as a control barrier to eliminate potential exposures. An EA would now need to consider the hood's ventilation exhausting the chemical into the air and may require additional barriers to comply with local, regional, or national regulations. An OS may act more locally in considering whether the chemical's vapors may create flammability or electrical concerns inside the hood and may have barrier requirements to prevent these potential central events. Whether acting within these EHS disciplines, or acting as a singular EHS Generalist, all of these decisions will be based on potential risk. This figure clearly illustrates how communication of this risk is just as important for convincing management that investment in these barriers and their maintenance over time is necessary as it is for training workers that the proper use of these control barriers is essential.
Figure 2 Bow‐tie presented in a multidisciplinary format.
Looking at each of the EHS professions separately, this left‐side preference in (Figure 2 can also be seen in ergonomics, where the multiple strategies for controlling musculoskeletal risk factors can be seen as left‐side barriers 14, 15). However, an IH does not see work‐related risk prevention in the same manner. Chemical exposures are seen as the central event, and in most instances, their emission, the right side, is expected and full enclosure, elimination, and substitution are the only left‐side components. EAs are quite like IHs in this respect as both professions accept some level of exposure, whether to workers or the environment, as long as they are kept below regulatory limits or OELs by utilizing the barriers on both the left and right side of the central event. OPs also are more applied on the right side of the bow‐tie, perhaps even more so as they most often see patients that are experiencing signs of pending injury or illness or have already acquired adverse consequences. In fact, the OP and the services they offer can be seen as an effective right‐side barrier themselves, with medical surveillance blood draws, hearing tests, and respirator use examinations as examples. Although they are certainly key players for identifying the need for EHS expertise to assess and intervene in workplaces with identified issues, the OP's primary left‐side barrier utility is for their influence on job selection and allocation as examples of preventative actions. Therefore, when the bow‐tie is viewed as a multidisciplinary model for simplified risk communication, for the role of barriers to workers and management alike, it can be seen as a progressive process in which EHS disciplines unite to seek prevention and mitigation of unwanted work‐related injury, illness, or disease consequences (11).
4 CONTROL BANDING AS RISK COMMUNICATION
Control banding (CB) is a qualitative occupational risk assessment strategy developed as a simplified approach to reduce work‐related injury and illness (11, 16). This model presents a complementary, graded approach that provides an effective means for determining standardized responses and controls for common work‐related issues, including environmental issues, that take into account the level of risk. This simplified approach with standardized outcomes is at the foundation of the CB strategy also serving as an effective risk communication approach. To better understand its historical background, the banding of occupational risks began in the 1980s for explosives events, radiation, lasers, and biological agents and in the early 1990s, the qualitative risk assessment process of CB was developed to control potential chemical exposures to workers in the pharmaceutical industry (17, 18). Beginning in the 2000s, CB models for chemical agents became internet‐based and their popularity grew in the IH profession internationally. Toward the end of that decade, CB became an essential component for assessing and controlling exposures in the nanotechnology industries, as it was a logical and proven approach to utilize in the absence of information, as can also be seen with OELs and regulations . In the 2010s, multidisciplinary CB strategies are being designed for integration within standardized occupational health and safety management systems (OHSMS) like ISO 45001 and OSHAS 18001 standards and Environmental Management Systems like ISO 14001 with the goal of providing a unified environmental and occupational risk management (EORM) approach (10, 11, 22).
4.1 Traffic Light Approach
The individualized CB models for chemical agents are commonly known as toolkits and were often developed with the IH profession in mind, however, the derivative structure of these models showed potential for other EHS professions. For many of the toolkits currently available, the art of qualitative risk assessment is quite basic (23). A hazard is defined and considered, the level of risk is stratified to a minimal number of components, and the commensurate controls necessary to reduce each risk level (RL) to an acceptable outcome becomes the output. Determining the number of RLs, which fits the concept of bands or binning, is a result of balancing the intricacy or complexity of the hazard with the needs of the worker. Throughout this process, keeping in mind that the worker is the end‐user of the method is often the most difficult thing to remember.
Theoretically, for the worker, there is a functional understanding that there are two RLs relating to their tasks when performing work; one that is unsafe and should not be done (red light) and one that is safe and should be done (green light). In practice, this is not the case, as it is commonly presented as three levels of risk as in the common safety control approach found in the red, yellow, and green lights of automobile traffic signals around the world. However, this approach has been found in practice to have its limitations with the middle, yellow light option leading to inappropriate judgment over a wide range of risk as it can cover a wide range of often frequent, adverse outcomes. The red/stop and green/go signals are an easily understood and objective risk communication that is readily followed by drivers. However, the subjective responses to yellow lights can vary from slowing down, to speeding up, and often involves some aspect of looking around for police before deciding to slow or speed through the intersection. In fact, this checking for “police” before deciding to comply with a safety measure is an excellent analogy to workers considering the potential presence of EHS professionals in the workplace within their decision to use establish risk reduction controls.
4.2 Risk Matrix Communication
To cope with this ambiguous middle band, the classic CB delineation of bands, or RLs tends toward four as it divides the yellow light in two and provides a better decision matrix to ensure the commensurate controls are in place. This is the basis of the standardized four‐by‐four risk matrix using inputs of relative severity and probability (Figure 3). It is a popular basis for CB models, but is also used throughout industry, in project management, and in corporate board rooms, providing a simple mechanism to increase visibility of potential impact, eases communication of risks, and assists in all manners of decision making. From the CB model perspective, it is all about scaling prevention to a given situation in a toolkit designed as a complement to the EHS professions, rather than a replacement. The more difficult a toolkit is perceived to be in its conceptual phase, the less likely it is to make it to the development phase. Therefore, limiting the number of factors within a given CB model to four on each axis avoids the “yellow light” objectivity, reduces its complexity, and increases its applicability for nonexperts. With severity and probability input factors tailored to a given workplace hazard, the RL1–RL4 risk matrix outcomes are provided in a graded approach that is paired with commensurate controls to reduce the risk of the given workplace‐related hazard. For the many chemical agent CB models used as an example, these four control strategies are a grouping of three levels of engineering controls based on sound IH principles: general ventilation (RL1), local exhaust ventilation or fume hoods (RL2), containment (RL3), and professional IH expertise for the RL4 category. Commonality of form and function, toward identifying and reducing workplace‐related risks and controlling and reducing injuries and illnesses, has built international demand for simplified approaches to banding risk 24).