# A Review on Ergonomics in Agriculture. Part II: Mechanized Operations
## 1 Introduction  
Agriculture provides food, raw materials for other industries and employment opportunities. As a consequence, given the key role of agriculture in global economy, safety and health of its employees are regarded to be of major importance. However, rural occupation involves a considerable number of harmful illnesses. Epidemiological studies have identified several health problems such as cancers, respiratory and pesticide-caused diseases, hearing loss and musculoskeletal disorders (MSDs) [1; 2; 3]. The most widespread and alarming non-lethal disease among farmers is considered to be the MSDs [4]. Manual operations such as harvesting and pruning are very common, in particular in developing countries [5]. These tasks involve working in awkward postures, prolonged and repetitive trunk bending, kneeling, heavy carrying and lifting, which constitute the main risk factors for the pathogenesis of MSDs [6; 7]. Nowadays, mechanization in agriculture covers most farming operations as a means to lessen intensive manual labor, optimize timeliness of the tasks and increase productivity [8]. Nevertheless, in many cases, the introduction of machinery did not eliminate the health problems of workers. Operators of the agricultural machines, for example, are exposed to engine fumes, harvesting dust and whole-body vibration (WBV) effects [5]. The definition of WBV according to the European Directive 2002/44/EC [9] is: _\"The mechanical vibration that, when transmitted to the whole body, entails risks to the health and safety of workers, in particular lower-back morbidity and trauma of the spine\"_. Experiencing of high levels of WBV can either cause or worsen back injuries. Intensive and frequent vibrations, long durations and severe shocks contribute to the aggravation of MSDs. Overall, WBV can be as vital as manual and repetitive carrying of heavy loads and awkward postures (such as stooping) in provoking low back pain and injury [10]. Taking also into account that usually agricultural workers are exposed to a series of risk factors, because of the both manual and mechanized nature of the executed tasks, the epidemic proportions of low back disorders among them appear to be plausible [5; 6; 7; 11]. An illustrative example of exposure to WBV is the use of tractor. Tractor is considered to constitute a primary origin for severe musculoskeletal injuries to operators [5]. Similar observations have been noted for all-terrain vehicles and other agricultural machines with driving seats. These machines can be particularly dangerous when operating by young adolescents, since they lack the physical size, experience and strength required for the safe operation [12]. Other usually operated self-propelled machines are power fillers, grass trimmers and handheld olive beaters [13; 14; 15]. These machines can be very hazardous to the workers, mainly because of the high levels of vibrations at the upper extremities, resulting from the contact of the hand with the handles. The sustained exposure to this kind of stresses may provoke the well-known hand-arm vibration syndrome (usually abbreviated as HAVS in the relative literature) that can affect the blood vessels, muscles, nerves, joints and connective tissues of forearm and hand [16; 17]. The vibrations, which are generated due to the engine operation and ground roughness, are transferred to the operator as a result of the body's contact with the seat, the cabin floor and handling operating tools [18]. WBV exposures regarding on-road vehicles are principally along the vertical axis (z). On the other hand, concerning the off-road vehicles, WBV is developed not only along z axis, but along the fore-aft (x) and lateral (y) axes [19] as well. Long-term high-level vibration can result in degenerative changes of joints, especially of lumbar spine [20]. Such multi-axial exposures of WBV can increase the rotational forces and shear in the spine as well as enlarge the muscle loads for the purpose of counterbalancing the head and torso inertia.