Health 0: Exposure under fire conditions would offer no hazard beyond that of ordinary combustible material. E.g. sodium chloride
code
H
1
Health 1: Exposure would cause irritation but only minor residual injury. E.g. turpentine
code
H
2
Health 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g. chloroform
code
H
3
Health 3: Short exposure could cause serious temporary or residual injury. E.g. chlorine gas
code
H
4
Health 4: Very short exposure could cause death or major residual injury. E.g. VX gas
code
F
0
Flammability 0: Will not burn. E.g. water
code
F
1
Flammability 1: Must be pre-heated before ignition can occur. Flash point over 93 °C (200 °F). E.g. canola oil
code
F
2
Flammability 2: Must be moderately heated or exposed to relatively high ambient temperature before ignition can occur. Flash point between 38 and 93 °C (100 and 200 °F). E.g. diesel fuel
code
F
3
Flammability 3: Liquids and solids that can be ignited under almost all ambient temperature conditions. Flash point between 23 and 38 °C (73 and 100 °F). E.g. gasoline
code
F
4
Flammability 4: Will rapidly or completely vaporize at normal atmospheric pressure and temperature, or is readily dispersed in air and will burn readily. Flash point below 23 °C (73 °F). E.g. propane
code
I
0
Instability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogen
code
I
1
Instability 1: Normally stable, but can become unstable at elevated temperatures and pressures. E.g. calcium
code
I
2
Instability 2: Undergoes violent chemical change at elevated temperatures and pressures, reacts violently with water, or may form explosive mixtures with water. E.g. white phosphorus
code
I
3
Instability 3: Capable of detonation or explosive decomposition but requires a strong initiating source, must be heated under confinement before initiation, reacts explosively with water, or will detonate if severely shocked. E.g. hydrogen peroxide
code
I
4
Instability 4: Readily capable of detonation or explosive decomposition at normal temperatures and pressures. E.g. nitroglycerin
code
S
OX
Special hazard OX: Oxidizer. E.g. potassium perchlorate
code
S
W, W, <s>W</s>
Special hazard W: Reacts with water in an unusual or dangerous manner. E.g. sodium, sulfuric acid
code
S
W+OX, WOX
Special hazard W+OX: Reacts with water in an unusual or dangerous manner AND is oxidizer
code
S
ACID
Special hazard ACID: Acid
code
S
ALK
Special hazard ALK: Alkaline
code
S
BIO
Special hazard BIO: Biohazardous. E.g. smallpox virus
code
S
COR
Special hazard COR: Corrosive; strong acid or base. E.g. sulfuric acid, potassium hydroxide