Hazmat is short for hazardous materials: substances or objects that can harm people, damage property, or contaminate an area. That can include radioactive sources, batteries, chemicals, fuels, pressurized containers, and other items that need special handling rather than casual inspection or resale.
In cyber security, hazmat matters because security work often happens in labs, data centers, maker spaces, and event venues where physical and digital risks overlap. A suspicious device may hide hazardous components, while a recovery site or swap meet may expose staff to unknown materials. Good defense practice is to treat unfamiliar items as unsafe, stop ad hoc handling, isolate the object, and escalate to trained personnel. Clear procedures for hazmat reduce injury, limit disruption, and keep an incident from becoming a broader safety event.