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的主要物理有害因素之一，暴露于该环境中的作业人员健康将受到损害。因此，开展农业机械辐射噪声的空间分布研究，有助于降低其对作业人员健康的有害影响。本研究旨在评估某农用拖拉机在旋耕机开启与关闭两种工况下，其辐射噪声的空间分布特征。本研究采用基于波动模型的地统计分析方法，依据现行法规标准划定符合职业健康要求的作业区域。实验采用额定功率75马力的拖拉机，以2000转/分钟的转速运行，分别设置旋耕机开启与关闭两种工况。在10米半径范围内，按规则布设2.0×2.0米的采样网格，采用数字声级计采集各网格点位的噪声数据。采用加权最小二乘法、波动模型与克里金插值法对半变异函数（semivariogram）进行拟合，以此生成噪声空间分布图谱。明确了该拖拉机辐射噪声的强度特征与空间分布结构。研究结果表明，该设备辐射的噪声级超出了巴西职业安全法规标准NR 15规定的限值要求。因此，拖拉机驾驶员及参与作业的相关人员均需配备个人防护装备（Personal Protective Equipment）。