When rendering in firefly using the atmosphere node, does anyone know how to simulate a 'dusty' air quality? I tried adding a noise node to the atmosphere color, and then the density, but neither produced the effect that I was looking for.. Ideas?

Do you have a background in the scene, it will only show up if there is some kind of backdrop or enclosure. 

Besides the density, there is the number of steps, and also setting in the light properties (atmospheric strength) for the strength in which it affects the atmosphere.  These all play a part in how it turns out, and can be tricky / a pain to get right. 

Hope this helps.

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Consider me insane if you wish, but is your reality any better?

I guess an image would have helped... Yes, the atmosphere shows up, I just want a sort of grainy, dusty effect to the light rays...