Aspects of Safety in the Stretching of Plastic Film During Greenhouse Covering.

Objectives The “Mediterranean greenhouse” is widely used for food and ornamental crops. In south-eastern Sicily alone it covers 7000 ha -7500 ha, for 13200 ULA (working days per years) and with a gross saleable production of € 255˙000˙000. Over the course of time the wood or cement supporting structure has been replaced with steel structures. In all cases the cover consists of polyethylene film (PE, PVC, EVA, ecc) and is replaced annually or at most every two years. The positioning of the film on the greenhouse frame represents an accident risk, with falls from a height, and the stretching of the film may provoke even fatal accidents. The equipment used contributes to such accidents. The objective of this work is to identify the cause of accidents occurring during the stretching of the plastic film and to propose solutions. Methods The trials were carried out by the work group, who observed and filmed the operations carried out by workers responsible for the positioning and stretching of the plastic film in modern greenhouses with a supporting structure made of galvanized steel. The greenhouses differed as regards surface (1400÷3000 m2), length (19÷40 m), eaves height (2.70÷4.00 m) e total height (2.70÷5.40 m). The field observations also regarded task times and methods. Furthermore, the equipment used for tightening the film (both the devices permanently inserted in the glasshouse structure and the often home made long lever - wrenches) used by the workers were examined. To measure the force involved during tightening, a torsiometer was used. The characteristics of this were established during preliminary trials and a procedure was set up for its correct use. An analytical model was prepared to verify the forces in play. Results The results show the significance of the forces used during stretching and indicate the danger involved in the operations. The research shows the need to set out guide lines, scrupulously train the operators, re-examine the devices in place in greenhouse structures to hold the film during stretching as well as the tools used by operators, as impact of these with parts of the body can have fatal consequences.