OBJECTIVETo measure and evaluate the personal noise exposure of cold rolling mill workers by using noise dosimeter.

METHODSAccording to job category and work type, all workers were divided into 11 groups. 3 to 5 day shift (8:00 to 16:00) workers from each group were selected as subjects for personal noise exposure measurement. SH-126 dosimeters were worn by each subject and collect noise data by a phone fix at collar. All subjects were asked to take notes about their working activities when they were wearing SH-126 dosimeters. Each worker's L(A)(eq) of 8 hours, geometric mean and range of each group were computed.

RESULTSThere were many noise sources in the workshop. Recorded data showed that noise exposure of cold rolling mill was unstable. The varieties of personal noise levels were quite large. Among 53 workers, the highest noise exposure level was 100.0 dB (A), the lowest was 81.2 dB (A); the highest work type was of the foreside welders [94.20 dB (A)], and the lowest was of the straight-cutters [89.02 dB (A)]; quality checkers had the biggest rang [16.3 dB (A)], and primary rolling workers had the lest [2.3 dB (A)].

CONCLUSIONNoise exposure of all the 11 groups were more than 85 dB (A). Noise protection of these workers should be improved. It suggested that measuring personal noise exposure individually with dosimeters might obtain the noise exposure level more integrally in the complicated environment.