Struck-by hazards occur when workers are hit by moving objects, falling objects, or flying projectiles. Falling objects from heights kill or seriously injure workers on the ground. The energy of a falling object is proportional to weight and height; even small objects falling from significant heights can cause serious injury. Hard hats protect against falling objects but do not eliminate the hazard. The primary control is preventing objects from falling. Guardrails prevent items from being knocked off platforms. Toeboards block items from rolling off edges. Protective netting catches objects before they reach the ground. Material handling procedures including securing loads and proper stacking prevent shifts and drops. Personnel working below elevated work areas must not be present. Barricading and warning signs prevent unauthorized entry. Flying objects from tools and equipment present hazards. Grinding wheels can disintegrate and throw fragments. Proper guards and shields contain fragments. Abrasive blasting equipment can eject particles at high velocity; proper enclosures protect bystanders. Compressed air and pressure systems can cause rapid ejection of materials or the system itself. Safety relief valves prevent overpressure. Straps and clamps secure system components. Eye protection including safety glasses and face shields protects against flying particles. Hard hats with face shields provide head and face protection. Heavy equipment operation can throw rocks or debris from wheels or undercarriage. Operators and spotters should position themselves outside the throw zone. Tracking equipment (dozers, excavators) can throw material from tracks; adequate clearance prevents hazards.