System used in industry to eliminate or minimize exposure to hazards
Hazard control methods at the top of the graphic are potentially more effective and protective than those at the bottom. Following thishierarchy of controls normally leads to the implementation of inherently safer systems, where the risk of illness or injury has been substantially reduced.[1]
Hierarchy of hazard control is a system used in industry to prioritize possible interventions to minimize or eliminate exposure tohazards.[a] It is a widely accepted system promoted by numerous safety organizations. This concept is taught tomanagers in industry, to be promoted as standard practice in theworkplace. It has also been used to inform public policy, in fields such asroad safety.[13] Various illustrations are used to depict this system, most commonly a triangle.
The hazard controls in the hierarchy are, in order of decreasing priority:
The system is not based on evidence about effectiveness but based on If elimination of the hazard is possible, it frees workers of being aware of the hazard and protecting themselves. Substitution has less priority than elimination because the substitute can possibly also come with a hazard. Engineering controls depend on a well-functioning system and human behaviour. Administrative controls and personal protective equipment are always dependent on human behaviour which makes these controls less reliable.
During the 1990sTB outbreak, resulting from theHIV epidemic in the United States, thehierarchy of controls was described as a way for healthcare workers to mitigate their exposure to TB. Starting from page 10, the hierarchy can be summarized, from most to least preferable, like this:[14]
"Substitution" - Avoids the hazard, which is not possible in a healthcare setting.
"Contain [the hazards] at their source" - Using administrative controls, screen for a given health hazard (in this case, TB).
This can includesource control, which can involve masking an infected patient.
"Engineering controls" - This usually involves configuring isolation rooms and HVAC systems to prevent the spread of infection.
Physical removal of the hazard is the most effective hazard control.[5] For example, if employees must work high above the ground, the hazard can be eliminated by moving the piece they are working on to ground level to eliminate the need to work at heights. However, often elimination of the hazard is not possible because the task explicitly involves handling a hazardous agent. For example, construction professionals cannot remove the danger of asbestos when handling the hazardous agent is the core of the task.[3]
This pesticide containsDDT; an effective substitution would be to replace it with agreen pesticide.
Substitution, the second most effective hazard control, involves replacing something that produces a hazard with something that does not produce a hazard or produces a lesser hazard. However, to be an effective control, the new product must not produceunintended consequences. For example, if a product can be purchased with a largerparticle size, the smaller product may effectively be substituted with the larger product due to airborne dust having the possibility of being hazardous.[5]
The third most effective means of controlling hazards is engineered controls. These do not eliminate hazards, but rather isolate people from hazards.[3] Capital costs of engineered controls tend to be higher than less effective controls in the hierarchy, however they may reduce future costs.[6] A main part of Engineering controls, "Enclosure and isolation," creates a physical barrier between personnel and hazards, such as using remotely controlled equipment. As an example,Fume hoods can remove airborne contaminants as a means of engineered control.[5]
Administrative controls are changes to the way people work. Examples of administrative controls include procedure changes, employee training, and installation of signs and warning labels, such as those in theWorkplace Hazardous Materials Information System.[3] Administrative controls do not remove hazards, but limit or prevent people's exposure to the hazards, such as completingroad construction at night when fewer people are driving.[5]
Personal protective equipment (PPE) includes gloves,Nomex clothing, overalls,Tyvek suits,respirators,hard hats,safety glasses,high-visibility clothing, andsafety footwear. PPE is often the most important means of controlling hazards in fields such as health care and asbestos removal. However, considerable efforts are needed to use PPE effectively, such as training in donning and doffing or testing the equipment.[5] Additionally, some PPE, such as respirators, increase physiological effort to complete a task and, therefore, may require medical examinations to ensure workers can use the PPE without risking their health.
The hierarchy of controls is a core component ofPrevention through Design, the concept of applying methods to minimizeoccupational hazards early in the design process. Prevention through Design emphasizes addressing hazards at the top of the hierarchy of controls (mainly through elimination and substitution) at the earliest stages of project development.[15]
While the control hierarchy shown above is traditionally used in the United States and Canada, other countries or entities may use a slightly different structure. In particular, some add isolation above engineering controls instead of combining the two.[16][17][18] The variation of the hierarchy used in theARECC decision-making framework and process forindustrial hygiene (IH) includes modification of the material or procedure to reduce hazards or exposures (sometimes considered a subset of thehazard substitution option but explicitly considered there to mean that the efficacy of the modification for the situation at hand must be confirmed by the user). TheARECC version of the hierarchy also includes warnings as a distinct element to clarify the nature of the warning. In other systems, warnings are sometimes considered part ofengineering controls and sometimes part ofadministrative controls.
ARECC - Decision-making framework and process used in the field ofindustrial hygiene (IH) to anticipate and recognize hazards, evaluate exposures, and control and confirm protection from risks
Prevention through design – Reduction of occupational hazards by early planning in the design process
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This article incorporatespublic domain material from websites or documents of theNational Institute for Occupational Safety and Health.
