Hazardous Materials Identification System

[4] The second edition was released in 1986, HMIS II, which introduced letter codes for identifying personal protective equipment to be used, and the 'asterisk' to the Health bar, to identify when a substance poses a long term health hazard, such as carcinogens.

Concerns have been raised due to a contradiction that has occurred, as GHS and HMIS use conflicting scales, with HMIS going 1 (low) to 4 (High), verses OSHA and GHS scales that are 1 (High) to 4 (low).

In the latest version of HMIS, the Health bar has two spaces, one for an asterisk and one for a numeric hazard rating.

[12] However, HMIS is a proprietary system, and without referring to the actual criteria for each rating, it is not clear how similar they are.

In 1959, 13 firefighters in Charlotte, NC, were seriously injured by an explosion caused by water being poured onto a burning vat containing metallic sodium.

The fire department devised a system to inform firefighters of hazards, such as water reactivity or flammability, which became NFPA 704.

The health rating varies from NFPA 704, as a worker using a chemical daily has a different exposure over time compared to a firefighter at a single instance.

HMIS III also adopted the OSHA flammability criteria, as defined by Standard 1910.106.