Browse and search through United Nations numbers for hazardous substances and their classifications used in international transport.
This website is an independent informational resource and is not affiliated with, endorsed by, or connected to the United Nations or any governmental organization. We do not create, modify, or set these regulations. All UN number classifications and hazard information presented here are based on internationally recognized standards for informational purposes only. For official regulatory guidance, please consult the appropriate governmental authorities and official UN documentation.
When one thinks of hazard classification, those of us in emergency response think of the U.S. Department of Transportation (DOT). After all we use DOT's "Emergency Response Guidebook" upon arrival to identify the chemical that necessitated our presence. But hazard classification begins with the U.S. Department of Labor's (DOL) "Occupational Safety and Health Administration" (OSHA).
Hazard Classification is a process required under paragraph (d) of 29 Code of Federal Regulations (CFR) 1910.1200 (OSHA's Hazardous Communication Standard). Paragraph (d) states: “…For each chemical, the chemical manufacturer or importer shall determine the hazard classes, and where appropriate, the category of each class that apply to the chemical being classified…"
Classification lists the specific Classes of hazards, for example "acute toxicity" or "flammable liquids". Within the Hazard Classes the degree of hazard is indicated with a category. The Category is usually a number (1‐4) or letter (A, B, C), with 1 and A equaling the highest hazard and 4 equaling the least hazardous. THIS IS NOT THE SAME AS THE NFPA 704 SYSTEM!
The mission of the U.S. Department of Transportation (DOT) is to serve the United States by ensuring a fast, safe, efficient, accessible and convenient transportation system that meets our vital national interests and enhances the quality of life of the American people, today, and into the future.
Following and understanding OSHA classification standards, it is easy to see that many of DOT's regulations parallel or further define OSHA regulations regarding health and safety in the workplace. When first responders respond to a transportation incident it is an extension of the manufacturing workplace; just as it is an extension of the fire station worksite.
The hazard class of dangerous goods is indicated either by its class (or division) number or name. The following classification system is from the U.S. DOT – Pipeline and Hazardous Materials Safety Administration's (PHMSA) "Emergency Response Guidebook":
(and Combustible liquids [U.S.])
*The words "poison" or "poisonous" are synonymous with "toxic"
Hazardous materials and articles