Accelerating Toward New Hazards
Protecting Workers During the Transition to Electric Vehicles
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In April 1896, the Swedish physical chemist Svante Arrhenius published the paper “On the Influence of Carbonic Acid in the Air Upon the Temperature of the Ground” in the Philosophical Magazine and Journal of Science. Arrhenius laid out a series of calculations showing that an increase in atmospheric carbonic acid would result in an increase of temperatures on the ground. Arrhenius gave the effect in advance of the cause, and his paper was at first largely ignored.
THE EARLY AUTOMOBILE At the time, the automobile was just beginning to become established as a means of transport that could replace the horse, and many types of self-propelled vehicles were being tested and developed. Henry Ford is quoted, likely apocryphally, as having said “If I had asked people what they wanted, they would have said faster horses” when asked about his commitment to the automobile. Today, some would argue that the climate would have been better off if we had stuck with “horse power” instead of horsepower.
However, what would power Ford’s Model T—and replace our beasts of burden—was an open question in the late 1800s and early 1900s. The three main options for propulsion were steam, electricity, and gasoline. Steam-powered vehicles required a considerable amount of fuel and had a nasty habit of exploding. Gasoline-powered automobiles were prone to breakdowns and vibration and needed a hand crank to start. Electric vehicles at the time required enormous batteries, had short range, and required frequent charging. The discovery of vast quantities of oil in the United States, in conjunction with Ford’s mass production line and the lack of charging facilities, established hydrocarbons as the fuel of choice for the next 100 years. Electric vehicles became a novelty, an outlier on America’s highways and streets, and the atmospheric carbon dioxide concentration began to climb.
THE RESURGENCE OF THE ELECTRIC VEHICLE Fast forward to early 2021 and the United States Department of Transportation has committed to spending billions of dollars to subsidize the construction of an electric vehicle charging network across America. The U.S. government further committed to transitioning the federal vehicle fleet—some 645,000 cars, trucks, and other automobiles—to zero-emission vehicles. In addition, other state and national governments have made ambitious commitments to phasing out internal combustion engines entirely. General Motors has committed to selling only zero-emission vehicles by 2035; Ford recently released an all-electric version of the most popular truck in North America, the F-150; and Lamborghini has committed to making all its vehicles at least hybrid-electric by 2024. Rivian, an electric vehicle manufacturer, has focused mainly on small trucks and SUVs and plans to release an electric delivery van in 2023. A belief in climate change isn’t necessary to see the resurgence of the electric vehicle on the horizon.
In 2010, too few battery-electric vehicles (vehicles powered exclusively by batteries, usually lithium-ion), or BEVs, were purchased in America to be noted in the Bureau of Transportation Statistics report on new vehicle sales; by 2019, annual sales had grown to 242,000 vehicles, with hybrid-electric selling an additional 500,000. In 2019, this represented approximately five percent of all light-duty vehicle sales. In March of this year, 122,000 hybrid and battery-electric vehicles were sold, making up 7.6 percent of the total light-duty vehicle market—a new record high. While these numbers point to a new answer to Henry Ford’s initial question, the rate of growth in BEVs over the last decade will have to be maintained—if not exceeded—over the next decade to meet the conversion goals currently being established in various countries. This rate of growth presents challenges for workers, companies, and the occupational health professionals who work within them.
To mitigate the potential for thermal runaway and to limit the damage that a fire might cause, care must be taken in the design and use of electric vehicle charging locations.
NEW HAZARDS Substitution is high on the hierarchy of controls, but it may introduce other hazards in place of the original. In the case of substituting electric motors for internal combustion engines, the most obvious new hazard is the presence of a high-voltage, direct current battery supplying power to the motor or motors. The ability to store enough energy in a small-enough battery to make long-range travel and fast charging practical is one of the challenges that doomed early electric vehicles and tipped the advantage to the internal combustion engine. Relatively recently, battery technology advanced enough to allow for practical use of electric cars by everyday drivers.
Most lithium-ion batteries follow roughly the same principles of construction and operation. Small cells, slightly larger than AA batteries, contain a positively charged cathode and a negatively charged anode, with a plate separating them. These individual cells—thousands of them in a typical electric vehicle battery—are interconnected and make up the overall battery pack of the vehicle. The anode, cathode, and separator of each cell are immersed in an electrolyte containing positively charged lithium atoms. During charging, lithium atoms in the electrolyte are forced from the cathode to the anode to create chemical potential energy; when the battery is discharged, lithium atoms flow from the anode to the cathode, creating an electrical current.
Electric shock is most likely when the battery pack has been damaged and the engineered safety features have been disabled through damage to the electrical isolation system. First responders are at the highest risk of being exposed to damaged batteries, and the risks associated with responding to electric vehicle crashes have been well established by the National Transportation Safety Board. To allow for electrical isolation, electric vehicles are equipped with easily accessible cut-loops that first responders sever to isolate the battery; however, the battery remains energized and still contains stored energy, representing an electrical hazard.
Currently, damage to batteries occurs most often during vehicle crashes, but the expansion of electric vehicles into commercial applications will likely result in more day-to-day damage due to wear and tear associated with heavier use. Companies will need to determine what level of response and maintenance they are comfortable performing on the vehicles themselves as well as the precautions necessary to do that safely. One of the main features of electric vehicles is that they require less maintenance than internal combustion vehicles, but less maintenance does not mean zero maintenance. Maintenance programs will need to be revised and updated as electric vehicles become part of an organization’s fleet.
Another hazard associated with the use of BEVs is “thermal runaway,” when a fire is caused by an individual battery cell overheating due to damage. During thermal runaway, the flammable electrolyte solution combusts, breaching the battery cell walls due to gas expansion, then vents, ignites, and spreads to adjacent cells in a runaway reaction. These fires are rare and usually happen after a crash but may also develop due to hidden damage to the cells caused by battery abuse (mechanical, electrical, or thermal) and overcharging. One of the more notable examples is the lithium-ion battery fire aboard a Boeing 787-8 airliner in 2013 that the National Transportation Safety Board indicated was partly due to thermal runaway caused by manufacturing defects in the battery. Battery fires are notoriously difficult to extinguish and can flare up well after suppression activities have stopped unless they are continuously monitored.
Thermal runaway is preceded by the venting of gases from the failing battery cell; therefore, primary prevention requires early detection of the vent gases that precede ignition and the subsequent fire. Recent literature published in the February 2021 issue of eTransportation on the early detection of thermal runaway (see “Detection of Li-Ion Battery Failure and Venting with Carbon Dioxide Sensors”) indicates that voltage change is not a reliable indicator of damage within the battery. The authors suggest the placement of a CO2 sensor at the battery pack vent channel to detect early signs of thermal runaway.
The specific components of each vehicle company’s battery are proprietary, but a working number indicates that in the electrolyte solution, Tesla’s Model S battery contains the equivalent of approximately 12 kilograms of pure lithium; the cathodes contain up to approximately 20 kilograms of cobalt along with nickel and manganese. In the event of a fire, the generated smoke will contain a mixed assortment of compounds based on these materials, and—in addition to volatile organic compounds generated during combustion—other gases of concern released during a thermal runaway can include fluorinated compounds such as hydrofluoric acid.
To mitigate the potential for thermal runaway and to limit the damage that a fire might cause, care must be taken in the design and use of electric vehicle charging locations. This will be complicated due to the speed of the transition; many companies and organizations that move to electric vehicles will have to renovate and retrofit their current locations rather than design and construct a purpose-built facility. In many cases, electric vehicles will be shoehorned into existing infrastructure designed for internal combustion vehicles.
In addition to the hazards of the battery, depending on the type of electric motor used by the manufacturer, there may be permanent magnets in the vehicle. Maintenance personnel with pacemakers or other medical implants may be at risk if they come in close contact with these magnets during their work.
The implementation of an electric vehicle fleet will require a recognition and evaluation of the existing infrastructure and its limitations. Too often, design is done in a silo apart from a rigorous evaluation of health and safety concerns and results in a workspace that did not adequately consider the needs and safety of the worker. An organization considering a switch to electric vehicles—really, that’s most organizations; BEVs are coming, whether by choice or as wide societal adoption leads to them becoming commonplace—requires safety professionals to begin considering what that means for the workforce.
It can be imagined that more health and safety manuals will soon include a “BEV management program” or “electric vehicle safety” sections outlining the requirements for purchase, driving, maintenance, charging, disposal, and emergency response. Guidance on some of these issues is provided by bodies such as the American National Standards Institute and Underwriters Laboratories, but health and safety professionals will have to guide the implementati0n and development of the programs as well as train a workforce naïve to these new BEVs.
A FUNDAMENTAL CHANGE The adoption of electric vehicles is widely seen as a major step toward the elimination of vehicle emissions and as a partial solution to global warming. In reality, the elimination of internal combustion engines is a substitution, and significant hazards will replace the ones industrial hygienists and safety professionals have been familiar with for the lifespan of the gasoline engine. In addition to vehicles, large lithium-ion batteries will become common in buildings as renewable energy use increases the need for storage and capacity. The transition to electric is one of monumental scope, and it is being carried out with unprecedented (and necessary) speed to address climate change. The anticipation, recognition, evaluation, and control of hazards associated with this transition will be of considerable importance and a challenge to occupational health and safety professionals.
Arrhenius anticipated the hazard of carbon dioxide emissions to the temperature of the earth; others recognized and evaluated it, but it has taken us until now to try and control it in a meaningful way through a fundamental change in our vehicles and, by extension, virtually every aspect of our society. Skepticism in the adoption of battery-electric vehicles might have been justified in the past, but today it is clear what people are asking for, and it isn’t faster horses. Our challenge is to anticipate the speed bumps and reduce the potential for injury and illness resulting from the transition.
RYAN CAMPBELL, CIH, CRSP, is a senior occupational hygienist with NorthStar Occupational Hygiene & Safety in Calgary, Alberta.
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National Fire Protection Association, Fire Protection Research Foundation: “Lithium-Ion Batteries Hazard and Use Assessment” (PDF, 2011).
National Transportation Safety Board: “Safety Risks to Emergency Responders from Lithium-Ion Battery Fires in Electric Vehicles” (PDF, 2020).