The NA numbers (North American Numbers) are assigned by the United States Department of Transportation, supplementing the larger set of UN numbers, for identifying hazardous materials. NA numbers largely duplicate UN numbers, however a selection of additional numbers are provided for materials that are not covered by UN numbers as a hazardous material. In a couple of instances NA numbers provide an alternative description than the equivalent UN number.
See also List of UN numbers NA/UN exceptions - List of specific conflicts between NA numbers and UN numbers.
Notes
References
"UN/NA Datasheets". CAMEO Chemicals. Retrieved 2019-10-21. "Library - Hazardous Materials Table (HMT)". PHMSA. Retrieved 2017-08-25.