Indoor Air Quality in Offices

Subject: Healthcare Research
Pages: 25
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30 min
Study level: College

How Indoor Air Quality Affects Occupants’ Health and Comfort in Offices


A number of diseases have been associated with the office environment like sick building syndrome (SBS) and building related symptoms (BRS); in this chapter, they will be analysed first. Thereafter, a comparison of SBS and BRS will be done in order to comprehend the two types of diseases fully. This will be followed by an analysis of asthma as another effect (causes and facts on the disease will be examined). The next sub section will cover respiratory diseases. Other side effects will be analysed, and examples will be given. The chapter will end with a summary of the findings.

Sick building syndrome (SBS)

The term sick building syndrome refers to “all non specific vegetative and central nervous symptoms of the mucous membranes and the skin that occur in a building and normally disappear when the affected person leaves the building” (Engelhart et al., 1999, 139). Examples of central nervous symptoms include: lack of concentration, fatigue, and headaches. It can be stated that workers’ health and comfort are largely affected by indoor air quality through manifestation of SBS.

It may be difficult to identify specific causative factors of SBS, but Jaakkola (1998) propose an Office Environment Model that attempts to forge a relationship between SBS and the environment. In this model, it has been explained that all the symptoms used to describe the sick building syndrome are indicative of different health outcomes. Furthermore, the signs and symptoms may belong to a single environmental determinant or many of them (Heslop, 2002). There is a very complex relationship between environmental determinants and health outcomes in SBS so that one exposure can lead to several results. In this model, three major realms of the environment have been identified, and they include: the physical, the social and the psychological. In the physical environment, biological, chemical and mechanical factors can lead to the prevalence of SBS symptoms. However, the relationship is not as direct as one may expect. For example, an eye irritation in a worker may be a result of pollen, or it may be caused by the presence of formaldehyde in another individual. Therefore, the underlying mechanism for physical causes can be explained by toxicity, mechanical irritations, infections or allergic reactions (Skove et al., 1990). One environmental factor will lead to different results owing to the level of exposure or the traits of the individual. Psychological factors such as perceptions of a certain disease or prevalence of stress may also lead to different results. In fact, work-related stress is an important determinant of SBS complaints. If employees feel that certain job demands or external factors place them in a reduced sense of control where they cannot take decisions freely, then they are bound to manifest symptoms of stress. Sometimes the stressor can be job-related, or it may be a physical quality such as poor indoor ventilation (Baker, 1989). One’s social environment usually determines the rules and norms of how to react to SBS symptoms. Even rumours and organisational factors have a large role to play in this process. It is possible for psychological and physiological outcomes to affect the social environment, and this leads to different SBS complaints. A complex mix of air has the potential to mediate through dissimilar mechanisms and thus lead to different outcomes in SBS.

An analysis done by Engelhart et al. (1999) indicated that use of an office for previous storage and production of pharmaceutical goods may spoil indoor air quality. Some of the SBS effects that were reported by participants in this latter study included: eye irritations, headaches, unpleasant odours, dry mucous membranes as well as objectionable tastes.

A number of business owners have been creating office environments that are designed to consume or use up less energy. In doing so, these people have increased the degree of air tightness in buildings and thus created conditions that are conducive for the spread of microorganisms (Sundell, 1994). Biological agents may also lead to the development of SBS and if air quality is not adjusted to incorporate these components, then chances are that workers will develop symptoms. Those symptoms will show up when they are located in a building, and they will see them disappearing when they leave the building (Theodore, 1996).

Fisk et al. (2009) explain that the degree of ventilation affects SBS prevalence. This was illustrated through a secondary analysis of SBS prevalence rates. When the ventilation rates were decreased by half – say from 10-5 l/s-person – SBS symptoms increased by about 23 percent. On the other hand, when rates increased from 10 to 25 l/s-person, prevalence of SBS symptoms reduced by about 29%. A point of diminishing returns can be reached after which any increase in ventilation rates only leads to marginal decrease in SBS prevalence. Indoor air quality is assessed through the degree of ventilation (Teculescu et al., 1998). High ventilation implies a great degree of airflow rates, few tracer gases and low amounts of carbon dioxide (Kaczmarczyk et al., 2004). Once these qualities are present, then chances are that workers will not suffer from SBS symptoms (Teinjonsalo et al., 1996).

Utmost consideration needs to be given to objective causes of SBS since subjective factors can significantly increase SBS reports. Women tend to report higher instances of SBS than men. This may be as a result of differences in work-related and job-related characteristics encountered by men and women. In a sample collected by Brasche et al. (2001), it was found that men tended to work in better workplace environment conditions than women. For instance, they were exposed to natural lighting and had superior equipment than women. Additionally, men tended to be older and more educated than women. This had a significant effect on the work-related characteristics and the perception of the subjects on SBS. Gender differences at the workplace with regard to SBS sensitivity are directly affected by differences in work characteristics between the genders. Stenberg (1994) appears to support these findings as well. He also found that women tended to have greater paperwork loads and worked in conditions that made their psychosocial load unfavourable when compared to that of men. However, even when these work-related factors were held constant for men and women, it was still found that more women complained about sick building syndrome. Brasche et al. (2001) explain that this may be as a result of the psychic disposition of women to SBS. Therefore, a second theoretical model has been proposed to understand the prevalence of SBS. It starts from the prevalence of a “sick building” or an indoor office environment with certain air qualities. These are then perceived by workers; perception may be determined by work-related factors or one’s psychical disposition. The latter factors may independently lead to SBS complaints or may do so indirectly by affecting perception, which then causes the complaints (Brasche et al., 2001) & (Stenberg, 1994).

Building related symptoms (BRS)

Building-related symptoms also refer to a set of symptoms that are associated with the office environment but diminish away from the workplace (Buchanan et al., 2008). BRS has several causes just like SBS, but is largely caused by poor indoor air quality. Ventilation systems are just part of this overall system (Seltzer, 1994). The rate of airflow between the external and internal environment must be taken into consideration when looking at ventilation systems. Buchanan et al. (2008) explain that there is a great link between air conditioning quality and BRS prevalence, especially when compared to natural ventilation. BRS may increase by figures between thirty percent and two hundred percent when offices switch between natural ventilation and air conditioning. Furthermore, the rate of fibre emissions also plays a role. Niemela et al. (2006) carried out an intervention strategy in an insurance company where they adjusted the ventilation system to eliminate contaminants. They also stabilised airflows and replaced duct linings. Building-related symptoms were measured prior to the intervention and before. It was found that general symptoms of BRS reduced from 15.6% to 6.8%.

Fatigue, heavy headedness, headaches, concentration difficulties reduced by 15%, 22%, 2% and 5% respectively. Irritation symptoms reduced by 4.3%; irritation of the eyes increased by 6%; stuffy or irritated nose symptoms reduced by 20% while dry throats reduced by 1%. Lastly, coughs increased by 8%. These results indicate that there is indeed a serious value in the quality of indoor air. Since those changes can be measured quantitatively, then one can assert that BRS is highly dependent on the nature of the indoor environment. Building-related symptoms are highly prevalent when indoor environment quality parameters are unfavourable (Niemela et al. 2006). These can include high room air temperature, dust concentration on surfaces and on the air and concentration of volatile organic compounds (VOCs). These VOCs work by oxidisation. Oxidising agents such as ozone may initiate a chemical reaction that eventually creates a highly irritating product. Indoor chemistry has a great effect on BRS prevalence. Examples of the VOCs include formaldehyde, submicron particulate matter and certain low molecular weight organic compounds (Wallace, 1996). The products formed after the completion of these chemical reactions is even worse than the precursors in terms of effects created. BRS can be linked either to the indoor environment or specific building traits such as low ventilation, presence of contaminated carpets and air conditioning. Associations have been found between construction materials of certain buildings and prevalence of SBS. Alternatively, some unconventional indoor environmental quality traits also lead to these health problems; some of them include light quality.

Buchanan et al. (2008) explain that air filters are particularly dangerous because they tend to act as sites for chemical reactions between ozone and other chemicals. This creates hazardous products that eventually enter buildings. Workers are then exposed to chemicals that irritate them. Air filters contain a number of matrices that interact with ozone; they also possess certain particulate matter that may have been trapped inside. Once this matter interacts with ozone, it creates a dangerous environment for workers (Weschler, 2000). The reaction may occur in air filters alone, but also takes place in furnishings, internal building surfaces. In the study done by Buchanan et al. (2008), workers had a high level of sensitivity to air filters that had been used. These were manifested through certain symptoms that were associated with BRS, and they include: dizziness and headaches. As workers continued to be exposed to that kind of air, the above symptoms continued to increase. In fact, new filters substantially reduced susceptibility of workers to nose and eye irritations thus denoting that old filters affect employees’ health.

Concentration of ozone in the internal office environment is much lower than it is in the outside environment (Wolkoff et al., 2000). Consequently, ozone is incapable of creating visible BRS symptoms on its own, but it is its interaction with other compounds that leads to these adverse effects. Used filters are important sites for those reactions (Buchanan et al., 2008). In fact, these authors could quantify the degree to which ozone and filter mediums were related to the prevalence of BRS. Through the use logistic regression models, it was found that if polyester synthetic fibre (PS) was prevalent alone without interaction with ozone, or ozone existed without PS, then difficulties in concentrating and dizziness (some BRS symptoms) would occur. Corresponding odds ratios of 1.93 and 1.54 would be recorded. However, if workers were exposed to ozone and PS combined, then several other building related symptoms would occur such as coughs, headaches, fatigue and respiratory discomfort. The Odd ratios for these symptoms started from 2.26 and continued to 5.9. There was a multiplicative effect of ozone and PS, especially in terms of headaches, lower and upper respiratory symptoms. Therefore, BRS is highly related to the nature of air filters used.

General building related symptoms like heavy headedness, nausea, fatigue, dizziness and headaches are associated with high thermal discomfort. There is a building related symptoms’ index that has been used to show how workers are affected by BRS as postulated by Brightman et al. (2008). In this index, four divisions of the factors have been identified. The first factor is classified as tiredness. A worker who has BRS may report any of the following symptoms: headache, stiffness of the back, neck and shoulder stiffness, dry eyes, strained eyes, itching eyes, drowsiness, fatigue, body itchiness or unusual tiredness. The second classification is mucosal irritation; this encompasses irritations to the skin, throat and the nose. The third one consists of neuropsychological factors. Some of the symptoms included here are: tension, dizziness, nausea, nervousness and difficulties in concentrating. The fourth one is lower and upper respiratory symptoms; it encompasses chest tightness, wheezing, and shortness of breath. Brightman et al (2008) did a survey of one hundred random buildings in the United States. It was found that 20% of all the participants reported one of the major symptoms identified by the researchers. This implies that employees’ health is seriously affected by BRS at work.

Comparison of SBS and BRS

Both SBS and BRS are not associated with a certain etiology, and both tend to vanish once individuals leave a particular work building. Sometimes these terms are used interchangeably, but there are certain differences that are still prevalent. SBS and BRS are affected differently by ventilation rates. The incremental factor between SBS and ventilation differs from BRS and ventilation incremental factors. Furthermore, there are several differences in the symptoms identified as SBS and BRS. Mechanisms for detection of the two types of indoor air quality diseases are quite different with SBS being more complicated than BRS. SBS is more dependent on air-filter quality than BRS. Different classifications exist for these two concerns. A BRS index exists for all symptoms while an environmental model can be used to classify SBS symptoms. Ozone and the use of air filters adversely increase the possibility of developing BRS symptoms even more than SBS.

These two health issues are quite similar because they have very common effects upon workers. Some of them include: headaches, dizziness, nausea, eye irritations, mucosal irritations and fatigue. They are both caused by poor indoor air quality. All health complications respond to alterations or interventions in air quality. They are confined to buildings and office environments and usually go away when subjects leave the affected premises. Shown below is a summary of the similarities and differences.

Ventilation rate decreases of fifty percent lead to 23% increases in SBS Reduction of 8.8% of BRS when ventilation is increased
General symptoms not classified Classified through the BRS index
Chest complications not as common Chest tightness and wheezing may occur
Air filter quality and ozone increase SBS BRS and air filter quality link not fully understood
Both respond to poor air filter quality
Not associated with any etiology
Symptoms include headaches, dizziness, nausea, eye irritation, mucosal irritations and fatigue
Confined to buildings
Caused by poor indoor air quality


Asthmatic workers can be dramatically affected by the degree of dampness in their workplace (Ostro et al., 1994). Cox-Ganer et al. (2008) proved this when they analysed the respiratory health of employees in a hospital against the backdrop of their indoor environment. An assessment of the degree of dampness in floor dust, the air, furniture, and general surroundings revealed that workers reacted negatively to the water incursions and renovations being carried out in that environment. This was because new cases of asthma were reported at the time. Dampness usually comes from a series of sources; sometimes it may be the way a building was constructed (Koren & Utell, 1997). If this was done without sealing underground walls or protecting concrete slabs on the ground from water, it would eventually lead to the development of damp conditions within an office (Johnston et al., 2000). Additionally, prevalence of certain allergic factors in the environment such as dust led to these conditions (Molhave et al., 2002), (Nathell et al., 2004) & (Shwartz et al., 1993).

Respiratory diseases

When certain buildings are rich in moulds, one is likely to find those spores in the air. The spores can sometimes lead to very serious allergic reactions. They can take the form of a runny nose, throat irritations, sneezing and coughing or certain chronic illnesses like sinusitis (Davis, 2001). Dampness is the number one cause of moulds in the office environment. Sahakian et al. (2009) found that workers who complained much about dampness in their offices often had to ask for sick leave owing to respiratory symptoms. Their complaints were confirmed by an assessment of the degree of water damage in the home, water damage in the office, musty odour or presence of visible mould. It was found that these workers experienced upper and lower respiratory ailments and symptoms such as bronchitis, sinus infections, colds, seasonal allergies as well as fever. There was a positive correlation between the presence of mould and their health status. About seven percent of the workers had reported nasal symptoms, 3% suffered from low respiratory symptoms while 25% percent of the workers needed to leave their place of work in order to attend to their respiratory illnesses. It was also found that 5% has seen a pulmonologist while 10% had seen allergists. 12% had visited an otolaryngologist. It can therefore be said that damp office environments lead to development of the following conditions: colds and flu, sinus infections, runny or itching nose, bronchitis, lower respiratory symptoms such as chest tightness, shortness of breath, wheezing and coughing; constitution symptoms like fevers, fatigue, chills and muscle soreness also occur (Sakakian et al., 2009).

The presence of environmental tobacco smoke leads to the development of certain respiratory ailments like flu-like symptoms (one example is coughing); even more severe illnesses like bronchitis or lung cancer may arise (Leuenberger, 1995). When offices and other work buildings have poor ventilation, this exposes workers to ETS gases and particles that may increase their sense of discomfort at work (Strachan & Cook, 1997). In the end, this may lead to the above mentioned respiratory diseases. It has been shown that increasing the degree of ventilation can minimise the presence of ETS particles in an office, although the best remedy should be source control (Johnston et al., 2000). Exposure to indoor tobacco smoke has a much greater effect than outdoor tobacco smoke. When workers are not expected to be working inside an office, most of them will only suffer from respiratory illnesses as a result of active tobacco smoking or indoor ETS exposure at home (Mishra, 2003). Respiratory illnesses are often confounded by other factors such as age and exposure to passive smoke outside of work (Strachan & Cook, 1997). Since employees spend most of their time in the office, then their vulnerability to these respiratory ailments often increases when they are exposed to tobacco smoke at work.

Rhinitis and alveolitis can come about when an office environment is highly saturated with mould. Usually, the fungi from the air enter the nasal passages and then colonise workers’ airways (Dockery & Pope, 1994). At this point, employees can develop inflammatory responses or allergic responses as seen through rhinitis. When a person has this disease, one is likely to develop an unremitting cough, display continuous wheezing and posses other symptoms that look like hay fever. Alternatively, continued exposure of workers to fungi can lead to the development of allergies in the alveoli and thus lead to a condition known as lymphocytic alveolitis. Sometimes this may even develop into fibrosis. Most fungi are found in repeatedly damp environments in the workplace (Fink, 1998).

General side effects

Indoor air quality can affect individuals’ health through a series of illnesses, signs and symptoms. The major illnesses that are known are: SBS, BRS, asthma, and respiratory ailments like bronchitis, rhinitis and sinus infections (Hauschildt et al., 1999). All these diseases usually take the form of a number of common symptoms like: colds and flu, sinus infections, runny or itching nose, bronchitis, lower respiratory symptoms such as chest tightness, shortness of breath, wheezing and coughing, fevers, fatigue, chills and muscle soreness headaches, dizziness, nausea, eye irritation, mucosal irritations, heavy headedness, sensitivity of odours and tastes, skin irritations, throat irritations, nervousness, difficulties in concentrating, dry eyes, strained eyes, stiff back and stiff shoulders (Smedbold et al., 2002).


Moulds can be a source of respiratory diseases in the office environment. Although many human beings respond differently to mould depending on sensitivity and susceptibility of the concerned person, this type of fungus can still be highly detrimental to workers’ health. Moulds often produce certain volatile organic compounds, which are useful in indicating that foods have been spoilt by moulds (McNeel and Kruetzer, 1996). When these compounds are found in the air around an office, they can lead to irritations in the mucous membranes. They can also target the central nervous system and lead to symptoms such as dizziness, attention deficit and headaches. Moulds may also lead to other health complications such as vomiting, diarrhoea, liver damage, coughing blood nose bleeds and even impaired immune functions (Davis, 2001). It should be noted that the relationship between mould and BRS is not fully understood as it has not been studied. However, this is obviously a serious cause of concern. Some people’s health status may make them highly vulnerable to mould and this heightens its effects in the workplace (Pirhonen et al., 1996).

If a person has a disease like HIV/ AIDS, then that person is likely to respond adversely to the presence of mould. This is because the individual’s immune system has already been compromised. The same thing applies to those patients who may be undergoing chemotherapy or certain medical procedures such as bone marrow transplants. A vast number of people will be exposed at the workplace and may develop the above-mentioned symptoms while at work. Those symptoms may disappear once they leave the mould infected area (Friedman et al., 1993). Furthermore, some types of mould are more powerful than others and may create adverse effects on the affected people. Consideration of mould as an indoor air quality issue represents a shift in the field. During the 1980s to the mid 1990s, most air quality contaminants were chemically based. Nonetheless, an interdisciplinary approach has been adopted by stakeholders in the field because now physical, biological and chemical constituents are acknowledged as sources of poor indoor air quality (Smith, 2002) & (Spengler & Samet, 2003). This is the reason why moulds are now taken seriously.

Some particles such as dust can lead to the development of particular irritations, discomforts and illnesses (Preuss & Mariotti, 2000). For example, nose and throat irritations may come about, and eye lining irritations can also be recorded. This occurs because dust exposure minimises the tear film stability, and adds to the eosinophil cells in one’s naval lavages (Brunekeef, 1992). In other words, dust leads to inflammatory responses. It does also contribute to weak allergic responses. Molhave (2008) illustrated this when they carried out an experiment in an office to investigate the health effects of indoor dust exposure. It was found that if more than 75mg/m3 of dust particles were suspended in the air, then any of the above-mentioned effects would result (Murray et al., 2004).

Influenza is also another health effect determined by indoor air quality. If a certain office environment is rich in viral particles, then chances are that the concerned workers would be affected by the disease. Chen et al. (2009) carried out an analysis of the rate of viral transmission among workers whose co-workers sneezed and coughed around them. It was found that there was a link between the particle size of the droplets exhaled by already infected persons and the rate of new infections. Office owners can therefore protect workers from these effects by availing masks or certain barriers that can protect other non infected individuals from catching the disease. Gupta el al. (2009) also agree with these assertions because they studied the fluid dynamics of coughs. In their analysis, they used linear regression analysis to assess the kinetics of coughs to determine the dangers posed by these coughs to others in the office environment.


This chapter has focused on how the health and comfort of workers are compromised through indoor air quality. SBS was the first illness identified. It causes a series of symptoms that have an unknown etiology such as mucous irritations, headaches and fatigue. Their causes are not directly known but are associated with physical, chemical and biological factors in the office environment and are specifically linked to poor ventilation. BRS was the next health complication, and its symptoms are somewhat similar to those of SBS. It is caused by a series of conditions in the atmosphere such as thermal discomfort. Development of asthmatic symptoms is highly affected by indoor air quality owing to conditions of dampness and prevalence of mould. Presence of dust, tobacco smoke and mould increase the chances of developing respiratory ailments like bronchitis, rhinitis and other allergic responses. Bronchitis and alveolitis are common respiratory ailments that may come from the above-mentioned air quality contaminants. Other effects of poor indoor air quality include inflammatory and allergic responses, influenza, attention deficit, diarrhoea and vomiting.

How Indoor Air Quality Affects Occupants’ Performance and Productivity in Offices

SBS symptoms cause workers to be distracted from their work (Milton et al., 2000). Furthermore, if a businessman has very severe cases of SBS among his workers, then chances are that some investigations will need to be done in the building. This will take a toll on the performance of the occupants in the office because funds will be diverted away from operational needs and will be directed to health and safety personnel or the building engineers (Woos, 1989). Usually, when too much SBS is prevalent in a certain building, some employers have to alter their ventilation systems, remove their carpets and also clean out moulds. Sometimes, it may be necessary to relocate to another building as the damage may be excessive. This can cost a company huge sums of money. One must not also forget litigations that may arise from other employees who have developed severe symptoms of SBS or poor indoor air quality. When employers must meet all these costs, the productivity of the company is bound to reduce because funds will be diverted to all the SBS-related expenses (Fisk and Rosenfield, 1997).

The above-mentioned losses can be felt by the whole firm and are indirectly associated with SBS, BRS, asthma or any other health conditions that may result from poor indoor air quality. However, specific focus should be given to the direct effect of air quality on work performance and productivity in offices. In order to understand this correlation, it will be necessary to look at some case studies on the issue. The first case study was carried out by Bako-Biro et al. (2004). It encompassed thirty female subjects. Blind interventions were done so that polluting and non polluting conditions were introduced to the subjects unknowingly. The subjects continued to perform simulated work. The source of the pollution in this case study was a three-month old computer placed behind a screen that hid it away from the subjects. It was found that the personal computers emitted a range of chemicals such as styrene, formaldehyde, toluene, phenol, and 2-ethylhexanol. However, the researchers realised that the amount of these chemicals that was released into the atmosphere was not sufficient enough to cause any health effects on the workers. They concluded that it might have been other hidden sources in the PCs that may have contributed to the problems (Lioy, 1990).

Changes in work performance were noted prior to the intervention and after the intervention. This was analysed through the nature of text typing done by the individuals. The analysis was done by counting all the mistakes that workers made when typing texts. The type of mistakes noted included: poor punctuation, wrong spelling, and number of words skipped. It was found that these mistakes were much lower without the pollutants, and they increased when the pollutants were introduced. P values of less than 0.014 were reported in the presence of the pollutants. Another performance measure was typing speed. It was found that the difference before and after the experiment, was small. Here, p values of less than 0.03 were reported. The time taken to edit and proofread the answers was measured prior to introduction of the PCs and after. It was found that the number of false positives increased by one percent after the introduction of PCs. Missed errors also increased by one percent; reading speeds reduced by 0.5 lines per minute after polluting the office environment. Overly, it took the workers 9% longer to process the text in the presence of a pollutant. This case study was one of the most comprehensive ones done on indoor air quality and work pollution. Any decreases in work rate and quality (as denoted using quantifiable measures) are highly indicative of the effect of poor indoor air quality on work performance.

A very similar case study was also done by Wargocki et al. (1999) to determine the effect of indoor air pollution through a specific pollution source on the work productivity of individuals. The conditions in this experiment were similar to the former ones because tests were simulated too. An old carpet (20 years old) was placed behind a screen where the six female subjects could not see it. The difference between this analysis and Bako-Biro et al. (2004) was that the pollution source had been changed, and the work performance analysis was measured using different parameters. Subjects were fewer, and the results were analysed through a range of factors (not just typing performance). First, the number of characters typed in a simulated test was counted. It was found that 6.5% fewer characters were typed when the old carpet was present. This result corresponded to a p value of 0.003, which was similar to the Bako-Biro et al. (2004) analysis. The number of errors was found to increase by 5% when the pollution source was introduced. The p value was 0.01 for that parameter. Besides text processing, addition, logical reasoning, stroop and serial addition were also assessed. Added units increased by 3.8% when a pollution source was present.

Reaction time for logic reasoning increased by 3.4% when workers performed the task in the presence of the hidden carpet. Workers’ serial addition of correct digits increased by 2.5 % after the introduction of the carpet. There was a 3.1% increase in the speed of stroop performance when the pollution source was present. It was explained that the pollution source did not have a negative effect on the workers’ performance of adding, stroop, addition and logical reasoning because improvements of performance in successive tests were reported. The first task was typing while the other tests were done subsequently. Furthermore, the statistical significance of these increases in task performance in the presence of the pollution source was not sufficient. Addition, logical reasoning, serial addition and stroop corresponded to p values of 0.045, 0.08, 0.06, and 0.01 respectively. In fact, text typing was the only task that elicited a statistically significant p value; this was 0.003 (Montgomery, 1991). Therefore, focus should be given to this task, and it should be concluded that pollution sources minimise work productivity at the workplace. In order to ascertain that these results are accurate, then the same conclusions should be made in different settings.

Wargocki et al. (2002) carried out an experiment designed to compare results in different geographical settings concerning the relationship between indoor air quality (as altered by a pollution source) and work performance. One of the experiments was a Danish study, and the other one was a Swedish experiment. Although the temperature and air humidity were not kept at the same level, the basic components of the study still remained the same. The same pollution source was used in both settings. Furthermore, equal numbers of subjects were also employed in the Danish and Swedish experiments. Participants were expected to perform typing task in both settings. However, in the Danish tests, participants were expected to carry out psychological tests while the Swedes did proofreading. Other tests included creative thinking and addition. All the tests were administered using the same sequence to ensure that responses were not affected by order of tasks. After the tasks were analysed, it was found that the conditions had improved in almost all task performances when the pollution source had been eradicated. This was true in the Danish and the Swedish analyses. The number of characters typed increased in both locations and so did creative thinking tasks. Proofreading increased in one of the locations but was not measured in the other. Addition tasks also improved in the absence of the pollution source. The presence of similar results in both locations was proof of the fact that all aspects of performance had a tendency to decrease when a pollution source was introduced. The aim of the experiment was not to replicate the magnitude of the results, but it was to show the overall direction of the performance effects of a pollution source on air quality (Wargocki et al., 2002).

As noted earlier, SBS, BRS and many other health complications in the work area are largely caused by poor ventilation, presence of certain pollutants, moulds or dampness, and low temperature (Wolkoff et al., 1997). Bako-Biro et. al. (2004) and Wargocki et al. (1999) carried out their experiment using a pollutant as a source of poor indoor quality. Another study done by Seppanen et al. (2005) focused on ventilation rates as a source of poor indoor quality. In this analysis, the researchers focused on the relationship between ventilation rate and work performance. Although they did not carry out the experiments themselves, the writers obtained data from a number of sources that had measured work performance and ventilation. It was found that there were significant increases in performance for almost all the sources of data reported. Average performance improvements of 1-3% were reported when air ventilation rates increased by 10 l/s-person. However, there were limits to the benefits that workers could enjoy with regard to ventilation rates. If ventilation rates exceeded 45 l/s-person, negligible improvements in work performance were observed. Sometimes when the ventilation rates were excessive, performance was found to reduce because of the noise and the thermal discomfort. On the other hand, when ventilation rates fell below 45 l/s-person, work performance increased by a factor that was greater than 3%. The analysis indicated that there is indeed a dramatic relationship between indoor air quality and average work productivity.

Another interesting case study was carried out by Wyon et al. (2004). While the earlier mentioned analyses focused on air ventilation and air pollutants, this particular one dwelt on new parameters in indoor air quality, and they are: air temperature and humidity. In this analysis, subjects were placed in an office of 22oC. This was subsequently increased to 26 and 30 degrees after three-hour intervals. Work performance was also affected by noise distractions. A source of noise was introduced in the work area to confound the condition. Noise tended to decrease the effect of temperature increases. However, it was generally found that creative tasks tended to reduce at a higher temperature of 30 degrees. Therefore, indoor air quality as measured through increased temperature minimises work performance. Tham (2004) also carried out a very significant analysis between temperature and work performance. The difference between this case study and the one carried out by Wyon et al. (2004) was that work performance was assessed through the call centre talking time. The centre focused on offering billing inquiries; productivity within the firm is directly affected by the talking time each employee can provide. Blind interventions were done so that workers could not be biased with the results. Temperature was placed at 22.5oC and 24.5oC. Decreasing temperature in the room showed significant increases in talk time. P values of less than 0.01 were recorded. The talk time increased from 187 seconds to 216 seconds; this was a percentage increase of 15.5%. Workers talking time reduced from 201 seconds to 187 seconds when the reverse occurred; that is, when temperature was increased. The percentage decrease was about 11% in that instance. P values of less than 0.01 were recorded for temperature increases. These results are indicative of the fact that indoor air quality adversely affects work performance hence work productivity in the office environment.

A significant relationship between humidity and work performance was also found by Wyon et al. (2004). The participants were exposed to four different humidity levels. In these conditions, they were all expected to carry out certain computer simulated tasks for a period of five hours. These tasks included typing texts, proofreading or editing text as well as carrying out serial additions of numbers (two digits) as they appeared on a screen. It was found that in low humidity (Relative humidity of below 25%), text typing reduced by three percent while proofreading efficiency reduced by seven percent. The ability to do serial additions was also minimised by five percent. These results are in contradiction to what one would expect in an office environment. High humidity is indicative of a damp environment and one that is likely to harbour a range of contaminants that may lead to BRS. These experimental results were contradictory because of two main reasons. First of all, it may be that the humidity levels were reduced to an excessive level to the point of creating dry air in the office. The writers assert that eye irritations, eye dryness, and tear film mucous quality were all compromised in this condition of low relative humidity (Wyon et al., 2004). Consequently, one can assert that humidity can reduce efficiency of work performance either way; when it is excessive and when it is quite low. The researchers focused on the latter conditions more than the former. Another explanation is the confounding effect of temperature on the subjects. Thermal discomfort may have undermined their ability to perform work tasks as expected.

Fang et al. (2004) also carried out an experiment in which they intended to find out the effect of humidity (and other factors) on work performance. Minimal correlations were found between humidity adjustments and work performance. The writers affirmed that one should not assume that in the real world, no relationship exists between work performance and humidity. This was because there was an increase in headaches and fatigue among the concerned workers at a relative humidity of 60% (which was a relatively high level). It was asserted that over-motivation may explain why the results appeared contradictory. The participants may have placed too much effort in the tasks in the simulated environment to the point of overcoming the minor discomforts that were created by the high relative humidity. This scenario was compared to an experiment carried out by Tanabe (2003). These authors found that work productivity was not compromised in poorly illuminated work environments. In very dark rooms of 3lx, workers produced the same results that they did in 8000 lx environments. It was found that mental fatigue increased tremendously in the poorly illuminated conditions. The author concluded that maintenance of equal levels of productivity came at the cost of physical and mental well being. The same thing can be said about what had been found by Fang et al. (2004). It is likely that with continued exposure, mental fatigue may increase, and this may translate into lower productivity. Workers may no longer be willing to put in as much effort when the experienced mental strain is prolonged.

Chapter summaries

In chapter one, the focus was on the effect of indoor air quality on office workers’ health and comfort. Sick building syndrome was identified as one of the health effects of poor indoor quality. It was noted that SBS has no known etiology and soon disappears after workers depart from the ‘sick building’. Two models were discussed on the causes of SBS with the first being the office environment model and the second being the psychic disposition model. In the office environment model, three major parameters can lead to SBS and they include: physical, social and psychological factors. Some of the common symptoms associated with SBS include; eye irritations, headaches, unpleasant odours, dry mucous membranes as well as disagreeable tastes. SBS detection is sometimes dependent on the gender under consideration as women tend to report more of it than women. This is the reason why the psychic disposition model is useful in understanding SBS. Some of the indoor qualities that are likely to lead to the prevalence of SBS in any office include low ventilation rates and prevalence of a pollution source such as use of the building for storage of pharmaceuticals.

The next assessment was on building related symptoms (BRS). It may be caused by a range of factors in the internal and the relevant external environment. For instance, air ventilation systems highly determine whether BRS will exist within a building or not. Here, natural ventilation is preferred to air conditioning. When air conditioning is used, the type of filter medium also determines whether workers will develop BRS or not. This occurs when ozone combines with volatile organic compounds emitted from the air filters to form dangerous compounds. The level of thermal comfort or discomfort in the building can also lead to BRS and the same thing applies to the nature of materials used to construct it. Additionally, BRS can be caused by changes in humidity within the concerned building or prevalence of a contaminant in the materials used to construct the building or the interior components. Some of the common symptoms of BRS include: heavy headedness, nausea, fatigue, dizziness and headaches, chest tightness and wheezing. A comparison of BRS and SBS was done. It was found that the terms are more similar than different because symptoms are quite common, causes are analogous; they all have unknown etiology and are linked to particular buildings. However, BRS is highly associated with ozone and air filters. Symptoms such as chest tightness are associated with it, and classification systems differ. SBS factors are classified using the office environmental model while a BRS index is used to understand causative factors.

Thereafter, an analysis of how indoor air quality causes asthma was analysed. It was found that mould and dampness affect susceptibility to asthma. Presence of other allergic particles in the office environment can also cause certain people to be susceptible to asthma. In terms of respiratory diseases, it was found that bronchitis, sinus infections, colds, seasonal allergies, fever, runny nose, throat irritations, sneezing and coughing or certain chronic illnesses like sinusitis can occur when a building contains fungi or other contaminants that may get into the body’s respiratory system. Other general side effects that emanate from poor air quality include influenza, dizziness, vomiting and diarrhoea. The last four effects may be created by the presence of moulds.

Chapter two focused on the effect of indoor air quality on work performance and productivity. This was done by an analysis of various case studies on the topic. Focus was given to the relationship between work performance and different components of air quality. First, a case study on the relationship between productivity and presence of pollutants was done. It was found that less work was done in the presence of a pollutant. When similar experiments were done in different geographies, it was still found that presence of pollutants reduced workplace performance. The next case study related work productivity and ventilation rates. When ventilation rates increased, greater work output and fewer errors were reported. Thereafter, a case study of performance and air temperature was analysed. It was found that talking time in a call centre increased when temperature decreased, and the reverse was true. Lastly, the relationship between productivity and humidity was analysed. In both experiments, none of the information was conclusive. In one of the studies, no relationship was found between work performance and humidity. However, the authors explained that the observation may have been brought on by over motivation of the workers as seen through excessive fatigue and headaches experienced in the high humid environments. The second case study found that work performance actually decreased when relative humidity reduced, yet this contradicts previous assertions on dampness and its effect on worker’s health. It was found that the effects of temperature may have neutralised the low humidity effects. Furthermore, the relative humidity may have been reduced beyond reasonable parameters to the point of causing eye irritations. Generally, the case studies illustrated that elevated humidity (dampness), high temperature, low ventilation rates and presence of contaminants all reduced work productivity.


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