How long do industrial labels last outdoors?

There is no single figure, because outdoor life depends on the film grade, the print process, the laminate and the latitude of the installation. A supplier quoting a number should be able to say which material it applies to and under what weather conditions. For long service, a polymeric or cast film with a UV-stable laminate, a subsurface print, or an anodised aluminium plate hold up. A monomeric film with a surface digital print does not.