Sugestion,
Put some dust on the fog plane> Granite? Spots? Noice? Turbulence?
Perhaps blend with a cloud node?
Yeah a cloud node blended with granite or turbulence....

Is that a transmapped hair?

Also : Check preview render settings for multilayered transparancy setting.

Poser 1, 2, 3, 4, 5, 7, P8 and PPro2010, P9 and PP2012, P10 and PP2014 Game Dev
"Do not drive faster then your angel can fly"!