Analysis of occupational noise hazards and protective measures in a large shipbuilding enterprise in Shanghai

  Objective  The noise hazards and protective measures taken by a large shipbuilding enterprise in Shanghai were evaluated in order to provide a reference for the prevention and control of noise hazards in large enterprises.

  Methods  In March 2016, the noise exposure level of workers was measured according to noise measurement standards, and the classification of the noise hazard level of these workers was done according to the noise standard grading method.

  Results  Totally, the noise level in 149 noise-generating positions in this shipbuilding enterprise was measured, while the individual noise exposure level of 17 sand cleaning workers was measured using personal noise dosimeters. Among 149 positions, the noise level in 122 positions was qualified, with an overall compliance of 73.5%. The equivalent sound level (L_{EX, 8 h}) of noise at 26 polishing positions was higher than the national standard, ranging from 89.1 to 96.0 dB(A). Of 26 polishing positions, one was classified as having a mild noise hazard, 18 as a moderate noise hazard, and 7 as a severe noise hazard. Among 9 air compressor inspection positions, the noise level in 1 position was greater than 85 dB(A) with an equivalent sound level (L_{EX, 8 h}) of 92.7 dB(A), and was classified as a moderate noise hazard. The noise level in positions such as steel pretreatment, welding, assembly, and machine room inspection was all less than 85 dB(A). The individual noise exposure level of 17 sand cleaning workers was higher than the standard, ranging from 94.3 to 96.4 dB(A). Among them, the positions of 3 workers were classified as having moderate noise hazards, and 14 were classified as severe. After wearing earplugs, the converted maximum noise exposure level of polishing workers was 85.0 dB(A), while that of air compressor inspection workers was lower than 85 dB(A), and that of steel pre-treatment workers, welders, assemblers, and inspection workers was lower than 80 dB(A). After wearing earplugs, the converted maximum noise exposure values of 2 sand cleaning workers were 85.2 dB(A) and 85.4 dB(A), respectively, and still higher than 85.0 dB(A), while those of 15 other workers were lower than the national standard. Of 2 123 noise-exposed workers, occupational health examinations showed that 12 workers (3 polishing workers and 9 sand cleaning workers) had occupational contraindications to noise, accounting for 0.06%.

  Conclusions  Noise was the main occupational hazard in large shipbuilding enterprises. It is necessary to improve the process according to the situation of excessive noise, adopt low-noise equipment selection or targeted individual protection measures, and strengthen occupational health examinations to reduce the impact of noise on the health of operators.