Effect of Occupational Stress on the Work Ability of Iranian Firefighters


Azam Hatami 1 , 2 , Davood Afshari 1 , 3 , *

1 Human Environment and Sustainable Development Research Center, Najafabad Branch, Islamic Azad University, Najafabad, Iran

2 Department of Environmental Managment, Najafabad Branch, Islamic Azad University, Najafabad, Iran

3 Department of Occupational Health and Safety Engineering, School of Health, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran

How to Cite: Hatami A , Afshari D. Effect of Occupational Stress on the Work Ability of Iranian Firefighters, Jundishapur J Health Sci. 2019 ; 11(1):e83410. doi: 10.5812/jjhs.83410.


Jundishapur Journal of Health Sciences: 11 (1); e83410
Published Online: December 24, 2018
Article Type: Research Article
Received: August 17, 2018
Revised: November 24, 2018
Accepted: December 2, 2018


Background: Occupational stress is one of the factors affecting social life and is known as a serious threat to the workforce health in the world. Firefighters are subject to frequent occupational stress due to their working conditions and tasks.

Objectives: The current study aimed at investigating the effect of occupational stress dimensions on the work ability index of firefighters in a petrochemical company in Iran.

Methods: A total of 130 shift-working and day-working firefighters were selected from a petrochemical company using the census method. Occupational stress was evaluated using the health and safety executive (HSE) indicator tool, and the work ability index (WAI) was used to assess the work ability among firefighters. Pearson chi-square test was used to examine the correlation between the various dimensions of occupational stress and the WAI.

Results: The mean of occupational stress in the shift-working group was significantly higher than that of the day-working group (P = 0.029). The results of the Pearson correlation test showed a significant relationship between the mean score of occupational stress and that of the WAI (P = 0.01). Among the stressors, the perceived role and managerial support (R = +0.51), and colleagues support (R = +0.50) had the highest correlation with the work ability of firefighters.

Conclusions: The obtained results showed that occupational stress can affect the work ability of firefighters. Hence, to improve working conditions, identification of various dimensions of occupational stress, especially among shift workers, and implementation of constructive and managerial interventions should be prioritized.

1. Background

Occupational conditions sometimes have a negative impact on the health of workers and employees of administrative and especially industrial units. In recent decades, occupational stress is considered an annoying phenomenon by researchers as well as the World Health Organization (1, 2). Stress is a set of physical, psychological, and perceptual reactions exerted by human physiological and neurological systems against internal and external factors that disturb the natural stability and balance (3). Occupational stress refers to a stress that affects a person in a specific job, and depending on the individual’s experience, strength, and weakness in dealing with the existing conditions, certain feedbacks may appear in the person that can involve the person’s mental, physical, and behavioral aspects (4). The International Labour Organization explicitly states that occupational stress is the most recognized phenomenon that threatens the health of workers. Research shows that about 30% of the workforce in the developed countries have occupational stress (5-7). Other research results indicate that stress in the workplace affects many aspects of life. The prevalence and spread of this pressure in the workplace, especially in recent decades, led researchers to extensively analyze the issue in organizations and its impact on personnel performance (5). Occupational changes such as organizational changes, salary changes, job promotion, reduced or increased workforce, and social transformations are subjects that can put stress on a person resulting in agitation, worry, and anxiety (8). However, there are some jobs that are more prone to stress than the others due to their nature and tasks. Firefighting is one of these stressful occupations with paramount importance. Due to high risk, high sensitivity, complex and uncertain working conditions, direct exposure to various types of accidents and harmful factors, shift work, and the necessity of personnel readiness at any time of the day firefighting is classified as a hard and harmful occupation. These factors result in higher stress in this job than other occupations (9, 10). Therefore, as explained earlier, occupational stress in firefighters can affect various aspects of their lives and job. Some of these aspects are studied and definite results are obtained. However, some aspects such as work ability are studied less. Many scholars and psychologists believe that a moderate level of stress is needed to improve occupational performance in individuals. On the other hand, if this balance is disrupted and stress rises beyond a moderate level, it can result in impaired performance and reduced productivity (11). That is why in some countries, the retirement age in stressful occupations is declined, which leads the ability improvement to be recognized as one of the most effective ways to prevent work inability and early retirement in recent years.

Workability is a complex concept that can be evaluated using the work ability index. This index is a set of factors that enables a person to properly fulfill his/her job requirements under certain conditions (11). In recent years, the work ability index is introduced as an important tool in professional health studies, and can be used to improve health and system efficiency.

2. Objectives

According to the importance of evaluating the work ability among the workforce and that no study is conducted so far in Iran with the variables investigated in the current study, the current study aimed at investigating the impact of occupational stress on the WAI in firefighters in a petrochemical company in Iran. It is expected that the results of the current study can determine the impact of occupational stress dimensions on work ability of the firefighters, and the results can be used to determine appropriate strategies to increase the abilities and efficiency of firefighters.

3. Methods

The current study was conducted in 2017 among firefighters of a petrochemical complex in Mahshahr, Iran. A total of 51 day-working and 79 shift-working firefighters were selected from the petrochemical company using the census method. Data collection tools included two questionnaires, namely the work ability index and the health and safety executive indicator tool (HSE) as an occupational stress self-report questionnaire.

3.1. Work Ability Index

The current study employed the WAI that its high reliability and validity were confirmed in previous studies (12). The validity and reliability of the Persian version of WAI with a Cronbach’s alpha coefficient of 0.79 was determined in Iran by Abdolalizadeh et al. (13). Regarding the method of distribution and completion of the questionnaire, after providing the necessary information and training about the questionnaire and its questions, the data were received from firefighters through semi-structured interviews. This questionnaire was evaluated by presenting a multifaceted image of work ability, including occupational health status, occupational nature of individuals (physical and mental), and work-related factors such as subjective ability of individuals and their estimation of work-induced disorders and their impact on occupational activity. This index was calculated by summing the scores obtained from each item. Based on these dimensions, each worker can obtain a score of 7 (as the worst estimate) to 49 (as the best estimate). The questionnaire is scored based on a Likert scale (14). Finally, based on the obtained scores, the work ability of firefighters was divided into four groups, namely poor (7 - 27), moderate (28 - 36), good (37 - 43), and excellent (44 - 49) (13).

3.2. Occupational Stress Questionnaire

In order to investigate the effect of stressors on the work ability, the Persian version of the HSE indicator tool was used (15). Several studies previously used the questionnaire (16-19). The questionnaire consists of four criteria related to the job content aspects (such as needs or demand, control, managerial support, and coworker support) and three criteria for the job concept (communication, role, and change). The HSE questionnaire items are scored based on a five-point Likert scale (never, rarely, sometimes, often, and always). The scores of each item represent the value measured for them, ranging from 1 (undesirable) to 5 (desirable), i.e., higher scores indicate higher health and safety in terms of stress and lower scores represent more stress among individuals (15).

3.3. Statistical Analysis

All statistical analyses were performed with SPSS version 16.0 (SPSS Inc., Chicago, IL, USA) at 0.05 significant level (P ≥ 0.05).

Paired t-tests (two-tailed) were used to compare values of the WAI between day-working and shift-working firefighters. The Pearson correlation coefficient was used to investigate the correlation between stressors and the work ability of firefighters.

4. Results

Table 1 shows the demographic characteristics of the participants. The results of the Pearson correlation coefficient showed a significant correlation between the mean scores of the occupational stressors and the mean WAI (Tables 2 and 3). Among the stressors in the field of occupation, managerial support and coworker support, and in the job content, the perceived role had the highest correlations with the WAI in firefighters.

Table 1. Characteristics of Respondents
Marital status
High school32.31
Associate degree3224.62
Bachelor’s degree2720.77
Master’s degree75.38
Work experience, y
< 107356.15
11 - 152116.15
16 - 2096.93
> 212720.77
Age, y
< 303325.38
31 - 405139.23
41 - 502720.78
> 501914.61
Table 2. Comparison of Mean Scores of the Work Ability Index in Different Age Groups
Age GroupNumberMean ± Standard Deviation
20 - 302743.50 ± 3.5
31 - 403341.78 ± 3.9
50 - 415134.30 ± 4.12
51 - 602728.85 ± 2.56
60 - 651924.83 ± 4.29
Table 3. Job Stress Status and Pearson Correlation Test Among WAI and Job Stress Among Firefighters
VariableLevel of StressWAI
No StressLowMediumHighRP
Social communication30462220.290.01
Management support3252131.50.510.01
Support of colleagues44411320.500.01
Role Understanding78174.500.510.01

Investigation of the relationship between occupational stress in the shift-working and day-working groups showed that the mean of stress in the shift-working group was higher, and a significant difference was observed between occupational stress and the WAI between the two groups (Table 4).

Table 4. The Difference Between Means of Job Stress and WAI Both in Fixed and Rotating Working Shifts
VariableType of Working ShiftP Value
Day-Working, N = 51Shift-Working, N = 79
Job stress98 (18)113 (23)0.029
WAI39 (5.8)37.8 (4.3)0.16

5. Discussion

The current study aimed at determining the relationship between occupational stressors and the work ability in firefighters of a petrochemical complex.

According to the results of the study, the mean scores of occupational stressors, namely need (demand), control, change, and coworker support were above 30, and the mean scores of relationships and mass communication, managerial support, and perceived role were less than 30. Therefore, relationships and mass communication, managerial support, and perceived role may have a greater impact on stress than other dimensions. The current study results showed that the mean score of WAI of the firefighters was 34.65, indicating the moderate ability of firefighters. The WAI of Iranian firefighters was less than those of other occupations including healthcare workers (40.3) (20), bus drivers (36.8) (21), construction workers(36.46) (22), power plant workers (39.16), metal industry workers (40.7) (23), Finnish police officers (39), and Belgian firefighters (40/6) (24), indicating the inappropriateness of the index. Kim et al. in his study showed that excessive job stress was related to the occurrence and the frequency of occupational injuries in Korean firefighters (25). Kujala et al., considered the working ability scores below 40 unfavorable for workers aged 30 - 40 years , while it was also unfavorable for those participating in the current study (mean age: 36 years) (26). In a study by Koohpayezad et al., in a power station, the average WAI with a mean age of 37 years was reported 12.39 (27).

Also, the result of a study by Sell et al., on the working ability showed that the physical needs of the occupation were among the most important risk factors to reduce work abilities (28). Estryn-Behar et al., showed that unfavorable physical working conditions and inappropriate physical working conditions were among the causes with the greatest effect on the low work ability (29).

The mean score of WAI in different age groups showed that the age group 20 - 30 years obtained the highest mean (43.50 ± 3.5), suggesting the higher work ability of young workforce.

An objective of the current study was to investigate the relationships and effects of different dimensions of occupational stress on the WAI. In the current study, the correlation coefficient between the need (demand) factor and the WAI was negatively significant, which was consistent with the results of previous studies (25, 30). This relationship suggested that some of the working conditions of individuals such as combination of some physical and mental activities, high workloads, lack of time to rest, and being under pressure for a long time at work may reduce the work ability in such personnel. On the other hand, a significant and positive correlation of the control factor coefficient with the work ability indicated that if firefighters can increase their control over the work process through the decision-making process and adjust their work, they feel useful and their WAI increases; these findings were also consistent with the results of previous studies (30). A study from Japan also showed that high quantitative workloads, high variance in workload and high cognitive demands were associated with occupational injury in males working in small-to-medium sized manufacturing enterprise (31).

Among occupational stressors, the change factor had a negatively significant relationship with the WAI, which was consistent with the results of previous studies (25, 30). Therefore, with regard to the results of the current study, if the staff does not have the time to ask the manager about the changes in the organization and their opinions are not considered, their WAI decreases. According to the significant association between relationships and mass communication factor with the WAI observed in the current study, it can be stated that if the firefighters have strong social relationships, create trust among each other, and are not worried about tension in the work environment, they are interested in their workplace, their occupational motivation and the WAI increase (25, 30).

The current study results showed a positive and significant relationship between managerial support, coworker support, and perceived role of the person with the WAI. This finding suggested that if firefighters were involved in decision-making, received positive comments, and feedback on their work, were supported by the manager when dealing with a problem or needing help, were understood when doing psychologically heavy tasks, and were encouraged at work by supervisors, their WAI score increases. In addition, when the firefighters face a problem, if they get the necessary and sufficient respect from their coworkers at workplace, they can express their problems, and try to solve each other’s problems, and accordingly, their WAI increases.

The relationship between occupational stress and the shift-working group showed that the mean stress score in the shift-working group was higher than that of the day-working group, and there was a significant difference between occupational stress and the WAI among these two groups. In addition, the WAI in the day-working group was higher than that of the shift-working group. Therefore, it can be concluded that shift-working firefighters may have higher occupational stress and, consequently, a lower WAI. This can be attributed to being away from the family, the biometric characteristics of the body, and other physiological and psychological factors, which affect the severity of stress. In a study by Samadi and Golmohammadi (30) on the relationship between the WAI and occupational stressors in nurses, it was observed that shift-working nurses had significantly more occupational stress than day-working nurses. Cavalheiro et al. (32), and Hsu et al. (33), found a significant relationship between intermittent shift-working and night-working with stress (31, 34). The negative relationship between occupational stress and WAI is in agreement with the results from diverse occupational groups (35-38). And also, some studies indicated that increased stress and musculoskeletal pain were independently associated with lower work ability (39, 40).

5.1. Conclusions

The findings of the current study showed that the WAI in the studied firefighters was moderate and there was a significant relationship between the night-working and different dimensions of occupational stress in firefighters. Occupational stress seemed to affect the night-working of firefighters. Therefore, to improve working conditions, identification of various dimensions of occupational stress, especially among shift workers, and implementation of constructive and managerial interventions should be prioritized.

5.2. Limitations

One of the limitations of the current study was that its results cannot be generalized to other occupations due to the nature of the firefighters’ job. In addition, data were collected through participants’ self-reports. Therefore, the views and perceptions of the respondents may be mixed with biases, thoughts, and judgments, which may affect the results of the study.




  • 1.

    Thomas RJ. Occupational health-recognizing and preventing work-related disease and injury. J Occup Environ Med. 2000;42(11):1131-2. doi: 10.1097/00043764-200011000-00021.

  • 2.

    Laposa JM, Alden LE, Fullerton LM. Work stress and posttraumatic stress disorder in ED nurses/personnel. J Emerg Nurs. 2003;29(1):23-8. [PubMed: 12556825].

  • 3.

    Ross RR, Altmaier EM. Intervention in occupational stress: A handbook of counselling for stress at work. Sage; 1994.

  • 4.

    Aghilinejad M, Farshad AA, Mostafaei M, Ghafari M. [Occupational medicine practice]. Tehran: Arjmand Pub; 2001. Persian.

  • 5.

    Klein S, Alexander DA. Epidemiology and presentation of post-traumatic disorders. Psychiatry. 2006;5(7):225-7. doi: 10.1053/j.mppsy.2006.04.009.

  • 6.

    Laposa JM, Alden LE. Posttraumatic stress disorder in the emergency room: Exploration of a cognitive model. Behav Res Ther. 2003;41(1):49-65. [PubMed: 12488119].

  • 7.

    Raessi P, Monajjemi F. [Job stressores for medical records personnel in teaching hospitals of Iran University of Medical Sciences]. Iran J Psychia Clin Psychol. 1999;5(1-2):45-55. Persian.

  • 8.

    Dehshiri GR. [Study of relationship between emotional intelligence and time management with high school teachers job stress]. Counseling Res Dev. 2005;3(12):53-64. Persian.

  • 9.

    Burbeck R, Coomber S, Robinson SM, Todd C. Occupational stress in consultants in accident and emergency medicine: A national survey of levels of stress at work. Emerg Med J. 2002;19(3):234-8. [PubMed: 11971836]. [PubMed Central: PMC1725872].

  • 10.

    Mirzabeigi GH, Salemi S, Sanjari M, Shirazi F, Heidari SH, Maleki S. [Job satisfaction among Iranian nurses]. J hayat. 2009;15(1):49-59. Persian.

  • 11.

    Safari S, Habibi E, Dehghan H, Mahaki B, Hassanzadeh A. [Job stress, education and work ability among refinery workers]. Occup Med Q J. 2013;5(3):1-10. Persian.

  • 12.

    Silva Junior SH, Vasconcelos AG, Griep RH, Rotenberg L. [Test-retest reliability of the work ability index (WAI) in nursing workers]. Rev Bras Epidemiol. 2013;16(1):202-9. Portuguese. [PubMed: 23681336].

  • 13.

    Abdolalizadeh M, Arastoo AA, Ghsemzadeh R, Montazeri A, Ahmadi K, Azizi A. The psychometric properties of an Iranian translation of the work ability index (WAI) questionnaire. J Occup Rehabil. 2012;22(3):401-8. doi: 10.1007/s10926-012-9355-3. [PubMed: 22438127].

  • 14.

    Leinweber J, Rowe HJ. The costs of 'being with the woman: Secondary traumatic stress in midwifery. Midwifery. 2010;26(1):76-87. doi: 10.1016/j.midw.2008.04.003. [PubMed: 18562056].

  • 15.

    Marzabadi Azad E, Fesharaki Gholami M. [Reliability and validity assessment for the HSE job stress questionnaire]. J Behav Sci. 2011;4(4):291-7. Persian.

  • 16.

    Gharibi V, Mokarami H, Taban A, Yazdani Aval M, Samimi K, Salesi M. Effects of work-related stress on work ability index among Iranian workers. Saf Health Work. 2016;7(1):43-8. doi: 10.1016/j.shaw.2015.10.005. [PubMed: 27014490]. [PubMed Central: PMC4792919].

  • 17.

    Kiani F, Samavtyan H, Poorabdiyan S. The relationship between job stress workers perceived and their dimensions with attitude to safety in an industrial unit. 3rd National Conference on Safety Engineering and Management HSE. 2010.

  • 18.

    Gharibi V, Malakouti J, Jang Arsang S, Gholami A. Prevalence of occupational stress and its relationship to individual characteristics in tunneling industry workers. Health Sys Res. 2013;9(1):57-65.

  • 19.

    Nasiry Zarrin Ghabaee D, Haresabadi M, Bagheri Nesami M, Esmaeili R, Talebpour Amiri F. [Musculoskeletal disorders in nurses and their relationship with occupation-related stress]. J Mazandaran Univ Med Sci. 2016;25(132):91-102. Persian.

  • 20.

    Mehrdad R, Mazloumi A, Arshi S, Kazemi Z. Work ability index among healthcare personnel in a university hospital in Tehran, Iran. Work. 2016;53(4):851-7. doi: 10.3233/WOR-162277. [PubMed: 26967041].

  • 21.

    Sampaio RF, Coelho CM, Barbosa FB, Mancini MC, Parreira VF. Work ability and stress in a bus transportation company in Belo Horizonte, Brazil. Cien Saude Colet. 2009;14(1):287-96. [PubMed: 19142333].

  • 22.

    Hajizadeh F, Motamedzade M, Golmohammadi R, Soltanian A. Work ability assessment and its relationship with severity of musculoskeletal disorders among workers in a cement plant. J Occup Heal Eng. 2015;2(2):15-22.

  • 23.

    Tuomi K, Vanhala S, Nykyri E, Janhonen M. Organizational practices, work demands and the well-being of employees: A follow-up study in the metal industry and retail trade. Occup Med. 2004;54(2):115-21. doi: 10.1093/occmed/kqh005.

  • 24.

    Alavinia SM, de Boer AG, van Duivenbooden JC, Frings-Dresen MH, Burdorf A. Determinants of work ability and its predictive value for disability. Occup Med (Lond). 2009;59(1):32-7. doi: 10.1093/occmed/kqn148. [PubMed: 19073989].

  • 25.

    Kim HC, Min JY, Min KB, Park SG. Job strain and the risk for occupational injury in small- to medium-sized manufacturing enterprises: A prospective study of 1,209 Korean employees. Am J Ind Med. 2009;52(4):322-30. doi: 10.1002/ajim.20673. [PubMed: 19142960].

  • 26.

    Kujala V, Remes J, Ek E, Tammelin T, Laitinen J. Classification of work ability index among young employees. Occup Med (Lond). 2005;55(5):399-401. doi: 10.1093/occmed/kqi075. [PubMed: 16040772].

  • 27.

    Koohpayezadeh J, Kabir Mokamelkhah E, Alavinia MA, KarimiFarshi L, Akbari F. [Study on predictive value of work ability index to predict sick leave and disability caused by work]. Razi J Med Sci. 2014;21(125):126-30. Persian.

  • 28.

    Sell L, Faber A, Søgaard K, Masaharu K. Impacts from occupational risk factors on self reported reduced work ability among Danish wage earners. Promotion of workability towards productive aging: Selected papers of the 3rd International Symposium on Workability, Hanoi, Vietnam, 22-24 October 2007. London, UK. Taylor and Francis; 2008. p. 105-12.

  • 29.

    Estryn-Behar M, Kreutz G, Le Nezet O, Mouchot L, Camerino D, Salles RK, et al. Promotion of work ability among French health care workers value of the work ability index. International Congress Series. Elsevier; 2005. p. 73-8.

  • 30.

    Samadi S, Golmohammadi A. [Study the relation between occupational stress and work ability index among nurses of selected military hospital]. J Police Med. 2013;2(4):223. Persian.

  • 31.

    Kim YK, Ahn YS, Kim K, Yoon JH, Roh J. Association between job stress and occupational injuries among Korean firefighters: A nationwide cross-sectional study. BMJ Open. 2016;6(11). e012002. doi: 10.1136/bmjopen-2016-012002. [PubMed: 27888173]. [PubMed Central: PMC5168540].

  • 32.

    Cavalheiro AM, Moura Junior DF, Lopes AC. Stress in nurses working in intensive care units. Rev Lat Am Enfermagem. 2008;16(1):29-35. [PubMed: 18392527].

  • 33.

    Hsu HC, Kung YW, Huang HC, Ho PY, Lin YY, Chen WS. Work stress among nursing home care attendants in Taiwan: A questionnaire survey. Int J Nurs Stud. 2007;44(5):736-46. doi: 10.1016/j.ijnurstu.2005.12.006. [PubMed: 16476432].

  • 34.

    Mamidaramrod H, Nori A, Samavatian H. The relationship between stress, workload and burnout in nurses of Isfahan hospital. The 2nd National Congress of Industrial and Organizational Psychology. Isfahan Islamic Azad University, Isfahan. 2011.

  • 35.

    Yong M, Nasterlack M, Pluto RP, Lang S, Oberlinner C. Occupational stress perception and its potential impact on work ability. Work. 2013;46(3):347-54. doi: 10.3233/WOR-121556. [PubMed: 23324708].

  • 36.

    Bresic J, Knezevic B, Milosevic M, Tomljanovic T, Golubic R, Mustajbegovic J. Stress and work ability in oil industry workers. Arh Hig Rada Toksikol. 2007;58(4):399-405. doi: 10.2478/v10004-007-0032-4. [PubMed: 18063524].

  • 37.

    Ma XM, Kang HL, Shi CB, Li Y, Wu YF, Liu ZH, et al. [Relationship between occupational stress and working ability of workers in a petroleum processing enterprise in high altitude area]. Zhonghua Lao Dong Wei Sheng Zhi Ye Bing Za Zhi. 2017;35(12):907-10. Chinese. doi: 10.3760/cma.j.issn.1001-9391.2017.12.006. [PubMed: 29495152].

  • 38.

    Habibi E, Dehghan H, Safari S, Mahaki B, Hassanzadeh A. Effects of work-related stress on work ability index among refinery workers. J Educ Health Promot. 2014;3:18. doi: 10.4103/2277-9531.127598. [PubMed: 24741658]. [PubMed Central: PMC3977403].

  • 39.

    Jay K, Friborg MK, Sjogaard G, Jakobsen MD, Sundstrup E, Brandt M, et al. The consequence of combined pain and stress on work ability in female laboratory technicians: A cross-sectional study. Int J Environ Res Public Health. 2015;12(12):15834-42. doi: 10.3390/ijerph121215024. [PubMed: 26690466]. [PubMed Central: PMC4690960].

  • 40.

    Oberlinner C, Yong M, Nasterlack M, Pluto RP, Lang S. Combined effect of back pain and stress on work ability. Occup Med (Lond). 2015;65(2):147-53. doi: 10.1093/occmed/kqu190. [PubMed: 25634953].

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