white and seem to be emitting light which is not the effect I want. How can I make them darker and stop them glowing in the dark?

Thanks!

EDIT: It seems the particles are getting brighter the longer the effect is running, even though I have no ‘colour over time’ module. When you look at the effect in the particle system editor, you can’t see this happening. It is only when I use the effect in the real world that it gets brighter.