Any substance that is regulated by a specific OSHA standard must be labeled accordingly by the manufacturer. Hazard warnings on labels may consist of words, pictures, symbols, or any combination thereof. Word warnings may also indicate the degree of hazard.
Higher numbers indicate more severe hazards.
This system is useful for alerting emergency response personnel to hazards and also for assessing storage and emergency needs. However, it does not adequately indicate precautionary measures or occupational hazards. Labels on containers of hazardous chemicals should not be defaced or removed.