As my previous response indicated, building use and occupancy classification would be the primary determining factor for exit signs, whether the location were electrically classified or not.
I was curious about the electrical area classification, because I wouldn?t normally expect the facility you described to be classified. I don?t know the ??pesticides, fertilizers and other chemicals?? being used, of course, but if it were classified at all, I would tend to expect it to be Class II, rather than Class I. I would gather up the relevant MSDSs and review them to ensure I had them as part of the proper documentation required by Section 500.4(A)