The Science of Keeping Workers Safe
Ergonomic safety has had a profound impact on the utility industry over the last decade, without many workers even knowing it. Yet as professional tool ergonomists, we have seen many erroneous “ergonomic” product claims over the years, so in this article we want to highlight the importance of knowing how ergonomic products are measured and if the tools you’re using are truly advancing ergonomics at your company.
Before we dive into the technical aspects of ergonomic measurements, let’s review some background information. OSHA continues to define line work as a high-risk occupation in terms of the risks of electrocution, falls and human error, but also in terms of risks for musculoskeletal disorders and ergonomic injuries. The agency has gone so far as to say that one in three injuries is an ergonomic injury. Examples of these injuries include carpal tunnel syndrome, rotator cuff tendinitis, elbow epicondylitis (tennis elbow) and trigger finger tendinitis.
These injuries translate into an incredible number of dollars spent by employers. According to the 2017 Liberty Mutual Workplace Safety Index, U.S. businesses spend more than a billion dollars a week on serious, nonfatal workplace injuries. Of the billion dollars a week, over 20 percent of the injuries – which account for nearly $14 billion a year – are directly attributed to overexertion involving outside sources.
Objectively Measuring Ergonomics
Based on the information presented above, it’s clear that quality workplace ergonomics are good for both employee health and an employer’s bottom line. But while almost every tool manufacturer talks about ergonomics, are their claims about ergonomics true or just a marketing stunt? It’s important to understand how a company tests their products prior to purchasing them. The truth is that some tool manufacturers have not measured ergonomics at all, some outsource the measurement process and some do partial measurements but don’t perform the complete process. At Milwaukee Tool, not only do we conduct measurements in-house, but we also have teams of subject matter experts who implement ergonomic designs into the tools utilities use every day.
Objectively measuring ergonomics is a very precise task. Some ergonomic risk factors to look for in your tools are high levels of noise, vibration and required force. While some exposure to these risk factors isn’t necessarily hazardous, exposure to high thresholds of these categories puts workers at serious risk for eardrum damage, vibration-induced white fingers, trigger finger tendinitis and carpal tunnel syndrome, among others.
Noise
Oddly enough, measuring noise is a quiet task. It is measured in decibels (dBA) and has a finely set exposure limit. Methods for determining sound power level are set by the International Organization for Standardization (ISO). A normal conversation produces approximately 65 dBA whereas headphones at a high volume produce an output of approximately 105 dBA. While a 40-dBA increase may not seem like a lot, perceived sound power doubles at about 10 dBA, so compared to a normal conversation, on average headphones at a high volume double four times in perceived sound. At 100 dBA, OSHA recommends only a two-hour exposure before hearing protection is required (see the “Permissible Noise Exposures” table at OSHA 29 CFR 1910.95(b)(2)). After two hours of continuous exposure, the risk for eardrum damage – referred to as acoustic trauma – is present.
To help those who are concerned about the impact of noise, NIOSH has released a free sound-level meter app that users can download on their smartphone to measure noise exposure. This helps to promote and raise awareness of hearing health. See https://blogs.cdc.gov/niosh-science-blog/2017/01/17/slm-app/ for more information.
At our company, product sound power tests are conducted in one of the industry’s largest, fully isolated, hemi-anechoic sound chambers. Signals are recorded and processed with powerful software that was developed with nearly unlimited capabilities in the sound/vibration realm. The chamber can assess excessive sound by measuring that information directly, producing the frequency-domain plots of the data and thus enabling engineers to determine the root cause of the problem. Once assessed, work can be done to develop tools with reduced dBA output, such as Milwaukee Tool’s M18 FUEL SURGE Hydraulic Driver. The driver’s output is 76 dBA, which means it can operate continuously for an eight-hour day without the need for hearing protection and without the risk for acoustic trauma.
Vibration
A vibration can be as minimal as your cellphone’s ringtone or as great as the continuous use of a jackhammer. There are two main types of human vibration: whole-body vibration, during which the vibration is transmitted through the entire body, and hand-arm vibration, in which the vibration is transmitted only to the hands and arms, such as when using a hand-held power tool.
Measurements of vibration are conducted using accelerometers, which independently measure three axes of direction of vibration. Through the use of accelerometers, ergonomists can smooth out signals, integrate and differentiate signals, automatically apply any type of audio weighting and apply many types of tachometer inputs. They also can calculate all psychoacoustic metrics to audio data; psychoacoustics can measure sharpness, specific loudness and articulation index, and determine if masking is occurring on acoustic signals.
Force
One of the most accurate ways to measure force is with a high-capacity testing system. This type of equipment can measure pounds of force (lbf) upward of 135,000 lbf. If the triggers on the tools you were using required that much force, you would not be able to use the tools anymore.
Force testing at a tool company can be used to measure connector and wire strength and failure loads, as well as trigger engagement and retraction force. Using tools with over 12 tons of hydraulic pressure can build up a lot of resistance and provide a breeding ground for trigger finger tendinitis. By utilizing closely monitored methods at our facility, we were able to reduce trigger force retractions using a 12-ton tool to just under 8 lbf. Compared to competitive tools that require upward of 35 lbf to retract the same process, this tool significantly reduces the risk for trigger finger tendinitis and improves safety to users.
The time it takes to complete a force test can range from hours to weeks depending on the testing procedure. While other load frames measure force, the testing system at our facility can deliver data to help improve ergonomics, user interface and safety in a unique way. Accuracy is high, and the instrument and all sensors are calibrated annually to ensure the accuracy of force, displacement and velocity measurements during testing. The software is able to perform many calculations – including slope/intercept, modulus and percentage yield – plot test data and readily export preformatted reports summarizing the data and results of any calculations. These features help engineers optimize ergonomics and calculate injury reductions.
Leaving Subjectivity Behind
Historically, ergonomics has been a subjective measurement. The best ergonomic tool companies leave subjective viewpoints out of their data collection and design and have turned to an ergonomics innovation referred to as electromyography, or EMG. This process uses the electrical activity produced by a person’s skeletal muscles to record muscle effort during a tool’s use. When companies invest in this technology and bring on an experienced team of certified ergonomists and other subject matter experts to focus on tool ergonomics, they begin to acquire large amounts of objective feedback about the topic. This information can help them design, develop and manufacture the safest tools. With the ability to measure up to 108 unique muscle groups throughout the body, the use of EMG technology to produce tools that reduce peak muscle efforts and fatigue is helping utility and other workers age and retire with greater strength and health.
Focusing on Price, Health
For years tool companies have been making investments into the ongoing improvements of tool safety. For any companies that focus primarily on price point, opting for less expensive tools may solve a short-term need, but a safety-focused company’s primary goal should be buying tools that keep workers safe and healthy.
In addition, workers are demanding attention to their ergonomic health and want objective data to back up the claims of ergonomic tool manufacturers. Forward-thinking manufacturers have made improving ergonomics a priority. Through improving acoustic safety, reducing vibration risks, decreasing trigger force and measuring muscle effort and fatigue, these manufacturers are making the job site safer for field workers – one tool at a time.
In closing, given the investments that some of the world’s biggest tool companies have made into objectively measuring ergonomics, and given the worker demands mentioned above, today we find ourselves asking the following questions: When will OSHA once again make ergonomic standards to protect workers in the workplace? When will they make ergonomics mandatory, not optional?
About the Authors: Raffi Elchemmas, MBA, AEP, is an industry-leading ergonomist with board certification in professional ergonomics. He completed degrees in kinesiology at Michigan State University and an MBA in health sector management at DePaul University in Chicago. Elchemmas has worked in the tool industry for his entire career, helping to disrupt the injury-prone environment by reducing thousands of work-related ergonomic injuries; he also has helped to quantify millions of dollars in customer savings through ergonomics. After his post-graduate studies in ergonomics at Harvard University, he joined Milwaukee Tool to help reduce and eliminate ergonomic tooling injuries worldwide.
Sarah Hall is a trained ergonomics technician and technical specification manager at Milwaukee Tool. She completed her degree at San Diego State University and has spent a great deal of time focused on tool use injuries, reducing job site accidents and improving productivity. Her specialized training in finance allows Milwaukee Tool to quantify the benefit of ergonomic safety and prove the ROI of tool safety. Hall has worked in the tool industry for six years, helping to improve tool design, quality and overall user experience.