What does the number "9" indicate on a hazardous materials placard?

The number "9" on a hazardous materials placard indicates "miscellaneous hazardous materials." This designation is used to signify materials that do not fit into the other classification categories but still pose a potential hazard during transportation. It is essential for first responders to recognize this classification so they can approach these materials properly, as they may include substances that present various risks, even though they are not as easily categorized as others. The miscellaneous hazardous materials category helps ensure that all potentially dangerous materials are adequately identified and managed.