How do I make this effect?

Support Particles and Physics Simulations
1

In this Minecraft Animation by Black Plasma Studios

from 0:05 to 0:16 you can see some orange reddish particles floating around the screen. I think he said it had something to do with camera focus, but I was wondering if there was any way to recreate that particle effect without any camera focus?
And also how to create that effect in general, thanks.

2

You will have to extend the life of the particle system, change the size of the halo material and add a bit of Brownian motion as well as a wind empty to gently blow it around.