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Vital Surveillances: Surveillance of Noise Exposure Level in the Manufacturing Industry — China, 2020

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  • Abstract

    Introduction

    Occupational noise exposure is a widespread issue in the manufacturing industry in China. Since 2019, the National Surveillance System for Occupational Hazards in the workplace was established to understand different occupational hazards, especially occupational noise, in workplaces in China.

    Methods

    Both environmental and individual noise exposure levels were measured for 19,378 enterprises according to the Work Plan for Surveillance of Occupational Hazards in the Workplace (2020) issued by National Health Commission of the People’s Republic of China. Median and interquartile range (IQR) were calculated to describe the distribution of the noise exposure level by industry classification, enterprise-scale, and ownership type of the enterprise.

    Results

    Overall, 25.14% of the individual noise exposure samples exceeded the Chinese national standard among the selected enterprises. The overall median of environmental noise exposure level was 82.8 dB(A) in selected enterprises, while the median of individual noise exposure level was 81.3 dB(A). The individual noise exposure level in the manufacture of metal products, manufacture of motor vehicles, mini-sized enterprises, collective enterprises and private enterprises was relatively high.

    Conclusion

    Occupational noise is still one of the occupational hazards that cannot be ignored in the manufacturing industry, especially in mini-sized and private enterprises. The risk of noise exposure in the target industry is still high and will pose a threat to the health of workers.

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  • Funding: Supported by the Occupational Disease Hazard Surveillance and Occupational Disease Report Project, NIOHP, China CDC (No.131031109000190001)
  • [1] Themann CL, Masterson EA. Occupational noise exposure: a review of its effects, epidemiology, and impact with recommendations for reducing its burden. J Acoust Soc Am 2019;146(5):3879 − 905. http://dx.doi.org/10.1121/1.5134465CrossRef
    [2] Zhou JN, Shi ZH, Zhou LF, Hu Y, Zhang MB. Occupational noise-induced hearing loss in China: a systematic review and meta-analysis. BMJ Open 2020;10(9):e039576. http://dx.doi.org/10.1136/bmjopen-2020-039576CrossRef
    [3] Chen YL, Zhang MB, Qiu W, Sun X, Wang X, Dong YW, et al. Prevalence and determinants of noise-induced hearing loss among workers in the automotive industry in China: a pilot study. J Occup Health 2019;61(5):387 − 97. http://dx.doi.org/10.1002/1348-9585.12066CrossRef
    [4] Office of the Leading Group for the Fourth National Economic Census of the State Council. Chinese economics census yearbook 2018. Beijing: China Statistics Press. 2020. http://www.stats.gov.cn/tjsj/pcsj/jjpc/4jp/zk/indexch.htm. (In Chinese). http://www.stats.gov.cn/tjsj/pcsj/jjpc/4jp/zk/indexch.htm.
    [5] Xiang YP, Zhou W, Wang XY, Zhong XH, Yang GT. Investigation and analysis of noise hazards in three key industries in Shenzhen City. Chin J Ind Hyg Occup Dis 2021;39(2):154 − 6. http://dx.doi.org/10.3760/cma.j.cn121094-20190929-00449 (In Chinese). CrossRef
    [6] Hu SQ, Hu WJ, Yang S, Zhu XH, Sun K, Jiang SS, et al. Investigation on noise exposure level and health status of workers in transportation equipment manufacturing industry. Chin J Ind Hyg Occup Dis 2021;39(7):498 − 502. http://dx.doi.org/10.3760/cma.j.cn121094-20200513-00258 (In Chinese). CrossRef
    [7] National Bureau of Statistics. GB/T 4754-2017 Industrial classification for national economic activities. Beijing: China Standards Press, 2017. http://www.stats.gov.cn/tjsj/tjbz/201709/P020180720515075120537.pdf. (In Chinese). http://www.stats.gov.cn/tjsj/tjbz/201709/P020180720515075120537.pdf
    [8] The Central People’s Government of the People’s Republic of China. Notice on the adjustment of the provisions on the classification of enterprise registration types. 2011. http://www.gov.cn/zwgk/2011-11/17/content_1995548.htm. [2011-9-30]. (In Chinese). http://www.gov.cn/zwgk/2011-11/17/content_1995548.htm
    [9] National Bureau of Statistics. Methods for classifying large, medium, small and mini-sized enterprises statistically. 2011. http://www.stats.gov.cn/tjsj/tjbz/201109/t20110909_8669.html. [2011-9-9]. (In Chinese). http://www.stats.gov.cn/tjsj/tjbz/201109/t20110909_8669.html
    [10] Hormozi M, Ansari-Moghaddam A, Mirzaei R, Haghighi JD, Eftekharian F. The risk of hearing loss associated with occupational exposure to organic solvents mixture with and without concurrent noise exposure: a systematic review and meta-analysis. Int J Occup Med Environ Health 2017;30(4):521 − 35. http://dx.doi.org/10.13075/ijomeh.1896.01024CrossRef
    [11] Duan JL, Lin YF, Wu NJ, He ZM. Investigation on occupational health management of 200 enterprises in Pingshan District of Shenzhen City. Occup Health 2021;37(10):1297 − 302. http://dx.doi.org/10.13329/j.cnki.zyyjk.2021.0328 (In Chinese). CrossRef
  • TABLE 1.  Distribution of noise exposure levels among the manufacturing industry in different divisions — China, 2020.

    Division*Total number of enterprisesTotal number of workersEnvironmental noise exposure level [dB(A)]Individual noise exposure level LEx,8h/LEx,40h [dB(A)]The proportion of individual noise exposure levels ≥85 dB(A) (%)
    Number of samplesMedian (IQR)Number of samplesMedian (IQR)
    Manufacture of furniture2,43045,82615,75083.2 (80.2–86.5)13,95581.7 (77.4–84.8)24.01
    Printing and reproduction of recorded media2,14839,7309,45781.1 (78.0–83.8)9,02280.5 (76.3–83.4)15.21
    Manufacture of coke and refined petroleum products35927,5523,47082.9 (78.8–87.1)2,19678.3 (73.8–82.0)9.39
    Manufacture of chemicals and chemical products1,40140,1218,35480.1 (75.9–83.5)6,43977.4 (72.7–81.0)7.59
    Manufacture of other non-metallic mineral products8,228166,93841,47183.8 (80.3–88.9)36,06682.0 (77.3–86.9)32.08
    Casting of iron and steel80844,0226,82182.6 (78.7–86.8)5,61580.5 (76.4–84.2)21.52
    Casting of non-ferrous metals1,00155,6407,73382.2 (78.6–85.8)6,20280.5 (76.3–84.2)20.39
    Manufacture of metal products1,36835,7157,68883.2 (80.2–87.1)7,22482.2 (78.8–85.9)29.01
    Manufacture of motor vehicles1,53370,24610,27882.8 (79.7–86.7)9,91782.2 (78.7–85.6)27.76
    Manufacture of electrical equipment1027,92883682.4 (79.8–85.5)78381.8 (78.4–84.9)24.58
    Total19,378533,718111,85882.8 (79.3–87.0)97,41981.3 (76.9–85.0)25.14
    * P<0.001.
    LEx,8h: Normalization of equivalent continuous A-weighted sound pressure level to a nominal 8 hours working day. LEx,40h: Normalization of equivalent continuous A-weighted sound pressure level to a nominal 40 hours working week.
    Download: CSV

    TABLE 2.  Distribution of noise exposure levels among the manufacturing industry in different enterprise-scale and ownership type — China, 2020.

    ItemTotal number of enterprisesTotal number of workersEnvironmental noise exposure level [dB(A)]Individual noise exposure level LEx,8h/LEx,40h* [dB(A)]The proportion of individual noise exposure level ≥85 dB(A) (%)
    Number of samplesMedian (IQR)Number of samplesMedian (IQR)
    Enterprise-scale
    Large45876,9236,29183.3 (80.1–87.2)4,88481.1 (76.6–84.5)22.07
    Medium1,878169,13920,55683.1 (79.7–87.2)17,27780.9 (76.1–84.6)23.13
    Small9,926236,32559,90182.5 (79.1–86.5)52,77481.2 (76.9–84.8)24.00
    Mini-sized7,11651,33125,11083.2 (79.3–88.1)22,48481.7 (77.4–86.2)30.11
    P-value<0.001<0.001
    Ownership type
    State-owned68342,5266,40583.4 (80.1–87.6)4,67780.6 (76.9–84.1)19.53
    Collective1201,78446183.0 (79.8–86.2)43481.6 (78.1–84.3)20.97
    Joint-equity cooperative enterprises2219,2461,42583.0 (79.2–87.2)1,19681.6 (77.3–85.1)25.42
    Joint-operate312,28520581.0 (78.4–84.7)18780.0 (76.0–84.1)17.65
    Private6,421114,06529,95783.0 (79.3–87.5)25,68781.4 (77.2–85.6)27.91
    Incorporated company52733,2653,99582.2 (78.5–86.0)3,33581.0 (76.8–84.3)21.71
    Limited liability company10,062275,99860,57382.8 (79.3–86.7)54,07581.3 (76.7–84.9)24.70
    Hong Kong, Macau, and Taiwan-invested enterprises36419,4472,93182.3 (79.1–86.2)2,70981.0 (75.9–84.3)22.55
    Foreign47626,6383,62582.3 (78.9–85.8)3,16781.1 (76.9–84.5)22.99
    Others4738,4642,28183.1 (79.3–87.6)1,95281.7 (77.1–85.8)28.54
    P-value<0.001<0.001
    Total19,378533,718111,85882.8 (79.3–87.0)97,41981.3 (76.9–85.0)25.14
    * LEx,8h: Normalization of equivalent continuous A-weighted sound pressure level to a nominal 8 hours working day. LEx,40h: Normalization of equivalent continuous A-weighted sound pressure level to a nominal 40 hours working week.
    Download: CSV

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Surveillance of Noise Exposure Level in the Manufacturing Industry — China, 2020

View author affiliation

Abstract

Introduction

Occupational noise exposure is a widespread issue in the manufacturing industry in China. Since 2019, the National Surveillance System for Occupational Hazards in the workplace was established to understand different occupational hazards, especially occupational noise, in workplaces in China.

Methods

Both environmental and individual noise exposure levels were measured for 19,378 enterprises according to the Work Plan for Surveillance of Occupational Hazards in the Workplace (2020) issued by National Health Commission of the People’s Republic of China. Median and interquartile range (IQR) were calculated to describe the distribution of the noise exposure level by industry classification, enterprise-scale, and ownership type of the enterprise.

Results

Overall, 25.14% of the individual noise exposure samples exceeded the Chinese national standard among the selected enterprises. The overall median of environmental noise exposure level was 82.8 dB(A) in selected enterprises, while the median of individual noise exposure level was 81.3 dB(A). The individual noise exposure level in the manufacture of metal products, manufacture of motor vehicles, mini-sized enterprises, collective enterprises and private enterprises was relatively high.

Conclusion

Occupational noise is still one of the occupational hazards that cannot be ignored in the manufacturing industry, especially in mini-sized and private enterprises. The risk of noise exposure in the target industry is still high and will pose a threat to the health of workers.

  • 1. National Institute of Occupational Health and Poison Control, Chinese Center for Disease Control and Prevention, Beijing, China
  • Corresponding author:

    Weijiang Hu, Huwj@niohp.chinacdc.cn

  • Funding: Supported by the Occupational Disease Hazard Surveillance and Occupational Disease Report Project, NIOHP, China CDC (No.131031109000190001)
  • Online Date: October 22 2021
    doi: 10.46234/ccdcw2021.222
    • Noise has been one of the most prevalent occupational hazards in many industries both in China and worldwide, which affects more than 10 million Chinese workers’ health (1-2). With an annual growth of incidence of 24.2% from 2014, occupational noise-induced deafness has been the second leading occupational disease after pneumoconiosis in China (3). Since China’s reform and opening-up, China’s manufacturing industry has developed rapidly. In 2018, the number of enterprises exceeded 3 million, accounting for 15% of the total number of enterprises, with more than 100 million workers (4). Meanwhile, 67.56% of the diagnosed cases of occupational otolaryngological and stomatological diseases in China were from the manufacturing industry in 2020, which was reported from the National Surveillance System of Key Occupational Diseases. Studies reported that the noise exposure level in many workplaces exceeded 85 dB(A) among several manufacturing industries such as the wood furniture manufacturing industry, the transportation equipment manufacturing industry, and the automotive industry (3,5-6). Therefore, it is necessary to understand the noise exposure level in the workplace in the overall manufacturing industry from different dimensions and provide evidence for measures to reduce the noise exposure level and protect workers’ health.

    • In order to estimate the noise exposure level among the overall manufacturing industry on a national scale, 19,378 enterprises were selected from the database of National Surveillance System for Occupational Hazards in the workplace in 2020. The surveillance was conducted according to the Work Plan for Surveillance of Occupational Hazards in the Workplace (2020) issued by the National Health Commission of the People’s Republic of China. Based on the plan’s requirement, the average number of enterprises included in the surveillance in each county should not be less than 20, and a minimum total number of 55,890 enterprises should be monitored. Furthermore, all the enterprises included in the surveillance should be exposed to major occupational hazards selected according to the epidemiological trends of occupational disease in China. The surveillance was conducted mostly by Occupational Disease Prevention and Control Institutes at the county level and occupational health technical service institutions. Quality control of the surveillance was conducted by provincial and municipal Occupational Disease Prevention and Control Institutes. The selected enterprises in this study were from 31 provincial-level administrative divisions (PLADs) and the Xinjiang Production and Construction Corps in China and were categorized according to their industrial classification, enterprise-scale, ownership type of the enterprise (7-9).

      Both environmental and individual noise exposure levels were measured for each enterprise, the specific measurement guidelines were as follows: 1) at least 20 noise exposure areas should be measured in the workplace in large and medium-sized enterprises, and all of the noise exposure areas should be measured in the workplace in small and mini-sized enterprises; 2) the level of environmental noise onsite should be measured in each noise exposure area, and individual noise exposure measurements should be conducted for at least four operating posts in each enterprise; individual noise exposure measurements should be conducted for all operating posts if operating posts comprise less than four units; and 3) the sampling method and noise measure method for both environmental and individual noise exposure were determined according to the Measurement of Physical Agents in the Workplace Part 8: Noise (GBZ/T 189.8–2007).

      Statistical analysis was performed using SPSS (version 22.0, SPSS Inc, Chicago, IL, USA). The median and interquartile range (IQR) were calculated to describe the distribution of the noise exposure by industry classification, enterprise-scale, and ownership type of the enterprise. Kruskal-Wallis H test was used to compare noise exposure levels among different dimensions. The significance level of tests was P<0.05.

    • In this study, 19,378 enterprises from 10 major divisions of the manufacturing industry were included, and more than 530,000 workers were found exposed to occupational noise. As shown in Table 1, a total number of 111,858 environmental noise samples and 97,419 individual noise samples were detected. Overall, 25.14% of the individual noise exposure samples exceeded the Chinese national standard among the selected enterprises. The proportions of individual noise exposure levels equal to or above 85 dB(A) were much higher in the manufacturing of other non-metallic mineral products, which was 32.08%.

      Division*Total number of enterprisesTotal number of workersEnvironmental noise exposure level [dB(A)]Individual noise exposure level LEx,8h/LEx,40h [dB(A)]The proportion of individual noise exposure levels ≥85 dB(A) (%)
      Number of samplesMedian (IQR)Number of samplesMedian (IQR)
      Manufacture of furniture2,43045,82615,75083.2 (80.2–86.5)13,95581.7 (77.4–84.8)24.01
      Printing and reproduction of recorded media2,14839,7309,45781.1 (78.0–83.8)9,02280.5 (76.3–83.4)15.21
      Manufacture of coke and refined petroleum products35927,5523,47082.9 (78.8–87.1)2,19678.3 (73.8–82.0)9.39
      Manufacture of chemicals and chemical products1,40140,1218,35480.1 (75.9–83.5)6,43977.4 (72.7–81.0)7.59
      Manufacture of other non-metallic mineral products8,228166,93841,47183.8 (80.3–88.9)36,06682.0 (77.3–86.9)32.08
      Casting of iron and steel80844,0226,82182.6 (78.7–86.8)5,61580.5 (76.4–84.2)21.52
      Casting of non-ferrous metals1,00155,6407,73382.2 (78.6–85.8)6,20280.5 (76.3–84.2)20.39
      Manufacture of metal products1,36835,7157,68883.2 (80.2–87.1)7,22482.2 (78.8–85.9)29.01
      Manufacture of motor vehicles1,53370,24610,27882.8 (79.7–86.7)9,91782.2 (78.7–85.6)27.76
      Manufacture of electrical equipment1027,92883682.4 (79.8–85.5)78381.8 (78.4–84.9)24.58
      Total19,378533,718111,85882.8 (79.3–87.0)97,41981.3 (76.9–85.0)25.14
      * P<0.001.
      LEx,8h: Normalization of equivalent continuous A-weighted sound pressure level to a nominal 8 hours working day. LEx,40h: Normalization of equivalent continuous A-weighted sound pressure level to a nominal 40 hours working week.

      Table 1.  Distribution of noise exposure levels among the manufacturing industry in different divisions — China, 2020.

      The surveillance results showed that all the medians of both environmental and individual noise exposure levels were below 85 dB(A). The overall median of environmental noise exposure level was 82.8 dB(A) in selected enterprises, while the median of individual noise exposure level was 81.3 dB(A). The medians of individual noise exposure levels in the categories of manufacturing of metal products, manufacturing of motor vehicles, and manufacturing of other non-metallic mineral products were higher compared to other divisions, and their upper quartiles showed that more than 25% of the operating posts were exposed to a noise level of 85 dB(A). The occupational noise exposure level was relatively high in the workplace among divisions of manufacturing of other non-metallic mineral products, manufacturing of furniture, and manufacturing of metal products, as shown by the median and their IQR, which were 83.8 (80.3–88.9), 83.2 (80.2–86.5), and 83.2 (80.2–87.1), respectively. The difference between the medians of environmental and individual noise exposure level in the manufacture of coke and refined petroleum products was 4.6 dB(A) (H=697.894, P<0.001), which was larger compared to other divisions.

      As presented in Table 2, the proportions of individual noise exposure levels equal to or exceeding 85 dB(A) increased with the decline of the enterprise-scale. The mdian of individual noise exposure levels in mini-sized enterprises was the highest when compared to the other three enterprise scales (Table 2). The difference between the medians of environmental and individual noise exposure levels was 2.2 dB(A) in both the large and medium enterprise-scales, which were bigger than those in small and mini-sized [1.3, 1.5 dB(A)]. Table 2 also presents the distribution of the noise exposure states among the manufacturing enterprises in different ownership types. The proportions of individual noise exposure levels equal to or exceeding 85 dB(A) were the highest in private and joint-equity cooperative enterprises. Incorporated enterprises were found to have the lowest occupational noise exposure risk, as shown by the medians of both environmental and individual noise exposure levels.

      ItemTotal number of enterprisesTotal number of workersEnvironmental noise exposure level [dB(A)]Individual noise exposure level LEx,8h/LEx,40h* [dB(A)]The proportion of individual noise exposure level ≥85 dB(A) (%)
      Number of samplesMedian (IQR)Number of samplesMedian (IQR)
      Enterprise-scale
      Large45876,9236,29183.3 (80.1–87.2)4,88481.1 (76.6–84.5)22.07
      Medium1,878169,13920,55683.1 (79.7–87.2)17,27780.9 (76.1–84.6)23.13
      Small9,926236,32559,90182.5 (79.1–86.5)52,77481.2 (76.9–84.8)24.00
      Mini-sized7,11651,33125,11083.2 (79.3–88.1)22,48481.7 (77.4–86.2)30.11
      P-value<0.001<0.001
      Ownership type
      State-owned68342,5266,40583.4 (80.1–87.6)4,67780.6 (76.9–84.1)19.53
      Collective1201,78446183.0 (79.8–86.2)43481.6 (78.1–84.3)20.97
      Joint-equity cooperative enterprises2219,2461,42583.0 (79.2–87.2)1,19681.6 (77.3–85.1)25.42
      Joint-operate312,28520581.0 (78.4–84.7)18780.0 (76.0–84.1)17.65
      Private6,421114,06529,95783.0 (79.3–87.5)25,68781.4 (77.2–85.6)27.91
      Incorporated company52733,2653,99582.2 (78.5–86.0)3,33581.0 (76.8–84.3)21.71
      Limited liability company10,062275,99860,57382.8 (79.3–86.7)54,07581.3 (76.7–84.9)24.70
      Hong Kong, Macau, and Taiwan-invested enterprises36419,4472,93182.3 (79.1–86.2)2,70981.0 (75.9–84.3)22.55
      Foreign47626,6383,62582.3 (78.9–85.8)3,16781.1 (76.9–84.5)22.99
      Others4738,4642,28183.1 (79.3–87.6)1,95281.7 (77.1–85.8)28.54
      P-value<0.001<0.001
      Total19,378533,718111,85882.8 (79.3–87.0)97,41981.3 (76.9–85.0)25.14
      * LEx,8h: Normalization of equivalent continuous A-weighted sound pressure level to a nominal 8 hours working day. LEx,40h: Normalization of equivalent continuous A-weighted sound pressure level to a nominal 40 hours working week.

      Table 2.  Distribution of noise exposure levels among the manufacturing industry in different enterprise-scale and ownership type — China, 2020.

    • Surveillance of occupational hazards in the workplace has been carried out by the Chinese government since 2019. Occupational noise was selected as one of the major hazards in the surveillance, and more than a quarter of enterprises were from the manufacturing industry. The proportion of individual noise exposure levels equal to or exceeding 85 dB(A) was still high in the manufacturing industry. The medians of environmental noise exposure levels of all industries exceeded 80 dB(A), and the same was true of the individual noise exposure levels in eight industries except the manufacture of petroleum coke and other refined petroleum products. Based on the Classification of Occupational Hazards at Workplaces Part 4: Occupational Exposure to Noise (GBZ/T 229.4–2012), more than 50% of operating posts in those 8 divisions could be classified as having exposure to noise.

      According to the surveillance results, the median of individual noise exposure levels was 82.2 dB(A), both in the manufacture of metal products and manufacture of motor vehicles, which were higher than the other divisions. However, as shown from the National Surveillance System of Key Occupational Diseases, the incidence of occupational noise deafness among the manufacture of metal products was much higher than that of the manufacture of motor vehicles in China. This may be due to the relatively high proportion of large and medium enterprises in the manufacture of motor vehicles, with better occupation health management and stronger self-protective awareness of workers (4). As for the manufacture of metal products, this category mostly consisted of small and mini-sized enterprises. The poor sense of self-protection results in serious hearing loss of workers in this industry. In addition, it is worth noting that there are methylbenzene, xylene, ethylbenzene, and other ototoxic substances that exist in the other three industries with lower noise exposure level. Another study showed that combined exposure of ototoxic substances and noise was more likely to cause hearing loss than noise exposure at the same exposure level (10).

      The analysis of the noise exposure levels among different enterprise-scales shows that the noise hazard of small and mini-sized enterprises was more serious than that of large and medium enterprises. This phenomenon was mainly due to the insufficient investment in noise control and lower technical levels among small and mini-sized enterprises (11). Meanwhile, more than 80% of enterprises in China were small and mini-sized enterprises, so it is urgent to increase investment in the occupational disease prevention of small and mini-sized enterprises (4). Furthermore, the individual noise exposure levels of private enterprises were about 1 dB(A) higher than that of state-owned enterprises, which was mainly related to the decreased investment in occupational disease prevention among private enterprises.

      This is the first comprehensive report presenting noise exposure levels in manufacturing industry in China based on different divisions, enterprise-scales, and ownerships based on National Surveillance for Occupational Hazards in the workplace in 2020. The risk of noise exposure in the target industry is still high and will threaten the health of a large number of the worker population. The detailed insight of the noise exposure will provide the government with evidence to improve the occupational health management and develop special governance measures in the target enterprises. Meanwhile, the data will also be used for the reversions of regulations related to occupational health and the implementation of national or local projects of occupational disease prevention and control. The limitation of this study is that we did not acquire the information of workers’ occupational health during the surveillance. We will improve the method in the future study.

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