Hierarchy of Ergonomic Controls
Ergonomic solutions have different methods of implementation. Once the risk and root cause have been identified, the goal of each control is to improve the work environment by the reduction of the ergonomic risk. Depending on the situation, the assessor may choose either one or a combination of the following solutions to implement:
- Equipment/Engineering Controls
- Administrative Controls or
- Behavioural/Work Practices
A quality root cause analysis will typically steer the type of controls that are required.
Engineering controls are often the most cost-effective and the most preferred solution in the long-term because of their direct and positive effect on the user’s workstation. These do not require ongoing administrative efforts and/or costs to ensure that they are adhered to. With these solutions, you basically change or ‘engineer out’ any ergonomic concerns that you may observe or measure during the workstation assessment. The focus here is to change the workstation to eliminate or significantly reduce the exposure to the identified risk factor. Compared to Administrative or Behavioural/Work practice controls, these do not depend on the user following safe working practices as a method of injury prevention. An example of this would be replacing the user’s mouse with a more neutrally fit one.
It is important to note that in many cases a reduction of the user’s exposure to ergonomic risk factors should proportionally decrease their symptoms. There are also some cases in chronic injury or long term exposure scenarios wherein symptoms may not immediately reduce following a reduction of risk exposure. In circumstances like this, the user may need to be referred to a medical specialist.
Trial and Error
When implementing new equipment, it is ideal for the user to ‘trial’ the new device for between one and two weeks. This is a huge benefit to you if you are uncertain of the fit of the equipment or unsure if the user will like its fit or feel. This ‘trial and error’ strategy works best with mice and keyboards, since there is such a wide variety of alternatives on the market today.
Designing for the Average?
Have you ever heard the term ‘one size fits all’? This is very useful to keep in mind when looking at equipment controls, because technically an ‘average’ person does not exist. A person may be average on one or two body dimensions, but because there are no perfect correlations it is virtually impossible to find anyone who is average with respect to more than a few dimensions. This is why adjustability in any ergonomic recommendation should always be considered an option first, especially in areas such as keyboard tray height, monitor height, and chair height. Another consideration is in mouse size, especially for very large or small hands, as mice which are sized for an average hand can bring risk to those hands that are either above or below average.
2. Administrative Controls
In terms of hierarchy of ergonomic controls, administrative controls are less effective than engineering controls, but they tend to be more effective than behavioural/work practice controls. This is because the ergonomic risk is not fully eliminated. Administrative controls reduce the duration and/or frequency of the user’s exposure to the risk factor by optimizing the organization’s processes or procedures. There are many different options on how to implement administrative controls. One example of this (relating to the previous mousing example), would be to change the organization’s written policies so that job rotation or job enlargement are mandatory in order to reduce each user’s total amount of time spent mousing. This method would reduce the user’s overall exposure to the risk associated with mousing.
Behavioural/work practice-type controls tend to be the least effective because instead of eliminating the ergonomic risk (via Engineering controls) or administratively controlling the risk, the efficacy of this method is determined by the choices and habits of the user. Using these controls can add effectiveness to already established engineering or administrative controls, but it is generally advised that behavioural/work practice controls should not be the sole ergonomic control for a workstation. An example of a behavioural/work practice control would be for the user to change the way that they hold the mouse in order to reduce their exposure to ergonomic risk factors. This may be implemented with a one-on-one review of behaviours within the user’s control such as the duration and frequency of rest breaks or pro-ergonomic postures.