IMHO, but I think that effect looks like shit.
I suggest using a dust effect instead.
You know, those dust particles which flies around in the air.
Was used in Counter-strike Source - De_dust2 I believe, in the big room.
That technique is fine when talking GoldSrc, but this is Source.
I've forgotten the name of the entity to use when you are making dust particles, but I think that the name of the entity is rather obvious.
Anyways, that's just my opinion.