Which class is indicated by a label or placard featuring a three-bladed fan?

The label or placard featuring a three-bladed fan is indicative of materials that are classified as radioactive. This symbol is a recognized sign indicating the presence of radioactive substances, which can pose significant health risks due to radiation. Proper recognition of this symbol is essential for emergency responders, as it directs them to utilize specific safety protocols and protective measures when handling or approaching areas with radioactive materials. Understanding these labels and their meanings is crucial for ensuring safety while responding to incidents involving hazardous materials.