A computer-based method and apparatus for identifying hazardous materials based on observable physical properties and signs and systems of exposure to the hazardous materials. The observable physical properties are obtained by preprocessing plain language data to obtain normalized descriptors and modifiers pertaining to a plurality of properties and signs and symptoms. The normalized descriptors and signs and symptoms are presented to a user in lists for comparison with a sample in the field. Once a material is identified, information can be obtained from the apparatus which is necessary for response to an incident involving the hazardous material. The preferred embodiments of the invention are particularly useful to responders to a hazardous waste incident.