Background Noise is widespread occupational hazard in iron and steel industry. Overhead-traveling cranes are widely used in this industry, but few studies characterized the overhead-traveling crane drivers＇ noise exposure level so far. In this study, we assessed and characterized personal noise exposure levels of overhead-traveling crane drivers in two steel-rolling mills.Methods One hundred and twenty-four overhead-traveling crane drivers, 76 in the cold steel-rolling mill and 48 in the hot steel-rolling mill, were enrolled in the study. Personal noise dosimeters （AIHUA Instruments Model AWA5610e, Hangzhou, China） were used to collect full-shift noise exposure data from all the participants. Crane drivers carried dosimeters with microphones placed near their collars during the work shifts. Work logs had been taken by the drivers simultaneously. Personal noise exposure data were divided into segments based on lines in which they worked. All statistical analyses were done using SPSS 13.0.Results The average personal noise exposure （LAeq.8h） of overhead-traveling crane drivers in the hot steel-rolling mills （（85.03±2.25） dB（A）） was higher than that in the cold one （（83.05±2.93） dB（A）, P〈0.001）. There were 17 overhead traveling cranes in the hot steel-rolling mill and 24 cranes in the cold one, of which carrying capacities varied from 15 tons to 100 tons. The average noise exposure level based on different lines in the hot and cold steel-rolling mills were （85.2±2.61） dB（A） and （83.3±3.10） dB（A） respectively （P=-0.001）, which were similar to the average personal noise exposure in both mills. The noise exposure levels were different among different lines （P=-0.021）. Conclusion Noise exposure levels, depending upon background noise levels and the noise levels on the ground, are inconstant. As the noise exposure levels are above the 85 dB（A） criteria, these drivers should be involved in the Hearing Conservation Program to protect their hearing.
Background Task-based measurement （TBM） is a method to assess the eight-hour A-weighted equivalent noise exposure level （LAeq. 8h） besides dosimeter. TBM can be better used in factories by non-professional workers and staffs.However, it is still not clear if TBM is equal or similar with dosimeter for LAeq.8h measurement in general. This study considered the measurement with dosimeter as real personal noise exposure level （PNEL） and assessed the accuracy of TBM by comparing the consistencies of TBM and dosimeter in LAeq.8h measurement.Methods The study was conducted in one automobile firm among 387 workers who are exposed to unstable noise.Dosimeters and TBM were used to compare the two strategies and assess the degree of agreement and causes of disagreement. Worker＇s PNEL was measured via TBM for noise; the real PNEL was also recorded. The TBM for noise was computed with task/position noise levels measured via sound level meter and workers＇ exposure information collected via working diary forms （WDF） filled by participants themselves. Full-shift noise exposure measurement via personal noise dosimeters were taken as the real PNEL. General linear model （GLM） was built to analyze the accuracy of TBM for noise and the source of difference between TBM for noise and real PNEL.Results The LAeq.8h with TBM were slightly higher than the real PNELs, except the electricians. Differences of the two values had statistical significance in stamping workers （P ＜0.001）, assembly workers （P=0.015） and welding workers （P=0.001）. The correlation coefficient of LAeq.8h with TBM and real PNELs was 0.841. Differences of the two results were mainly affected by real PNEL （F=11.27, P=0.001）; and work groups （F=3.11, P ＜0.001） divided by jobs and workshops were also independent factors. PNEL of workers with fixed task/position （（86.53±8.82） dB（A）） was higher than those without （（75.76±9.92） dB（A）） （t=8.84, P ＜0.01）. Whether workers had fixed task/position was a
LI NanYANG Qiu-lingZENG LinZHU Liang-liangTAO Li-yuanZHANG HuaZHAO Yi-ming
