HMIS is the Hazardous Materials Information System, and HMIS ratings are used to show the relative safety of something. For a good example, look at your can of commpressed air. Mine's Health, 1; Flammability, 0; Reactivity, 1

Summary of HMIS ratings


  1. Health hazard rating

    0: Minimal hazard no significant risk to health.

    1: Slight hazard irritation or minor reversible injury possible.

    2: Moderate hazard temporary or minor injury may occur.

    3: Serious hazard major injury likely unless prompt action is taken and medical treatment is given.

    4: Severe hazard life-threatening, major or permanent damage may result from single or repeated exposures.


  2. Flammability hazard rating

    0: Minimal hazard materials that are normally stable and will not burn unless heated.

    1: Slight hazard materials that must be preheated before ignition will occur. Flammable liquids in this catagory will have flash points (the lowest temperature at which ignition will occur) at or above 220°F.

    2: Moderate hazard materials that must be moderately heated before ignition will occur, including flammable liquids with flash points at or above 100°f and below 200°F.

    3: Serious hazard materials capable of ignition under almost normal temperature conditions, including flammable liquids with flash points below 73°F and boiling points above 100°F as well as liquids with flash points between 73°F and 100°F

    4: Severe hazard very flammable gases or very volatile flammable liquids with flash points below 73°F and boiling points below 100°F.


  3. Reactivity hazard rating

    0: Minimal hazard materials that are normally stable, even under fire conditions, and will not react with water.

    1: Slight hazard materials that are normally stable but can become unstable at high temperatures and pressures. These materials may react with water but they will not release energy violently.

    2: Moderate hazard materials that in themselves, are normally unstable and will readily undergo violent chemical change but will not detonate. These materials may also react violently with water.

    3: Serious hazard materials that are readily capable of detonation or explosive reaction but require a strong initiating source or must be heated under confinement before initiation; or materials that react explosively with water.

    4: Severe hazard materials that are readily capable of detonation or explosive decomposition at normal temperatures and pressures.

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