Most of the 'industrial' rated electronic assemblies I've come across were in a oil refinery before I retired. Most of the boards had a conformal coating on them, looked like the whole thing was painted in clear epoxy. It was tough stuff and a real pain if you had to try and remove and re-solder a component. A refinery is subject to some nasty atmospheres at times and I've seen trace amounts of H2S gas turn PCB traces blue. :-[
Anyway I think normal commerical grade electronic assemblies like an Arduino would do ok if packaged in a case rated for the service it was going to be subjected to.
Lefty