The building code is quite specific as to what is "hazardous". When hazardous materials and processes occur, the building is designated Hazardous Occupancy. As such, it is required to be separated from almost all other occupancies -- including live/work where it is so treated in local codes. Numerous cities have designated certain limited amounts of hazardous materials and processes that can occur in open, or live-with™ spaces. Sometimes this is in combination with requirements for sprinklers or extra layers of sheet rock on walls between units, as detailed in the separation section.

Artists, some of the earliest users of live/work spaces, use materials in their work which can be dangerous or are associated with short or long-term health problems. Much work has been done to address this issue, and in some cases separation between living and working spaces are indicated for this reason.