As you learned earlier, there are many different types of hazards in the workplace. Hazardous conditions include unsafe materials, equipment, the environment, and employees. Unsafe work practices include: allowing untrained workers to perform hazardous tasks, taking unsafe shortcuts, horseplay, or long work schedules. To combat these hazardous conditions and unsafe work practices, control strategies referred to as the "Hierarchy of Controls" have been developed.
Traditionally, a hierarchy of controls, listed from most to least effective, has been used as a means of determining how to implement feasible and effective controls. ANSI Z10, Occupational Health and Safety Management Systems, encourages employers to employ the six hazard control strategies.
The idea behind this hierarchy is that the control methods at the top of the list are usually more effective and protective than those at the bottom. Following the hierarchy leads to the implementation of inherently safer systems, ones where the risk of illness or injury has been substantially reduced.
For more information on evaluating safety management systems, see OSHAcademy Course 716, Safety Management System Evaluation, and OSHAcademy's Ultimate Safety Management System Audit.
Let's take a closer look at the hierarchy of control strategies.
Hazard abatement (reduction) measures required to prevent a hazard should be technologically and economically feasible (reasonable) for the employer. This means that the measures required to prevent a possible hazard should be 1) possible given currently available technology, and 2) financially reasonable.
OSHA uses the following criteria to determine the feasibility of hazard controls:
Elimination and substitution, while most effective at reducing hazards, also tend to be the most difficult to implement in an existing process. If the process is still at the design or development stage, elimination and substitution of hazards may be inexpensive and simple to implement. For an existing process, major changes in equipment and procedures may be required to eliminate or substitute for a hazard.
Safety professionals consider these strategies first because they can completely eliminate the hazard. Eliminating the hazard will also eliminate the possibility of exposure to the hazard.
When using elimination, the hazard is completely removed, making it impossible for an accident to occur. The hazard is not simply reduced, but it is completely eliminated.
When using substitution, the hazard is reduced or eliminated by using a less hazardous component. Although it is possible to eliminate the hazard, the substitution method does not necessarily eliminate the hazard. This is why the elimination is preferred over substitution.
Some examples of these two strategies include:
The basic concept behind engineering control strategies is that, to the extent possible, tools, equipment, machinery, and work environment should be designed to eliminate or reduce exposure to hazards. While this approach is called engineering controls, it does not necessarily mean that an engineer is required to design the control.
Some examples of this strategy include:
When you cannot remove a hazard or replace it with a less hazardous alternative, the next best control is enclosure. Enclosing a hazard usually means that there is no hazard exposure to workers during normal production operations.
There may be potential exposure to workers during maintenance operations or if the enclosure system breaks down. For those situations, additional controls such as safe work practices or personal protective equipment (PPE) may be necessary to control exposure.
Some examples of enclosure designs are:
When the potential hazard cannot be removed, replaced, or enclosed, the next best approach is a barrier to exposure or, in the case of air contaminants, local exhaust ventilation to remove the contaminant from the workplace.
This engineering control involves potential exposure to the worker even in normal operations. Consequently, it should be used only in conjunction with other types of controls, such as safe work practices designed specifically for the site condition and/or PPE. Examples include:
With the release of ANSI Z10-2012, "warnings" have been promoted to their own hierarchy level. Previously they were considered part of administrative controls. Warnings do not prevent exposure to a hazard, but they do provide a visual or audible indicator to warn people of potential danger.
Warnings can be either visual, audible, or both. They may also be tactile. Some examples of warnings are:
For instance, a door could have both a sign warning of a hazard as well as an alarm if opened. Warnings can be effective deterrents, but are not as effective as elimination, substitution, or engineering controls.
OSHA's 1910.145, Specifications for accident prevention signs and tags details the following types of signs:
One potential problem when using warnings is the misinterpretation of the warning itself. Does the symbol or text clearly explain what the hazard is to the public? For example, if a sign only contains a written warning, someone might read the sign but not know what the warning actually means. Or, if an alarm sounds, what does the alarm mean? These are challenges when using warnings and why they are not as effective as higher-level controls.
Administrative controls are developed by management for the purpose of preventing or reducing exposure by controlling behaviors that may result in exposure to hazards. These controls are needed when hazards can't be adequately eliminated or mitigated through elimination, substitution, and engineering controls.
Administrative controls are policies, programs, processes, procedures, and practices that include the following examples:
Be careful to distinguish rules from guidelines when developing administrative controls. It's important to understand that mandatory safety "rules" are required and must be followed. On the other hand, discretionary "guidelines" are voluntary. Safety managers may be justified when disciplining employees for non-compliance with rules, but they are not justified in disciplining if employees choose not to follow guidelines.
Ultimately, effective administrative controls are only as effective as the safety management system that supports them. It's always better to eliminate the hazard so that you don't have to rely on administrative controls that tend to work only if employees behave.
Safe work practices may be quite specific or general.
In terms of scope, safe work practices may be a very important part of a single task or applicable to many jobs in the workplace. Here are some examples of safe work practices:
When a hazard is recognized, the preferred correction or control cannot always be accomplished immediately. OSHA believes there is always some kind of interim measure that can be used to temporarily abate a hazard. These can range from taping down wires that pose a tripping hazard to actually shutting down an operation temporarily.
The importance of taking these interim protective actions cannot be overemphasized. There is no way to predict when a hazard will cause serious harm, and no justification to continue exposing workers unnecessarily to risk.
When engineering, work practice and administrative controls are not feasible or do not provide sufficient protection, employers must provide PPE to their employees and ensure its use. PPE is actually used primarily in conjunction with other controls.
It's important to remember that, like administrative controls, the use of PPE does not control the hazard itself, but rather it merely controls exposure to the hazard by setting up a barrier between the employee and the hazard. Use of PPE may also be appropriate for controlling hazards while engineering controls are being installed or work practices developed.
We'll cover PPE in more detail in the next module.
For more information on PPE, take OSHAcademy Course 700, Personal Protective Equipment, and see OSHA's Publication 3151, Personal Protective Equipment.
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