Maybe due to the fear cage effect. High Emf could definitely be in warehouses.
Humm I looked up Fear cage effect and found some very interesting articles,
and that got me to wondering about EMF and I tried a couple of experements
this evening with my homemade detector umm don't laugh to loudly K?
and it's a given that most warehouses have a lot of wire, and any current flow will generate an emf (even a long enough unenergized wire will have a 60hz natural current on it) my problem is the tunable coil for the reciever great big unwieldy thing.
But I did encounter high field strengths in the ware house strangely enough in the 340 hz band quite possibly because of the ballasts in the lighting.
Thanks for the suggestion!