HMIS Classification

Symbol	Meaning
0	No significant risk to health
1	Irritation or minor reversible injury possible
2	Temporary or minor injury may occur (eg: diethyl ether)
3	Major injury likely unless prompt action is taken and medical treatment is given
4	Life-threatening, major or permanent damage may result from single or repeated overexposures (eg: hydrogen cyanide)

Symbol	Meaning
0	Materials that will not burn (eg: Water)
1	Materials that must be preheated before ignition will occur Includes liquids, solids and semi solids having a flash point above 200 °F (93 °C) (eg: canola oil)
2	Materials which must be moderately heated or exposed to high ambient temperatures before ignition will occur Includes liquids having a flash point at or above 100 °F (38 °C) but below 200 °F (93 °C) (eg: diesel fuel)
3	Materials capable of ignition under almost all normal temperature conditions. Includes flammable liquids with flash points below 73 °F (23 °C) and boiling points above 100 °F (38 °C), as well as liquids with flash points between 73 °F and 100 °F
4	Flammable gases, or very volatile flammable liquids with flash points below 73 °F (23 °C), and boiling points below 100 °F (38 °C) Materials may ignite spontaneously with air (eg: propane)

Symbol	Meaning
0	Materials that are normally stable, even under fire conditions, and will not react with water, polymerize, decompose, condense, or self-react Non-explosives (eg: helium)
1	Materials that are normally stable but can become unstable (self-react) at high temperatures and pressures Materials may react non-violently with water or undergo hazardous polymerization in the absence of inhibitors (eg: propene)
2	Materials that are unstable and may undergo violent chemical changes at normal temperature and pressure with low risk for explosion Materials may react violently with water or form peroxides upon exposure to air (eg: potassium, sodium)
3	Materials that may form explosive mixtures with water and are capable of detonation or explosive reaction in the presence of a strong initiating source Materials may polymerize, decompose, self-react, or undergo other chemical change at normal temperature and pressure with moderate risk of explosion (eg: ammonium nitrate)
4	Materials that are readily capable of explosive water reaction, detonation or explosive decomposition, polymerization, or self-reaction at normal temperature and pressure (eg: chlorine dioxide, nitroglycerin)

Symbol	Meaning
A
B
C
D
E
F
G
H
I
J
K
L	Site-specific label. Ask your supervisor or safety specialist for handling instructions.
M	Site-specific label. Ask your supervisor or safety specialist for handling instructions.
N	Site-specific label. Ask your supervisor or safety specialist for handling instructions.
O	Site-specific label. Ask your supervisor or safety specialist for handling instructions.
P	Site-specific label. Ask your supervisor or safety specialist for handling instructions.
Q	Site-specific label. Ask your supervisor or safety specialist for handling instructions.
R	Site-specific label. Ask your supervisor or safety specialist for handling instructions.
S	Site-specific label. Ask your supervisor or safety specialist for handling instructions.
T	Site-specific label. Ask your supervisor or safety specialist for handling instructions.
U	Site-specific label. Ask your supervisor or safety specialist for handling instructions.
V	Site-specific label. Ask your supervisor or safety specialist for handling instructions.
W	Site-specific label. Ask your supervisor or safety specialist for handling instructions.
X	Site-specific label. Ask your supervisor or safety specialist for handling instructions.
Y	Site-specific label. Ask your supervisor or safety specialist for handling instructions.
Z	Site-specific label. Ask your supervisor or safety specialist for handling instructions.