Pressure washers operate at very high pressures (1,000 to 4,000 psi) and can cause serious injury. Water jets traveling at such high velocity can penetrate skin and cause injection injuries. Cleaning chemicals or solvents present additional hazards if injected into the body. Injection injuries can appear minor externally but cause severe internal damage. Immediate medical attention including emergency room evaluation is required for any suspected injection injury. Pressure relief valves must be functioning properly to prevent excessive pressure buildup. Regular testing verifies the valve operates at the rated pressure. Safety-interlock handles ensure the nozzle cannot discharge unless the trigger is held. The nozzle must be rated for the operating pressure; a nozzle rated for lower pressure can rupture. Appropriate nozzle selection for the task provides adequate flow without excessive pressure. Operator training must cover injection hazards, proper handling, and emergency procedures. Hearing protection is required due to high noise levels. Eye protection is needed to prevent water splash. Slip-resistant footwear prevents slipping on wet surfaces. The hose and connections must be securely fastened and inspected regularly. Disconnecting hoses can result in whip injuries. Confined space ventilation is critical when using pressure washers indoors; water spray and chemical mists must be removed.