very interesting question, thanks to share.
My personal experience on field can make me say: yes, the light traps can helps.
Specially the yellow glue boards are more actrattive because usually yellow color is good to attract Diptera like flies,mosquitoes and gnats.
I agree with rdeboer1986 first check out why there are so many gnats.
This problem is very easy to find in all the food factories working fermented products producing CO2 during the process like wine,beer,bread,croissants etc.
so during the clean operations if remain some water with organic part like sugar,flour,pasta some uncontrolled fermentations can start.
All the areas should be separeted and you have to close the doors as soon as possible of course.
Furthermore I council you to chek out behind the cold cells because there is often water on the floor helps gnats to increase.
Installing the light traps at the wall is a good way to keep out the fling insect from the producing area, far from tanks and tapes.
For the other internal areas specially next to the external doors you can to talk with the PCO to install double face light trap..
Hopes you can find some helps in this.