No no no do NOT use particles for this type of thing. Its the worst idea ever if you ever plan to ship your product, if its just for portfolio shots and framerate dosnt matter then go right ahead.
You should only use Atmospheric fog for theese kinds of effects. Of course you can pair that with a particle system that you might want to attach to the player, but make it super sparse, just to enhance the atmospheric fog effect or have like small ground whisps.
The reason im so strongly against this idea beacuse i haev seen others try to do the same, have a massive particle system cover all of the screen, and it has devistating effects on framerates.