FIGURE 1 Life‐cycle process reprinted with permission from ANSI/ASSP Z590.3‐2011(R2016).
Source: From ANSI/ASSP (11). © 2016.
FIGURE 2 Prevention through design during system's lifecycle (8).
Source: From Lyon and Popov (8) © 2018.
FIGURE 3 ANSI Z590.3‐2011 (R2016) prevention through design risk reduction hierarchy of controls model reprinted with permission.
Source: From ANSI/ASSP (11) © 2016.
The objective of operational risk management is to implement appropriate risk reduction plans to reduce risks associated with each decision made to achieve an acceptable risk level. OSH professionals should be able to effectively lead risk assessments, develop appropriate risk reduction strategies, and advise decision‐makers in making appropriate decisions. Risk treatments (i.e. risk controls) are designed to reduce the risk of a hazard's effects and/or reduce the likelihood of its occurrence. A risk treatment plan should include options and alternatives that eliminate the hazard or reduce its risk. To provide OSH professionals a broader range of risk reduction strategies that include “inherently safer design” concepts, the authors have proposed a Hierarchy of Risk Treatment (HoRT) Strategies Hierarchy model illustrated in Figure 4 (9).
The HoRT model includes 10 risk treatment strategies divided into three categories: (i) design, (ii) engineering, and (iii) administrative controls. Of the three categories, design risk treatments are the only measures that are long lasting and resistant to degradation. Hazards that are avoided, eliminated, or reduced through substitution will not change unless the design changes. Engineering and administrative controls are less resilient, effective, or reliable. Engineering controls can be circumvented, degrade over time, and require periodic inspection, testing, service, and repair. The least effective group of controls are administrative measures. Variations in application, quality, and management as well as human error make such measures a less effective and less reliable option (9). Brief descriptions and examples for each risk treatment strategy are presented in Table 1.
FIGURE 4 Hierarchy of risk treatment (HoRT) (9).
Source: From Lyon and Popov (9). © 2019 American Society of Safety Engineers.
Table 1 Brief descriptions and examples for risk treatment strategies.
| Strategy | Description | Examples |
|---|---|---|
| Avoid | New hazards/risks are intentionally avoided in new designs, and redesigns, additions, and modifications to existing systems and workplaces | New facility avoids falls from heights by designing all working and walking surfaces at the same level |
| Eliminate | Existing hazards/risks are eliminated or removed from systems/workplaces through redesign | A hazardous chemical process is eliminated from the workplace by redesign of the process or removed from the workplace and isolated away from workers |
| Substitute | New or existing hazards/risks are intentionally substituted and replaced with less hazardous materials that meet the needs of the system/workplace | A highly hazardous chemical such as pure sulfur dioxide is replaced with a less hazardous chemical such as potassium meta‐bisulfite |
| Minimize | The amount or quantity of a particular hazard is minimized to a level that presents a lower severity risk | The size and weight of materials are minimized to a level that can be handled easily by workers; the smallest quantity of hazardous materials feasible for the process are used; lower voltage or energy required in system; or reduced operating temperatures and pressures |
| Simplify | The likelihood of error or occurrence is reduced through simplifying the systems/workplace processes and controls | Reduce unnecessary complexity in controls and displays; reduce the number of steps to complete a critical task; incorporate human factors engineering design into systems to reduce human error potential |
| Engineer with passive controls | Hazards are controlled and/or contained by passive engineering controls that protect/function without activation | Containment dike around a hazardous material storage tank; fixed/permanent guard on a machine; hard/fixed barriers |
| Engineer with active controls | Hazards are controlled by active engineering controls that require activation to protect or function | Presence sensing devices on machines; process controls and safety instrumented systems (SISs); automatic fire suppression systems and sprinkler systems |
| Warn | Awareness device that informs or warns of residual risks by sight, sound, or touch | Forklift backup alarms; perimeter warning tape and signage; highway “rumble strips” to indicate drifting off road |
| Procedures and training | Hazards are managed by applying work procedures and worker training for safe operation of the system/workplace | Written standard operating procedures and protocols; employee orientation and training; behavior‐based safety efforts |
| Personal protective equipment | Hazards are managed by donning and wearing protective clothing and equipment to prevent or reduce contact, exposure, and impact or harm from hazards | Respiratory protection; FR/flame resistant clothing; fall protection harness and lanyard |
4 PD AND SYSTEM SAFETY
System safety can be described as the effort to make things as safe as is practical by systematically using engineering and management tools to identify, analyze, and control hazards (10). Principles or tenets of system safety described by Stephans in his book, System Safety for the twenty‐first century seem to align closely with PtD concepts found in Z590.3 and the ANSI/ASSP 31000:2018 risk management standard and are shown in Table 2 (1).
Table 2 System safety tenets and prevention through design alignment (1).