Which class includes materials that are considered miscellaneous hazards, like airbags?

The correct choice is Class 9, which categorizes materials that do not fall under the other specific classes of hazardous materials but still pose a risk. This class is defined by the Department of Transportation as encompassing miscellaneous hazardous materials that don't fit neatly into other predefined categories. Airbags, for example, are classified here because they contain potentially hazardous components and are affected by certain regulations, despite not being explicitly flammable, toxic, or explosive.

Class 9 is important for recognizing materials that might not be dangerous in typical circumstances but still require careful handling and transportation. This designation helps ensure that additional safety measures are taken when dealing with these types of products, enhancing overall safety in handling and transportation.

The other classifications pertain to specific characteristics of hazards such as radioactive materials in Class 7, flammable solids in Class 4, and oxidizers in Class 5, none of which include the broader and more miscellaneous category that encompasses airbags. Thus, Class 9 is the appropriate designation for such materials.