Dwindling fossil fuel resources and continued climate change have encouraged the development of new propulsion technologies, mainly in the automobile sector. The electrification of vehicles reduces CO2 emissions and is relevant to attainment of the predefined climate targets throughout the European Union. Electromobility implies a fundamental change of system, in turn representing a major challenge for occupational safety and health. The following article describes the OSH risks encountered throughout the life cycle of electric vehicles. It depicts which sectors and workers are particularly affected, what prevention measures are required and where future demand for action is likely to arise to ensure safe handling of electric vehicles.
The term electromobility (e-mobility) denotes the application of electric propulsion for the transport of people and goods. Automotive engineering offers three main types of electric vehicles (EV):
- those that are fully battery-powered (BEV);
- those that are powered by an on-board electrical generator, such as an internal combustion engine (a hybrid electric vehicle, HEV) or a hydrogen fuel cell;
- and finally those that are powered by stored electricity originally generated by an external power source, termed plug-in hybrid vehicles (PHEV), which utilise rechargeable batteries.
Electric vehicles can furthermore be equipped with additional onboard recharging units (“range extenders"). These are generally small internal-combustion engines with a generator.
Although the focus lies upon electric cars, commercial vehicles such as lorries or buses can also be propelled by electricity, as can bicycles (pedal electric cycles or “pedelecs"). Supercapacitor technology is deployed for this purpose, e.g. on hybrid buses or garbage-collection trucks. These capacitors, also referred to as ultracapacitors, represent a novel type of electrochemical technology. Unlike batteries, supercapacitors can be charged and discharged in seconds and can withstand many thousands of such charging cycles.
In the automotive sector, particularly in hybrid and fuel cell technology and on electric vehicles, high voltage (HV) systems comprise voltages >60 V and ≤1,500 V direct current (DC) and >30 V and ≤1,000 V alternating current (AC). Most electric vehicles are equipped with high voltage systems, and commercial vehicles may employ up to 1,000 V DC .
Electric drive – what is new?
Electromobility is a novel technology implying a fundamental change of system. The relevant differences between it and conventional technology relate to the basic components of an HV system: a rechargeable battery serving as energy storage, the electric motor for transformation of the electric energy into motive force, and enhanced power electronics. The battery technology primarily used in electric vehicles is the lithium-ion battery. Alternatively, nickel-metal hydride (NiMH) batteries may be used (predominantly in hybrid vehicles), as may (super)capacitors.
The transition from conventional mechanical components to electrical elements gives rise to a pivotal change in supply-chain relationships within the automotive sector. Electric propulsion technologies will also result in changes. The development of new materials (e.g. carbon composites) for lightweight vehicle bodies is vital in order for electric vehicles with an acceptable cruising radius to be manufactured. Additionally, high numbers of electrical connections between electrical and electronic components result in development of new types of high-voltage plug connectors.
The application of these and other elements, together with the switch to new modes of production, inevitably affects working conditions and can also lead to greater risks, all the more so with the onset of series production. Electric drive technology will in due course also directly affect other sectors such as car repair shops, servicing, and recycling and disposal. OSH aspects must be addressed in all these sectors at an early stage in this developing area. Aspects relating to vehicle safety, road safety and accidents must also be taken into consideration well in advance in this growing market.
Role and impact of e-mobility
The European Commission regards the electrification of transport as a major topic for the foreseeable future, and the Directive on the Promotion of Clean and Energy Efficient Road Transport Vehicles aims at broad market introduction of environmentally friendly vehicles . The Commission is engaged in research and development activities, and for example is promoting the European Green Cars Initiative  as part of the European Economic Recovery Plan  and the Europe-wide electromobility initiative, Green eMotion, worth €41.8 million .
Greening road transport is vital to achieve EU and world targets in emissions reductions, to ensure energy security and to minimise the EU’s growing dependency on primary energy sources. In the EU, 73% of all oil and approximately 30% of all primary energy is consumed by the transport sector . Correspondingly, almost 30% of carbon dioxide emissions are linked to the transport sector and in contrast with the general decline in emissions in the European Union, there is high growth in both passenger and freight transport . Electromobility is a future-oriented technology which is considered appropriate for ensuring private and public mobility whilst at the same time reducing the climatic impact and enhancing the long-term sustainability of energy supply by the use of renewable energies. However, electromobility can achieve its environmental advantages only by exploiting electricity from renewable power sources. The major technical obstacle to its widespread adoption is the availability of efficient, safe, and cost-efficient batteries. The restricted lifetime of most batteries not only reduce consumer acceptance, but may also have a negative environmental impact owing to the amount of scarce materials needed and the substances involved that may be hazardous to human health and the environment.
Electric vehicles have a high overall energy conversion efficiency ('well-to-wheels' analysis). Their partial efficiency when generation of the source power is disregarded ('tank-to-wheels' analysis) is in fact around three times that of internal combustion-engined vehicles; a substantial contribution to the reduction of CO2 emissions is therefore possible . The whole spectrum of renewable energies can be utilised to provide the electricity to charge the batteries. The transport sector, vulnerable to oil supply disruption and price volatility, can progressively become independent of fossil fuels.
Furthermore, electrically powered vehicles emit no tailpipe carbon dioxide or pollutants such as nitric oxide and nitrogen dioxide (NOx), non-methane hydrocarbons (NMHCs) and particulate matter (PM). Electric vehicles are ultimately ideal for urban transport, providing quiet and smooth operation. They substantially reduce exposure to noise and vibration and consequently allow for a greater proportion of freight transport within urban areas to take place at night. This would ease the problem of road congestion during rush hours . The oils and lubricants needed for combustion engines are superfluous in strictly electrically propelled vehicles, making maintenance and repair activities cleaner and less harmful to health.
OSH implications at all stages of the vehicles’ life cycle
The danger potential of electromobility can primarily be ascribed to the use of high-voltage lithium-ion or NiMH batteries and to the high-voltage systems in the vehicles. These systems are formed by the connection of discrete lithium cells (with low voltages) in series in order for the required power to be attained. The batteries can give rise to hazardous situations throughout the product life cycle. The life cycle of electric vehicles comprises the following main stages: research and development, manufacture (prototype and series production), road transport, service/repair, and disposal/recycling. Storage and (cargo) transport of components or entire vehicles can be interposed as intermediate steps. Related to these phases, the following hazards can be identified: electrical risks, chemical risks, associated fire/explosion risks, risks posed by electromagnetic fields (EMF), ergonomic risks such as those of musculoskeletal disorders, and psychosocial risks, which may for example result in work-related stress. Finally, there are risks attributable to the technological characteristics of electric vehicles. These arise in road traffic and affect not only the drivers of EVs, but all traffic participants. Scarcely audible driving noise is most relevant, but a failure of drivers to adjust their driving behaviour and other human errors (e.g. unintended starting in the “ready-mode") are also crucial issues. These risks are not OSH aspects in a strict sense – apart from the case of professional drivers or risks in the area of in-company or in-plant traffic – but must nevertheless be given special attention.
The high electric currents associated with the batteries and high-voltage systems in electric vehicles, reaching several hundred amperes, can cause magnetic fields which can induce eddy currents in the human body. Risks arising from electromagnetic fields are therefore potentially dangerous for people with cardiac pacemakers. Exposure to electromagnetic fields can affect workers throughout the life cycle of electric vehicles. However, this danger is very low in the course of manufacture, use, and waste separation/recycling. Nevertheless, safety distances must always be observed, particularly during the rectification of faults or other emergency maintenance activities involving the motor, the starter, or the lighting or ignition systems .
These high-voltage systems in electric vehicles also are a source of electrical risks for workers Touching live parts can cause electrical shocks or even electrocution, and electric arcs or short circuits can provoke burns or fires. Electrical short circuits or excess load (more than 4 V per single cell) may also overheat the battery, which may ignite when heated to more than 120 °C . The reason for overheating is a self-energising exothermic reaction (“thermal runaway") and the subsequent emergence of hot gases, which increase the explosion and fire risks. Mechanical damage aggravates electrical risks; particular attention is therefore necessary following road accidents and during repair work. Even apparently undamaged batteries are potentially dangerous: they may catch fire up to two weeks after a vehicle collision .
The chemical hazards are complex, owing to the wide variety of substances and different combinations of materials used . Workers can be exposed to hazardous substances during the manufacturing of the batteries and possibly during the assembling of the vehicles with the batteries if the batteries are damaged unintentionally. Lithium-ion batteries are gas-tight to prevent the contents of the battery from leaking during normal use. Mechanical damage to the casing, caused for example by manufacturing defects, improper handling, overheating or collisions, can lead to the leakage of gases or liquids. This can particularly happen during the waste collection and waste management stages where workers may therefore be at risk of exposure to the hazardous substances leaking from batteries. Electrolytes often consist of carbonates with lithium hexafluorophosphate (LiPF6) serving as the conducting salt. LiPF6 can produce highly toxic and corrosive hydrofluoric acid (HF). Leakage of vaporised electrolytes presents an explosion risk and can produce decomposition products such as alkanes (often flammable and pyrophoric) or aldehydes (mostly irritant or toxic); furthermore, extremely toxic phosphine may build up . The solvents are flammable and strongly irritant, especially dimethyl carbonate (DMC), which is volatile, highly flammable, and forms explosive mixtures.
Musculoskeletal disorders (MSD) may arise from manual handling of the vehicles’ components, which are often heavy and bulky and therefore awkward to handle; the weight of high-voltage batteries is for example several times that of conventional batteries. Workers may be subjected to physical strains and the corresponding MSDs throughout the life cycle of EVs; lifting aids and devices are therefore necessary to prevent these. This is particularly relevant during the fitting, disassembling, storage and transport of batteries and other heavy components.
Psychosocial hazards and work-related stress must also be taken thoroughly into account: in manufacturing, during service/repair, recycling, and in the event of accidents. The gradual transition to the electric drive presents greater complexity for production workers assembling both conventional, hybrid and electric vehicle types, as well as for rescue service personnel, car repair workers and recycling workers as they must become familiar with a growing number of different vehicle types . The handling of high-voltage components may generate a fear of injury in workers and thus result in increased stress levels. Stress may also be caused by the fact that the introduction of a new technology such as e-mobility necessitates the acquisition of different or new skills and knowledge. Fears of job losses could also be a consequence; fewer mechanics may for example be needed, being replaced by electricians .
New risks and known risks
The deployment of high-performance rechargeable batteries (predominantly lithium-based) and the handling of extremely complex high-voltage components used in electric vehicles have a strong impact on the safety and health of workers. Besides high voltages and therefore greater electrical hazards, electric drive propulsion systems also involve the use of new hazardous materials. Most of them contain lithium (e.g. lithium cobaltite, lithium titanate, lithium hexafluorophosphate, lithium perchlorate, lithium hexafluoroarsenat) or are organic solvents like DMC and give rise to chemical risks. These risks are significant throughout the vehicles’ life cycles, and are changing all the time owing to the rapid pace of development of new technologies and materials. Electrical, chemical, fire and explosion risks are emerging risks to workers involved in electromobility. At the very least, the existing risks increase to a new order of magnitude: conventional car batteries operate at 12 V (24 V for lorries), whereas EVs typically involve voltages of over 400 V. In addition, the number of people exposed to these hazards is growing rapidly with the onset of series production.
Manual handling issues and physical strains are not novel risks, since workers in the entire automotive sector have always been confronted with the manual handling of heavy objects, repetitive movements, and awkward postures. Nevertheless, the new technology increases the weight of parts requiring manual handling – primarily the batteries – and the number of affected workers. Mental strain and stress at work may be exacerbated by the necessity for workers to acquire new skills and knowledge rapidly and fears of failure. These changes must be addressed by adequate prevention measures (see section "Promotion of occupational safety and health in the field of e-mobility").
Who is affected by the hazards?
The risks associated with electromobility apply to many groups of workers across many different occupational areas. Essentially, four main fields of work can be identified in the life cycle of electric vehicles: manufacture, road traffic, service/repair and disposal/recycling.
Assembly-line workers – and, during the development of prototypes, researchers and scientists – are exposed to chemical, electrical and fire/explosion risks, risks related to the musculoskeletal system and work-related stress. Workers in the areas of storage and logistics are likewise affected. Although the storage of lithium-ion batteries does not appear critical, it should be noted that mechanical damage during transport or (invisible) technical defects of the batteries give rise to a risk of spontaneous ignition, even after several weeks. The hazards for workers in the waste management and recycling sector (car breaking companies) are similar to those in the production sector. Special attention must be paid to the electrical hazards, since HV vehicles are not always identifiable externally as such. Exposure to hazardous substances may increase when the dismantling and recycling of lithium-ion batteries becomes more common than their incineration .
Accidents involving EVs give rise to electrical and fire risks, and also to chemical hazards should the battery be damaged and dangerous liquids or gases leak. HV components are generally fitted within the vehicle in such a way as to protect them against damage in the event of an accident. Despite this, parts of a damaged vehicle could be live after an accident. Fire services, emergency services, first aiders, physicians, the police and towing services may be at risk. Likewise, workers in car workshops face electrical, fire and chemical hazards during the handling of high-voltage batteries and their components in the course of machine maintenance and repair operations. Should the cable insulation or the shrouding of the HV components be damaged or destroyed, risks exist of arcing induced by short circuits or electric shock in the event of contact with the live parts . Table 1 summarizes the sectors which are exposed to the different hazards at the respective stages of the life cycle of electric vehicles . The growing adoption of the technology will inevitably increase the number of workers who are subjected to the dangers.
|Affected occupations, sectors and workers/employees||Manufacture: single items + prototype||Manufacture: series||Road traffic||Service, repair||Disposal, recycling|
|Research institutes, universities||X||X|
|Development, construction, car companies||X||X|
|E-filling stations, car parks||X||X||X|
|Car wash sites||X|
|External logistics, towing services, car breaking companies||X||X||X|
|Fire services, emergency services, roadside assistance||X|
|Emergency physicians, paramedics, police||X|
|Persons fitted with cardiac
The basic idea of prevention lies in anticipating risks and incorporating safety aspects into the design of products or technologies in order to eliminate or minimise these risks. In this regard, technical standardisation and the approval of products by independent authorities – EU-wide or ideally international – can help from the outset to improve the safety of electric vehicles at all stages of their life cycle. Important issues are for example the standard design and unified marking of high-voltage systems to make the hazardous parts easily recognisable; and harmonized installation arrangements for HV modules and cables for isolating the vehicle from the power source more quickly, for example in case of accidents in order to facilitate the rapid rescue of casualties. Harmonised installation arrangements for HV units and safe design of the components can minimise risks for workers during manufacture, maintenance activities and recycling, and contribute to the avoidance of risks for fire services, the police and first responders during rescue operations after an accident.
In addition, adequate workplace design and technical equipment and features provide a number of possibilities for the limiting of hazards. Specially designed insulated and certified tools (cutters, pliers, screwdriving tools, testing instruments, protective covers etc.) should be obligatory for work on live parts in order for electrical shocks and secondary accidents to be prevented. Novel structural elements or materials implemented in EVs may also necessitate novel risk assessment tools and new test procedures and testing facilities . The fitting and removal of heavy components requires measures to minimise manual handling risks; these include modified ergonomic solutions, such as vacuum lifting devices. IA particularly dangerous situation for workers arises when a battery slips from the hands, resulting in serious injuries (for example bruises, bone fractures) and in damage to the batteries which may lead to leakage of hazardous gases or liquids. Lithium-ion batteries must be stored in locations suitable for dangerous goods; these locations must be fire-resistant and equipped with fire detection and pressure-release facilities. Restrictions in the number of batteries held in storage and the installation of sprinkler systems may also improve the safety of workers. Air-conditioning of the storage facilities ensures constant environmental conditions (temperature, air humidity), thereby avoiding ageing of the batteries. The transport of the batteries requires precautionary measures according to the transport of dangerous goods. Finally, the procedures for recycling and disposal require modification owing to new and demanding tasks, e.g. the removal and separate disposal or recycling of the HV elements. The treatment of dangerous substances such as the heavy metals and electrolytes contained in lithium-ion batteries requires appropriate prevention methods to minimise risks of exposure (e.g. safe work procedures, deployment of closed systems, ventilation systems.
Organisational methods are an essential part of efficient prevention. Work on electric vehicles (production, maintenance, repair, recycling, dismantling) requires specific skills. Workers therefore need to be adequately trained and qualified in order to perform these activities safely . Emergency service personnel must be specially prepared for the properties and hazards of high-voltage systems. Growing associated with work on electric vehicles can increase the physical and psychosocial load complexity on workers. This workload can be reduced by putting in place adequate organisational measures, for example by job rotation to workplaces with diversified physical and psychosocial risk factors wherever possible . Such measures can also reduce workers’ exposure to hazardous substances. The use of team work is another means by which the workload can be distributed between the workers. Combining the specialised knowledge and experience of the team members can also reduce mental stress. A team of mechanics and electricians for example would appear particularly appropriate in the interests of effective work practices for the production of hybrid vehicles .
The utilisation of personal protective equipment (PPE) such as insulating gloves or a helmet with visor can become indispensable to ensure safe working on electric vehicles. Essentially, four main fields of or a helmet with visor can become indispensable to ensure safe working on electric vehicles. However, PPE should always be used as last resort when risks could not be reduced sufficiently by following the hierarchy of controls as per EU Directive 89/391/EEC, giving priority to elimination of the hazards, followed by substitution by other less hazardous processes/substances, then implementation of technical control measures at source, collective organisation measures, and finally the use of PPE as last resort. It should also be borne in mind that wearing PPE may place additional burden upon workers for example owing to its dead weight or because it may limit workers’ freedom of movement, which may therefore reduce workers’ acceptance of PPE.
Future demands for adequate workplace design
The rapid progress of new technologies, notably those concerning lithium-ion batteries, makes sound projections difficult on the application of future materials, substances and their combinations in electric vehicles. This means that compatible prevention methods cannot be developed and evaluated long in advance. In particular, the deployment of hazardous substances used in novel lightweight construction technologies requires adaptation of the existing prevention methods. Examples are innovative solvent-based adhesives for aluminium-magnesium alloys and the use of fibre-reinforced synthetic materials such as carbon fibres. Compounding techniques for the bonding of carbon fibres are still at the development stage, which considerably hampers risk assessment. Therefore it is important to integrate OSH consideration at a very early stage, into the very design and development of these new technologies to ensure that they are safe once in use.
At present, recycling concepts envisage the recovery of only minor amounts of lithium from lithium-ion batteries, since the metal is comparatively cheap and the batteries contain comparatively small quantities of lithium. This will probably change in the medium or long term with the growing scarcity of lithium and other raw materials. Recycling processes are already technically feasible and controllable, albeit complex and not economically viable on an industrial scale . For this reason, the recycling of electric vehicle batteries is currently still at the conceptual stage. Some concepts envisage the use of decommissioned batteries as stationary buffer storage devices in the power supply system . This would of course still necessitate recycling at the very end of the batteries’ lives. Any fundamental change in recycling technology would by necessity entail reassessment of the situation, the specific hazards, and appropriate prevention measures. Generally, prevention in the field of electromobility should place priority on precise and attentive surveillance of developing technologies, in order to permit swift response and integration of OSH into the design.
Electromobility brings with it a variety of OSH risks which must be considered. As yet, the market for electrically powered vehicles is only small. Consequently, experience gained so far is correspondingly limited and estimations on future developments and potentially associated hazards are vague. At the same time however, the situation offers the chance for the course to be set for adequate consideration to be given to OSH issues from the outset. In this regard, OSH engagement faces three main areas of responsibility. First, new developments must be closely monitored to permit a timely response to emerging risks. Second, qualification, training and ongoing education of workers must be stepped up in all areas along the life cycle of electric vehicles. The existing OSH requirements must be applied diligently and refined in consideration of new technical expertise. New standards should preferably be established Europe-wide or even on a global scale, since the automotive industry is largely global. Together, these activities form the basis of safe work with electric vehicles at all workplaces throughout their life cycle.
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