HEALTH (Blue)

4Deadly: Even the slightest exposure to this substance would be life threatening.
  Only specialized protective clothing, for these materials, should be worn.

3Extreme Danger: Serious injury would result from exposure to this substance.
  Do not expose any body surface to these materials. Full protective measures should
  be taken.

2Dangerous: Exposure to this substance would be hazardous to health. Protective
  measures are indicated.

1Slight Hazard: Irritation or minor injury would result from exposure to this substance.
  Protective measures are indicated.

0No Hazard: Exposure to this substance offers no significant risk to health.

  FLAMMABILITY (Red)

4Flash Point Below 73° F: This substance is very flammable, volatile or explosive
  depending on its state.
  Extreme caution should be used in handling or storing these materials.

3Flash Point Below 100° F: Flammable, volatile or explosive under almost all normal
  temperature conditions.
  Exercise great caution in storing or handling these materials.

2Flash Point Below 200° F: Moderately heated conditions may ignite this substance.
  Caution procedures should be employed in handling.

1Flash Point Above 200° F: This substance must be preheated to ignite.
  Most combustible solids would be in this category.

0Will Not Burn: Substances that will not burn.

  INSTABILITY (Yellow)

4May Detonate: Substances that are readily capable of detonation or explosion
  at normal temperatures and pressures. Evacuate area if exposed to heat or fire.

3Explosive: Substances that are readily capable of detonation or explosion by a
  strong initiating source, such as heat, shock or water. Monitor from behind
 explosion-resistant barriers.

2Unstable: Violent chemical changes are possible at normal or elevated temperatures
  and pressures. Potentially violent or explosive reaction may occur when mixed with
  water.   Monitor from a safe distance.

1Normally Stable: Substances that may become unstable at elevated temperatures
  and pressures or when mixed with water. Approach with caution.

0Stable: Substances will remain stable when exposed to heat, pressure or water.