Relating Sick Building Symptoms to Environmental Conditions and Worker Characteristics

Abstract Recent concern has centered on “sick buildings” in which there has been an unusually high percentage of health complaints by the building's occupants. Typically, these symptoms are thought to be tied to indoor air quality characteristics, such as high levels of respirable particles or volatiles, thermal conditions, etc. In addition, recent studies have drawn connections between “sick building syndrome” (SBS) symptoms and non-environmental variables, i.e., personal and occupational factors. This paper presents a brief review of a study by Hedge et al. (1995) and additional analyses of their data. In a study of 27 air-conditioned office buildings, Hedge et al. measured nine indoor environmental conditions at various locations within each building and concurrently questioned workers on sixteen SBS symptoms and a number of other personal factors. The additional analyses presented in this paper attempt to draw formal statistical connections between SBS symptoms and both personal worker characteristics and indoor air pollutants simultaneously. The analyses were based on symptom severity response variables whic include information not only on the frequency with which an individual experienced a symptom, but also on how much the symptom disrupted the individual's work. Results from sixteen linear mixed effects models indicate that significant predictors are primarily personal and occupational in nature rather than environmental. For a number of the symptoms, additional variability attributable to buildings exists. However, any physical explanation of this variability remains unclear.     

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     

Evaluating building-related symptoms using the US EPA BASE study results

In order to develop baseline data about United States office buildings, the United States Environmental Protection Agency conducted the Building Assessment Survey Evaluation (BASE) study, a systematic survey of 100 randomly selected United States office buildings, in the 1990s. This paper analyzes the self-reported work-related symptoms and job and workplace characteristics of 4326 respondents and compares results to the National Institute for Occupational Safety and Health's (NIOSH) study of 80 'complaint' buildings. Four distinct groups of symptoms, representing 'tiredness', 'mucosal irritation', 'neuropsychological', and 'lower respiratory' conditions emerged from factor analysis of work-related symptoms. The symptom grouping is identical for both surveys. Although the prevalence of each symptom is significantly higher in the NIOSH than in the BASE sample, there is overlap of the symptom distributions. In the BASE survey, 45% of the work force reported at least one work-related health symptom; 20% reported at least three symptoms. These findings imply that it is counterproductive to dichotomize buildings into healthy vs. unhealthy; instead the prevalence of health problems related to buildings span a continuum. PRACTICAL IMPLICATIONS: These results indicate that most office buildings have occupants who report building-related symptoms. This paper provides practical guidance for the comparison of building prevalences to the BASE normative data. Work-related symptom distributions and symptom groups can improve investigators' ability to identify IEQ problems.     

Association of ventilation system type with SBS symptoms in office workers

This paper provides a synthesis of current knowledge about the associations of ventilation system types in office buildings with sick building syndrome (SBS) symptoms and discusses potential explanations for the associations. Most studies completed to date indicate that relative to natural ventilation, air conditioning, with or without humidification, was consistently associated with a statistically significant increase in the prevalence of one or more SBS symptoms, by approximately 30 to 200%. In two of three analyses from a single study (assessments), symptom prevalences were also significantly higher in air-conditioned buildings than in buildings with simple mechanical ventilation and no humidification. The available data also suggest, with less consistency, an increase in risk of symptoms with simple mechanical ventilation relative to natural ventilation. Insufficient information was available for conclusions about the potential increased risk of SBS symptoms with humidification or recirculation of return air. The statistically significant associations of mechanical ventilation and air conditioning with SBS symptoms are much more frequent than expected from chance and also not likely to be a consequence of confounding by several potential personal, job, or building-related confounders. Multiple deficiencies in HVAC system design, construction, operation, or maintenance, including some which cause pollutant emissions from HVAC systems, may contribute to the increases in symptom prevalences but other possible reasons remain unclear.     

Personal Risk Factors Associated with Mucosal Symptom Prevalence in Office Workers

In 1989 the Madison Building of the Library of Congress was investigated to determine the source of occupant complaints about health symptoms and the indoor air quality. Questionnaires, distributed to all 3176 building occupants, assessed information on workstation characteristics, symptom occurrence, odors, thermal comfort, and demographic and health factors. Multivariate logistic regression analyses were conducted to assess personal risk factors associated with mucosal symptom reporting and reported sensitivity to irritants. Symptom prevalence was higher for women (odds ratio (OR) = 1.72, 95% confidence interval (CI) 1.40-2.10), those who reported being especially sensitive to irritants (OR = 1.57, 95% CI1.27-1.93), those with self-reported allergies, flu, or chest illness, and those who took frequent fresh air breaks. It was found that females and non-smokers and those reporting other adverse health effects tended to report sensitivity to irritants more frequently.     

Indoor Air Humidity And Sensation Of Dryness As Risk Indicators Of Sbs

Questionnaire reports on symptoms and sensations from 4943 office workers, measurements of indoor climate from 540 office rooms in 160 buildings, and measurements of TVOC in 85 rooms were used in an analysas of the role of indoor air humidity and the sensation of dryness as risk indicators of SBS (Sick Building Syndrome) symptoms. The sensation of dryness was strongly associated with the prevalence of SBS symptom reports. There were no associations between measured indoor air humidity and the prevalence of SBS symptoms or the sensation of dryness. A number of significant associations were demonstrated between the sensation of dryness and technical, air quality, psychosocial and personal variables. The frequency of reports of perceived “dry air” is an important indicator of the “sickness” of a building; indoor air humidity is not an indicator.     

Indoor gaseous air pollutants determinants in office buildings—The OFFICAIR project

The aim of this study was to identify determinants of aldehyde and volatile organic compound (VOC) indoor air concentrations in a sample of more than 140 office rooms, in the framework of the European OFFICAIR research project. A large field campaign was performed, which included (a) the air sampling of aldehydes and VOCs in 37 newly built or recently retrofitted office buildings across 8 European countries in summer and winter and (b) the collection of information on building and offices’ characteristics using checklists. Linear mixed models for repeated measurements were applied to identify the main factors affecting the measured concentrations of selected indoor air pollutants (IAPs). Several associations between aldehydes and VOCs concentrations and buildings’ structural characteristic or occupants’ activity patterns were identified. The aldehyde and VOC determinants in office buildings include building and furnishing materials, indoor climate characteristics (room temperature and relative humidity), the use of consumer products (eg, cleaning and personal care products, office equipment), as well as the presence of outdoor sources in the proximity of the buildings (ie, vehicular traffic). Results also showed that determinants of indoor air concentrations varied considerably among different type of pollutants.     

Outdoor ozone and building-related symptoms in the BASE study

Reactions between ozone and indoor contaminants may influence human health and indoor air quality. The U.S. EPA Building Assessment Survey and Evaluation (BASE) study data were analyzed for associations between ambient ozone concentrations and building-related symptom (BRS) prevalence. Multiple logistic regression (MLR) models, adjusted for personal, workplace, and environmental variables, revealed positive relationships (P < 0.05) between ambient ozone concentrations and upper respiratory (UR), dry eyes, neurological and headache BRS (odds ratios ranged from 1.03 to 1.04 per 10 mug/m(3) increase in ambient ozone concentrations). Other BRS had marginally significant relationships with ambient ozone (P < 0.10). A linear dose-response in UR symptoms was observed with increasing ambient ozone (P = 0.03); most other symptoms showed similar but not statistically significant trends. Ambient ozone correlated with indoor concentrations of some aldehydes, a pattern suggesting the occurrence of indoor ozone chemistry. Coupled with the MLR ambient ozone-BRS analysis, this correlation is consistent with the hypothesis that ozone-initiated indoor reactions play an important role in indoor air quality and building occupant health. Replication with increased statistical power and with longitudinal data is needed. If the observed associations are confirmed as causal, ventilation system ozone removal technologies could reduce UR BRS prevalence when higher ambient ozone levels are present. PRACTICAL IMPLICATIONS: This paper provides strong statistical evidence that supports (but does not prove) the hypothesis that ozone entrained into buildings from the outdoor air is involved in increasing the frequency that occupants experience and a range of upper and lower respiratory, mucosal and neurological symptoms by as much as a factor of 2 when ambient ozone levels increase from those found in low-ozone regions to those typical of high-ozone regions. Although replication is needed, the implication is that reducing the amount of ozone entrained into building ventilation systems, either by ambient pollution reduction or engineered gas-phase filtration, may substantially reduce the prevalence of these symptoms experienced by occupants.     

Association of Personal and Workplace Characteristics with Health,Comfort And Odor: A Survey of 3948 Office Workers in Three Buildings

A questionnaire on health symptoms, workplace conditions, and perceived indoor air quality was administered to 3948 employees of the Environmental Protection Agency in Washington, DC in the winter of 1989. The main goal was to determine the personal or workplace characteristics associated with health symptoms. A principal components analysis of 32 health symptoms identified 12 health factors. Each factor was generally associated with a particular body system (eyes, nose, throat, chest, central nervous system, etc.). The 12 health factors were regressed linearly on the 50-100 personal, workplace, and spatial characteristics identified from the questionnaire and building blueprints. Significant variables (p < 0.01) were included in a second logistic regression to determine a final model. Eleven variables were associated with multiple health factors. The main workplace variables were dust and glare. Personal characteristics of importance were mold allergies and sensitivity to chemicals. Among women, lack of a college degree was an important factor. Air quality factors of importance included hot stuffy air and dry air: The odor of paint and other chemicals, and the odor of cosmetics were also associated with four or more of the health factors. Two measures of stress – heavy workload and conflicting demands – were also associated with several health factors.     

The impact of information on perceived air quality--'organic' vs. 'synthetic' building materials

As indoor air quality complaints cannot be explained satisfactorily and building materials can be a major source of indoor air pollution, we hypothesized that emissions from building materials perceived as unfamiliar or annoying odors may contribute to such complaints. To test this hypothesis, emissions from indoor building materials containing linseed oil (organic) and comparable synthetic (synthetic) materials were evaluated by a na?ve sensory panel for evaluation of odor intensity (OI) and odor acceptability (OA). The building materials were concealed in ventilated climate chambers of the CLIMPAQ type. When information was provided about the identity and type of building material during the evaluation, i.e. by labeling the materials in test chambers either as 'organic' or 'synthetic', the OI was significantly lower for all the 'organic' materials compared with evaluations without information. Similarly, OA was increased significantly for most 'organic' samples, but not the 'synthetic' ones. The major effect is probably that OA is increased when the panel is given information about the odor source. PRACTICAL IMPLICATIONS: As providing information about the source of odors can increase their acceptability, complaints about indoor air quality may be decreased if occupants of buildings are well informed about odorous emissions from the new building materials or new activities in their indoor environment.     

Self‐reported health and comfort in ‘modern’ office buildings: first results from the European OFFICAIR study

In the European research project OFFICAIR, a procedure was developed to determine associations between characteristics of European offices and health and comfort of office workers, through a checklist and a self‐administered questionnaire including environmental, physiological, psychological, and social aspects. This procedure was applied in 167 office buildings in eight European countries (Portugal, Spain, Italy, Greece, France, Hungary, the Netherlands, and Finland) during the winter of 2011–2012. About 26 735 survey invitation e‐mails were sent, and 7441 office workers were included in the survey. Among respondents who rated an overall comfort less than 4 (23%), ‘noise (other than from building systems)’, air ‘too dry’, and temperature ‘too variable’ were the main complaints selected. An increase of perceived control over indoor climate was positively associated with the perceived indoor environment quality. Almost one‐third of office workers suffered from dry eyes and headache in the last 4 weeks. Physical building characteristics were associated with occupants’ overall satisfaction (acoustical solutions, mold growth, complaints procedure, cleaning activities) and health (number of occupants, lack of operable windows, presence of carpet and cleaning activities). OFFICAIR project provides a useful database to identify stressors related to indoor environmental quality and office worker's health.     

Association of subjective health symptoms with indoor air quality in European office buildings: The OFFICAIR project

The aim of this study was to explore the association between the building-related occupants’ reported health symptoms and the indoor pollutant concentrations in a sample of 148 office rooms, within the framework of the European OFFICAIR research project. A large field campaign was performed in 37 office buildings among eight countries, which included (a) 5-day air sampling of volatile organic compounds (VOCs), aldehydes, ozone, and NO₂ (b) collection of information from 1299 participants regarding their personal characteristics and health perception at workplace using online questionnaires. Stepwise and multilevel logistic regressions were applied to investigate associations between health symptoms and pollutant concentrations considering personal characteristics as confounders. Occupants of offices with higher pollutant concentrations were more likely to report health symptoms. Among the studied VOCs, xylenes were associated with general (such as headache and tiredness) and skin symptoms, ethylbenzene with eye irritation and respiratory symptoms, a-pinene with respiratory and heart symptoms, d-limonene with general symptoms, and styrene with skin symptoms. Among aldehydes, formaldehyde was associated with respiratory and general symptoms, acrolein with respiratory symptoms, propionaldehyde with respiratory, general, and heart symptoms, and hexanal with general SBS. Ozone was associated with almost all symptom groups.     

Indoor air microbes and respiratory symptoms of children in moisture damaged and reference schools

Microbial indoor air quality and respiratory symptoms of children were studied in 24 schools with visible moisture and mold problems, and in eight non-damaged schools. School buildings of concrete/brick and wooden construction were included. The indoor environment investigations included technical building inspections for visible moisture signs and microbial sampling using six-stage impactor for viable airborne microbes. Children's health information was collected by questionnaires. The effect of moisture damage on concentrations of fungi was clearly seen in buildings of concrete/brick construction, but not in wooden school buildings. Occurrence of Cladosporium, Aspergillus versicolor, Stachybotrys, and actinobacteria showed some indicator value for moisture damage. Presence of moisture damage in school buildings was a significant risk factor for respiratory symptoms in schoolchildren. Association between moisture damage and respiratory symptoms of children was significant for buildings of concrete/brick construction but not for wooden school buildings. The highest symptom prevalence was found during spring seasons, after a long exposure period in damaged schools. The results emphasize the importance of the building frame as a determinant of exposure and symptoms.     

Ventilation rates and health: multidisciplinary review of the scientific literature

The scientific literature through 2005 on the effects of ventilation rates on health in indoor environments has been reviewed by a multidisciplinary group. The group judged 27 papers published in peer-reviewed scientific journals as providing sufficient information on both ventilation rates and health effects to inform the relationship. Consistency was found across multiple investigations and different epidemiologic designs for different populations. Multiple health endpoints show similar relationships with ventilation rate. There is biological plausibility for an association of health outcomes with ventilation rates, although the literature does not provide clear evidence on particular agent(s) for the effects. Higher ventilation rates in offices, up to about 25 l/s per person, are associated with reduced prevalence of sick building syndrome (SBS) symptoms. The limited available data suggest that inflammation, respiratory infections, asthma symptoms and short-term sick leave increase with lower ventilation rates. Home ventilation rates above 0.5 air changes per hour (h(-1)) have been associated with a reduced risk of allergic manifestations among children in a Nordic climate. The need remains for more studies of the relationship between ventilation rates and health, especially in diverse climates, in locations with polluted outdoor air and in buildings other than offices. PRACTICAL IMPLICATIONS: Ventilation with outdoor air plays an important role influencing human exposures to indoor pollutants. This review and assessment indicates that increasing ventilation rates above currently adopted standards and guidelines should result in reduced prevalence of negative health outcomes. Building operators and designers should avoid low ventilation rates unless alternative effective measures, such as source control or air cleaning, are employed to limit indoor pollutant levels.     

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.     

Optimizing energy efficiency and occupant comfort with climate specific design of the building

Designing energy efficient and comfortable buildings requires harmonizing the complex interactions of architecture, construction and building service engineering. The building envelope has a particular importance, since it integrates many functions and has direct influence on indoor climate. Focusing on satisfaction of the user means that the indoor climate is a key for a holistic design approach. Only a satisfied user will not intervene with the designed energy concept or the indoor climate control; dissatisfaction results in multiple system interventions which may cause waste of energy and sometimes even damage to building envelope components. Satisfaction with the indoor environment also increases working productivity or enables effective recreation of residents.The paper deals with international research activities in the field of climate specific building design. Various comfort and energy monitoring surveys of office buildings as well as residential buildings provide substantial information about the occupants' behavior and their needs during specific situations under different outdoor climates. This information allows summarizing basic climate dependent design principles which architects should keep in mind during the early stages of the design process. It also helps to develop strategies aiming at reducing building energy demand and at the same time consider comfort aspects. The second part of this paper demonstrates application of the climate dependent design principles in a housing project in Dubai.     

Bayesian adaptive comfort temperature (BACT) of air-conditioning system in subtropical climate

Indoor thermal climate is an important issue affecting the health and productivity of building occupants. In the designing of commercial air-conditioning systems, it is believed that the conventional fixed temperature set point concept is limited because indoor comfort temperature depends on the business culture, such as the nature of activities and dress code of occupants, etc. Researchers have been interested in investigating adaptive temperature control for a realistic in-situ control of comfort. Unfortunately, those studies put great emphasis on energy saving opportunities and sometimes might result in thermal discomfort to individuals. This study argues that complaints of thermal discomfort from individuals, despite representing only a small portion of the population, should not be ignored and can be used to determine the temperature setting for a population in air-conditioned environment. In particular, findings of a new notion of Bayesian adaptive comfort temperature (BACT) in air-conditioned buildings in a humid and subtropical climate like Hong Kong are reported, and the adaptive interface relationship between occupants’ complaints of thermal discomfort and indoor air temperature is determined. This BACT algorithm is intended to optimise the acceptance of thermal comfort, as determined by physical measurements and subjective surveys.     

Indoor environmental quality in Hellenic hospital operating rooms

Indoor environmental quality (IEQ) in hospital operating rooms (ORs) constitutes a major challenge for the proper design and operation of an energy efficient hospital. A subjective assessment of the indoor environment along with a short monitoring campaign was performed during the audits of 18 ORs at nine major Hellenic hospitals. A total of 557 medical personnel participated in an occupational survey, providing data for a subjective assessment of IEQ in the audited ORs. The OR personnel reported work related health symptoms and an assessment of indoor conditions (thermal, visual and acoustical comfort, and air quality). Overall, personnel reported an average of 2.24 work-related symptoms each, and 67.2% of respondents reported at least one. Women suffer more health symptoms than men. Special dispositions, such as smoking and allergies, increase the number of reported symptoms for male and female personnel. Personnel that perceive satisfactory indoor comfort conditions (temperature, humidity, ventilation, light, and noise) average 1.18 symptoms per person, while for satisfactory indoor air quality the average complaints are 0.99. The perception of satisfactory IEQ (satisfactory comfort conditions and air quality) reduces the average number of health complaints to 0.64 symptoms per person and improves working conditions, even in a demanding OR environment.     

The 3-year follow-up study in a block of flats - experiences in the use of the Finnish indoor climate classification

Indoor climate of two new blocks of flats was investigated. The case building was built for people with respiratory diseases by following the instructions of the Finnish Classification of Indoor Climate, Construction and Finishing Materials, while the control building was built using conventional building technology. The main indoor air parameters (temperature, relative humidity and levels of CO, CO2, ammonia, total volatile organic compounds, total suspended particles, fungal spores, bacteria and cat, dog and house dust mite allergens) were measured in six apartments of both the buildings on five occasions during the 3-year occupancy. In addition, a questionnaire to evaluate symptoms of the occupants and their satisfaction with their home environment was conducted in connection with indoor air quality (IAQ) measurements. The levels of indoor air pollutants in the case building were, in general, lower than those in the control building. In addition, the asthmatic occupants informed that their symptoms had decreased during the occupancy in the case building. This case study showed that high IAQ is possible to reach by careful design, proper materials and equipment and on high-quality construction with reasonable additional costs. In addition, the study indicated that good IAQ can also be maintained during the occupancy, if sufficient information on factors affecting IAQ and guidance on proper use and care of equipment are available for occupants.     

Indoor air quality and occupant satisfaction in five mechanically and four naturally ventilated open-plan office buildings

Occupant responses and indoor environment characteristics were recorded and compared in five mechanically and four naturally ventilated open-plan office buildings by using a simple approach that enabled us to survey many buildings simultaneously. All occupant responses were obtained during one afternoon. In a pre-experiment, temperature and the concentration of CO₂ were monitored in 2–10 locations/office to evaluate the variation throughout the offices. A representative measurement point was subsequently selected and measurements of the same parameters were made during one week. All offices were monitored during the same week and occupant responses to the indoor environment were collected via the internet on the same day within that week. The temperature and the CO₂ concentration varied more and were in some cases higher in the naturally ventilated buildings, but occupant responses in terms of symptoms and adverse perceptions differed only modestly between the two building types. Although rarely supported by statistical significance, the results indicated a somewhat higher degree of satisfaction with the indoor environment and a lower prevalence/intensity of symptoms among the occupants in the naturally ventilated buildings.