Background Shoemaking industry workers are prone to work-related musculoskeletal disorders (WMSDs) due to long-term awkward postures during the work process. There is little research on the prevalence and influencing factors of WMSDs in the knee region of this industry, and it should be taken seriously. Objective To estimate the prevalence of work-related knee pain among shoemaking workers and analyze the related influencing factors. Methods A total of 6982 shoemaking workers were selected from 26 shoemaking factories in Guangdong, Hubei, Fujian, Chongqing, Shandong, Zhejiang, and Jingxi by convenience sampling. Prevalence of work-related knee pain in past year, demographic characteristics, occupational related factors, and work posture were collected by a cross-sectional survey using the electronic version of Musculoskeletal Disorder Questionnaire. Logistic regression analysis was used to analyze the influencing factors that may lead to work-related knee pain. Results This survey collected 6982 valid questionnaires with a recovery rate of 98.3%. The prevalence of work-related knee pain of shoemaking workers in the past 12 months was 13.0% (908/6982). According to the results of logistic regression analysis, compared with workers with less than 5 years of service, workers with 5-10 years of service (OR=1.21, 95%CI: 1.02, 1.45) and more than 10 years (1.53, 95%CI: 1.27, 1.83) showed a higher risk of knee WMSDs; sometimes, often and very frequent (reference : rarely or never) long-term standing (OR=1.33, 95%CI: 1.08, 1.64; OR=2.67, 95%CI: 2.10, 3.39; OR=2.75, 95%CI: 2.08, 3.63) and sometimes, often and very frequent (reference: rarely or never) long-term squatting or kneeling (OR=1.80, 95%CI: 1.47, 2.21; OR=2.43, 95%CI: 1.58, 3.75; OR=3.22, 95%CI: 1.66, 6.24) increased the risk of knee pain: long-term bending (OR=1.59, 95%CI: 1.34, 1.89) and often repeated movement of lower limbs and ankles (OR=1.48, 95%CI: 1.25, 1.75) were also risk factors for knee WMSDs among shoemaking industry workers (P<0.05). Adequate rest time (OR=0.58, 95%CI: 0.49, 0.68) and able to stretch or change leg posture (OR=0.75, 95%CI: 0.64, 0.88) reduced the risk of knee WMSDs (P<0.05). Conclusion In the shoemaking industry, length of service and awkward postures are risk factors for knee pain. The shoemaking enterprises should ensure that workers have sufficient rest time, reduce long-term standing, squatting, kneeling, and bending postures, as well as lower limbs repetition in order to reduce the occurrence of knee WMSDs of workers.

Bus drivers, as an important occupational group in urban public transportation system, are prone to suffer from work-related musculoskeletal disorders (WMSDs) due to prolonged fixed postures and repetitive movements. The T/WSJD 14.9-2024 Ergonomic Guidelines for the Prevention of Work-related Musculoskeletal Disorders: Part 9: Bus Driving Work is a recommended standard developed to prevent WMSDs among bus drivers. This standard, guided by the principles of T/WSJD 14.1-2020 Ergonomic Principle for the Prevention of Work-related Musculoskeletal Disorders: Part 1: General Principles, is based on a preliminary work of comprehensive review of domestic and international research, workplace on-site surveys and questionnaires, data analysis, and factor identification. It defines the scope of application, identifies relevant risk factors and potential affected body parts, and offers ergonomic solutions in the form of intervention examples. The issuance of this guideline as a organization standard will facilitate the promotion and implementation of intervention measures.

Background Prolonged awkward postures during occupational activities can lead to excessive musculoskeletal load on the wrist of workers and symptoms such as wrist pain or discomfort. Objective To survey the prevalence of wrist pain among workers in 10 key industries and analyze its correlation with wrist working postures. Methods By using stratified cluster sampling method, workers from 10 key industries, such as footwear manufacturing industry, shipbuilding manufacturing industry, and automobile manufacturing industry, were selected from seven regions in North China, East China, Central China, South China, Southwest China, Northwest China, and Northeast China. The demographic information, wrist working postures, pain in wrist of the workers were collected through a cross-sectional survey. Pearson χ² test was used to compare prevalence by selected factors, trend χ² test for between group comparison, and unconditional logistic regression models for the association of wrist working postures with wrist pain. Results There were 64052 workers enrolled in this survey, and 56286 provided valid questionnaires (the effective rate was 87.8%). According to the survey, the prevalence of wrist pain was 23.3% (13112/56286), and the industries with higher prevalences were footwear manufacturing (27.1%, 1927/7106), automobile manufacturing (24.9%, 5378/21560), and shipbuilding and related equipment manufacturing (24.4%, 850/3488) industries. Finger pinching (OR=2.09, 95%CI: 1.95-2.24), frequent wrist bending (OR=2.03, 95%CI: 1.92-2.15), fixed wrist bending (OR=1.77, 95%CI: 1.69-1.85), wrist on hard edge (OR=1.34, 95%CI: 1.28-1.40), and arms over shoulders (OR=1.11, 95%CI: 1.05-1.17) increased the risk of reporting wrist pain. Conclusion Awkward postures are related to wrist pain among workers in selected 10 key industries. The related factors are wrist on hard edge, frequent wrist bending, finger pinching, fixed wrist bending, and arms over shoulders.

Background Furniture manufacturing is one of the typical labor-intensive industries, and workers in this industry face a high risk of work-related musculoskeletal disorders (WMSDs), which seriously affect the physical and mental health of workers. Objective To explore the prevalence and potential risk factors of WMSDs among workers in a large-scale furniture manufacturing factory. Methods A cross-sectional study of 3431 workers in a furniture factory in Guangdong Province was conducted from September to December 2019. Information including reported WMSDs in various body parts in the past year, demographic characteristics, work organization factors, job characteristics, and work postures was collected by an electronic version of Musculoskeletal Disorders Questionnaire. Pearson χ² test and binary logistic regression were used to analyze the risk factors leading to WMSDs. Results The overall prevalence rate of WMSDs was 32.12% (1102/3431). The most common WMSDs symptoms occurred in the neck (16.85%), followed by the feet (15.27%), shoulders (14.81%), and hands (14.25%). The prevalence rates of WMSDs in the neck, shoulders, elbows, hands, legs, and feet were significantly different among different types of work (P<0.05). The results of multiple logistic regression analysis showed that individual factors, work organization factors, job characteristics, and awkward work postures were associated with the frequency of reporting WMSDs in specific parts of workers. Comparatively poor physical health (including moderate, poor, and very poor) was positively correlated with neck, shoulder, hand, and foot WMSDs (OR=1.479-4.077); working with an uncomfortable posture (OR=1.983) and doing the same task almost every day (OR=1.783) were positively correlated with neck pain; doing the same task almost every day (OR=2.408) and neck twisting for a long time (OR=1.830) were positively correlated with shoulder pain; bending wrists up and down frequently (OR=1.948) and bending wrists for a long time (OR=2.081) were positively correlated with hand pain; prolonged standing (OR=1.953) and often working overtime (OR=1.627) were positively correlated with feet pain; sufficient rest time was negatively correlated with WMSDs in the neck, shoulders, hands, and foot (OR=0.544-0.717). Conclusion The prevalence rate of WMSDs in furniture manufacturing workers is relatively high, and neck, feet, shoulders, and hands are the most involved body parts. The frequency of reporting WMSDs is related to individual factors, work organization factors, job characteristics, and awkward work postures.

Background Work-related musculoskeletal disorders (WMSDs) are one of the major occupational health problems in the world. Pharmaceutical industry is an important part of China's national economy. At present, there are few related studies reported at home and abroad. Objective To investigate the status and influencing factors of WMSDs in chemical pharmaceutical industry. Methods A cross-sectional epidemiological survey was conducted among all workers from three chemical pharmaceutical enterprises in Guangzhou. The Musculoskeletal Disorders Questionnaire was used to collect information on demographic characteristics, symptoms of musculoskeletal disorders, types of work, work organization, and and work postures. Multiple logistic regression method was used to analyze the risk factors of WMSDs in chemical pharmaceutical workers. Results In this study, 563 workers were selected as subjects. The total prevalence rate of WMSDs symptoms in the chemical pharmaceutical workers was 43.9% (247/563), and the leading body part-specific prevalence rate from high to low was 34.3% in the lower back, 24.3% in the upper back, 24.0% in the shoulders, and 23.8% in the neck. The prevalence rate of WMSDs symptoms in multiple body parts (30.0%) was 2.16 times higher than that in single body part (13.9%), and the prevalence rate of WMSDs symptoms in four body parts was the highest (11.4%). The results of multiple logistic regression analysis showed that age ≥50 years (reference age <30 years) (OR=2.140, 95%CI: 1.054-4.345), often or very often (reference never/rarely) long-time head rotating (OR=2.695, 95%CI: 1.753-4.142) and long-time keeping arms above shoulders (OR=1.902, 95%CI: 1.108-3.265) increased the risk of reporting WMSDs symptoms (P<0.05). Regarding education level, workers with high school and technical secondary school (OR=0.333, 95%CI: 0.175-0.636) or college and above (OR=0.413, 95%CI: 0.216-0.790) education had a lower risk of reporting WMSDs symptoms than those with middle school or below (P<0.05). Conclusion The prevalence rate of reporting WMSDs symptoms in chemical pharmaceutical industry is high, the involving body parts are lower back, upper back, shoulders, and neck, and reporting simultaneous occurrence of WMSDs symptoms in multiple body parts is common. The chemical pharmaceutical manufacturers can reduce the risk of WMSDs by strengthening the training on workers' ergonomics knowledge, paying attention to the less educated personnel, protecting the elderly workers, and avoiding awkward work postures, like rotating head for a long time and raising arms over shoulders.

Objective: To analyze the current status of work-related musculoskeletal disorders (WMSDs), work fatigue and musculoskeletal pain in Chinese occupational population, and to study the relationship between work fatigue and musculoskeletal pain and WMSDs. Methods: A total of 66 961 employees from 323 enterprises in 15 key industries in China were selected as the study subjects using stratified cluster sampling method. The incidence of WMSDs in the past year was investigated using the Chinese version of the Musculoskeletal Disorders Questionnaire, and the work fatigue and musculoskeletal pain were investigated using Borg 6-20 Rating of Perceived Exertion Scale and visual analogue scale. The data were standardized using the age composition data of 18 to 60 years from the seventh national population census. Results: The standardized annual incidence of WMSDs was higher in the front-line workers than that in the administrative and other supportive staff (38.82% vs 36.30%). The detection rates of work fatigue and musculoskeletal pain in the study subjects were 44.54% and 63.08%, respectively. The result of S-curve fitting showed that the risk of WMSDs increased with the level of work fatigue (P<0.01). Among the front-line workers, the average of monthly fatigue frequency in the neck, shoulder, lower back, upper back, wrist/hand, foot and ankle, knee, leg, and elbow were higher in the group with WMSDs compared to those without WMSDs (all P<0.01). The pain degree of musculoskeletal pain was higher in all nine sites in the fatigued group than in the no-fatigue group (all P<0.01). The standardized detection rate of musculoskeletal pain was higher in the fatigued group than in the non-fatigued group (80.38% vs 25.71%). The work fatigue was moderate and positively correlated with musculoskeletal pain in all seven sites except the lower back and elbow, with Kendall Tau-b correlation coefficients ranging from 0.423 to 0.546 (all P<0.01). Conclusion: There is a good correlation between work fatigue and local musculoskeletal pain, work fatigue and WMSDs in Chinese occupational population. Implementing ergonomic interventions to control the development of work fatigue can be an effective measure for preventing WMSDs.

Objective: The spatial distribution model of particulate matter based on time change in a specific place was established to analyze the spatial and temporal distribution characteristics and movement of particulate matter. Methods: A convenience store was selected as the research subject. The micro-climate and particle number concentration (PNC) of the site were detected, and numerical simulation was carried out by computational fluid dynamics (CFD) simulation method. Based on the discrete phase model, the temporal and spatial distribution characteristics and movement rules of simulated particles were analyzed. Results: The wind speed at the entrance of the convenience store was low and almost unchanged during the detection, while the wind speeds outside and inside outlets were high and changed sharply. The PNC of particle size of 0.02-1.00 μm was higher than that of particle size >1.00 μm (all P<0.05). The PNC with particle size of 0.02-1.00 μm from high to low were checkout counter, entrance, outer outlet and inner outlet (all P<0.05). The PNC of the checkout counter and entrance varies greatly, while the PNC of the outer outlet and inner outlet was relatively steady. The CFD simulation results showed that particles exhaled by individuals near the entrance of the checkout counter of the convenience store could be expelled outdoors more quickly with the influence of airflow. However, particles exhaled by individuals in the middle of the shelves remained suspended indoors for a longer period of time compared to those near the checkout counter. Particles emitted from the air conditioning outlet diffuse throughout the entire store and reach a steady state in 300 seconds. Conclusion: The particulate matter in the convenience store was mainly small particle with the size less than 1.00 μm. The residence time, downward trend and number of suspended particulates of human exhaled particles were related to air flow. The particulates escaped from the air conditioner could quickly spread to almost the entire convenience store.

Background Long-term exposure to whole-body vibration (WBV) will affect the health of occupational drivers. However, research on the characteristics of WBV exposure by urban bus drivers and health risk evaluation is still insufficient. Objective To identify the characteristics of occupational WBV exposure of bus drivers serving 31 bus routes provided by three branches of Haikou Public Transport Group, and to evaluate their occupational health risks related to WBV. Methods A total of 31 out of 142 bus routes run by three branches of Haikou Public Transport Group were selected to monitor WBV exposure of 31 bus drivers during driving. WBV parameters such as triaxial frequency weighted acceleration (a_wx, a_wy, a_wz) and triaxial crest factor (CF_x, CF_y, CF_z) of the drivers were determined with a six-channel human vibration meter. Two methods, 8-hour daily value of the weighted root mean square average weighted vibration [A(8)] based on a_w and 8-hour daily value of vibration dose [VDV(8)] based on vibration dose value (VDV), were used for health risk assessment and classified WBV health risk results into three levels (high, medium, and low) by the exposure action value (EAV) and exposure limit values (ELV) for A(8) and VDV(8) recommended by ISO 2631-1:1997. The two evaluation methods, A(8) and VDV(8), were compared by Fisher's exact test. Results Regarding the WBV parameters, the vector sum of acceleration (a_v) was 0.321-0.680 m·s⁻², the VDV of monitoring interval was 3.824-10.174 m·s^−1.75, and the VDV(8) was 6.039-13.505 m·s^−1.75; their values in mean ± standard deviation were (0.480±0.100) m·s⁻², (6.987±2.737) m·s^−1.75, and (9.773±4.540) m·s^−1.75, respectively. Positive correlations were found between a_wx and a_wz, a_v and a_wz, CF_x and CF_y, CF_y and CF_z. No bus route's WBV exposure level was graded as high health risk by either A(8) or VDV(8). The number of routes graded as low health risk by A(8) was 26, while the number by VDV(8) was 12. The consistency rates of health risk levels evaluated by the two methods were 66.7% (6/9), 54.6% (6/11), and 45.5% (5/11) for the three bus group branches, respectively. The difference in WBV health risk assessment results between the two evaluation methods was not statistically significant. Conclusion Positive correlations are found between triaxial acceleration and triaxial crest factor. There is no difference in the results of using A(8) and VDV(8) to evaluate health risks of WBV in urban bus routes.

{L-End}Objective To analyze the prevalence of multi-site work-related musculoskeletal disorders (WMSDs) and their influencing factors among workers in the chemical pharmaceutical industry. {L-End}Methods A total of 563 workers from three chemical pharmaceutical factories in Guangzhou City were selected as the research subjects using the judgment sampling method. The prevalence of multi-site WMSDs in the past 12 months was investigated using the electronic questionnaire of Chinese Version of Musculoskeletal Disorders Questionnaire. {L-End}Results The prevalence of multi-site WMSDs in the research subjects was 30.0% (169/563). The results of multivariable logistic regression analysis showed that workers who smoked regularly/frequently and those who had their hands above shoulder level for long periods of time had a lower risk of multi-site WMSDs than those who never/occasionally smoked (all P≤0.05). Workers with a high school, secondary specialty, college degree, or above had a lower risk of multi-site WMSDs than those with a middle school education or below (all P<0.05). The longer the daily working hours, the higher the risk of multiple WMSDs (all P<0.05). Workers with regular/frequently work shifts had a lower risk of multi-site WMSDs than those with none/occasional work shifts (P<0.05). {L-End}Conclusion The prevalence of multi-site WMSDs among workers in the chemical pharmaceutical industry is relatively high. The influencing factors are individual factors, unreasonable work organization and poor ergonomics factors.

{L-End}Objective To analyze the local muscle response under continuous ergonomic workload by simulating manual lifting, and to screen the sensitive metabolic biomarkers during fatigue process. {L-End}Methods A total of 13 healthy male volunteers were selected as the study subjects using simple random sampling method. Study subjects underwent repetitive simulated manual lifting for four periods (T1 to T4), each lasting 12 minutes. The degree of work-related fatigue in the forearm, upper arm, shoulder, back, and leg muscles, and the whole body was accessed using Borg 6-20 Rating of Perceived Exertion (RPE) Scale. The venous blood samples were collected from elbow between each two periods to detect the levels of eight metabolic biomarkers: ammonia, lactate, creatine kinase, lactate dehydrogenase (LDH), C-terminal telopeptide of type Ⅰ collagen (CTX-Ⅰ), C-terminal telopeptide of type Ⅱ collagen (CTX-Ⅱ), cartilage oligomeric matrix protein (COMP), and calcium ions. {L-End}Results The RPE scores of the study subjects for the muscles of five body parts and the whole body increased with the increasing lifting periods (all P<0.01). Fatigue was observed in all target muscles, with overall body fatigue occurring in the T2 period. The levels of ammonia, lactate, creatine kinase, LDH, COMP, and calcium ions in the serum of study subjects were higher in the T1 to T4 periods than in the T0 period (all P<0.05). The serum CTX-Ⅰ level was higher in the T1 and T3 periods than that in the T0 period (all P<0.05) , and the serum CTX-Ⅱ level was higher in the T1, T2 and T4 periods than that in the T0 period (all P<0.05). The level of these eight serum metabolic biomarkers fluctuated during the T1 to T4 periods. The serum creatine kinase level increased with the period of lifting (all P<0.05). The serum lactate level was higher in the T3 period than those in the T1 and T2 periods (all P<0.05). The serum LDH and calcium ion levels were higher in the T2 to T4 periods than that in the T1 period (all P<0.05). The serum COMP level was higher in the T2 and T3 periods than that in the T1 period (all P<0.05). Except for CTX-Ⅰ, the levels of other seven metabolic markers in serum were higher in individuals after fatigue than before fatigue (all P<0.05). {L-End}Conclusion Serum metabolic biomarkers such as ammonia, lactate, creatine kinase, calcium ions, LDH, CTX-Ⅱ, and COMP exhibit significant changes before and after fatigue. These metabolic biomarkers could be used as sensitive biomarkers for evaluating muscle fatigue during repetitive works.