How do HazCom/GHS labeling requirements differ from NFPA or HMIS labeling systems?

HazCom/GHS uses hazard categories. NFPA and HMIS uses hazard ratings. These systems run opposite of each other.

Under HazCom/GHS, hazard categories usually begin at “1” for the most severe and “4” or “5” for the least severe hazards. Some hazard categories are identified by an “A”, “B”, or other letter of the alphabet. The number identifying the hazard category will not appear on the label — only on the SDS for the product. This is different from NFPA and HMIS labels, which use a scale where the number “4” indicates the most severe hazard, working down to a “0” which represents no hazard.