Characterization of noise emitted by a low-profile tractor and its influence on the health of rural workers

Abstract Noise is one of the main physical agents in the rural work environment and it can be harmful to the health of workers exposed to it. Thus, research on the spatialization of noise emitted by agricultural machinery can help minimize harmful health effects. This study sets out to evaluate the spatial distribution of the noise emitted by an agricultural tractor with and without the activation of a rotary cutter. A wave model geostatistical analysis was used to identify healthy working zones according to current legislation. The experiment was carried out using a 75 hp tractor at 2000 rpm with the rotary cutter on the on and off modes. A digital sound level meter was used to register noise in a regular 2.0 x 2.0 m sample mesh within a 10-meter radius. The semivariogram was adjusted using the weighted least squares method, wave model and kriging interpolation to obtain the maps. The magnitude and spatial structure of the noise emitted by the tractor were identified. The results show that the equipment produced noise levels above the limits recommended by Brazilian regulatory standard NR 15. Thus, both the machine operator and the workers involved in the operation should use Personal Protective Equipment.

摘要：噪声是农村作业环境中主要的物理有害因素之一，暴露于噪声环境中的作业人员健康可能受到损害。因此，针对农业机械辐射噪声的空间分布特征开展研究，有助于降低其对健康的有害影响。本研究旨在评估某农用拖拉机在开启与关闭旋耕机工况下辐射噪声的空间分布特征。本研究采用波动模型地统计分析方法，依据现行法规标准划定安全作业区域。本实验采用一台75马力（horsepower, hp）的拖拉机，在2000转每分钟（revolutions per minute, rpm）的工况下，分别开展旋耕机开启与关闭两组测试。通过数字声级计在半径10米范围内的2.0×2.0米规则采样网格内采集噪声数据。采用加权最小二乘法、波动模型与克里金（Kriging）插值法对半变异函数进行拟合，进而生成噪声空间分布图谱。研究明确了该拖拉机辐射噪声的强度与空间结构特征。结果显示，该设备的辐射噪声水平超出了巴西监管标准NR 15的限值要求。因此，拖拉机驾驶员与参与该作业的相关人员均应配备个人防护装备（Personal Protective Equipment, PPE）。