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The Hazardous Materials Identification System (HMIS) is a visual and numerical method by which information about material safety can be quickly and effectively conveyed. This system uses four sections that can each have a number applied to them, with higher values indicating greater risk within that category. The four categories are health risks, flammability potential, physical hazards with regard to reactions to other materials, and personal protection that should be worn.
Created by the National Paint and Coatings Association (NPCA), now the American Coatings Association (ACA), the system is intended as a way to easily convey safety information about various materials. There are four different categories within the HMIS, and each of these can have a value from zero to four. A rating of zero means there is no risk associated with that category, while a four indicates extremely high risk within that category.
The first category on the Hazardous Materials Identification System is “health,” which indicates potential health risks associated with a substance and is blue in color. A rating of zero indicates there are no risks, while a one indicates minor irritation can result from exposure to materials. Ratings of two indicate a short-term health risk or minor injury, while three means a major issue that likely requires immediate medical attention, and a four indicates that exposure can be deadly. The “health” category can also have an asterisk that indicates that long-term exposure can create ongoing issues and health risks.
After “health” is a red bar for the “flammability” of a substance. Flammability is based on the temperature at which a substance ignites. Low numbers indicate substances that are inflammable or that require high temperatures, while higher numbers are used for materials that can ignite quite easily at room temperature or spontaneously.
The third category is colored orange and indicates “physical hazards” associated with a material. This usually refers to how a substance interacts with other materials, and high ratings indicate materials that can become volatile when exposed to other substances. These materials may become explosive when combined with other elements, or may cause quick erosion or decay. In previous versions of the HMIS, this was yellow in color and labeled “reactivity,” though it was changed in the third version of the system.
“Personal protection” is the fourth section of the Hazardous Materials Identification System and is white in color. This section designates how much protection is needed when handling these materials, with higher numbers indicating greater precautions should be taken. Illustrations are often provided in this section to show specific pieces of equipment that should be worn, such as gloves or goggles.