© Inštitut za sanitarno inženirstvo, 2014 Original scientific article Prevention and control of Sick Building Syndrome (SBS). Part 1: Identification of risk factors Andreja KUKEC1, Mateja DOVJAK2* ABSTRACT Problem: People in the developed countries spend around 90 % of their time indoors, so the design of healthy and comfortable buildings presents a key fundament. Construction of energy-efficient buildings with increased air tightness of the building envelope and poorly maintained ventilation systems often results in unhealthy and uncomfortable indoor conditions as well as in Sick Building Syndrome (SBS). In Part 1, risk factors for SBS are identified. In Part 2, an interactive influences among risk factors are detected and a preventive and control strategy to lower the occurrence of SBS is designed. Purpose: The purpose of this study is to identify and classify risk factors for SBS, as well as to define relevant parameters for the occurrence of SBS. Method: In the period of January to February 2014, comprehensive literature Received: 20. 2. 2014 review was carried out studying risk factors for SBS. We searched two Acc epted: 16. 10. 2014 bibliographic databases (Pub Med and Science Direct) for peer-reviewed publications from 1974 to 2014. Results and discussion: Based on the results of the comprehensive literature review, the risk factors for SBS can be classified into six major groups, i.e. physical, chemical, biological, 1 University of Ljubljana, psychosocial, personal and others. Conclusions: Identification of risk factors Faculty of Medicine, Centre of Public Health presents a first step towards integral prevention and control of SBS. The Zaloška 4, 1000 Ljubljana, Slovenia 2 identified and classified risk factors and their parameters are used for the University of Ljubljana, Faculty of Civil and Geodetic Engineering, design of a preventive strategy to lower the occurrence of SBS (Part 2). Chair for Buildings and Constructional Complexes Jamova cesta 2, 1000 Ljubljana, Slovenia Key words: Sick Building Syndrome, risk factors, identification ∗ Corresponding author Mateja Dovjak University of Ljubljana, Faculty of Civil and Geodetic Engineering, Chair for Buildings and Constructional Complexes Jamova cesta 2, 1000 Ljubljana, Slovenia mdovjak@fgg.uni-lj.si Article with the title “Prevention and control of Sick Building Syndrome (SBS). Part I: Identification of risk factors” presents an original work. It has not been sent to any other publisher. All authors have read the article and agreed with its content. 16 International Journal of Sanitary Engineering Research Vol. 8 No. 1/2014 Prevention and control of Sick Building Syndrome (SBS). Part 1: Identification of risk facto rs A. Kukec, M. Dovjak INTRODUCTION The characteristic symptoms of SBS that may occur singly People in the developed countries spend around 90 % of their time in- or in combination with each doors and around 20 % in working environments [1, 2]. During that time we are exposed to numerous health hazards that can be classified other are headache, eye, into biological, chemical, physical, biomechanical and psychosocial [3, nose, or throat irritation, dry 4]. Exposure to these hazards could affect human health. The extent of cough, dry or itchy skin, the effects is dependent on their exposure dose, exposure time and in- dizziness and nausea, dividual characteristics [3, 4]. On the other side, design of healthy and difficulty in concentrating, comfortable built environment is fundamental for the prevention and fatigue and sensitivity to control of health hazards [5, 6]. odours. Current design of energy-efficient buildings is mainly focused on the solving of energy problems. Solutions are defined in the direction of im- proved thermal insulation, increased air tightness of the building enve- lope as well as in the installation of energy-efficient ventilation systems [7]. Such partial solutions often results in unhealthy and uncomfortable conditions and may be related to the occurrence of a Sick Building Syn- drome (SBS). US Environmental Protection Agency [8] describes SBS as situations in which building occupants experience acute health and comfort effects that appear to be linked to time spent in a building, but no specific illness or cause can be identified. The complaints may be localized in a particular room or zone, or may be widespread through- out the building. The characteristic symptoms of SBS that may occur singly or in combination with each other are headache, eye, nose, or throat irritation, dry cough, dry or itchy skin, dizziness and nausea, dif- ficulty in concentrating, fatigue and sensitivity to odours [9-11]. In con- trast, the term Building Related Illness (BRI) is used when symptoms of diagnosable illness are identified and can be attributed directly to air- borne building contaminants [8]. The World Health Organization [12] estimated that up to 30 % of new and renovated buildings worldwide may be related to SBS. Comprehen- sive study [13] performed in the UK on 4373 office workers in 42 pub- lic buildings revealed that 29 % of those studied experienced five or more of the characteristic SBS symptoms. An investigation carried out by Woods et al. [14] on 600 office workers in the USA concluded that 20 % of the employees experience SBS symptoms and most of them were convinced that this reduces their working efficiency. Additionally, a study on 1390 workers in 5 public buildings in Quebec, Canada [15] showed that 50 % of workers experienced SBS symptoms. SBS may also occur in other environments such as schools, kindergartens and residential buildings [16-20]. In studies on residential buildings [18-20] from 12 % to 30.8 % of occupants were identified as having SBS. The purpose of this study is to Identification of risk factors, main parameters and their interactions are identify risk factors for SBS important for integral prevention and control of SBS. The purpose of and their main parameters. this study is to identify risk factors for SBS and their main parameters. Identification of risk factors Identification of risk factors presents a first step towards integral pre- vention and control of SBS. The identified and classified risk factors will presents a first step towards be used for the detection of interactive influences among risk factors integral prevention and control and their parameters as well as for the design of a preventive and con- of SBS. International Journal of Sanitary Engineering Research Vol. 8 No. 1/2014 17 A. Kukec, M. Dovjak Prevention and control of Sick Building Syndrome (SBS). Part 1: Identification of risk factors trol strategy to lower the occurrence of SBS. The interactions among risk factors and their parameters, and the designed strategy are pre- sented in Part 2 . METHODS Comprehensive literature review was carried out studying risk factors for SBS. In the period of January to February 2014 we searched two biblio- graphic databases (Pub Med and Science Direct) for peer-reviewed publi- cations from 1974 to 2014. The key-words were written in English: “sick building syndrome”, together with “air temperature”, “surface tempera- ture”, “relative humidity”, “air velocity”, “heating”, “cooling”, “ventilation”, air-conditioning”, “noise”, “vibrations”, “daylight”, “indoor air quality”, “air pollutants”, “volatile organic compounds”, “construction products”, “household products”, “phthalates”, “formaldehyde”, “tobacco smoke”, “odours”, “bacteria”, “mould”, “dust”, “gender”, “age”, “stress”, “social status”. Titles, abstracts or both, of all articles, were reviewed to assess their relevance. We reviewed reports, guidelines, legislative and other documents of the World Health Organization (WHO), Centers for Disease Control and Pre- vention (CDC), Environmental Protection Agency (EPA), Health Protec- tion Agency (HPA), Occupational Safety and Health Administration (OSHA), International Labour Organization (ILO), National Institute for Occupational Safety and Health (NIOSH), American Institute of Archi- tects (AIA), Canadian Centre for Occupational Health and Safety (CCOHS), International Agency for Research on Cancer (IARC), National Institute of Public Health of the Republic of Slovenia (NIPH), European Commission (EC), Eurostat, Official Journal of RS, EUR-Lex, Ministry of Health of the Republic of Slovenia (MZ GOV SI); ISO standards; manu- als and handbooks of the American Society for Heating, Refrigerating, and Air–Conditioning Engineers (ASHRAE). On the basis of the literature review, the risk factors were identified, classified and their main parameters were defined. In the presented study, 96 various sources of literature were analysed according to re- searched risk factors (Table 1). Literature review included all sources of literature addressing the scientific question of association between spe- cific risk factor and its impact on SBS. The detection of interactive influ- ences among risk factors and the design of preventive and control strat- egy to lower the occurrence of SBS are presented in Part 2. Table 1: Number of recorded literature sources according to research fields/risk factors from 1974 to 2014. Research fields/risk factors Number of recorded reference sources Physical risk factors for SBS 25 Chemical risk factors for SBS 47 Biological risk factors for SBS 9 Psychosocial, personal and others risk factors for SBS 15 Abbreviations: SBS – Sick Building Syndrome 18 © Inštitut za sanitarno inženirstvo, 2014 Prevention and control of Sick Building Syndrome (SBS). Part 1: Identification of risk facto rs A. Kukec, M. Dovjak RESULTS Figure 1: Classified risk factors for SBS with Classified risk factors and their key parameters are presented in Figure their main parameters. 1. The main findings of literature review are presented hereinafter. Source: Own source summarised from [1-129] Physical risk factors for SBS The most relevant parameters in the group of physical risk factors are environmental parameters of thermal comfort, parameters of building ventilation, noise, vibrations, daylight, electromagnetic fields, ions as well as ergonomic issues and universal design. Environmental parameters of thermal comfort Indoor air temperature ( T ) and relative humidity ( RH ) present two of ai in the environmental parameters of thermal comfort. Studies show that general dissatisfaction with the T and RH may be related with the in- ai in crease of SBS symptoms [21, 22]. Jaakkola et al. [23] carried out a study in a modern eight floor office building in Finland (N=2150 work- ers) and found out a linear correlation between the amount of SBS symptoms, sensation of dryness, and a rise in T above 22 °C. SBS ai symptoms increased both when the T was considered to be too cold ai and too warm. Nordström et al. [24] performed a study in new and well ventilated geri- atric hospital units in southern Sweden (N=104 employees). It was stated that in Scandinavia, the indoor relative humidity ( RH ) in well in International Journal of Sanitary Engineering Research Vol. 8 No. 1/2014 19 A. Kukec, M. Dovjak Prevention and control of Sick Building Syndrome (SBS). Part 1: Identification of risk factors The experiment showed that ventilated buildings was usually in the range 10-35 % in winter that re- sults in increased number of dissatisfied persons. It was concluded that very low RH (less than in air humidification during the heating season in colder climates can de- 20 %) can cause, in some crease symptoms of SBS and perception of dry air among employees. individuals, drying of the Andersen et al. [25] performed an experiment in a climate chamber, mucous membranes and of where eight young healthy men were exposed to clean dry air with Tai the skin. 23 °C. The experiment showed that very low RH (less than 20 %) can in cause, in some individuals, drying of the mucous membranes and of the skin [25]. High RH usually appears in the buildings that are located in a hot-hu- in mid climate. However, higher RH (more that 80 %) may also occur in in other buildings, especially due to incorrectly designed building enve- lopes, systems and installations, processes of increased steam produc- tion, water damage and flooding. These conditions may lead to damp- ness, stuffy odour, visible mould and adverse health effects. Dampness may be a strong predictor of SBS symptoms. Li et al. [26] evaluated the association between measures of dampness in 56 day care centres in the Taipei area and symptoms of respiratory illness in 612 employees. Dampness was found in 75.3 % of the centres, visible mould in 25.8 %, stuffy odour in 50.0 %, water damage in 49.3 %, and flooding in 57.2 %. Furthermore, prevalence of SBS symptoms in the day care workers was statistically significant among those who worked in centres that had mould or dampness. Beside air temperature and humidity, surface temperatures also have to be considered due to their large influence on perceived temperature. Additionally, lower surface temperatures may result in local discomfort, radiative asymmetry and water condensation. Studies [27] showed that low surface temperatures often result in thermally uncomfortable condi- tions and higher prevalence of SBS symptoms. Parameters related to building ventilation The main causes for SBS symptoms related to building ventilation and defined by studies were inadequate functioning, obsolete and unmain- tained HVAC system, decreased number of air changes and decreased volume of clean air [9]. Literature review of 41 studies [28] showed that ventilation rates below 10 L/s per person in office buildings were asso- ciated with statistically significant worsening in one or more health or perceived air quality outcomes. Some studies determined that increases in ventilation rates up to approximately 20 L/s per person, were associ- ated with further significant decreases in the prevalence of SBS symp- toms or with further significant improvements in perceived air quality. The reviewed studies reported relative risks of 1.5-2 for respiratory ill- nesses and 1.1-6 for SBS symptoms for low compared to high ventila- tion rates. Numerous researchers examined the prevalence of SBS symptoms in naturally ventilated buildings and air-conditioned buildings. Literature review on office buildings [29] indicated that occupants of naturally ventilated offices had fewer SBS symptoms than occupants of air-condi- 20 © Inštitut za sanitarno inženirstvo, 2014 Prevention and control of Sick Building Syndrome (SBS). Part 1: Identification of risk facto rs A. Kukec, M. Dovjak tioned offices. Similar study was performed by Costa and Brickus [30] in a central-air-conditioned dropping centre and in natural-ventilation commercial shops in Rio de Janeiro, Brazil. Air-conditioned building [30] were associated with increased SBS symptoms. Noise and vibrations Excessive noise seriously harms human health and interferes with peo- ple’s daily activities [31]. It can disturb sleep, cause cardiovascular and psychophysiological effects, reduce performance and provoke annoy- ance responses and changes in social behaviour [31]. From engineering point of view, noise control in buildings includes protection against out- side noise, direct sound transmission through structures, equipment noise and reverberation sound. Wonga [32] studied the prevalence of SBS among apartment residents of 748 households in Hong Kong. The major indoor environmental qual- ity problem perceived by residents was the noise. Beside excessive noise, low frequency noise (20-100 Hz) which is found in buildings with industrial machines or ventilation machinery, may also cause health problems. Certain body organs (specifically the eyes), have characteris- tics resonance frequencies in the range 1-20 Hz [9]. Hodgson et al. [33] observed that irritability and dizziness experienced by a group of secretaries working in new offices correlated significantly with the vi- brations measured on their desks. The vibrations were caused by an adjacent pump-room. Daylight Daylight (DL) has an important benefit on well-being, including visual, psychological and non-visual effects. Non-visual effects of DL are relat- ed to the regulation of circadian rhythms (i.e. hormone secretion, body temperature, heart frequency and arterial pressure), non-circadian ef- fects (i.e. mood, alertness, concentration) and synthesis of vitamin D [34-36]. Abdel-Hamid et al. [37] carried out a cross-sectional study at the Faculty of Medicine, Ain Shams University, Cairo, Egypt. Results of self-administered questionnaire on 826 workers showed that fatigue and headache were the most prevalent symptoms related to SBS (76.9 and 74.7 %). Poor lighting, lack of sunlight and absence of air currents were associated statistically with SBS symptoms, besides other param- eters (poor ventilation, high noise, temperature, humidity, environmen- tal tobacco smoke, use of photocopiers and inadequate office cleaning). Electromagnetic fields In the area of adverse health effects of exposure to electromagnetic The main causes for SBS (EM) fields many articles have been published over the years. Based on symptoms related to building a recent in-depth review of the scientific literature, WHO [38] conclud- ventilation and defined by ed that current evidence did not confirm the existence of any health consequences from exposure to low level EM fields. Exposures to high- studies were inadequate er levels that might be harmful are restricted by national and interna- functioning, obsolete and tional guidelines. However, a number of epidemiological studies [38] unmaintained HVAC system. International Journal of Sanitary Engineering Research Vol. 8 No. 1/2014 21 A. Kukec, M. Dovjak Prevention and control of Sick Building Syndrome (SBS). Part 1: Identification of risk factors suggest small increases in risk of childhood leukemia with exposure to low frequency magnetic fields in the home. Some individuals reported “hypersensitivity” to electric or magnetic fields. Eriksson and Stenberg [39] investigated the prevalence of general, mucosal, and skin symp- toms in the Swedish population (N=3,000, age 18-64). The survey addressed 25 symptoms, principally general, mucosal and skin symp- toms. SBS symptoms, skin symptoms and symptoms similar to those reported by individuals with “electric hypersensitivity” were significantly more prevalent among employees with extensive display screen equip- ment usage. Ions In general, air contains negative and positive ions that can be produced naturally or artificially [40]. Concentrations of ions in the air vary with environmental and meteorological conditions [40]. Researchers [40, 41] support the view that negative ions have a net positive effect on health, including improved mood, stabilized catecholamine regulation and circadian rhythm, enhanced recovery from physical exertion and protection from positive ion-related stress and exhaustion disorders. The most important The acceptable minimum concentration of negative ions for indoor air is parameters for SBS among 200–300 ions per cm3. The optimal level is 1000–1500 negative ions chemical risk factors are per cm3 [42]. The lack of negative ions in the air may be responsible for used constructional and SBS [9]. household products and All sources of fire [43, 44], and especially cigarette smoking [42], elec- emitted pollutants, especially trical radiators and air-conditioners increase the concentration of posi- formaldehyde, phthalates, tive ions considerably. Contrary, positive ions may be related to SBS. According to Sulman [43, 44], the reported physiological effects of pos- volatile organic compounds, itive ions include inhibition of growth of tissue cell cultures, increased odours, environmental respiratory rate, increased basal metabolism, increased blood pressure, tobacco smoke, biocides, produced headache, fatigue, nausea, produced nasal obstructions, sore and others. throat, dizziness, increased skin temperatures. The researchers found that the electrical charges (positive ionization) engendered by every in- coming weather front produce the release of serotonin and weather sen- sitivity reactions (irritation syndrome, exhaustion syndrome; hyperthy- roidism) [43, 44]. Hedge et al. [45] define that worker ergonomics (designing the work / environment / process / equipment to fit the worker, instead of forcing the worker to fit the work / environment / process / equipment) and is- sues of universal design (barrier free environment for all groups of func- tional disabilities) [46] also present important physical risk factors that have to be considered for prevention of SBS. Chemical risk factors for SBS The most important parameters for SBS among chemical risk factors are used constructional and household products and emitted pollutants, especially formaldehyde, phthalates, volatile organic compounds, odours, environmental tobacco smoke, biocides, and others. 22 © Inštitut za sanitarno inženirstvo, 2014 Prevention and control of Sick Building Syndrome (SBS). Part 1: Identification of risk facto rs A. Kukec, M. Dovjak Constructional and household products Constructional products may According Simmons and Richard [47] many construction products used emit harmful substances in for waterproofing, insulating, fireproofing, roofing, painting, plastering, the surrounding environment building and treating of floors, as well as surface coating contain toxic during their whole life cycle. chemicals. Constructional products may emit harmful substances in the surrounding environment during their whole life cycle [48, 49]. In addition to constructional products, also household products have to be considered from the aspects of indoor environment quality. For exam- ple, use of air-fresheners may be related with poor indoor air quality and may lead to SBS symptoms [50-52]. Studies [50-52] proved that air- fresheners may have adverse health effects. Within the follow-up of the European Community Respiratory Health Survey in 10 countries, Zock et al. [51] identified 3,503 persons doing the cleaning in their homes and who were free of asthma at baseline. The results showed that the use of cleaning sprays at least weekly (42 % of participants) was associated with the incidence of asthma symptoms or medication and wheeze. The incidence of physician-diagnosed asthma was higher among those using sprays at least 4 days per week. Dose-response relationships were appar- ent for the frequency of use and the number of different sprays. Moreover, due to low air humidity in buildings, humidifiers are often used. Humidifiers in the ventilation circuit provide a place for microbes to flourish, and also provide a reason for adding biocides to humidified water. Many of these biocides are irritants or allergens [11]. These prod- ucts are highly irritant in concentrated form; when dispersed in the in- door atmosphere, at low concentrations, they may cause mucous mem- brane irritation in susceptible individuals [11]. Formaldehyde Constructional products and wooden furniture (i.e. plywood, particle- board, fibreboard, OSB, panel boards, urea-formaldehyde foam, etc.), paints, adhesives, varnishes, floor finishes, disinfectants, cleaning agents and other household products emit formaldehyde (HCHO) [49]. The results of several studies of indoor / outdoor ratios of formaldehyde in buildings are approximately from 3 to 18 [53-55]. Formaldehyde may be the cause of SBS since it irritates both the eyes and the upper or lower respiratory tract. It may also be responsible for allergic disor- ders including asthma [56]. Šestan et al. [49] reviewed 11 epidemio- logical studies (9 studies-residential buildings and 2 studies-public buildings) and found out that measured concentrations of formaldehyde were from 0.0016 ppm (2 μg/m3) to 0.109 ppm (134 μg/ m3). Meas- ured concentrations from the reviewed studies may cause irritation of the upper respiratory tract in the exposed individuals. An examination of studies carried out in 2005 or after [57] indicated that the average ex- posure of the population to formaldehyde seems to lie between 0.0163 ppm (20 μg/m3) and 0.0326 ppm (40 μg/m3) under normal living con- In addition to constructional ditions. Salthammer et al. [57] emphasised that new buildings with products, also household changed microclimate conditions may be related to higher average and products have to be maximum concentrations, which may lead to the increased exposures considered from the aspects and health risks, particularly in the group of sensitive individuals. of indoor environment quality. International Journal of Sanitary Engineering Research Vol. 8 No. 1/2014 23 A. Kukec, M. Dovjak Prevention and control of Sick Building Syndrome (SBS). Part 1: Identification of risk factors Phthalates Polyvinyl chloride (PVC) constructional products usually contain plasticis- ers, phthalate esters that may be emitted from PVC during the whole life cycle of the product. PVC materials are problematic during normal use of the building or during emergency situations (i.e. a case of fire). Compre- hensive literature review [48] indicated that the use of PVC constructional products in indoor environment may have adverse health effects. Phtha- lates are thought to be responsible for low testosterone level, declining sperm counts and quality, genital malformations, retarded sexual devel- opment or even reproductive abnormalities and increased incidences of certain types of cancer [58]. Epidemiologic studies at children [59, 60] evidence that the presence of PVC flooring and walls is related to asthma, rhinitis, wheeze, cough, phlegm, nasal congestion, nasal excretion and eczema. These findings underline the need to consider the health aspects of materials used in indoor environment. Systematic review and meta- analysis on 14 laboratory toxicology studies in adults (1950 to May 2007) assessed the relationship between PVC-related occupational expo- sure (meat wrappers, hospital and office workers, fire fighters, PVC proc- essors) and the risk of asthma, allergies, or related respiratory effects [61]. During emergency situations (i.e. a case of fire) it forms hazardous products such as carbon monoxide, carbon dioxide, hydrogen chloride, Comprehensive literature hydrochloric acid, dioxins, smoke/soot, etc. [48]. review indicated that the use Phthalates can be adsorbed onto indoor surfaces (carpet, wood, and of PVC constructional skin) and re-emitted in the indoor air [62]. products in indoor environment may have Man-made mineral fibres adverse health effects. Man-made mineral fibre (MMMF) is a generic name used to describe an inorganic fibrous material manufactured primarily from glass, rock, min- erals, slag and processed inorganic oxides. According to IARC [63] MMMF is classified into five categories: continuous glass filament, glass wool (insulation wool and special purpose wool), rock wool, slag wool, refractory ceramic and other. According to results from epidemiological studies, MMMF have adverse health effects [64]. Acoustic ceilings may contain MMMF that may be transferred from such surfaces to skin and eyes, normally by direct hand contact. However, MMMF may be trans- ferred via air transmission modes. Nielsen [65] proved that especially high concentrations were found in the rooms with uncovered ceilings, but also where the fibres were bound by a water-soluble glue and ex- posed to water damage. Unsealed fibreglass and other insulation mate- rial lining the ventilation ducts can release particulate material into the air. Such material can also become wet, creating an ideal and often concealed site for the growth of microorganisms [10]. Volatile organic compounds Volatile organic compounds (VOCs) are suspected to be one of the ma- jor causes of SBS [66-74]. Sources of VOCs in indoor environments are constructional products, furniture, household products (waxes, deter- gent, insecticides), products of personal hygiene (cosmetics), do-it-your- 24 © Inštitut za sanitarno inženirstvo, 2014 Prevention and control of Sick Building Syndrome (SBS). Part 1: Identification of risk facto rs A. Kukec, M. Dovjak self goods (resins), office materials (photocopier ink) or environmental tobacco smoke (ETS). Wolkoff [66] found out that concentrations of volatile organic compounds (VOC) depend on the type of the room, ac- tivity and time. VOCs may affect human health and also sometimes are source of odours [9]. Takigawa et al. [67] conducted a study in residen- tial buildings in Okayama, Japan (N=86 men, 84 women). The results showed that aldehyde levels increased frequently and markedly in the newly diseased and ongoing SBS groups. About 10 % of the subjects suffered from SBS in both years. Similar findings were made by Taki- gawa et al. [12]. Takigawa et al. [12] studied 871 people living in 260 single-family houses in 2004 and 2005. Approximately 14 % and 12 % of subjects were identified as having SBS in the first and second year, respectively. Elevated levels of indoor aldehydes and aliphatic hy- drocarbons increased the possible risk of SBS in residents living in new houses. Odours Odours are organic or inorganic compounds that originate from within the building, or they can be drawn into a building from the outdoors as well. Indoor sources of odours are usually associated with construction- al products, household products, furnishings, office equipment, insuffi- cient ventilation, problems with mould, bioeffluents, etc. Odours are an According to the Report of important source of indoor environmental quality problems in buildings European Commission on [75]. According to the Report of European Commission on SBS [9], the SBS, the hidden olfs from hidden olfs from materials and systems are claimed to be the major rea- son for the SBS. materials and systems are claimed to be the major Nakaoka et al. [68] examined the correlation between the sum of VOCs, reason for the SBS. total odour threshold ratio and SBS symptoms. The findings indicated that the total odour threshold ratio and the concentration level of VOCs were correlated with SBS symptoms among sensitive people. Wang et al. [76] studied the prevalence of perceptions of odours and sensations of air humidity and SBS symptoms in domestic environments. Parents of 4530 1–8 year old children from randomly selected kindergartens in Chongqing, China participated. Stuffy odours, unpleasant odour, pun- gent odour, mould odour, tobacco smoke odour, humid air and dry air in the last three months (weekly or sometimes) was reported by 31.4 %, 26.5 %, 16.1 %, 10.6 %, 33.0 %, 32.1 % and 37.2 % of the parents, respectively. The prevalence of parents’ SBS symptoms were: 78.7 % for general symptoms, 74.3 % for mucosal symptoms and 47.5 % for skin symptoms. Multi-nominal regression analyses for associations be- tween odours/sensations of air humidity and SBS symptoms showed that the odds ratio for “weekly” SBS symptoms was consistently higher than for “sometimes” SBS symptoms. Environmental tobacco smoke Environmental tobacco smoke (ETS) is composed of both mainstream and side-stream smoke. ETS usually contains more than 4,000 differ- ent chemicals. Undiluted side-stream smoke contains higher concentra- tions of several chemicals than the mainstream smoke inhaled by the International Journal of Sanitary Engineering Research Vol. 8 No. 1/2014 25 A. Kukec, M. Dovjak Prevention and control of Sick Building Syndrome (SBS). Part 1: Identification of risk factors smoker. These chemicals include 2-naphthylamine, N-nitrosodimethyl-amine, 4-aminobiphenyl, and carbon monoxide [77]. The side-stream smoke may even be more irritant than the mainstream [9]. ETS presents one of the main causes for SBS symptoms [78]. The studies on examination of the relations between ETS exposure and SBS showed that SBS was statistically more pronounced in smokers than in non-smokers [22] and there was an excess of symptoms in non-smok- ers and ex-smokers exposed to ETS compared with the same non ex- posed categories [79]. Mizoue et al. [80] analysed the data from a 1998 cross-sectional survey of 1,281 municipal employees who worked in a variety of buildings in a Japanese city. Among non-smokers, the odds ratio for the association between SBS and 4 hours of ETS expo- sure per day was 2.7, and for most symptom categories, odds ratios in- creased with increasing hours of ETS exposure. Working overtime for 30 or more hours per month was also associated with SBS symptoms, but the crude odds ratio of 3.0 for SBS was reduced by 21 % after ad- justment for variables associated with overtime work and by 49 % after further adjustment for perceived work overload. Other indoor air pollutants ETS presents one of the main One of the most important indicators for indoor air quality and adequa- causes for SBS symptoms. cy of building ventilation is CO . The main indoor source of CO in most 2 2 buildings is human metabolic activity. In terms of worker safety, Occu- pational Safety and Health Administration (OSHA) has set a permissible exposure limit (PEL) for CO of 5,000 parts per million (ppm) over an 8 2 Working overtime for 30 hour work day. Similarly, the American Conference of Governmental In- dustrial Hygienists (ACGIH) TLV (threshold limit value) is 5,000 ppm or more hours per month for an 8-hour workday, with a ceiling exposure limit of 30,000 ppm for was also associated with a 10-minute period based on acute inhalation data [81]. According to SBS symptoms. national Rules on the ventilation and air-conditioning of buildings [82], the permissible value of CO in indoor air is 3000 mg/m3 (1667 ppm). 2 However, also lower levels than those recommended or regulated may lead to occupant dissatisfaction and decreased productivity [83]. For example, a concentration higher than 1000 ppm was associated with an increased percentage of dissatisfied occupants [9]. Seppänen et al. [28] reviewed 41 studies with over 60,000 subjects on the associations of ventilation rates and CO concentrations in non-resi- 2 dential and non-industrial buildings (primarily offices) with health out- comes. The risk of SBS symptoms continued to decrease significantly with decreasing CO concentrations below 800 ppm. Similar conclusion 2 was presented in the study by Erdmann et al. [84], Apte et al. [85] and Tsai et al. [86]. Erdmann et al. [84] found out that higher dCO (work- 2 day time-averaged indoor minus outdoor CO concentrations) was asso- 2 ciated with increased prevalence of certain mucous membrane and lower respiratory SBS syndrome symptoms. Even at peak dCO concen- 2 trations it was below 1,000 ppm. Apte et al. [85] evaluated relationship between indoor CO concentrations and SBS symptoms in occupants 2 from 41 U.S. office buildings. Results showed that dose response rela- tionship with odds ratios per 100 ppm dCO ranged from 1.2 to 1.5 for 2 26 © Inštitut za sanitarno inženirstvo, 2014 Prevention and control of Sick Building Syndrome (SBS). Part 1: Identification of risk facto rs A. Kukec, M. Dovjak sore throat, nose/sinus, tight chest, and wheezing. Tsai et al. [86] evaluated the SBS symptoms among 111 office workers in August and No- vember 2003. The most prevalent symptoms of the five SBS groups were eye irritation and nonspecific and upper respiratory symptoms. Tsai et al. [86] proved that workers exposed to indoor CO levels greater 2 than 800 ppm were likely to report more eye irritation or upper respira- tory symptoms. Biological risk factors for SBS Biological contaminants present in indoor air include bacteria, moulds, mildew, viruses, animal dander and cat saliva, house dust, mites, cock- roaches, and pollen [87]. There are many indoor or outdoor sources of these pollutants (i.e. people, animals, and soil and plant debris). Micro- bial pollution involves hundreds of species of bacteria and fungi that grow indoors when sufficient moisture is available. Exposure to micro- bial contaminants is associated with respiratory symptoms, allergies, asthma and immunological reactions [88]. Moulds The study by Straus [89] emphasised the importance of moulds and their mycotoxins in the phenomenon of SBS. Zhang et al. [90] studied the associations between dampness and indoor moulds in workplace buildings and selected biomarkers as well as incidence and remission of SBS. The study was based on a ten-year prospective study (1992– 2002) in a random sample of adults (N=429) from the Uppsala part of the European Community Respiratory Health Survey. Dampness was associated with increased incidence and decreased remission of SBS. Dampness and moulds increased bronchial responsiveness and eosi- nophilic inflammation. Similar study was performed by Sahlberg et al. [91] in 159 homes of the participants in three EU cities (Reykjavik, Uppsala, Tartu). The associations between SBS, MVOC, and reports on dampness and mould were examined. The results showed that the in- door levels of some MVOCs were positively associated with SBS. Levels of airborne moulds and bacteria and some MVOCs were higher in dwell- ings with a history of dampness and moulds. The problems with damp- ness exist also in other environments, such as dorm rooms and schools. Sun et al. [92] carried out a study in 1569 dorm rooms in Tianjin, Chi- na (2006–2007; N=3712 students). A “mouldy odour” or “dry air” was perceived by occupants in 31 % dorm rooms. The adjusted odds ratio (AOR) of perceived mouldy odour for general SBS symptoms was 2.4, for mucosal symptoms 2.2, and for skin symptoms 2.0. Local mouldy odour around room corners or under radiators was reported by inspectors in 26 % dorm rooms. The study concluded that local mouldy odour perceived by inspectors was a significant risk factor for nose irri- tation (AOR 2.8). Zhang et al. [93] analysed the relationship between the concentration of allergens and microbial compounds and new onset of SBS. The study was based on a two-year prospective analysis in pupils (N=1143) in a random sample of schools in China. The prevalence of mucosal and International Journal of Sanitary Engineering Research Vol. 8 No. 1/2014 27 A. Kukec, M. Dovjak Prevention and control of Sick Building Syndrome (SBS). Part 1: Identification of risk factors general symptoms was 33 % and 28 %, respectively, at baseline, and it increased during follow-up. At baseline, 27 % reported at least one symptom that improved when away from school (school-related symp- toms). The authors concluded that fungal exposure could increase the incidence of school-related symptoms. Bacteria Teeuw et al. [94] carried out a survey of SBS among 1355 employees working in 19 governmental office buildings in the Netherlands. Physi- cal, chemical, and microbiological characteristics between mechanically ventilated and naturally ventilated buildings were examined. Mechani- cally ventilated buildings were grouped as “healthy” or “sick” based on symptom prevalence (mean symptom prevalence < 15 % or > or = 15 %). The authors found no differences in physical characteristics. However, the concentration of airborne endotoxin and gram-negative rods were found in higher numbers in the “sick” mechanically ventilated buildings than in the “healthy” mechanically ventilated buildings and naturally ventilated buildings. The study concluded that airborne micro- bial contamination, in particular with gram-negative rods and perhaps with endotoxin, may have a role in the causation of SBS. Microbes volatile organic compounds Microbes volatile organic compounds (MVOCs) are products of the mi- crobes’ primary and secondary metabolism. They are associated with mould and bacterial growth and responsible for the odorous smells [95]. Araki et al. [19] measured indoor MVOC levels in single family homes and evaluated the relationship between exposure to them and SBS. The most frequently detected MVOC was 1-pentanol. Among 620 participants, 19.4 % reported one or more mucous symptoms; irritation of the eyes, nose, airway, or coughing every week (weekly symptoms), and 4.8 % reported that the symptoms were home-related. Weekly symptoms were not associated with any of MVOC, whereas significant associations between home-related mucous symptoms and 1-octen-3- ol and 2-pentanol were obtained. Additionally, Sahlberg et al. [91] ex- amined whether MVOCs, and airborne levels of bacteria, moulds, for- maldehyde, and two plasticizers in dwellings were associated with the prevalence of SBS, and studied associations between MVOCs and re- ports on dampness and mould. A total of 159 adults (57 % females) participated (19 % from Reykjavik, 40 % from Uppsala, and 41 % from Tartu). The results showed that MVOCs such as 1-octen-3-ol, formalde- hyde and the plasticizer Texanol, may be a risk factor for sick building syndrome. Moreover, concentrations of airborne moulds, bacteria and some other MVOCs were slightly higher in homes with reported damp- ness and mould. Some MVOCs may have adverse effects on respirato- ry, nervous and circulatory system and may have carcinogenic effects [96]. 28 © Inštitut za sanitarno inženirstvo, 2014 Prevention and control of Sick Building Syndrome (SBS). Part 1: Identification of risk facto rs A. Kukec, M. Dovjak House dust Dust in homes, offices, and other built environments contains various organic and inorganic matter [97]. Quantity and composition of house dust varies greatly with seasonal and environmental factors and also depends upon the HVAC system, cleaning habits, occupant activities, etc. Poor building service maintenance, poor cleaning or cleanability in- creased the prevalence of SBS [98]. Nexo et al. [99] demonstrated a correlation between the organic dust content of carpets (predominantly skin scales, bacteria and moulds) and the symptoms of SBS. Among 12 employees, 5 employees had symptoms related to the work place. Dust often contains substances that are emitted from constructional products (i.e. phthalate esters and other plasticisers emitted from PVC constructional products). Many emitted substances may have important health concerns. Kishi et al. [100] performed a study in which dust samples were collected from the living room of 182 single family dwell- ings in 6 cities in Japan. The prevalence of SBS, asthma, atopic dermati- tis, allergic rhinitis and conjunctivitis was 6.5 %, 4.7 %, 10.3 %, 7.6 % and 14.9 %, respectively. Significant associations between the medical treatment of asthma and floor bis(2-ethylhexyl) adipate (DEHA) and multi-surface di-n-butyl phthalate (DnBP), dermatitis and floor BBzP Dust often contains and DEHA, conjunctivitis and floor Bis(2-ethylhexyl) phthalate (DEHP) substances that are emitted were obtained after adjustment. from constructional products Office buildings normally present very low concentrations of mites, be- (i.e. phthalate esters and cause they do not provide appropriate conditions for the growth of such other plasticisers emitted microorganisms. Mites are, however, relatively abundant in household from PVC constructional dust. Mites can be destroyed keeping absolute humidity below 7 g/kg products). Many emitted of air (about 45 %) during the winter time [ECA, 1989]. Airborne house substances may have dust frequently causes allergic symptoms. However, house dust may also be problematic for healthy subjects without hypersensitivity reac- important health concerns. tions, as it was presented by Mo⁄lhave et al. [101]. This Danish Office Dust Experiment [101] investigated the response of 24 healthy non- sensitive adult subjects to exposure to normal office dust in the air. The responses were both subjective sensory reactions and other neurogenic effects even at exposure levels within the range found in normal build- ings. Some of the effects appeared acutely and decreased through ad- aptation while others increased during prolonged exposure and re- mained for more than 17 h after the exposure ended. The threshold level for the dose–response relationships was below 140 μg/m3. Psychosocial, personal and other risk factors Psychosocial, personal and other risk factors for SBS are gender, indi- vidual characteristics, health condition, stress, feelings of loneliness and helplessness, working position, social status, others. Gender, working position, health characteristics A screening questionnaire study of 4943 office workers and a case-ref- erent study of SBS in 464 subjects were completed by Stenberg et al. [102]. Females reported SBS more often than males [102]. The same International Journal of Sanitary Engineering Research Vol. 8 No. 1/2014 29 A. Kukec, M. Dovjak Prevention and control of Sick Building Syndrome (SBS). Part 1: Identification of risk factors conclusions were found in the studies by Sun et al. [92] in dorm environment in Tianjin, China (2006–2007) and Engvall et al. [103] in mul- ti-family buildings in Stockholm. Additionally, the importance of gender to the prevalence of the SBS symptoms was investigated on 590 em- ployees of three office buildings in Norway [104]. The results showed that greater percentage of females than males reported having SBS symptoms. Women are often employed under less favourable working conditions than men, as it was confirmed in the study by Bullinger et al. [105]. Questionnaire results from 2517 female employees in Germany (as compared to 2079 male employees) showed that women report higher scores in sensory irritation, higher bodily complaint rate and more nega- tive evaluation of the indoor climate. In addition, most psychosocial variables showed less favourable scores for women as compared to men. The relative influence of gender, atopy, smoking habits and age on re- ported SBS symptoms among office workers was investigated through questionnaire studies among 1293 employees in 10 nonindustrial build- ings [104]. The occurrence of atopy among the office workers was not found to be different from that of the general population. The preva- lence of symptoms was higher among atopic individuals than among nonatopics, and higher among females than among males. While gen- Women are often employed der was found to be important for some symptoms, atopy was impor- under less favourable working tant for all of them. The results indicated interrelations between smok- conditions than men, as it ing and atopy, with enhanced prevalence of some symptoms. Age of the was confirmed in the study persons was also included in the present analyses. Different ways of by Bullinger et al. grouping age indicated different trends in associations between age and the prevalence of symptoms, but the study did not show any unambigu- ous associations between the age and the prevalence of symptoms. The same conclusion was made in the literature review by Norbäck [106]. Norbäck [106] showed that there was no consistent association be- tween age and SBS. Symptoms are generally more common and more problematical in the stressed, the unloved, and in individuals who feel powerless to change their situation. There is a strong association between lack of control of the office environment and symptoms [11]. There is an association be- tween lower social status and SBS symptoms [11]. Norlen and Anders- son [107] showed that residents in single-family houses reported less SBS than those in multifamily houses, although measurements suggest a less favourable indoor environment in single-family houses. Stress Occupational stress has been shown to have a detrimental effect on the health and wellbeing of employees, as well as a negative impact on workplace productivity and profits [108]. Some researchers [109, 110] have investigated the possible links between SBS symptoms and occu- pational stress. Occupational stress has been found to be correlated with symptoms of the SBS, but much of the research has been of a 30 © Inštitut za sanitarno inženirstvo, 2014 Prevention and control of Sick Building Syndrome (SBS). Part 1: Identification of risk facto rs A. Kukec, M. Dovjak cross-sectional nature, and it does not indicate whether stress is an active element or an outcome [111]. However, Ooi and Goh [112] exam- ined the role of work-related psychosocial stress among 2160 subjects in 67 offices in the aetiology of SBS. Ooi and Goh [112] found an incre- mental trend in the prevalence of SBS among office workers who re- ported high levels of physical and mental stress, and decreasing climate of co-operation. Lu et al. [113] investigated whether SBS complaints and indoor air pol- lution for 389 office workers in 87 government offices of 8 high-rise buildings in Taipei city are associated with oxidative stress. Oxidative stress was indicated by urinary 8-hydroxydeoxyguanosine (8-OHdG). The results showed that urinary 8-OHdG had significant associations with VOC and CO2 in offices, and with urinary cotinine levels. The mean urinary 8-OHdG level was also significantly higher in participants with SBS symptoms than in those without such complaints. The mean 8-OHdG increased as the number of SBS symptoms increased. This study indicated that the 8-OHdG level was significantly associated with SBS complaints after controlling for air pollution and smoking. Other factors Wang et al. [76] performed a study in domestic environments in Chong- Occupational stress has been qing, China and confirmed that living near a main road or highway, re- shown to have a detrimental decoration, and new furniture were risk factors for perceptions of odours effect on the health and and sensations of humid air and dry air. The presence of cockroaches, wellbeing of employees, as rats, and mosquitoes/flies, use of mosquito-repellent incense and other well as a negative impact on incenses were all risk factors. The analyses of 609 multi-family build- workplace productivity and ings with 14,235 dwellings in Stockholm [103] showed that subjects owning building reported less SBS, but the relationship between owner- profits. ship and building age was strong. According to the model, 5 % of all buildings built before 1961, 13 % of those built in the period 1976– 1984, and 15 % of those built in the period 1985–1990 would have significantly more SBS than expected. Another issue that has to be in- vestigated in relation to SBS are geopatogenic zones. DISCUSION Based on our comprehensive literature review the risk factors for SBS were classified into six main groups: physical, chemical, biological, psy- chosocial, personal an others. Studies where risk factors for SBS are systematically identified are for the moment scarce. Moreover, there are no appropriate methods for the identification of all risk factors for SBS. However, identification of risk factors for SBS and their relevant param- eters present an important step towards effective prevention and con- trol of SBS symptoms. The most important findings of the literature review show that many studies have examined the correlation between SBS symptoms and physical risk factors as well as the correlation between SBS symptoms and chemical risk factors, while the studies on the correlation between International Journal of Sanitary Engineering Research Vol. 8 No. 1/2014 31 A. Kukec, M. Dovjak Prevention and control of Sick Building Syndrome (SBS). Part 1: Identification of risk factors SBS symptoms and biological, psychological, personal and other risk factors are for the moment scarce. From the chronological point of view, the first studies appeared in the 1970s, where physical risk factors were pri- marily examined. The main reasons might be related to the introduction of thermal insulated building envelopes, synthetic materials and the ap- plication of mechanical systems. Solutions for lowering the energy use were party defined on the level of thermally improved materials and me- chanical systems. In the 1980s, beside physical risk factors a number of studies examined the biological risk factors. In the 1990s the researchers realized that the SBS was influenced also by psychosocial, personal and other risk factors. Nevertheless, psychosocial, personal and other risk factors still present neglected research areas. Among physical risk factors, a number of studies examine the correla- tions between T , RH and ventilation parameters. Additionally, other ai in parameters of physical risk factors were examined (i.e. noise, DL, EM and ions) in our study; they were studied in a small number of studies. Studies on chemical risk factors are mainly focused on the links be- tween SBS symptoms exposure to different emission sources, such as construction product, furniture and household products. They revealed the possible adverse health effects of constructional products on build- ing occupants, during normal use of the building or during emergency situations (i.e. a case of fire). Despite those issues, many of construc- Composition of construction tion and household products on the market may present potential and household products in health concerns. Composition of construction and household products relation to the content of in relation to the content of harmful substances is often questionable, harmful substances is often legislation and inspection are incomplete. questionable, legislation and Studies in the field of biological risk factors examine the association be- inspection are incomplete. tween the presence of many biological agents in the indoor environment in relation to dampness related problems (mould spots, damp stains, water damage and condensation) as well as inadequate ventilation. Studies on the exposure to other biological risk factors and SBS occur- rence are for the moment scarce, mainly due to the fact that beside SBS also BRI presents a common result of exposure to biological agents (i.e. asperigillosis) [8, 114]. The most important step in planning the strategies for prevention and control of SBS is risk assessment. Identification and classification of risk factors for SBS presents a crucial part of risk assessment. Qualita- tive and/or quantitative determination of the parameters of risk factors is defined in international and national legislation, standards, guidelines and recommendations. Legal requirements for physical risk factors, i.e. the parameters for thermal comfort, ventilation and air-conditioning of buildings (i.e. T , RH , mean radiant temperature, etc.), are hierarchi- ai in cally defined in international and national legal acts [115-117, 82], standards and recommendations [118-121]. The protection against noise and vibrations in buildings is also well defined [115, 122-125]. However, legal requirements are mainly related to the working environ- ment, while the living environment is often neglected. The qualitative and quantitative characteristics of DL (especially parameters important for non-visual biological effects of daylight on wellbeing), ions and EM 32 © Inštitut za sanitarno inženirstvo, 2014 Prevention and control of Sick Building Syndrome (SBS). Part 1: Identification of risk facto rs A. Kukec, M. Dovjak fields in built environment are partly defined or even not defined, nor The most important step in supervised. planning the strategies for prevention and control of The protection of workers from risks related to exposure to biological SBS is risk assessment. and chemical agents at work is well regulated [82, 119, 120, 126-129]. However, the requirements for biological and chemical risk factors are mainly defined for working environments [126-129]. For other environ- ments, the requirements for chemical risk factors are defined only for the indoor air quality, where limit values for key indoor air pollutant are required [82, 119, 120]. There even exist EU legislative documents for health and environment safety of constructional products [115], while the composition and emission rates of harmful substances from con- structional and household products are not monitored and supervised. Methods of identification are defined just for some parameters of risk factors. Ignored or disregarded legal requirements at the stage of build- ing design, construction, usage and maintenance as well as lack of leg- islation present problematic fields that have to be confronted in the fu- ture. Consequently, this may be one of the main cause for SBS [5]. At the moment, there are no standardized methods for the sampling and identification of risk factors for SBS in working and living environment. At the stage of preparation of standardized methods, the interdiscipli- nary cooperation of all subjects that are involved in the stage of design, construction, usage, maintenance and control of building is necessary. CONCLUSIONS Identification of risk factors for SBS and their relevant parameters presents an important step towards effective prevention and control of SBS symptoms. Based on the comprehensive literature review the risk factors for SBS were classified into the six main groups: physical, chemi- cal, biological, psychosocial, personal an others. The physical, chemical and biological risk factors in relation to SBS are well researched topics. However, psychosocial, personal and other risk factors are poorly investi- gated. For integral prevention and control of risk factors of SBS, addition- al research is needed. Future research should be focused on defining standardized methods for identifying risk factors with sampling proce- dures and analysis. This should be based on interdisciplinary cooperation of various experts. The occurrence of SBS symptoms may be a result of interactive influences among risk factors and their parameters. 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