Background The job content of aircraft maintenance workers is complex, with high intensity and high requirements, and they are prone to work-related musculoskeletal disorders (WMSDs), but related research is relatively rare. Objective To investigate the positive rate of WMSDs among aircraft maintenance workers, evaluate ergonomic load, and analyze the risk factors of WMSDs. Methods We used a self-compiled questionnaire for WMSDs and the Quick Exposure Checklist (QEC) to investigate the basic situation, positive rate of WMSDs, and the ergonomic load of 2271 male maintenance workers in 6 departments of an aircraft maintenance company, including airline maintenance, overall overhaul, accessory/landing gear overhaul, engine overhaul, product customization, and power assist. We used a logistic regression model to analyze the risk factors of WMSDs in the neck, shoulder, hand/wrist, and lower back. Results The positive rate of WMSDs in the past 12 months was 70.4% (1598/2271) and the positive rate of WMSDs in different body parts ranged from 6.6% to 49.5%, with the top three parts of lower back, neck, and knee, respectively. There were statistically significant differences in the positive rate among different departments (P<0.05). The average QEC scores for neck, hand/wrist, and back (static) were moderate, while those for shoulder and back (dynamic) were high, and the body part specific positive rate of WMSDs increased with the increase of ergonomic load level. Working years (5-<10 years, ≥20 years), working with back flexed or twisted or side bent (moderately, excessively), high maximum force level exerted by one hand, and feeling difficult (sometimes, often) and stressful (moderately, very) while working were associated with higher risks of lower back pain (OR=1.486, 1.505; 2.151, 3.769; 1.637; 2.110, 2.407; 1.637, 1.794; P<0.05). Working years (15-<20 years, ≥20 years), working with head/neck bent or twisted (occasionally, continuously), feeling difficult (sometimes) and stressful (very) while working were associated with higher risks of neck pain (OR=1.731, 1.586; 3.732, 8.341; 1.633; 1.696; P<0.05). Working years (15-<20 years, ≥20 years), working with hands in a high position (at shoulder or above), very frequent shoulder/arm movements, feeling difficult (sometimes, often) and stressful (moderately, very) while working were associated with higher risks of shoulder pain (OR=1.587, 1.709; 1.299; 1.521; 1.643, 2.239; 1.659, 1.977; P<0.05). Working with wrist at deviated or bent angle, high repetition of similar movements, feeling difficult (sometimes, often) and stressful (moderately, very) while working were associated with higher risks of hand/wrist pain (OR=1.692; 1.670; 1.827, 2.884; 2.190, 2.625; P <0.05) . Physical exercise after work (≥3 times·week⁻¹) was associated with a lower risk of neck pain (OR=0.582, P<0.05). Shift workers were at a lower risk of shoulder pain and hand/wrist pain (OR=0.737 and 0.554, P<0.05). Conclusion The high positive rate of WMSDs symptoms among aircraft maintenance workers is related to individual, occupational ergonomic, and psychological factors, and active prevention and intervention should be taken.

Objective:To investigate the status of work-related musculoskeletal disorders (WMSDs) in male large-scale mechanical maintenance workers, and to explore the relationship between WMSDs and thyroid indexes.Methods:From April to July 2022, male front-line maintenance workers in a large-scale mechanical maintenance enterprise who participated in occupational health examination were selected as the study subjects ( n=2036). The occurrence of WMSDs was investigated by questionnaire. The levels of triiodothyronine (T3), thyroxine (T4) and thyroid stimulating hormone (TSH) in serum were detected. χ2 test, t-test and Mann-Whitney U test were used to detect thyroid diseases and hormone levels of workers in WMSDs group and non-WMSDs group, and binary logistic regression model was used to analyze the relationship between thyroid disease, T3, T4, TSH and WMSDs. Results:The incidence of WMSDs among the male large-scale mechanical maintenance workers was 73.18% (1490/2036). The rate of thyroid disease in WMSDs group was higher than that in non-WMSDs group [8.26% (123/1490) vs. 4.95% (27/546), χ 2=6.42, P=0.011], and the TSH value was lower than that in non-WMSDs group[1.66 (1.23, 2.26) μIU/ml vs. 1.75 (1.30, 2.42) μIU/ml, Z=-2.40, P=0.019]. There were no significant differences in the levels of T3, T4 and abnormal levels of 3 hormones between the two groups ( P>0.05). After accounting for individual and occupational factors, workers with thyroid disease had an increased risk of WMSDs ( OR=1.656, 95% CI: 1.072-2.559, P=0.023), while workers with increased TSH had a decreased risk of WMSDs ( OR=0.897, 95% CI: 0.823-0.977, P=0.013) . Conclusion:The incidence of WMSDs in male workers of large-scale mechanical maintenance is high, and its incidence may be related to thyroid index. Thyroid disease may be a risk factor for WMSDs, and increased TSH may be a protective factor for WMSDs.

Objective:To investigate the status of work-related musculoskeletal disorders (WMSDs) in male large-scale mechanical maintenance workers, and to explore the relationship between WMSDs and thyroid indexes.Methods:From April to July 2022, male front-line maintenance workers in a large-scale mechanical maintenance enterprise who participated in occupational health examination were selected as the study subjects ( n=2036). The occurrence of WMSDs was investigated by questionnaire. The levels of triiodothyronine (T3), thyroxine (T4) and thyroid stimulating hormone (TSH) in serum were detected. χ2 test, t-test and Mann-Whitney U test were used to detect thyroid diseases and hormone levels of workers in WMSDs group and non-WMSDs group, and binary logistic regression model was used to analyze the relationship between thyroid disease, T3, T4, TSH and WMSDs. Results:The incidence of WMSDs among the male large-scale mechanical maintenance workers was 73.18% (1490/2036). The rate of thyroid disease in WMSDs group was higher than that in non-WMSDs group [8.26% (123/1490) vs. 4.95% (27/546), χ 2=6.42, P=0.011], and the TSH value was lower than that in non-WMSDs group[1.66 (1.23, 2.26) μIU/ml vs. 1.75 (1.30, 2.42) μIU/ml, Z=-2.40, P=0.019]. There were no significant differences in the levels of T3, T4 and abnormal levels of 3 hormones between the two groups ( P>0.05). After accounting for individual and occupational factors, workers with thyroid disease had an increased risk of WMSDs ( OR=1.656, 95% CI: 1.072-2.559, P=0.023), while workers with increased TSH had a decreased risk of WMSDs ( OR=0.897, 95% CI: 0.823-0.977, P=0.013) . Conclusion:The incidence of WMSDs in male workers of large-scale mechanical maintenance is high, and its incidence may be related to thyroid index. Thyroid disease may be a risk factor for WMSDs, and increased TSH may be a protective factor for WMSDs.

Background Bus drivers are a high-risk group for work-related musculoskeletal disorders (WMSDs). There are a large number of bus drivers in mega-cities. High volumes of passenger traffic and complexity of road conditions may elevate their risk of WMSDs, but there are few studies related to this group. Objective To investigate the prevalence of WMSDs among bus drivers in a mega-city and to analyze potential influencing factors. Methods Based on cross-sectional study design and self-administered questionnaire, the prevalence of WMSDs in past 12 months were estimated by stratified cluster sampling among bus drivers in a mega-city. Pearson χ² and logistic regression models were used to analyze the influencing factors for the body regions with a high prevalence. Results The overall prevalence of WMSDs in past 12 months among bus drivers in a mega-city was 49.5% (551/1113). The prevalence of WMSDs by body regions ranged from 4.0% to 38.5%, and led by neck pain (38.5%), lower back pain (25.5%), and shoulder pain (20.8%). The results of logistic regression showed that the risk factors for neck pain were age (>50 years), smoking, tiredness after work (moderate, severe), long sitting (frequently), awkward postures (sometimes, often, frequently), overtime(occasionally, often), workplace temperature (uncomfortable), and noise (severe) (OR=2.014、1.577、2.793、3.025、2.708、2.032、3.406、2.746、1.442、2.998、1.456、3.506；P<0.05); the lower back pain risk factors were current work experience (6-10 years, 11-15 years, and 16-20 years), smoking, tiredness after work (moderate, severe), and awkward postures(sometimes, often, frequently)(OR=1.777、2.130、2.400、1.503、2.951、3.364、1.836、4.569、2.786，P<0.05); and the shoulder pain risk factors were age (46-50 years, and >50 years), smoking, tiredness after work (moderate, severe), vehicle type (hybrid power, diesel oil), awkward postures (often, frequently), overtime (often), and workplace temperature (uncomfortable) (OR=1.737、2.357、1.553、2.259、2.489、1.659、3.295、2.777、3.320、2.266、1.426，P<0.05). Identified protective factors for neck and lower back pain were off-duty physical activity (1-2 times per week, and ≥3 times per week) (OR=0.553、0.470、0.586、0.485，P<0.05). Conclusion Nearly half of the bus drivers in the mega-city report symptoms of WMSDs, mainly in the neck, lower back, and shoulders. The prevalence is related to individual and occupational factors, and prevention and intervention measures should be actively taken.

{L-End}Objective To explore the suitable methods for individual occupational stress examination and evaluation for workers in China based on the electronics industry. {L-End}Methods A total of 1 164 workers from four electronics enterprises in Beijing City were selected as the research subjects using a convenient sampling method. The Occupational Stress Measurement Scale, which was developed based on the Japanese Brief Job Stress Questionnaire, was used to assess the occupational stress of the research subjects, and test the reliability and validity of the scale. Percentile norms and T-score norms were established, and the T-scores of the three dimensions of stress reaction (psychological reaction and physical symptoms), stress factors, and social support were divided into five stages using the normal distribution method with x¯±0.5 s and x¯±1.5 s, which was used to explore a proposed standard for assessing individual stress levels. {L-End}Results The revised scale consisted of 57 items, which could explain 64.0% of the total variation of occupational stress based on the result of item analysis and exploratory factor analysis. The results of confirmatory factor analysis showed that the model fitted well, with root mean square error of approximation of 0.052, standardized root mean square residual of 0.070, comparative fit index of 0.960, and Tucker-Lewis index of 0.958. The Cronbach's α coefficient of the scale was 0.951, and the Spearman-Brown coefficient was 0.837. Cronbach's α coefficients of the three dimensions ranged from 0.794 to 0.952, and the Spearman-Brown coefficients ranged from 0.737 to 0.850. The scores of the three dimensions of stress reaction, stress factors, and social support were (49.1±13.0), (44.9±7.7), and (18.1±3.6), respectively. Workers in the electronics industry met one of the following items were identified as the high level of occupational stress individuals: i) a score of stress reaction dimension ≥72.0 points; ii) a sum of stress factor and social support dimension scores ≥81.0 points, and a stress reaction dimension score ≥58.0 points. {L-End}Conclusion The Occupational Stress Measurement Scale and the criteria for determining high level of occupational stress can be used to assess the individual occupational stress levels of workers in the electronics industry in China. This method can provide a theoretical basis for the formulation of occupational stress examination and assessment for Chinese workers.