In March 2016, NIOSH researchers published a paper in the Journal of Occupational and Environmental Hygiene that described the effects of collaborative robots in workplaces. The researchers observed that robots “are creating three different types of workers: (1) human workers; (2) robot workers; (3) symbiotic workers.” Symbiotic workers are those “equipped with performance-enhancing robotic devices” or exoskeletons. The potential for exoskeletons to lower risks of musculoskeletal disorders makes them attractive from a health and safety perspective; research published in the Journal of Biomechanics has shown that a passive exoskeleton could reduce low back “compression and shear forces” and “added torque to assist the back muscles during lifting tasks.” An emerging concern for worker safety and health is how to integrate this new symbiotic worker with wearable technology into the modern workplace.  A few months after publication of the JOEH paper, an article in The Synergist predicted that “industrial hygienists will soon see exoskeletons in their workplaces” and described various types of exoskeletons currently available. The article also promised that the “potential for reducing stressors on the body and preventing injuries will drive the production of exoskeletons from novel technological wonders to common ergonomic aids.” But which human jobs should be transformed into a symbiotic relationship with an exoskeleton? The response is not necessarily straightforward. “Managers and engineers establish the required task and how it shall be done [whether symbiotically], and often have control over the external environment,” according to Engineering Physiology, an ergonomics textbook. “They must adjust the work to be performed (and the work environment) to suit the operator’s physiologic capabilities.” From this perspective, jobs where traditional engineering controls or administrative controls (including work practices) did not effectively reduce the risks of musculoskeletal disorders are good initial candidates for use of exoskeletons, as are jobs that cannot be readily automated due to the current limitations of robots.
EVALUATING EXOSKELETONS Exoskeletons currently do not have regulatory or voluntary standards. However, that is changing. Several federal agencies coordinated a series of open meetings in 2017 for technical exchange leading toward voluntary consensus standards. The purpose of these standards is to ensure that products can be compared and evaluated in a consistent and reliable manner, which creates fairness and competition among manufacturers and improves market efficiency.  Engineering Physiology presents a best-practice evaluation flowchart on matching human capacity to the demands of a work task. This process can be used before and after exoskeleton deployment. The key is determining if there is agreement between human capabilities and the task’s requirements. If there is agreement, then a match is achieved. If there is disagreement, the job is a candidate for transformation into a symbiotic relationship. After transformation, the human capabilities should again be compared with the task’s requirements. The AIHA Ergonomics Committee’s Ergonomic Assessment Toolkit provides 20 tools to aid in quantifying the degree of agreement between human capabilities and a task’s requirements. Observations using tools such as the Rapid Upper Limb Assessment, the Strain Index, and the NIOSH Lifting Equation can provide information to rank tasks for possible revisions. Interviewing workers directly is also a way to understand the interaction between the task’s demands and worker capacity. The Borg Rating of Perceived Exertion and Borg CR10 are two methods to quantify workload. These tools can be used before and after exoskeleton deployment to characterize worker perceptions. A key factor in maximizing the potential value of the exoskeleton is fit. Ideally, an exoskeleton can be adjusted to align with the user’s size and shape and joint locations. This type of data (anthropometry) is “needed to make equipment and tools accommodate the human body,” according to Engineering Physiology, whose authors warn against “using the imaginary ‘normal adult’ as design prototype” and recommend recognizing the natural variability in “‘not-ordinary’ people of different body sizes, genders, ages, and abilities.” TOWARD AN EXOSKELETON CONTROL PROGRAM Whether an employer is focused on keeping the human on the task, delegating to a robot, or creating a symbiotic relationship, each condition has a different risk profile for workers. Anticipating and reducing current mismatches with an exoskeleton and specifying a symbiotic relationship can reduce risk by potentially increasing capacity. 
Exoskeletons have parallels with respirators. Both are wearable technology that create a symbiotic relationship to limit exposure to environmental stressors. 
It is useful to acknowledge that exoskeletons have parallels with respirators. Both are wearable technology that create a symbiotic relationship to limit exposure to environmental stressors. Both confront donning and doffing issues that can either limit or promote effectiveness. Both also require the complex selection of type; for exoskeletons, the choice is between passive and powered, while respirators can be half-face, full-face, powered air-purifying respirators, or supplied air respirators, and selection is related to body shape, medical clearances, and type of workplace hazards. IHs have familiarity with Respiratory Protection Programs, so applying and voluntarily transferring some key elements to an Exoskeleton Control Program can reduce the learning curve and speed more effective exoskeleton deployments in the absence of formal standards.  The following sections describe the creation and implementation of an ECP. Create a Written Program Establish a written ECP and assign an exoskeleton coordinator to oversee the exoskeleton technology lifecycle and interactions with people and the work environment. Ensure that the written ECP is properly implemented. Consult with exoskeleton users to learn their views on the ECP’s effectiveness and to share problems. Assure that exoskeleton use does not interfere with overall workplace performance.  Evaluate Need Systematically evaluate the need to establish symbiotic worker and exoskeleton relationships for tasks within the work environment. Have traditional ergonomic methods not sufficiently eliminated or mitigated the MSD risks of job tasks to acceptable levels? Is there reason to believe a new symbiotic relationship will be cost-effective and materially reduce MSD risks? What data support this, and with what degree of uncertainty? Who and what are the deployment drivers? Selection of Exoskeletons Establish a rubric to select the types of exoskeleton to potentially deploy based on the nature and extent of the ergonomic risks, work requirements and conditions, and the characteristics and limitations of the currently available exoskeletons. Partner with vendors to learn the features, costs, and potential benefits. For example, arrange with vendors to try different brands of exoskeletons for the mismatched tasks. Evaluate their functionality to mitigate MSD risks. As standards are developed and published, incorporate them into purchasing and use decisions. User Acceptance Assess user acceptance. How do workers perceive their transformations into symbionts? User acceptance of the exoskeleton is vital to maximizing the potential symbiotic benefits. Involve employees from the start. Remember that they will be wearing these devices on their bodies for hours each day. Have various exoskeleton models available for workers to try on.  Matthew Marino, the lead ergonomist at Briotix, an ergonomics firm based in Portland, Ore., cautioned against allowing workers to share exoskeletons for reasons such as hygiene and fit. “Workers don’t like the idea of wearing something their coworker has just worn without first cleaning it, which is not always possible in the work environment,” Marino said. “And once the fit is dialed in, it may be best to leave the device alone in order to prevent adjustment errors.” Factually describe the intended purpose and how the exoskeleton could benefit workers. Be cautious and do not oversell. Refer to standards as they are developed. Comply with applicable health and safety regulations.  Medical Surveillance Determine if there are medical requirements for workers’ ability to use exoskeletons. Workers assigned to tasks requiring exoskeleton use must be physically able to perform the work while using an exoskeleton. Consider that exoskeletons could add new physiological stress from the exoskeleton’s weight, heat generation, pressure points, range of motion restrictions, or new motion patterns. Implementing surveillance can help assess the short- and long-term impact of exoskeleton use. Can the worker tolerate the physiological and psychological burden of being a symbiotic worker? Provide an evaluation and ascertain readiness prior to using the exoskeleton. Re-evaluate if the task or workplace conditions change. Real-time sensor data (for example, heart rate) during use can provide insight about work demands. If you’re collecting sensor data, then develop appropriate safeguards for the medical information including who can access it and how it will be used.  Fitting and Training Properly fit the exoskeleton to workers. Understand what individual adjustments for donning and doffing may be necessary to acquire the best fit and benefit. Ideally, an exoskeleton can be adjusted to align with the user’s size and shape and joint locations.  Maintenance and Use Follow the manufacturer’s instructions for use. Establish inspection protocols before and after each use by checking function and the condition of parts including elastomeric parts for pliability and signs of deterioration. Allow sufficient time before work for the user to retrieve the exoskeleton from storage, inspect it, and don it, and then after work to doff, re-inspect, and store the exoskeleton. Also allow users time to don and doff for periodic breaks. Provide users with an exoskeleton that is clean, sanitary, and in good working order. Store exoskeletons to protect against damage and to prevent potential deformation. Training  Provide clear and comprehensive annual training about why the exoskeleton is necessary and how improper fit, usage, or maintenance can compromise its benefits. For each kind of exoskeleton used, train workers how to inspect, don and doff the exoskeleton, maintain and store the exoskeleton, and recognize medical signs and symptoms that may limit or prevent effective use (such as dermal abrasion). Program Evaluation Conduct program effectiveness evaluations in mitigating MSD risks to acceptable levels. A fundamental criterion is whether the ECP provided protection against MSDs. Did it eliminate or reduce the known risk factors? How does the ECP document the degree and type of protection?  The NIOSH paper in JOEH observed, “The greatest human judgment error results from becoming so familiar with the robot’s redundant motions that personnel are too trusting in assuming the nature of these motions and place themselves in hazardous positions.” While this caution was intended for workers interacting just with robot workers, it also applies to those in symbiotic relationships with exoskeletons. There must be ongoing evaluation of the short- and long-term interdependency of workers, exoskeletons, and the work environment. Another issue is augmentation. By allowing the physical work output to be increased, exoskeleton use could result in a “zero-sum game” if production quotas are merely increased as worker capacity is augmented. Best practices and exposure assessment methods are needed to determine the worker’s “margin of safety”—the difference between the task’s requirements and the worker’s capabilities. Without an increase in the margin of safety, the symbiotic worker and exoskeleton relationship cannot be claimed to protect or benefit worker safety and health.  PROTECTING 21ST CENTURY WORKERS The American Board of Industrial Hygiene Code of Ethics compels IHs “to follow appropriate health and safety procedures, in the course of performing professional duties, to protect clients, employers, employees and the public from conditions where injury and damage are reasonably foreseeable.” The strategy described in this article suggests a framework to begin to protect 21st century workers using exoskeletons. Standardization is a needed and important step as these technologies are commercialized. But standardization alone is not likely to be sufficient to protect workers. Industry best practices will still be important to complement emerging exoskeleton standards.  Research published in Clinical Biomechanics poses some interesting questions for reasonably foreseeable concerns, such as how the exoskeleton impacts spinal stability and fatigue, whether muscles become de- conditioned after wearing an exoskeleton, and whether exoskeleton use could result in constrained lifting or other motions. Other issues concern the accommodation of requirements under the Americans with Disabilities Act and the return to work of injured workers. Moving forward, IHs can modify the strategy outlined in this article to reduce MSD risks for symbiotic workers in their unique work environments. Exoskeletons are likely here to stay, and the time is now to prepare for their use.   ALBERT W. MOORE II, MS, CIH, CPE, CLSO, is writing as a PhD student in the Grado Department of Industrial and Systems Engineering at Virginia Tech in Blacksburg, Va. He also serves as the University Ergonomist and Laser Safety Officer for Virginia Tech. He can be contacted via email. DIVYA SRINIVASAN, PhD, CPE, is an assistant professor in the Department of Industrial and Systems Engineering at Virginia Tech. Her research focuses mainly on human factors, physical ergonomics, and biomechanics. She can be contacted via email. Send feedback to The Synergist.

Acknowledgement: The authors thank Brian Lowe of NIOSH for his invaluable assistance in developing this article.
RESOURCES AIHA: A Strategy for Assessing and Managing Occupational Exposures, 4th edition (2015). AIHA: Ergonomic Assessment Toolkit (PDF). Clinical Biomechanics: “An On-Body Personal Lift Augmentation Device (PLAD) Reduces EMG Amplitude of Erector Spinae During Lifting Tasks” (June 2006). Journal of Biomechanics: “Mathematical and Empirical Proof of Principle for an On-Body Personal Lift Augmentation Device (PLAD)” (April 2007). Journal of Occupational and Environmental Hygiene: “Working Safely with Robot Workers: Recommendations for the New Workplace” (March 2016).  NIOSH: National Framework for Personal Protective Equipment Conformity Assessment – Infrastructure (November 2017). Springer: Engineering Physiology: Bases of Human Factors Engineering/Ergonomics, 4th edition (2010). The Synergist: “Wearable Help” (May 2016).  
A Strategy to Achieve the Promise of Exoskeletons
The Symbiotic Workplace
Although the print version of The Synergist indicated The IAQ Investigator's Guide, 3rd edition, was already published, it isn't quite ready yet. We will be sure to let readers know when the Guide is available for purchase in the AIHA Marketplace.
My apologies for the error.
- Ed Rutkowski, Synergist editor
Disadvantages of being unacclimatized:
  • Readily show signs of heat stress when exposed to hot environments.
  • Difficulty replacing all of the water lost in sweat.
  • Failure to replace the water lost will slow or prevent acclimatization.
Benefits of acclimatization:
  • Increased sweating efficiency (earlier onset of sweating, greater sweat production, and reduced electrolyte loss in sweat).
  • Stabilization of the circulation.
  • Work is performed with lower core temperature and heart rate.
  • Increased skin blood flow at a given core temperature.
Acclimatization plan:
  • Gradually increase exposure time in hot environmental conditions over a period of 7 to 14 days.
  • For new workers, the schedule should be no more than 20% of the usual duration of work in the hot environment on day 1 and a no more than 20% increase on each additional day.
  • For workers who have had previous experience with the job, the acclimatization regimen should be no more than 50% of the usual duration of work in the hot environment on day 1, 60% on day 2, 80% on day 3, and 100% on day 4.
  • The time required for non–physically fit individuals to develop acclimatization is about 50% greater than for the physically fit.
Level of acclimatization:
  • Relative to the initial level of physical fitness and the total heat stress experienced by the individual.
Maintaining acclimatization:
  • Can be maintained for a few days of non-heat exposure.
  • Absence from work in the heat for a week or more results in a significant loss in the beneficial adaptations leading to an increase likelihood of acute dehydration, illness, or fatigue.
  • Can be regained in 2 to 3 days upon return to a hot job.
  • Appears to be better maintained by those who are physically fit.
  • Seasonal shifts in temperatures may result in difficulties.
  • Working in hot, humid environments provides adaptive benefits that also apply in hot, desert environments, and vice versa.
  • Air conditioning will not affect acclimatization.
Acclimatization in Workers