A hazardous material is defined by the California Health and Safety Code, Section 25501(o), to be “any material which because of its quantity, concentration, or physical or chemical characteristics, poses a significant present or potential hazard to human health and safety or to the environment if released into the workplace or the environment.”
Common hazardous materials include fuels, motor oil, and related petroleum products, and antifreeze. Hazardous wastes, such as used oil and used antifreeze, are also hazardous materials. Used oil filters that have been drained are not hazardous materials (but are subject to hazardous waste regulations).
Clues that the material is hazardous include wording on the label on the container. The material is a hazardous material if the label has wording with such terms as: danger, irritant, warning, flammable, sensitizer, combustible, caution, reactive, corrosive, hazard, carcinogen, poison, toxic, oxidizer, avoid contact (with skin or eyes), do not store or use near heat, use with adequate ventilation, wear protective equipment. Also, if there is a MSDS for the product it is also a likely hazardous material.