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Prevalence and risk factors of sick building syndrome among office workers

Abdel-Hamid, Mona A.; A. Hakim, Sally; Elokda, Elsayed E.; Mostafa, Nayera S.

The Journal Of The Egyptian Public Health Association: August 2013 - Volume 88 - Issue 2 - p 109–114
doi: 10.1097/01.EPX.0000431629.28378.c0
Original articles

Background Sick building syndrome (SBS) is a group of symptoms relatively common among office workers; such symptoms could have an impact on the workers’ productivity. The aim of this study is to measure the prevalence of SBS symptoms among office workers in the Faculty of Medicine, Ain Shams University, Cairo, Egypt, and to determine the possible risk factors.

Participants and methods A cross-sectional study was carried out at the Ain Shams Faculty of Medicine including 826 workers. Data were collected through a self-administered questionnaire that included sociodemographic and occupational histories, work environment, and symptoms related to SBS.

Results Fatigue and headache were the most prevalent symptoms (76.9 and 74.7%, respectively). Using univariate analysis, poor lighting, poor ventilation, lack of sunlight, absence of air currents, high noise, temperature, humidity, environmental tobacco smoke, use of photocopiers, and inadequate office cleaning were associated statistically with SBS symptoms (P<0.05). High work load and poor job satisfaction were also associated significantly with SBS symptoms (P<0.05). Logistic regression analysis showed that poor ventilation, poor lighting, environmental tobacco smoke, high temperature, poor job satisfaction, and inadequate office cleaning were the risk factors of SBS.

Conclusion and recommendations SBS was highly prevalent among office workers and was influenced by physical and psychosocial working conditions. Good ventilation, reducing room temperature, effective cleaning routines, providing proper lighting, restricting smoking in the workplace, and improving psychosocial working conditions are important ways to reduce SBS symptoms.

Community, Environmental and Occupational Medicine Department, Faculty of Medicine, Ain Shams University (ASU), Cairo, Egypt

Correspondence to Mona A. Abdel-Hamid, MD, Community, Environmental and Occupational Medicine Department, Faculty of Medicine, Ain Shams University (ASU), Ramsis Street, Abbaseya, 11566 Cairo, Egypt Tel: +20 100 497 6136; fax: +20 224 837 888; e-mail:

Received April 6, 2013

Accepted May 28, 2013

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Sick building syndrome’ (SBS) is a group of symptoms experienced by individuals working in various buildings. This term or another one, ‘building-related illness’ (BRI), is used to define illnesses related to nonindustrial and nonresidential buildings, mainly modern offices, in which individuals spend many working hours. Specific BRI applies to a group of illnesses with a fairly homogeneous clinical picture and known etiology (infectious, immunological, or allergic). Nonspecific BRI applies to a group of heterogeneous and nonspecific, work-related symptoms, including irritation of the skin and mucous membranes of the eyes, nose and throat, headache, fatigue, and concentration difficulties 1.

To differentiate between SBS and BRI, there are indicators for each; the indicators for SBS are building occupants complain of symptoms such as headache, nose and throat irritation, dry cough, and itchy skin, where the cause of these symptoms is not known and most of the occupants report relief soon after leaving the building. As for BRI, the indicators include symptoms such as cough, fever, and muscle aches such that these symptoms can be clinically defined and have clearly identifiable causes and the complainants may require a prolonged recovery period after leaving the building 2.

According to the Environmental Protection Agency, the term ‘SBS’ is used to describe situations in which building occupants experience acute health and comfort effects that appear to be linked to the time spent in a building, but no specific illness or cause can be identified 2. The syndrome can only be induced after elimination in the individual concerned of a disease related to the building, the etiological agent of which is identifiable. The symptoms described during SBS (headaches, concentration problems, asthenia, irritation of the skin or nasal mucosa of the eyes and upper respiratory tract) are nonspecific and frequently observed in the general population 3.

Office workers are especially subjected to SBS. It is experienced more often in air-conditioned buildings than naturally ventilated buildings 4. SBS seems to be related to inadequate ventilation, humidity and temperature changes, and chemical and biological contaminants from indoor and outdoor sources 1,5. New studies have added evidence for the role of personality traits and the psychosocial work environment, reactive chemistry, and the inflammatory properties of indoor particles for SBS. The heterogeneity of symptoms suggests that they do not represent a single disorder 6,7.

Evidence for the hypothesis that building characteristics and the resultant indoor environmental quality affect health outcomes continues to accumulate. These health outcomes include SBS symptoms, allergy and asthma symptoms, and respiratory illnesses. Indoor air quality also appears to influence rates of absence, work performance, and health care costs 8.

SBS is considered an important problem of occupational medicine, bearing in mind that 50% of the entire workforce in industrialized countries works in buildings with inadequate ventilation, humidity and temperature changes, and chemical and biological contaminants, and almost 20–30% of this group of workers report symptoms suggesting the prevalence of SBS 1.

SBS may have important economic implications. Environmental Protection Agency reported that poor indoor air is estimated to cost the USA 10 billion dollars each year in lost productivity and countless hours of illness and discomfort 9.

SBS is an increasingly common problem. Although objective physiological abnormalities are not generally found and permanent sequelae are rare, the symptoms of SBS can be uncomfortable, even disabling, and entire workplaces can be rendered nonfunctional 10. The aim of this study is to measure the prevalence of SBS symptoms among office workers and also to determine the possible risk factors.

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Participants and methods

Study design and setting

A cross-sectional comparative study was carried out at different office buildings including administrative departments of Faculty of Medicine, Ain Shams University.

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Study population and sample

Using the Epi Info program 11, and an assumed prevalence of SBS among office workers of 7%, 95% confidence level and 80% power of the test, a convenience sample of 900 office workers at different administrative departments was invited to participate in the study. Of these, 826 workers consented to participation and completed the questionnaire (response rate 91.8%).

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Methods of data collection

All office workers included in the study completed a self-administered questionnaire that provided data on their personal, smoking, and work histories. It also inquired about symptoms that have been linked with the ‘SBS’, their work environment, and working conditions 12.

A participant was considered (positive) for SBS when he/she complained of at least two of the symptoms, had no clinical condition to explain these symptoms, and reported partial or complete relief of symptoms soon after leaving the building 2.

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Ethical considerations

Ethical considerations were applied after obtaining permission from the concerned authorities; a detailed explanation of the study procedures was provided to all the participants and confidentiality was ensured.

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Statistical analysis

Data entry and analysis were carried out using SPSS program version 20 13. The data collected were analyzed by descriptive as well as inferential analysis. Descriptive analyses used were mean, SD, and range (for quantitative variables) as well as frequency distribution tables (for qualitative variables). For the inferential analysis, the χ 2-test was used to compare qualitative variables between groups. Unpaired t-test was used to compare quantitative variables for parametric data (SD<50% mean). The Mann–Whitney U-test was used instead of an unpaired t-test for nonparametric data.

On the basis of the results of the univariate analysis, logistic regression analysis was carried out to select all the independent variables that had a significant effect on the qualitative dependent variable. The backward likelihood ratio technique was used. The estimated model provides the direct effect of each independent variable on the dependent variable. The significance level was set at P value less than 0.05.

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Study of the sociodemographic and occupational characteristics of the participating group showed that 62.6% of them were women and 37.4% were men. More than 18% were smokers and the majority of them were clerk workers (77.4%). The average duration of work was 18.1±10 years and the average working hours per day were 6.6±1.1 h (Table 1).

Table 1

Table 1

A description of the workplace in different office buildings as reported by the participating group showed that more than 36% of the participants reported that the lighting was uncomfortable in their offices and more than 38% of them reported uncomfortable ventilation. Sunlight entered about 66% of offices; air currents were available in 77.2% of offices. About 32.2% reported that there were no fans and 56.4% reported that were no air conditioners in their workplaces (Table 2).

Table 2

Table 2

The prevalence of SBS symptoms among the participating office workers was estimated; fatigue and headache were considered the most frequent symptoms (76.9 and 74.7%, respectively), followed by joint pain and runny nose (65.8 and 58%, respectively). Results also showed that symptoms were completely relieved after leaving the workplace in 432 (55%) of cases and in the rest of cases (354 workers, 45%), symptoms were only partially relieved after leaving the workplace. It was also found that coworkers had the same symptoms in 576 (73.3%) of cases (Fig. 1).

Figure 1

Figure 1

To study the risk factors of SBS, the participating workers were classified into two subgroups according to the presence or absence of at least two SBS symptoms that could not be attributed to any clinical condition and that were completely or partially relieved soon after leaving the building 2. No statistically significant differences were detected between both groups in terms of sociodemographic and occupational characteristics (Table 3).

Table 3

Table 3

Study of the relation between the presence of SBS symptoms and the work office environment as reported by the workers showed that poor lighting, poor ventilation, lack of sunlight, absence of air currents, high noise, temperature, humidity, environmental tobacco smoke (ETS), use of photocopiers, and cleanliness of the workplace were associated statistically with the occurrence of SBS symptoms using the χ 2-test. However, there was no significant association with the use of air conditioners or fans as a method of ventilation in the workplace and the use of computers (Table 4).

Table 4

Table 4

In terms of the relation between the presence of SBS symptoms and the psychosocial factors at the workplace, results showed that high work load and poor job satisfaction were associated significantly with the occurrence of SBS symptoms using the χ 2-test. However, there was no significant association between the occurrence of SBS symptoms and poor relationships with colleagues, poor relationships with supervisors, and the ability to modify the work environment (Table 5).

Table 5

Table 5

A logistic regression model was used to study different risk factors related to SBS symptoms. It showed that poor ventilation, poor lighting, ETS, high temperature, poor job satisfaction, and poor office cleaning were independent predictors of SBS (Table 6).

Table 6

Table 6

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On studying the prevalence of SBS among the participating office workers, it was found that fatigue, headache, running nose, and joint pain were the most prevalent symptoms. This finding is in agreement with the findings of Gomzi and colleagues, who studied the work-related symptoms attributed to SBS. They reported that participants had a high prevalence of fatigue (60.2%) and headache (44.4%) 14. In addition, Godish 15 and Tietjen et al. 16 reported that blocked nose, dry throat, and headache were the most common work-related symptoms.

In the current study, the symptoms of SBS were either relieved completely (55%) or partially (45%) after leaving the workplace. According to the National Safety Council 17, several sick occupants may report individual symptoms that do not appear to be connected at that time; the key to the diagnosis of SBS is the increased incidence of illnesses in general with onset or exacerbation with a fairly close time frame. In most cases, the symptoms of SBS will be relieved soon after the occupants leave the particular room or zone 17.

There was no significant association between SBS symptoms and factors such as age, sex, smoking history, work duration, and working hours. However, previous studies reported that female sex and young age were associated with symptoms of SBS 18–20.

In terms of the office environment, about 36.2% of the participants reported that lighting was uncomfortable in their offices and about 38.3% reported that ventilation was uncomfortable. About 32.2% reported that there were no fans, 56.4% had no air conditioners in their workplaces, and 34.2% had no sunlight entering their offices. It was important to ask about the working environment as several studies have shown a link between building characteristics and symptoms of SBS 7,21.

Poor lighting and ventilation, lack of sunlight, absence of air current, high temperature, high humidity, presence of photocopiers, inadequate cleaning of work area, and exposure to ETS were found to be related to the occurrence of SBS symptoms. This finding agrees with the results of recent studies that reported that the possible risk factors for SBS may include poor ventilation 22, high temperature 23, excess noise and poor lighting 18, photocopiers and printers 24, and poor standards of cleanliness in the working environment 21. In another study, high relative humidity was also found to contribute toward SBS as it leads to water condensation, thus enhancing microbial growth 6.

The results of the current study are also consistent with those of Mizoue et al. 25, who reported that ETS exposure in the workplace is a major risk factor for SBS symptoms, especially with a high prevalence of smoking and absence of workplace smoking restrictions.

On comparing the two subgroups for the psychological risk factors of SBS, it was found that the percentage of workers with SBS symptoms who had a high work load and lack of job satisfaction was significantly higher than those who did not have SBS. These findings are in agreement with the results of a Swedish study that reported that many employees experience SBS because of high demands at work. It also found that under high stress or when a huge deadline is approaching for a work group, it is common for employees to feel ill. Stress can cause employees to feel very ill when at work and the symptoms subside when at home 26. Other studies proved that indoor air problems at workplaces are associated with psychosocial factors in the work environment 27,28.

In the current study, logistic regression shows that the predictors of SBS were poor ventilation and illumination, ETS, high temperature, work dissatisfaction, and inadequate workplace cleanliness. This is consistent with the results of previous researches that reported an association between SBS and poor ventilation 29, poor lighting 18, high indoor temperature (over 23°C), poor building cleaning 21, ETS 25,28, and low job satisfaction 30.

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Limitations of the study

  • Assessment of risk factors relied on participants’ reports; however, some objective methods could have been used.
  • The possibility of over-reporting by workers. In particular, the majority were women, for whom some of these symptoms may have been associated with the stress because of their multiple roles and household activities.
  • The results of the present study could not be compared with other studies because of the scarcity of Egyptian studies.
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Conclusion and recommendations

SBS was highly prevalent among office workers in the faculty of medicine, Ain Shams University, Cairo, Egypt. The most frequently occurring symptoms were headache and fatigue. In most cases, the symptoms were relieved after leaving the workplace and coworkers usually had the same symptoms. Poor ventilation, lighting, high temperature, ETS, poor office cleaning, and poor job satisfaction were found to be significant risk factors of SBS.

According to the results of the current study, it is recommended that:

  • Ventilation and air-conditioning systems that meet ventilation standards, reducing room temperature, effective cleaning routines, and providing proper lighting are simple and important ways to reduce SBS symptoms.
  • Smoking in the workplace should be banned or restricted to well-ventilated areas away from the working areas.
  • Intervention programs should be implemented to improve psychosocial working conditions, especially workers’ relationships with colleagues and supervisors and to improve job satisfaction.
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Conflicts of interest

There are no conflicts of interest.

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job satisfaction; office workers; psychosocial working conditions; sick building syndrome; work office environment

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