Exposição ocupacional termoacústico a operadores de tratores agrícolas

Abstract

The operation of agricultural tractors exposes the operator to a condition of occupational insalubrity that has a detrimental effect not only on comfort but also on health and income. This research was conducted with the objective of evaluating the occupational exposure levels to thermal and acoustic stress, present in the work platform of agricultural tractors operators, with ergonomic cabin (air conditioning) and without ergonomic cabin, during periodic soil preparation for the cultivation of sugarcane and to formulate a multivariate mathematical model of the occupational comfort index. The research was carried out in areas of sugarcane cultivation of the Petribu Plant, located in Carpina, PE. Tractors coupled to implements used in plowing, harrowing and furrowing operations were used. Data logging on the operator's work platforms were air temperature (°C), black globe temperature (°C), relative air humidity (%), operator heart rate (bpm), temperature of the operator's skin surface (oC), noise, dB (A) and air velocity (m s-1), recorded every 10 s, by means of specific instrumentation, with automatic data recording. The soil was periodically prepared in an area of 8.4 ha, for a daily working day of eight hours (8 a.m. to 5:00 p.m., one hour of meal break) for each operation, in the respective tractor models, without a cab (4.3 ha) and with ergonomic cabin (4.1 ha), executed by the same operator. To characterize the magnitude of the thermal exposure of the operator, the wet bulb index and globe thermometer (WBT) were determined. Data were submitted to descriptive and exploratory statistical analysis using the principal components technique. The elaboration of the operational comfort Index (ICO) prediction model was performed through multivariate linear regression analysis. The use of the tractor without ergonomic cab pointed out residual unhealthy noise in all operations, which allows the operator a daily working day of only 4 hours. The other indicators of thermoacoustic stress and physical work load, for the tractor without cabin and with ergonomic cabin, indicated acceptable values for a daily working day of 8 hours. The thermoacoustic indicators, noise, relative air humidity and skin surface temperature of the operator's head allowed the elaboration of a multivariate mathematical model, representative of ICO. The validation of the ICO achieved an excellent performance, based on the high values of agreement and confidence, which allows its use to characterize the physical work load and occupational insalubrity of agricultural tractor operators, in the periodic preparation of the soil for sugarcane cultivation.