What Is Safety?

Safety is the condition of being protected from harm, injury, or loss, and, as a discipline, it encompasses the systematic methods used to identify, analyze, and mitigate hazards in engineered systems, workplaces, and products. The field draws on mechanical engineering, systems engineering, human factors, and regulatory science to establish practices that reduce the probability and severity of adverse events. Safety engineering addresses hardware and software reliability alongside the human-machine interfaces and organizational processes that shape how systems behave under both normal and degraded conditions.

Modern safety practice is grounded in the recognition that hazards are inevitable features of complex systems and that risk reduction requires structured analysis rather than reactive response alone. Standards bodies including the International Electrotechnical Commission and the International Organization for Standardization have developed frameworks that formalize the safety lifecycle from initial design through decommissioning.

Hazard Identification and Risk Assessment

Hazard analysis is the foundational step in any safety program. A hazard is a condition or agent with the potential to cause harm; severity characterizes the extent of the potential consequence, and likelihood characterizes how probable it is that the hazard will lead to an adverse event. Together, severity and likelihood form the axes of a risk matrix, which guides decisions about where to invest in risk controls. Widely used analytical methods include Hazard and Operability (HAZOP) studies, Failure Modes and Effects Analysis (FMEA), and Fault Tree Analysis (FTA). Comparative Safety Assessment is used to benchmark the risk levels of competing design alternatives, helping engineers select options that deliver acceptable residual risk. These methods are codified in standards such as IEC 61882 (HAZOP) and IEC 60812 (FMEA), which specify procedures for identifying safety hazards across industrial, electrical, and software-intensive systems.

Product Safety

Product safety addresses the hazards that arise from manufactured goods during their intended use and reasonably foreseeable misuse. It encompasses design requirements, material specifications, testing protocols, and labeling obligations. Regulatory regimes such as the European Union's General Product Safety Directive and the US Consumer Product Safety Commission establish minimum requirements, while technical standards from bodies such as UL (Underwriters Laboratories) and ISO provide detailed test criteria. Eye protection, for example, is governed by standards that specify lens impact resistance, optical quality, and marking requirements to ensure that protective equipment performs as claimed. The ISO 45001 occupational health and safety management system standard provides an overarching framework for organizations to manage product and workplace safety risks through a Plan-Do-Check-Act cycle, and has been adopted by organizations in over 130 countries.

Safety Devices and Controls

Safety devices are physical or electronic systems whose function is to detect hazardous conditions and initiate a protective response. Alarm systems detect anomalies such as smoke, gas, temperature exceedance, or unauthorized entry and alert occupants or trigger automated shutdowns. Interlock systems prevent dangerous operations from being initiated unless specified preconditions are met, as in the door-closure interlocks on industrial presses. Guard and barrier devices provide passive protection by placing a physical boundary between personnel and hazardous energy sources. In electrical systems, overcurrent protection devices, ground-fault circuit interrupters, and arc-fault detectors are safety devices that address specific electrical hazard categories. Forensic investigation of accidents draws on safety engineering methods in reverse: by reconstructing the sequence of events and the failure modes involved, forensic analysis identifies the hazard pathways that safety systems failed to interrupt, informing improvements to future designs. Guidance on integrating these device requirements into a broader safety lifecycle is provided by the IEC overview of functional safety standards.

Applications

Safety has applications across a wide range of industries, including:

• Industrial manufacturing, where machine guarding and lockout-tagout procedures protect workers
• Transportation, including automotive crash safety systems and aviation hazard analysis
• Healthcare, through medical device risk management under ISO 14971
• Consumer electronics, where product safety testing prevents electrical and thermal hazards
• Construction and infrastructure, via occupational safety management and structural hazard controls