The Status of Occupational Burnout and Its Influence on the Psychological Health of Factory Workers and Miners in Wulumuqi, China

The purpose of this study was to investigate the status of occupational burnout and its influence on the psychological health of factory workers and miners, in order to provide theoretical basis and reference for alleviating occupational burnout and promoting psychological health. The cross-sectional study investigated 6130 factory workers and miners with online questionnaire; the Chinese Maslach Burnout Inventory (CMBI) and Symptom Check List-90 (SCL-90) were used. In total, 6120 valid questionnaires were collected; effectiveness was 99.8%. The percentage of the factory workers and miners suffering from occupational burnout was 85.98% and psychological health problems was 38.27%. A statistically significant difference was observed in relation to the prevalence of occupational burnout among factory workers and miners of different sex, education level, labor contracts, work schedule, monthly incomes, weight, hypertension, age, working years, working hours per day, working hours per week, coal dust, silica dust, asbestos dust, benzene, lead, and noise. The detection rate of psychological health was higher for males than females. The detection rate of psychological health was higher for working days per week less than 5 days than more than 5 days. The detection rate of psychological health with high school education, senior professional title, night shift, divorced, monthly income less than 3000 yuan, weight more than 75 kg, age more than 45 years, and working years between 25 and 30 years was higher than that of the other groups. The results showed that sex, education level, professional title, work schedule, monthly income, hypertension, age, working years, asbestos dust, benzene, and occupational burnout affected psychological health among factory workers and miners. Factory workers and miners had high levels of occupational burnout, and occupational burnout was a risk factor that can lead to psychological health.


Introduction
Occupational burnout refers to physical or mental exhaustion caused by overwork or stress [1]; it also can be described as a psychological syndrome characterized by exhaustion, cynicism, depersonalization, and reduced professional efficacy [2]. With the development of society and the increase of life pressure, people bear more and more pressure from society, work, and life. Occupational burnout has been regarded the crisis and illness in modern society and life.
Occupational stress, lifestyle, and personal relaxation have been shown to contribute to the development of occupational burnout and cause a series of psychological problems [3][4][5]. Previous literature review of studies in different occupational groups has indicated that classic risk factors such as high demands, low job control, high job strain, low reward, and job insecurity increased the risk for developing burnout [6]. Several studies have showed the effects of occupational burnout on psychological health, such as neurasthenia, anxiety disorder, and depression [7,8]. But other surveys did not find the correlation between occupational burnout and psychological health [9,10]. Thus, the relationship of occupational burnout and mental health needs to be further explored.
Factory workers and miners belong to a special occupational group who work in high-tension conditions, and a demanding work environment with dust, chemical factors, physical factors, and biological factors can detrimentally affect employees' psychological health, leading to job stress and burnout [11]. There is a lack of research about the association between occupational burnout and individual characteristics or occupational hazards of factory workers and miners. Therefore, this study administered a questionnaire survey to factory workers and miners in Wulumuqi, China, to investigate the status of occupational burnout and its influence on psychological health, in order to provide theoretical basis and reference for alleviating occupational burnout and promoting psychological health.

Participants.
This survey was carried out from January to May 2019. Workers on the occupational exposures of coal dust, silica dust, asbestos dust, benzene, lead, noise, and Brucella in factories and mines in Urumqi, China, were investigated. A total of 6500 factory workers and miners were initially selected using a cluster sampling method. Participants without the occupational exposures according to their working environment were excluded. Those with work experience less than one year or taking psychoactive drugs were also excluded. According to the inclusion and exclusion criteria, 6130 participants were included in this survey. The cross-sectional study was conducted by online questionnaire using a mobile phone. The respondents volunteered to participate in the survey, and the written informed consent was provided. Finally, 6120 questionnaires were collected and 10 copies of continuous answer questionnaires were excluded. The effectiveness was 99.8%.

Chinese Maslach Burnout Inventory (CMBI).
The Chinese Maslach Burnout Inventory (CMBI) was established by Li Yongxin which was based on Maslach Burnout Inventory (MBI). The Cronbach α for the CMBI was 0.88, split-half reliability coefficient was 0.84, and KMO was 0.91, respectively. The CMBI consisted of 15 items about three dimensions: emotional exhaustion, depersonalization, and reduced personal accomplishment; subjects responded to each item ranging from 1 (completely fitting) to 7 (completely unfitting). According to the critical values (emotional exhaustion ≥ 25, depersonalization ≥ 11, and reduced personal accomplishment ≥ 16), occupational burnout was divided into four levels: none (subjects' scores on three factors were lower than the critical value), mild (subjects' scores on any one factor were equal to or higher than the critical value), moderate (subjects' scores on any two factors were equal to or higher than the critical value), and severe (subjects' scores on three factors were equal to or higher than the critical value) [12][13][14][15].

Symptom Check List-90 (SCL-90). The Symptom Check
List-90 (SCL-90) was established by L.R. Derogatis in 1975 and widely used in psychiatric outpatient examination because of its high authenticity in evaluating various mental health surveys [16,17]. The Cronbach α for the SCL-90 was 0.99, split-half reliability coefficient was 0.98, and KMO was 0.99, respectively. There were 9 dimensions (including 90 items) in SCL-90, and each item was assigned a score ranging from 1 (not have) to 5 (serious). The 9 dimensions were somatization, obsessive-compulsive symptoms, interpersonal sensitivity, depression, anxiety, hostility, phobia, paranoid ideation, and psychosis. The higher score showed a worse psychological symptom. The result was positive, and further examination was needed, when the total score was more than 160, or any item score was more than 2, or the number of positive items was more than 43 [18].

Quality Control.
All the investigators were trained before the survey. In order to ensure the completeness of the online questionnaire, each item was set as required. If there was any missing value, the questionnaire cannot be submitted. The validity analysis of the data was completed by senior data analysts.
We facilitated the preinvestigation before the formal investigate, in order to train investigators and foster cooperation. We contacted face-to-face interviews with each participant to complete the online questionnaire and solve their concerns timely.

Statistical
Methods. The results were analyzed by R software (Version: 3.5.2). A chi-squared test was used for the counting data; multiple logistic regression analysis was used to estimate the relationship between multiple factors. The significance level (α) was set at 0.05.

Exploration of Factors Influencing Psychological Health.
Multiple logistic regression analysis was used to analyze the effects of different characteristics and occupational burnout on the psychological health of factory workers and miners. All the independent variables in the logistic regression were stratified. The results showed that education level of junior college and higher (P < 0:001), work schedule of shift and day and night shift (P < 0:001), monthly income (except for 7000~) (P < 0:005), hypertension (P < 0:001), working years (P < 0:005), asbestos dust (P < 0:001), benzene (P = 0:021), and occupational burnout (P < 0:001) affected psychological health of factory workers and miners. Higher education, shift work or day and night shift, lower income, hypertension, longer working years, exposure to asbestos dust and benzene, and occupational burnout were risk factors related to poorer psychological health (Table 4).

Discussion
Occupational burnout is a state of pressure that is a significant issue worldwide which is related to efficiency and quality of work, and it is also regarded as particularly harmful to the social psychological of the working population [19,20]. A study conducted by Inger et al. examined the occupational burnout of southern Sweden teachers and found that 46.8% teachers suffered from burnout [21]. Guan et al. found that the rate of occupational burnout among civil servants was 45.0% [22]. A survey in China had revealed that the prevalence of occupational burnout in the military was 88.14% [23,24]. While occupational burnout can affect physical and psychological health, it also adversely impacts upon the working ability and quality.
Factory workers and miners belong to a special professional group, whose mental health is closely related to the development of the industry. However, the workers and miners' social status is low, and they work hard but the income is relatively low [19]. Long periods of heavy work caused them to languish and burnout. And they often worked in a special environment of high temperature, high pressure, darkness, or dust; some studies already proved that people living in harsh environments have a higher risk of developing mental illnesses, and the special environments affect the degree of job burnout [25][26][27][28]. Our research presented here revealed that 85.98% of factory workers and miners experience occupational burnout, reminding that occupational  The higher the level of occupational burnout, the poorer the psychological health of factory workers and miners, suggesting that occupational burnout is a risk factor that can influence psychological health.
This survey investigated occupational burnout levels among factory workers and miners. The occupational burnout level of night shift workers was higher than that of others, which may due to long-term working at night causing night and day reversal and lack of rest, thereby resulting in fatigue. Chronic diseases such as hypertension could cause changes in the body's functioning that can make workers feel more tired at work. People under 30 years old or with less than 10 working years were more likely to develop occupational burnout. Most of them had acquired professional skills and had good stamina so that they were more eager to seek promotion opportunity or to increase their personal income [29]. Workers who worked more than 7 hours per day or more than 5 days per week need to maintain a high level of stress, and lack of time of recreation, leisure, and relaxation increased their burnout levels, which might enhance the risk of mental health problems [30,31]. Long-term occupational exposure to coal dust, silica dust, asbestos dust, benzene, lead, and noise would cause varying degrees of pulmonary diseases and other illness, thereby affecting respiration and body metabolism, which makes them prone to fatigue and tired. The study found that education level had influence on psychological health; the risks of psychological health problems at junior college and bachelor's degree or above were 1.80 times and 2.03 times that of junior high school and below, respectively. Maslach' study had showed that people who had higher education may have more self-expectation and social expectation [32]. When the job cannot meet one's personal needs and expectation, one may experience strain response such as job satisfaction drops, occupational burnout, and mental illness [33][34][35]. Work schedule was a risk factor related to poor psychological health, particularly at shift and day and night shift. The risk of psychological health problems increased with changing a way of work schedule and/or of day and night shifts was the highest. The longterm day and night shifts made workers' day and night reversed, resulting in the different physical functions and thereby leading to mental illness. Khajehnasiri et al.'s research also showed that shift workers had a high level of stress and depressive symptoms [36]. The influence of marital status on psychological health was statistically significant  7 BioMed Research International in univariate analysis, but not in multiple logistic regression analysis, which meant marital status was not an independent risk factor of psychological health. But some studies confirmed the correlation of divorce and psychological problems due to lack of a sense of family and kinship [37,38]. Due to the poor physical health, workers with hypertension were liable to suffer from cardiovascular diseases and thereby have some psychological changes, which was consistent with other studies [39]. The influence of occupational burnout at any level on psychological health was statistically significant, and the risks of psychological health problems increased 1.43 times, 3.82 times, and 25.53 times with aggravating occupational burnout level, respectively. According to psychological theories, excess psychological stress could decline psychological function (such as distracted attention and reduced working will and desire) and cause negative physiological responses (such as declined strength, stiffened body, and disorders in sense and memory) [40]. The higher the occupational burnout, the more significant the adverse physiological function and psychological reaction, leading to increasing the possibility of work errors. When workers and miners can no longer utilize their internal and social resources to relieve their psychological burden caused by work errors, their psychological balance will be disturbed, resulting in emotional fluctuations and psychological health problems [41].
It reminded that reasonable arrangement of work shift, promotion of occupational personal protection and health education, guidance to spare time arrangement of workers, enhancement of disease prevention, and psychological counseling should be taken into consideration to keep physical and mental health of factory workers and miners.
The present survey used online questionnaire; compared with paper questionnaire, the recovery rate was higher, but there were still repeated answers and cross-sectional investigation cannot establish a causal relationship between diseases; in the future, further studies will continue to explore the relationship between the factors and diseases by using cohort studies.

Conclusion
In conclusion, this survey found that the factory workers and miners generally suffered from occupational burnout, and sex, education level, professional title, work schedule, monthly income, hypertension, age, working years, asbestos  dust, and benzene were related risk factors. In addition, occupational burnout influenced the psychological health. Measures need to be taken to ease occupational burnout among factory workers and miners in order to improve their psychological health.

Data Availability
The data used to support the findings of this study are available from the corresponding author upon request.

Disclosure
The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript; or in the decision to publish the results.