The Office Environment Model: A Conceptual Analysis of the Sick Building Syndrome*

Abstract This paper examines the phenomenon sick building syndrome and related concepts, and proposes a theoretical model, the Office Environment Model, to explain the relationship between office environment and health. The sick building syndrome should be thought of as a figurative concept of everyday language, rather than as a single disease entity. This is because the phenomenon consists of several types of relations between different environmental determinants and health. Based on Popper's framework of three worlds, the model divides the office environment ontologically into physical and social, and the health outcomes into physiological and psychological. The outcome is further categorized into two dimensions: anatomic site (eyes, respiratory tract, skin, and central nervous system), and hypothesized underlying mechanism (mechanical irritation and inflammation, immunological reaction, toxicity, infection, and environmental psychological stress). The model stipulates the following types of causal relations. The physical environment causes physical and psychological effects via physiological and/or psychological processes. The social environment causes physical and psychological effects via psychological processes. The physical and social environment may have synergistic effects, and constitutional factors such as gender and atopy are additional determinants of the outcomes, as well as possible modifiers of the relations between environment and health. To understand the health effects of the office environment, it is necessary to focus separately on different determinant-outcome relations, bearing in mind that the different determinants affect human health concurrently and sometimes the effects may be synergistic.     

Dust and the Sick Building Syndrome

Background. In the Danish Town Hall Study" it has previously been shown that the sick building syndrome is a widespread phenomenon. This has given rise to speculations as to whether biologically active components in dust or whether absorbed organic gases and vapours in the indoor climate may be partly responsible for the sick building syndrome. Therefore, we wished to study whether qualitative conditions in dust, of a physical, chemical, and biological nature, are related to the prevalence of symptoms of the sick building syndrome. Material and methods. The study included 12 town halls in the Copenhagen area. A total of 870 persons participated, 584 women and 286 men. All the participants filled out a questionnaire regarding health and working conditions, and dust samples were collected with a special vacuum cleaner in the working environment of the participants, after which the contents of inorganic and organic particles as well as of human source fragments the (hair, nails, skin) and various fibres were determined. Results. There was a significant correlation (P<0.05) between the prevalence of gram-negative bacteria in the indoor climate dust, and general symptoms (fatigue, heavy-headedness, headache, dizziness, concentration problems) (corr.coeff.=0.73), as well as symptoms from the mucous membranes of the upper respiratory tract (corr.coeff.=0.76). Also, there was a significant relation between the prevalence of particles in the dust and the prevalence of symptoms from the mucous membranes (corr.coeff.=0.81). There was a strong and significant correlation between the total amount of volatile organic components (TVOC) and lack of concentration (corr.coeff. =0.85) and feeling heavy-headed (corr.coeff.=0.72). Macromolecular dust (potentially allergenetic material) was significantly correlated to the prevalence of headache and general malaise/dizziness (corr.coeff.=0.66), while the ability of the dust to liberate histamine was significantly related to the prevalence of general malaise, dizziness (corr.coeff.=0.65) and lack of concentration (corr.coeff. =0.58). Further analyses including a number of potential confounders did not change the results of the above analyses. Conclusion. The results of this study support the hypothesis that qualitative properties of dust are important to the sick building syndrome. The study was based on relatively few buildings, but nevertheless strong correlations were found. In perspective, epidemiological intervention studies should be carried out to investigate whether minimizing the amount of both dust and bacteria in the indoor climate affect the prevalence of sick building syndrome.     

Mechanical Ventilation in Office Buildings and the Sick Building Syndrome. An Experimental and Epidemiological Study

The effects of mechanical ventilation on the sick building syndrome (SBS) were studied in an office building with 2150 employees, where the mechanical ventilation and indoor air quality were commonly blamed for causing symptoms typical of the SBS (nasal, eye, and mucous membrane symptoms, lethargy, skin symptoms and headache). The mechanical ventilation rates in the building were high (mean 26 l/s/person). To test the hypothesis that mechanical ventilation causes the SBS, a controlled experimental study was carried out by shutting off the ventilation in one part of the building and reducing the ventilation rate by 75% and 60% in two areas while leaving one part unaltered as a control. The experimental reduction of the ventilation rate did not alleviate the symptoms. On the contrary, the reduction of the ventilation rate caused a slight but statistically significant relative increase in symptoms (p < 0.05). In the cross-sectional analysis of the baseline data the SBS symptoms did not associate significantly with the ventilation rate (range 7–70 l/s/person). In the linear regression model, a positive correlation was found between temperatures above 22°C and the occurrence of symptoms (p < 0.05). Subjects exposed to environmental tobacco smoke had more symptoms than those not exposed (p < 0.01). Women reported more symptoms than men (p < 0.001). In addition, any prior history of allergic diseases (p < 0.001) and a negative attitude towards the social atmosphere at work (p < 0.001) were significant determinants of the SBS.     

Sick Building Syndrome: Cleanliness is Next to Healthiness

There is evidence that sick building syndrome (SBS) is caused, in part, by indoor surface pollution (ISP): contaminants such as dust, fibres and micro-organisms, deposited on or in surfaces in buildings. A study is described which clarifies the relative importance of a number of possible causes of SBS in a single building. The building, which had a high initial prevalence of SBS symptoms, was used in a doubleblind controlled intervention study with weekly symptom questionnaires. The four interventions were: ventilation system cleaning, air filtration, hot-water extraction cleaning of chairs and carpets, plus high grade filter vacuuming and dusting, and dust mite treatment (application of liquid nitrogen). Only the last two interventions brought about a reduction in symptoms. It is concluded that cleaning which effectively reduces ISP can reduce SBS symptoms. This may be related to the presence of dust mites in furnishings. Improved cleaning may entail better cleaning specifications and/or consideration of requirements for cleaning when selecting and positioning office furniture. If ISP and the temporary local pollution levels created by it are a problem, then monitoring of ambient conditions (by instruments or by human assessors) will not adequately represent the conditions to which occupants are exposed     

Individual and Occupational Correlates of the Sick Building Syndrome

Results of a questionnaire survey of 939 workers from 5 air-conditioned offices where smoking was prohibited are reported. Levels of carbon monoxide, carbon dioxide, formaldehde, respirable particulates, and temperature, relative humidity, and illuminance were measured in these buildings, but these did not correlate with symptom reports. The number of sick building syndrome symptoms per worker was related linearly to perceived indoor air quality, job stress, job satisfaction, allergies, eyewear, and seasonal affective disorder. Two hundred and fifty five of these workers also completed a battery of psychological measures. Measures of depression, personality variables, situational stress, vulnerability to stress, and individual differences in circadian rhythms did not correlate with the numbers of sick building syndrome symptoms per worker, although depression did correlate with the number of symptoms when these were weighted for their frequency of occurrence in the previous month. Job stress and perceptions of indoor air quality correlated with both the unweighted and weighted indices of sick building syndrome.     

Perceived Air Quality,Sick Building Syndrome (SBS) Symptoms and Productivity in an Office with Two Different Pollution Loads

Abstract Perceived air quality, Sick Building Syndrome (SBS) symptoms and productivity were studied in an existing office in which the air pollution level could be modified by introducing or removing a pollution source. This reversible intervention allowed the space to be classified as either non-low-polluting or low-polluting, as specified in the new European design criteria for the indoor environment CEN CR 1752 (1998). The pollution source was a 20-year-old used carpet which was introduced on a rack behind a screen so that it was invisible to the occupants. Five groups of six female subjects each were exposed to the conditions in the office twice, once with the pollution source present and once with the pollution source absent, each exposure being 265 min in the afternoon, one group at a time. They assessed the perceived air quality and SBS symptoms while performing simulated office work. The subject-rated acceptability of the perceived air quality in the office corresponded to 22% dissatisfied when the pollution source was present, and to 15% dissatisfied when the pollution source was absent. In the former condition there was a significantly increased prevalence of headaches (P= 0.04) and significantly lower levels of reported effort (P=0.02) during the text typing and calculation tasks, both of which required a sustained level of concentration. In the text typing task, subjects worked significantly more slowly when the pollution source was present in the office (P=0.003), typing 6.5% less text than when the pollution source was absent from the office. Reducing the pollution load on indoor air proved to be an effective means of improving the comfort, health and productivity of building occupants.     

Sick Building Syndrome and Psychosocial Factors - a Literature Review

Abstract Sick building syndrome (SBS) with an unknown etiology has led researchers to focus on the role of psychosocial factors in the work environment as well as on individual characteristics in SBS. Recent research has suggested that psychosocial factors are quite strongly associated with SBS. The associations have been confirmed in buildings that were beforehand considered to be problem cases, and also in buildings whose condition was not known in advance. However, SBS symptoms could not be attributed to psychosocial factors alone. Most of the previous studies have supported the conclusion that SBS most likely is of multifactorial origin related to chemical, physical, biological and psychosocial factors that interact or coincide with one another. Unfortunately, for the time being, it is not possible to characterize adequately the relationship between the various risk factors and the possible mechanisms of SBS. There is an urgent need for more empirical research, especially follow-up studies and interventions, for development of the methodology and for new theory-building in order to better understand the relations between environmental factors, personal factors and the symptoms of SBS. In this literature review, SBS is viewed from an occupational stress perspective.     

Phase 1 of the California Healthy Building Study: A Summary

Twelve public office buildings were selected for a study of relationships between worker's health symptoms and a number of building, workspace, job, and personal factors. Three buildings were naturally ventilated, three were mechanically ventilated, and six were air conditioned. Information on the prevalences of work-related symptoms, demographics, and job and personal factors were determined via a questionnaire completed by 880 occupants. Several indoor environmental parameters were measured. Logistic regression models were used to evaluate associations between symptom prevalences and features of the buildings, indoor environments, jobs, and personal factors. A substantial fraction of the occupants in these typical office buildings reported frequent work-related symptoms. The occupants of the mechanically ventilated and air conditioned buildings had sipifcantly more symptoms than occupants of the naturally ventilated buildings after adjustment for confounding factors. Increased prevalences of some symptoms were associated with several job and workspace factors including: presence of carpet, increased use of carbonless copy paper and photocopiers, space sharing, and distance from a window     

Effect of renovating an office building on occupants' comfort and health

An intervention study was performed in a mechanically ventilated office building in which there were severe indoor climate complaints among the occupants. In one part of the building a new heating and ventilation strategy was implemented by renovating the HVAC system, and a carpet was replaced with a low-emitting vinyl floor material; the other part of the building was kept unchanged, serving as a control. A comprehensive indoor climate investigation was performed before and after the intervention. Over a 2-week period, the occupants completed a daily questionnaire regarding their comfort and health. Physiological examinations of eyes, nose and lungs were performed on each occupant. Physical, chemical and sensory measurements were performed before and after the intervention. The renewal of the flooring material was performed after a sensory test of alternative solutions in the laboratory. Before the floor material was installed in the office building, a full-scale exposure experiment was performed in the laboratory. The new ventilation strategy and renovation of the HVAC system were selected on the basis of laboratory experiments on a full-scale mock-up of a cellular office. The severity of occupants' environmental perceptions and symptoms was significantly reduced by the intervention.     

Non-Specific Symptoms In Office Workers: A Review And Summary Of The Epidemiologic Literature

Epidemiologic research into the causes of non-specific symptoms among office workers has produced a variety of conflicting findings which are difficult to synthesize. This paper first discusses methodologic issues important in the interpretation of epidemiologic studies, and then reviews the findings of 32 studies of 37 factors potentially related to office worker symptoms. Among environmental factors assessed, there were generally consistent findings associating increased symptoms with air-conditioning, carpets, more workers in a space, VDT use, and ventilation rates at or below 10 liters/second/person. Studies with particularly strong designs found decreased symptoms associated with low ventilation rate, short-term humidification, negative ionization, and improved office cleaning, although studies reviewed showed little consistency of findings for humidification and ionization. Relatively strong studies associated high temperature and low relative humidity with increased symptoms, whereas less strong studies were not consistent. Among personal factors assessed, there were generally consistent findings associating increased symptoms with female gender, job stress/dissatisfaction, and allergies/asthma. For other environmental or personal factors assessed, findings were too inconsistent or sparse for current interpretation, and there were no findings from strong studies. Overall evidence suggested that work related symptoms among office workers were relatively common, and that some of these symptoms represented preventable physiologic effects of environmental exposures or conditions. Future research on this problem should include blind experimental and case-control studies, using improved measurements of both environmental exposures and health outcomes     

Sick building syndrome—A case study in a multistory centrally air-conditioned building in the Delhi City

Recently, airtight envelope system has become popular in the design of office buildings to reduce heating and cooling loads. Maintaining allowable indoor air quality (IAQ) for such airtight buildings totally depends on mechanical ventilation systems. Subsequently, poor operation of the ventilation system in such office buildings causes ineffective removal of polluted indoor air, and displays a sign of “sick building syndrome” (SBS). User's perception is an important parameter for evaluating IAQ. A questionnaire study was carried out to investigate the prevalence of the SBS at a multistory centrally air-conditioned Airport Authority of India (AAI) building in the New Delhi city. Quantification of the perceptions of the users regarding IAQ was done by converting their responses to a SBS score. The quantified answers were then subjected to statistical analysis. Qualitative analysis of the questionnaire was carried out to evaluate relationships between SBS score and carbon dioxide (CO₂) and other parameters related to building and work environment. Quantitative analysis of IAQ was also conducted by monitoring indoor concentrations of four pollutants, namely, nitrogen dioxide (NO₂), sulphur dioxide (SO₂), suspended particulate matter (SPM) and carbon monoxide (CO). Concentrations of pollutants were complying with IAQ standards as given by ASHRAE and WHO. The SBS was higher on the third floor as compared to other floors and the control tower. The main symptoms prevailing were headache (51%), lethargy (50%), and dryness in body mucous (33%). The third floor and the control tower were affected by infiltration, mainly from entrance doors. A direct relation between the average SBS score and CO₂ concentration was found, i.e., the average SBS score increased with CO₂ concentration and vice versa, clearly signifying the usefulness of SBS score in IAQ.     

Case Study of Factors contributing to a Crisis Building

Abstract Employees of a communications firm experienced an acute outbreak of nonspecific illness related to the workplace. Symptoms consisted primarily of coughing, throat irritation, shortness of breath and disorientation. Fifty-one individuals sought emergency medical care, and the building was evacuated. A multidisciplinary team was assembled to investigate and resolve the problem. Investigation activities focused on three major areas: epidemiology; environmental measurement; and mechanical engineering. Results indicated that the outbreak was due to multiple factors working in concert. The inside of the air handling system was contaminated with microbial growth and particulate matter; chemical products were used throughout the building with little control over use patterns; and the HVAC system was not delivering acceptable quantities of outdoor air to the employees’ breathing zones. Two unusual events may have triggered the employees’ response. An unusual odor/taste was reported, and the outside air damper abruptly opened and closed, possibly dislodging particulate matter from inside the air handling system. It appeared that psychosocial factors played an important role. Prevention of similar crises could be achieved by implementation of a policy/procedure that addresses specific responsibilities, communications, preventive maintenance, acceptable outdoor air ventilation rates, and guidelines for reporting and investigation.     

Particulate Matter Intervention Study: A Causal Factor of Building-Related Symptoms in an Older Building

Abstract Five floors of a 20-year old 6-story office building were investigated using an integrated step-by-step investigation strategy. This involved a walkthrough inspection, an occupant questionnaire, and targeted environmental monitoring of indoor air quality and comfort parameters. The initial questionnaire survey revealed a high occurrence of building-related symptoms. The walkthrough inspection and environmental monitoring identified deposits of surface dust (indoor surface pollution – ISP) on carpets and hard surfaces, and elevated levels of carbon dioxide and respirable suspended particulate matter (RSP) throughout the building. An intervention study (blinded to the occupants) was targeted at reducing ISP levels by replacing normal carpet cleaning practices with higher performance vacuum cleaners and improved cleaning practices. The intervention reduced ISP levels and significantly lowered RSP concentrations by approx. 80% from initial values and against control floors. A follow-up SBS questionnaire revealed significant reductions in all but two of the symptoms. The most significant reductions occurred with symptoms of eye irritation, throat irritation, dry unproductive cough, and nose irritation. The study showed that in older buildings with poor ventilation, a build-up of ISP, and elevated RSP levels, using higher performance carpet cleaning practices can reduce RSP to acceptable levels and can reduce SBS symptoms.     

Comparison of Self-Administered Questionnaire with Physician Diagnosis in the Diagnosis of the Sick Building Syndrome

The aim of the study was to compare the results of a self-administered questionnaire, designed to estimate the prevalence of the sick building syndrome, with an independent medical interview and clinical opinion. Six buildings were chosen for study from a sample of 47 with known measurements of the building symptom index. One building with a high and one with a low score was selected from each of three ventilation classes (natural ventilation, air-conditioning with induction units and air-conditioning with variable air volume systems). A stratified random sample of 160 workers in these buildings was studied. Each received, in random order, a self-administered questionnaire, and a medical opinion based on a free medical history. The doctor had no access to the self-administered questionnaire at the time. The average number of work-related symptoms per worker (the building symptom index), which is used to compare one building with another, showed a good agreement between the two methods. There were, however, consistent differences between the two assessments in individual symptoms. The self-administered questionnaire produced a higher prevalence of work-re- lated runny nose and flu-like symptoms, which were often regarded as being due to infections in the medical opinion. In individuals, work-related symptoms on the self-administered questionnaire were validated by the medical opinion in over 75% of cases for eye and throat symptoms, lethargy and headache. Only 31% of work-related runny nose and 21% of work-related flu-like symptoms were thought by the medical opinion to be work-related. The medical opinion identified an extra 5% of work-related symptoms that were missed on the self-administered questionnaire. The self-administered questionnaire therefore produced a satisfactory estimate of the building symptom index, removing the potential bias of an interviewer. The questions on ninny nose and flu-like symptoms would be improved by including only those that occurred more frequently. The building symptom index was calculated for the six buildings twice, with separate random samples of workers completing the questionnaire two years apart. The buildings were ranked in the same order (for the building symptom index) on both occasions, again confirming the validity of the self-administered questionnaire.     

Effects of a Furniture-integrated Breathing-zone Filtration System on Indoor Air Quality,Sick Building Syndrome,and Productivity

A field experiment evaluated the effect of a furniture-inte-grated breathing-zone filtration (BZF) system on indoor air quality, worker comfort, health, and productivity. The BZF system tested filters office air to remove volatile organic compounds and airborne particulates. The BZF system was installed on one floor of a 29 story air-conditioned office building. Another floor of the building served as a control. Comparisons of pre-installation and three month post-instal-lation surveys showed improvements in indoor air quality, sick building syndrome symptoms, and self-reported pro-ductivity with the BZF system References     

Field Measurements of Ventilation and Ventilation Effectiveness in an Office/Library Building

Mechanical ventalation system performance involves the provision of adequate amuunts of outdoor air, uniform distribution of ventilation air within the occupied space, and the maintenance of thermal comfort. Standard measurement techniques exist to evaluate thermal comfort and air change rates in mechanically ventilated buildings; procedures to evaluate air distribution or ventilation effectiveness in the field are still being developed. This paper presents measuremetlts of air change rates and ventilation effectivenes in an office/library building in Washington, DC. The tracer gas decay technique was used to measure whole building air change rates. The air change rates during the measurement period were essentially constant at about 0.8 air changes per hour, somewhat below the design specification and above the minimum recmmmded in ASHRAE Standard 62-1989. Ventilation effectiveness was investigated at several locations within the building through the measurement of local tracer gas decay rate and mean local age of air. The ventilation effectiveness measurements serve as an investigation of the applicability of the m e a s u r r n procedures employed, providing insight into the measurement issue of establishing initial conditions, the spatial variation in test results within a building, and the repeatabildy between tests. The results of the ventilation effectiveness meusurements are consistent with good distrhtion of the outdoor air by the ventilation system and good mixing within the occupied space.     

The prevalence and incidence of sick building syndrome in Chinese pupils in relation to the school environment: a two-year follow-up study

There are few incidence studies on sick building syndrome (SBS). We studied two-year change of SBS in Chinese pupils in relation to parental asthma/allergy (heredity), own atopy, classroom temperature, relative humidity (RH), absolute humidity (AH), crowdedness, CO?, NO?, and SO?. A total of 1993 participated at baseline, and 1143 stayed in the same classrooms after two years. The prevalence of mucosal and general symptoms was 33% and 28% at baseline and increased during follow-up (P < 0.001). Twenty-seven percent reported at least one symptom improved when away from school. Heredity and own atopy were predictors of SBS at baseline and incidence of SBS. At baseline, SO? was associated with general symptoms (OR=1.10 per 100 μg/m3), mucosal symptoms (OR=1.12 per 100 μg/m3), and skin symptoms (OR=1.16 per 100 μg/m3). NO? was associated with mucosal symptoms (OR=1.13 per 10 μg/m3), and symptoms improved when away from school (OR=1.13 per 10 μg/m3). Temperature, RH, AH, and CO? were negatively associated with prevalence of SBS. Incidence or remission of SBS was not related to any exposure, except a negative association between SO? and new skin symptoms. In conclusion, heredity and atopy are related to incidence and prevalence of SBS, but the role of the measured exposures for SBS is more unclear. PRACTICAL IMPLICATIONS: We found high levels of CO? indicating inadequate ventilation and high levels of SO? and NO?, both indoors and outdoors. All schools had natural ventilation, only. Relying on window opening as a tool for ventilation in China is difficult because increased ventilation will decrease the level of CO? but increase the level of NO? and SO? indoors. Prevalence studies of sick building syndrome (SBS) might not be conclusive for causal relationships, and more longitudinal studies on SBS are needed both in China and other parts of the world. The concept of mechanical ventilation and air filtration should be introduced in the schools, and when planning new schools, locations close to heavily trafficked roads should be avoided.     

成都某公司办公大楼空调通风设计

介绍了成都某公司办公大楼的空调、通风、防排烟系统和空调自动控制系统设计,详细阐述了空调系统形式,指出了通风空调系统防火措施、节能措施及环保与卫生防疫措施。     

造型源于场地 创新办公建筑——以武汉江夏区供电公司电力大楼设计为例

该文指出,特定的场地决定了建筑的平面形式,而平面形式是立面设计手法应用的源泉。