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Projects
A comparative study of volatile organic compounds (VOC) in homes in Sweden and Japan
A statistical model for the classification of multi-family resedential buildings with a higher prevalence of Sick Build Syndrome (SBS) than expected
Asthma, allergies and sick building syndrome in the school environment – a follow-up study after 10 years
Day care centres, building dampness and antioxidants
Health evaluation of different ventilation systems in schools
Healthy Sustainable Houses
HESE - Health Effects of the School Environment
Home environment, comfort and health – occupant reactions in a multi-family residential building with demand controlled ventilation
Incidence of asthma in relation to damp and mould in homes (ECRHS II)
Personality, stress and the Sick Building Syndrome
Signs of stress in children in relation to noise in school
The home environment in Shanghai
The school environment in Asia
The school environment in Knivsta, Uppsala County, Sweden
Validation of Stockholm’s Indoor Environment Questionnaire (SIEQ)
Ventilation to reduce allergen exposure in classrooms
A comparative study of volatile organic compounds (VOC) in homes in Sweden and Japan
Contact: Dan Norbäck
The home is the indoor environment where we spend two thirds of our life. Airborne chemical pollutants in homes can originate from various sources e.g. building materials, interior decorations and fittings, cleaning materials, and other household chemical products. Traffic exhausts and other airborne air pollutants such as nitrogen dioxide from the outdoor environment are additional sources of pollutants in the home. Exposure can vary between homes since building materials and chemical products are produced in different ways in different countries. There are few comparative studies between different countries concerning the chemical substances that are present in domestic air. This project entailed measuring different VOC, formaldehyde and nitrogen dioxide in 37 homes in Nagoya, Japan, and 27 homes in Uppsala, during the building heating season. The level of formaldehyde, nitrogen dioxide and chlorinated VOC were higher in both indoor and outdoor air in Nagoya. The level of formaldehyde in indoor air was on average 17.6 mg/m3 in Nagoya and 8.3 mg/m3 in Uppsala. The indoor level of nitrogen dioxide was 98.5 mg/m3 in Nagoya and 6.7 mg/m3 in Uppsala. The level of nitrogen dioxide outside the homes was on average 57.6 mg/m3 in Nagoya and 6.8 mg/m3 in Uppsala. WHO´s guidelines are 100 mg/m3 for formaldehyde (30-minute maximum level) and 40 mg/m3 for nitrogen dioxide (yearly average). The level of chlorinated VOC (1,1,1,-trichlorethane, carbon tetrachloride, trichlorethylene, tetrachlorethylene, and para-dichlorobenzene) were 3-40 times higher in Japan. In Nagoya, modern concrete buildings had in general higher levels of both formaldehyde and nitrogen dioxide in comparison with older wooden houses built in the traditional manner. Japanese homes with gas-fire heating without separate ventilation had higher levels of nitrogen dioxide (113.2 mg/m3) in comparison with homes with “clean” heating (70.5 mg/ m3). In addition, the level of paradichlorobenzene in the air was much higher in Japanese homes where mothballs containing this chemical were used. In Uppsala, there was no clear correlation between building factors and the level of pollutants in the homes. One article has been published and another concerning non-chlorinated VOC is planned.
Publications
Sakai K, Norbäck D, Mi Y-H, Shibata E, Kamijima M, Yamada T, Takeuchi Y. A comparison of indoor air pollutants in Japan and Sweden: Formaldehyde, nitrogen dioxide and chlorinated volatile organic compounds. Environmental Research 2004;94:75-85.
A statistical model for the identification of multi-family residential buildings with a higher prevalence of Sick Building Syndrome (SBS) than expected
Contact: Karin Engvall
The purpose of the project was to use stepwise multiple regression analysis to develop a model for the identification of multi-family residential buildings where occupants altogether had a higher prevalence of the Sick Building Syndrome (SBS) than expected. The analyses were carried out using a large dataset collected in 1991-93 with answers from occupants in 9808 apartments in 609 multi-family residential buildings from different building periods in Stockholm. Ten models were run on the dataset, one model for each of five symptoms (irritated eyes, nose, throat, and also cough and facial eczema), firstly for the problem itself and then if the occupant related the problem to the home environment. The factors that had largest explanatory value for general problems were the presence of allergy (OR 4.6 – 6.8), sex (OR 1.1 – 2.3), age (OR 0.4 – 1.6) and also living in rented public owned housing (OR 1.2-1.7).
The model was then applied to the dataset and probabilities could be calculated for respondents that fulfilled the different explanatory factors. A predicted prevalence of health problems could be calculated for the single building and be compared to the actual prevalence.If the difference between the expected and actual prevalence was significant then the house was classified as either a problem-house with too many symptomatic occupants, or a non-problematic house with a normal or lower level of problems. When applied on all buildings in the study it was found that younger houses, built 1985-1990, had a higher prevalence of occupants with symptoms, 15 %, compared to 10 % in the older houses, built 1961-1975. The conclusion was that classification of multi-home buildings with respect to health aspects requires that one controls for personal factors such as gender, age and allergy, and also the ownership/rent status of the property. The analyses and the model will be examined and validated within the project “ Healthy Sustainable Houses”.
The project was carried out as part of Karin Engvall’s doctorate thesis and the validation study will be in progress as a collaboration project between the Institution for Medical Science/Occupational and Environmental Medicine at Uppsala University, Dept of Public Health Sciences, Karolinska Institutet, Stockholm, Monitoring Detp. Environ. and Health and Adm, City of Stockholm and the company White Architects.
Publications
K Engvall et al. ” Development of Multiple Regression Model to Identify Multi-Family Residential buildings with a High Prevalence of Sick Building Syndrome (SBS)”
Indoor Air 2000; 10:101-110
Asthma, allergies and the Sick Building Syndrome in the school environment – a follow-up study after 10 years
Contact: Greta Smedje
The Department for Occupational and Environmental Health has carried out studies on asthma and sick building syndrome in relation to the school environment for a number of years. An epidemiological study of 39 schools selected at random in Uppsala county was started in 1993. The investigation indicated defects in the school environments, especially regarding ventilation rates and the presence of dust and allergens from furry animals. A relationship between these environmental factors and asthmatic problems in pupils was shown (Smedje, 2000).
The current project involves a follow-up 10 years after the original study. The purposes of the project are:
- to investigate the development of asthma, allergy and Sick Building Syndrome in pupils, adolescents and school personnel during the period from 1993-94 and 10 years forward.
- to explore environmental factors in randomly-chosen schools and compare with the conditions in the same schools 10 years earlier,
- to study the relationships between health and the school environment, as well as the effect of preventive measures on health
One can determine if the incidence of asthma and allergy has increased by investigating the same schools at 10-year intervals. The investigation of school environments gives information on, for example, the effect of the new provisions for building ventilation that came into force in 1994. During this period, poor economy of the local governments has been in focus and it has been suggested that school classes have become larger and that there have been cut-backs in cleaning. The level in schools of allergens from furred animals has been pointed out as a problem, but it is unclear whether this has lead to a reduction in the exposure to such allergens in the school environment.
Of the 39 schools that participated in the earlier investigation, 35 still operated as schools in 2003. All these schools participated in the follow-up study. A questionnaire with questions about the prevalence of health problems, as well as questions about the home environment was completed during 2003 by approximately 1200 school personnel and 2400 pupils (in the same age-group as 10 years earlier, that is to say pupils in the year-classes 1,4 and 7). The questionnaire was essentially the same as that used previously, complemented with questions used in the so-called ISAAC-study.
One hundred and twenty classrooms were inspected during 2003 and 2004 according to the same checklist used 10 years earlier. The concentration of formaldehyde and other volatile substances, nitrogen dioxide and ozone were measured in the air, together with levels of airborne particles, PM10, and ultrafine particles (< 0.1 µm). Dog, cat and horse allergens were analysed in settled dust that was collected with a vacuum cleaner, as well as in dust that had settled in Petri dishes after 1 week. The classrooms’ air exchange was measured, together with levels of carbon dioxide, room temperature and relative humidity.
Compilation and analysis of the results is in progress.
Reference:
Smedje G. The indoor environment in schools – respiratory effects and air quality. University of Uppsala 2000. Thesis.
Day care centres, building dampness and antioxidants
Contact: Gunilla Wieslander
Employees at two day care centres, one with and one without dampness problems, received dietary supplements in the form of buckwheat biscuits with and without the antioxidant rutin (a blinded dietary study).
We have carried out a study with the aim of increasing knowledge on how our health is affected by diet and damp-damaged indoor environments. Buckwheat is a crop, the kernel of which is used to produce gluten-free flour, which is used in Russian blini, buckwheat porridge, noodles and biscuits. It is consumed by approximately 200 million people in the world, including those who are oversensitive to gluten i.e. suffering from celiac disease. A number of healthy effects have been demonstrated for buckwheat, such as reduction in blood fats and reduced swelling of the legs. Pharmaceutical preparations have been made from buckwheat. There have, however, been no investigations into possible protective effects on eyes and respiratory mucous membranes of buckwheat strains with high levels of antioxidants. This study was carried out for five weeks on personnel in day care centres in the spring of 2005. Three clinical investigations on eyes and respiratory tracts were carried out before consumption of the dietary supplements (placebo biscuits and antioxidant rich biscuits), after two-weeks consumption, and finally after four weeks of consumption. A preliminary analysis of the results suggests that symptoms of tiredness, nasal blockage and headache were less frequent after eating biscuits. Those who received most antioxidants were less tired and showed somewhat of an improvement in inflammatory markers in nasal lavage fluid. More analysis will be performed. Some reduction of inflammatory markers (ECP, and MPO) in serum blood at the end of high consumption of antioxidants was also found.
Publications
Wieslander G, Fabjan N, Kreft I, Janson C, Spetz-Nyström U, Vomberger B, Tagesson C, Leandersson P., Norbäck D. An experimental study on health effects of consumption of an new type of tartary buckwheat biscuits with high levels of the antioxidant rutin. Proceedings from the Int Symposium on buckwheat and dietary culture. 8-12 August, 2005, Xichan, China.
Health evaluation of different ventilation systems in schools
Contact: Dan Norbäck
It is important to have adequate ventilation in schools and other teaching locales due to the high person density. There is also a need to reduce heating costs. These demands can be conflicting. We therefore need to evaluate different technical solutions for ventilation in schools and teaching locales with respect to health in order to determine systems that can offer both low heating costs and good health.
Are dirty ventilation filters a health problem?
Whilst there are clearly advantages to using mechanical ventilation in the school environment there are also disadvantages. Such systems need regular service: ventilation ducts must be cleaned and air-filters changed. There are sometimes health problems and complaints despite satisfactory air-flow. One hypothesis is that this could be caused by contamination of air due to the accumulation of mould, bacteria and other airborne contaminants in intake filters. We therefore carried out a double-blind experiment to study this problem. The experiment was performed in a school building in Uppsala with two ventilation units, which each supplied air to one half of the building. A new air-filter was installed in one unit whilst the other retained the 10-month-old air-filter. After two months the old filter was moved to the other unit, and a new filter was installed. Pupils filled in questionnaires during the two periods. The eyes and nasal mucous membranes of the pupils were investigated using objective clinical methods. The results showed that pupils had problems with eyes and throat twice as often when exposed to the old air-filters; the prevalence of nasal blockage also was higher according to the objective tests. The amount of mould and bacteria increased in the filter with time, especially during the autumn. The conclusion is that ventilation filters should be changed not only after the pollen season but also after the mould-rich damp autumn.
How is the school environment affected by filter-free ventilation systems?
Certain ventilation companies have developed filter-free ventilation systems in order to avoid problems with contaminants in intake filters. The disadvantage with these systems is of course that the occupants are not protected against particulate contaminants in the outdoor air. We performed an experiment in a school with a classroom with a filter-free ventilation system with displacement supply air. Another classroom was equipped with mixing supply air and exhaust ventilation including intake filters. The pupils in both classrooms were given medical examinations and then exchanged classrooms. Pupils in the classroom with filter-free ventilation said the air was fresher and they suffered less from tiredness and headaches, than the pupils in the other classroom. This could be at least partly explained by a temperature effect since the inlet air was cooler in the filter-free system. There was no significant difference between the two systems with respect to irritation of eyes or nasal mucous membranes, as measured with objective medical tests. The filter-free intake air contained somewhat higher levels of mould and bacteria, and even higher levels of ozone, as compared with intake air that had passed through a filter. On the other hand, the filter-free intake air contained lower levels of other chemical substances such as butanols. There was no difference in levels of mould and bacteria between the two classrooms. This is due to the fact that the children themselves, together with their activity, are the dominant source of particle contamination and the contribution from the intake air is not so significant.
Another investigation was performed in computer rooms at the University of Lund. This involved measuring the effect of energy-saving ventilation, which was controlled by carbon dioxide levels, on indoor environment and health. This investigation has not yet been reported.
Reports and proceedings:
Janson A, Pekonen T, Waher J. Airborne particle concentration in two classrooms with mixing and displacement ventilation. Proceeding from Indoor Air 2005, Beijing, China, Vol. 1, pp. 847-851.
Smedje G, Norbäck D, Wieslander G, Wålinder R. Effects of contaminated supply air filters on symptoms from the eyes and nose- a double-blind experimental study. Proceedings from 9th International Conference on Indoor Air quality and Climate, Indoor Air 2002,Santa Cruz, California, Vol 2, pp.1032-1037.
HESE - Health Effects of the School Environment
Contact: Dan Norbäck
This first study of European school environments was carried out during 2004-2005. The EU-financed project was performed in Sweden, Norway, Denmark, Italy and France, and included measurements of exposures in the school environment related to asthma, allergies and effects on eyes and the respiratory tract in primary school children. Forty-six classrooms were studied in 21 schools. The schools in Sweden and Norway generally fulfilled the ventilation norms since the majority had effective mechanical ventilation. The schools in the remaining countries did not meet the ventilation norm (<1000 ppm carbon dioxide) at all since they did not have mechanical ventilation systems. Allergens from furry animals were detected in all school rooms, both in south and north Europe. Classrooms in Sweden and Norway had the lowest airborne levels of cat and dog allergens, and lower levels of particulates, mould and bacteria. The levels of airborne allergens in France and Italy was 2-5 times higher than that in Sweden. Horse allergen in dust was, however, a phenomenon specific to Sweden: we have an unusually high number of riders in Sweden. The results show that an effective mechanical ventilation system is a prerequisite for a good indoor environment in schools. Extensive investment in ventilation in Scandinavia during the 90’s has improved the indoor environment in schools, but a corresponding investment in other parts of Europe still appears unlikely. The frequency of wheezing in pupils was high in those classrooms with higher levels of particles (PM10>50 mg/m3). Pupils in classrooms with higher levels of carbon dioxide ( >1000 ppm) had a higher frequency of dry cough at night, and ‘wheeze’.
The project was been reported to DG Sanco in the EU during 2006. The project leader was Dr Piersante Sestinin, Siena, Italy. Dan Norbäck was responsible for environmental monitoring and was also the local project leader in Uppsala.
Publications
Norbäck D, Sestini P, Elfman L, Wieslander L, Sigsgaard T, Canciani M, Ciarliegio G, Annesi-Maesano I, Nystad W, Viegi G, on behalf of the HESE group Health effects of the school environment (HESE): Indoor environment in primary schools in Italy, France, Denmark Norway and Sweden. Proceedings from the Healthy Buildings 2006, June 4-8, 2006, Lisbon.
Simoni M, Annesi-Maesano I, Sigsgaard T, Norbäck D, Wieslander G, Nystad W, Canciani M, Vieg G, Sestini P. Relationships between school indoor environment and respiratory/allergical health in children of five European Countries (HESE Study). Proceeding from the 16th Annual Congress of the European Respiratory Society , 2-6 September, 2006, Munich.
Home environment, comfort and health – occupant reactions in a multi-family residential buildings with demand-controlled ventilation
Contact: Karin Engvall
The purpose of the project was to determine if a new principle of ventilation is sustainable with respect to health, good comfort for the inhabitants, and also if it is user-friendly and robust. New energy-saving measures are being tested as a response to increased energy consumption for heating multi-home dwellings and also the EU directive (2002/91/EC), which concerns declaration of energy consumption in buildings. Demand-controlled exhaust air ventilation, which involves reducing airflow when no-one is at home, is being tested in a new multi-family residential building in Stockholm. Technical function controllers will evaluate the system after it has been in operation for at least one year. Additional technical measurements relevant for the occupant and his/her health will be made in order to relate comfort and health to the indoor environment. Furthermore, a questionnaire is being given to the occupants, and also those of a reference building in the same quarter. The reference building is fitted with a traditional exhaust air system. Through the integrated programme for measuring the performance of the ventilation system in relation to the building design and from the occupant’s point of view, interdisciplinary discussions are enabled within one and the same evaluated object.
This is a collaboration project between the Institution for Medical Science/Occupational and Environmental Medicine at Uppsala University, the building company JM, the consultant WSP, and The Swedish Energy Agency.
Incidence of asthma in relation to damp and mould in homes (ECRHS II)
Contact: Dan Norbäck
There are few longitudinal studies concerning the relationship between the incidence of asthma and the presence of damp-related damage or mould in homes. In the European Community Respiratory Health Survey 8740 young adults in 25 centres in Europe and 2 in USA and Australia have participated. The cohort has been followed from 1991-93 until 1998-2002, with an average follow-up time of 8.9 years. The follow-up involved visits by building inspectors, including dust-sampling, to 4576 homes (approximately 200/centre), generally involving homes occupied by the same person during the whole study period. A group of 1605 people already had asthma or asthma symptoms from the beginning and they were therefore excluded from the analysis. Tests were also carried out for allergy to common allergens, a metacholine test to measure bronchial hyperreactivity (BHR), and dynamic spirometry to measure lung function.
Water damage, damp patches and visible mould were common indoors. Forty-three percent reported that they lived in a home with water damage, and 44.3 % reported that they lived in a home with visible mould growth indoors, at some time during the study period. Damp and mould in homes was the least common in the Nordic countries and nearly ten times more common in Great Britain, USA (Portland), and Australia (Melbourne). The relative risk (RR) was calculated using multiple binomial regression. Incidence of asthma was more common in homes with water leaks (RR=1.29; 95% CI 1.00-1.66), damp patches (RR=1.36; 95% CI 1.00-1.70) and visible mould (RR=1.36;95% CI 1.08-1,70). Incidence of asthma with verified BHR was more common in homes with mould in living rooms (RR=2.28; 95% CI 1.17-4.45). When the data was stratified it could be seen that the correlation was strongest among those who had verified mould allergy against Cladosporium or Alternaria. There was also a correlation between damp damage and mould growth in homes, and incidence of asthma. Occupants in homes with damp and mould in any room (bedroom, living room, bathroom) had more frequently newly-diagnosed asthma (RR=1.50; 95% CI 1.01-2.23). In addition, there was a correlation between damp and mould in bedrooms and ‘wheeze’, as well as asthma in combination with BHR (RR=2.84; 95% CI 1.00-8.06). The conclusion from the study is that damp and mould in homes may be an important environmental factor for the incidence of asthma.
The project leader for the whole of ECRHS I and II was Peter Burney at the National Heart and Lung Institute, London. Dan Norbäck has been involved in the indoor environment group within ECRHII.
Publications:
Norbäck D, Zock J-P, Heinrich J, Svanes C, Sunyer J, Kunzli N, Villani S, Oliveri M, Soon A, Plana E, Jarvis D on behalf of the ECRHSII group. Onset of asthma in relation to indoor moulds and building dampness: The longitudinal European Community Respiratory Health Survey ECRHS-II. Proceedings from Healthy Buildings 2006, 4-8 June 2006, Lisbon.
Norbäck D, Zock J-P, Heinrich J, Svanes C, Sunyer J, Kunzli N, Villani S, Oliveri M, Soon A, Plana E, Jarvis D. Onset of asthma in relation to indoor moulds and building dampness: A nine year follow up study within ECRHS-II. Proceedings from the at 16th Annual Congress of the European Respiratory Society, 2-6 September, 2006, Munich.
Personality, stress and the Sick Building Syndrome (SBS)
Contact: Roma Runeson
The term “Sick Building” has sometimes been used to describe buildings where poor air quality can lead to medical symptoms such as irritation of the eye, nose or throat, facial skin problems, and also tiredness and headache. Since the symptoms are unspecific and the etiology is unclear, there is clearly a need to study to what extent these symptoms are caused by factors other than deficiencies in the indoor environment, in relation to individual sensitivities, vulnerability and stress at work or in social relationships.
The judgement of personality based on personality scales and personality tests is undergoing intensive development. An analysis of the literature on SBS indicated that few studies have considered the importance of vulnerability and stress in the individual, neither when concerning the reporting of symptoms in connection with problems with indoor environment nor the symptoms coupled to the indoor environment (symptoms concerning the eye, nose and throat, skin symptoms, headache and tiredness).
People who regard themselves as sick with diffuse symptoms turn to psychiatric care or medical care, with similar symptoms. It is therefore important to cover both physical and mental explanations to symptoms to ensure effective preventative and curative measures.
We have carried out a project in which we studied the relationship between on the one hand symptoms of the eye, nose, throat, and skin, together with headaches and tiredness, and, on the other, personality and work-related stress, as measured using a selection of well-established methods.
The verbal personality scales included Sense of Coherence (SOC), which was developed by Antonovsky, and Karolinska Scale of Personality (KSP). Stress in working life was measured with the demand-control-support model developed by Karasek and Thorell. Stress was also studied using a non-verbal test based on projective drawing, The Drawing Personality Profile (DPP).
The research was performed with epidemiological methodology, including cross-sectional studies and longitudinal incident studies. Two follow-up studies have been performed. The study population consisted of both employees in buildings with problematic indoor environments (a 9-year follow-up study) and random selections from the general public (a 10-year follow-up study).
Publications
Runeson R, Norbäck D, af Klinteberg B , Edling C. The influence of personality, measured by the Karolinska Scales of Personality (KSP), on symptoms among subjects in suspected sick-buildings. Indoor Air, 2004;14: 394-404.
Runeson R, Norbäck D, Stattin H. Symptoms and sense of coherence (SOC)- A follow-up study of personnel from workplace buildings with indoor air problems. Int Arch Occup Environ Health, 2003;76:29-30
Runeson R, Norbäck D. Associations between “Sick building syndrome”, psychological factors and personality traits. Perceptual and Motor skills, 2005;100:747-759).
Roma Runeson, Kurt Wahlstedt, Gunilla Wieslander, Dan Norbäck (2006) Personal and psychosocial factors and symptoms compatible with sick building syndrome (SBS) in the Swedish workforce. Indoor Air 2006; 16: 445-53.
Signs of stress in children in relation to noise at school
Contact: Robert Wålinder
Questionnaires have shown that there is an increase in reports of stress-related symptoms by Swedish children. The background is of course multi-factorial. The educational environment has been highlighted in the ongoing work concerning public health policy objectives. Physical, psychological and social defects in the school environment may cause stress-symptoms in children.
Previous research has demonstrated that noise in schools has a negative effect on learning. Exposure of children, as in adults, to loud noise has been linked to stress reactions such as increased blood pressure, increased excretion of catecholamines, irritation and reduced psychological well-being.
Research has to some extent supported the view that the acute stress-reaction leading to energy mobilisation during stressful situations (fight/flight), if repeated often and without sufficient possibility of recovery, can lead to a number of undesirable effects. These include defects in cellular repair, reduced immune defence, effects on the central nervous system, disturbances in hormonal control, and even changes in the expression of certain genes. Repeated mobilisation of energy reserves can even result in an inability to answer to external demands, which can in extreme cases lead to burn-out/exhaustion.
Various stress mechanisms in children can be investigated using a series of tests. The physiological effects that can be studied are blood pressure and pulse, together with the overall effect, “Rate Pressure Product”, which is the product of systolic blood pressure and pulse. The biochemical markers that can be related to stress are cortisol, adrenalin, noradrenalin, testosterone, prolactin, lyzozyme, and HbA1c. Methods for saliva analysis of cortisol and lyzozyme are developed and validated.
The effect of stress on children has previously been studied whereby emotional indicators in children’s drawings has been employed as a measure of stress. Other methods for studying stress consist of age-related questionnaires.
The primary goal of the study is to map out stress reactions to noise in children in the school environment through a battery of well-known biological stress-markers together with a selection of psychological tests of children’s psychosocial experiences. A secondary goal is to determine if the known stress-markers for adults are applicable to children, and also if there is a useable psychological stress test for children.
Results are presented in a first manuscript that has been submitted for publication.
Healthy Sustainable Houses
Contact: Karin Engvall
The projects primary goal is to reduce health-risks in indoor environments. In Sweden, the building sector now has an undertaking and directive to begin to declare the buildings indoor environment and energy consumption. It is important that the building’s environment is perceived as comfortable and healthy. Several large surveys in the 90’s, based on questionnaires, indicated that the risk of Sick Building Syndrome (SBS) was higher in younger buildings. One of these surveys was ‘House and Health’ in Stockholm’s multi-family residential buildings during 1991-93, which included 12 667 occupants in 609 buildings. The City of Stockholm implemented their environmental programme 2002-2006 in 2003, which describes the city’s goals and a large number of indicators which could be measured and followed-up. Several of these indicators concerned healthy buildings.
One objective of the project was to carry out a questionnaire-based survey of the same size as that performed in 1991-93. The results will be used to develop methods to describe the status and also change. This should provide references that can be used by those responsible for building, the owners of buildings, local government, and to steer towards goals for indoor environment and health.
This is a collaboration project between the Institution for Medical Science/Occupational and Environmental Medicine (research), the Environmental Department of Stockholm city (implementation), together with the Department of Occupational and Environmental Medicine at Karolinska Institutet, and the company White architects.
The home environment in Shanghai
Contact: Dan Norbäck
We have carried out several studies of the indoor environment in China and Korea during the 00’s, as part of a research collaboration with researchers in Asia. In one study, we investigated the presence of allergens, microbial components in dust, together with chemical pollutants in homes in Shanghai, a large city (population of 16 million) in the most well-developed region of China. Thirty homes in different parts of Shanghai were chosen through personal contacts. The majority (68 %) were new homes (<10 years), often (90 %) in multi-occupant dwellings. None of the occupants owned furry pets. The majority of the beds (90 %) had mattresses of the traditional Chinese type, which consist of bundles of cotton fibres.
Dust samples were taken from bed dust (N=27), and floor-dust (N=28) using special sampling devices from ALK, during visits to 29 homes during January and February, 2002. The bed samples were taken using the same method as used in the ECRHS-study. Dust samples were analysed for allergens from house dust mites (Der p 1 and Der f 1), cat, dog and horse, as well as the mould Alternaria alternaria, using the ELISA method. In addition, levels of formaldehyde, nitrogen dioxide, sulphur dioxide and ozone were measured both indoors and outside the homes for 1 week, and radon was measured in the homes for 3 months.
House dust mites were found in all samples, both in bed- and floor-dust. The median level was 8430 ng/g (<200-36400 ng/g) for Der p1 and 5410 ng/g (<200-105850 ng/g) för Der f 1. Seven bed samples contained cat allergen (26 %), and 7 (26 %) contained dog allergen. The maximum levels were >8400 ng/g Fel d 1 and 700 ng/g Can f 1 i bed dust. Floor-dust samples contained at most 8400 ng/g Fel d 1 and 900 ng/g Can f 1. One bed sample contained horse allergen at a very low level (90 ng/g Equ cx). Formaldehyde levels were high in certain homes, due to the presence of new building materials and new interior decorations.
It was concluded that allergen from house dust mites is common in homes in Shanghai, and in 78% of bedrooms the levels were so high (>2000 ng/g) as to give a risk of sensitisation. This can be explained by Shanghai’s damp, warm climate. Fifty-four percent of the bedrooms had detectable levels of allergens from furry animals, despite the fact that no-one had cats or dogs in the homes. This suggests that there is an indirect spread of animal allergen in Shanghai.
Formaldehyde and nitrogen dioxide were other pollutants that were present at relatively high levels. The level of formaldehyde exceeded WHOs guideline (100 mg/m3 ) in 10 % of homes, with a maximum of 321 mg/m3. The level of nitrogen dioxide was high both in the homes (33-89 mg/m3) and outside the homes (39-86 mg/m3) due to traffic outside and gas-cookers indoors, and almost always exceeded WHOs guideline (40 mg/m3). The level of radon was low (6-33 Bq/m3) in all homes.
The school environment in Asia
Contact: Dan Norbäck
We have carried out studies in schools in China and Korea during the 00’s as part of collaborative work on the indoor environment with researchers in Asia. PhD student Zhuohui Zhao has studied the school environment in Taiyuan in northwest China. This town lies in an area with some of the highest levels of airborne pollutants in the world. PhD student Jeong Lim Kim has studied the school environment in Korea. Research Assistant Yahong Mi has previously carried out school projects in Shanghai. Mechanical ventilation in schools in these regions is unknown, and the only ventilation is through windows. This can lead to problems since the pollutant levels in the outdoor air in Asian cities can be high. One can choose between opening the windows and letting in car exhaust fumes, or keeping the windows closed and having a poor indoor environment anyway. In addition, classes can have 40-60 pupils, with double the density of people as seen in Sweden. The Chinese classroom is much colder during the winter, with temperatures of 12-16 degrees, whilst the Korean classrooms had temperatures comparable to those in Sweden. The classrooms had the advantage of containing almost no bookshelves, textiles etc that could accumulate dust. In addition, the pupils cleaned the classroom themselves every day in both China and Korea. Cat and dog allergens were present in the air in Chinese and Korean classrooms but the level of cat allergen was low in Korea since only three percent of the children had a cat at home.
The medical aspects of the PhD studies are still be analysed. The first studies from Shanghai indicated that problems with asthma were more common in schools with higher levels of nitrogen dioxide in the classrooms. Asthma symptoms and respiratory infections were less common in schools with high levels of endotoxins and muramic acid in dust. Only a few percent of the classrooms had visible signs of dampness or mould.
These school projects also included an investigation into whether diet played a role in the occurrence of asthma symptoms in pupils in China and Korea. High consumption of fish, shellfish and fruit appeared to give a protective effect. This data is being published. An ongoing collaborative project is addressing the school environment in Malaysia.
Publications
Mi Y-H, Elfman L, Eriksson S, Johansson M, Smedje G, Tao J, Mi Y-L. Norbäck D. Indoor allergens in schools: a comparison between Sweden and China. Proceedings from 9th International Conference on Indoor Air quality and Climate, Indoor Air 2002,Santa Cruz, California, Vol 2, pp.449-454.
Mi Y-H, Norbäck D, Tao J, Mi Y-L, Ferm M. Current asthma and respiratory symptoms among pupils in Shanghai, China: Influence of building ventilation, nitrogen dioxide, ozone, and formaldehyde in the classrooms. Indoor Air 2006; 16:454-464.
Norbäck D, Wang Z-H, Wieslander G, Zhao Z-H, Mi Y-H, Li Y-Y, Zhang Z. Asthma, eczema, and reports on pollen and cat allergy among children in urban and rural parts of Shanxi province, China. Int Arch Occup Environ Health 2006 (in press)
Norbäck D, Mi Y-H, Larsson L, Wady L, Tao J, Mi Y-L. Current asthma, respiratory infections and hypersensitivity to moulds in pupils in Shanghai, China, in relation to microbial components in the classrooms. Proceedings from 9th International Conference on Indoor Air quality and Climate, Indoor Air 2002,Santa Cruz, California, Vol 3, pp.410-415.
Zhao ZH, Elfman L, Wang ZH, Zhang Z, Norbäck D. A comparative study of asthma, pollen cat and dog allergy among pupils and allergen levels in schools in Taiyuan city, China and Uppsala, Sweden. Indoor Air 2006; 16: 404-13.
The school environment in Knivsta, Uppsala County
Contact: Dan Norbäck
This study included all primary and secondary schools in Knivsta municipality, south of Uppsala. One school was recently built (1999) and another had been subject to major renovations 1999. The study was carried out in the eight schools during 2000 and included 1014 (68 %) of the pupils and 157 (76 %) of the personnel. A PhD student, Jeong-Lim Kim, studied the pupils’ asthma and allergy symptoms in relation to the schools’ indoor environment as well as dietary factors. She also studied the interaction between dietary factors and exposure to allergens in the classroom with respect to respiratory symptoms. Temperature, relative humidity and carbon dioxide levels were measured in the classrooms using continuous-monitoring instruments. Measurements also included levels of formaldehyde, volatile organic compounds (VOC) and microbial volatile organic compounds (MVOC), both in the classroom and outside the school. The air exchange rate was measured using tracer gas. Settled dust from the classrooms was collected by standardised vacuum cleaning through ALK-filters. Samples were subsequently analysed for allergens from cat (Fel d 1), dog (Can f 1), horse (Equ c x), and house-dust mites (Der p 1 and Der f 1), and cockroaches (Bla g 1).
Of the pupils, 7.7 % had diagnosed asthma, 6.8% allergy to cats, 4.8%, allergy to dogs, and 8.8% allergy to pollens. Those pupils who ate fruit more often, or lived in homes where food was prepared using olive oil had a lower frequency of diagnosed asthma. Those who drank milk or ate fish more often had lower frequency of asthmatic symptoms the last year. Those who ate fast-food such as hamburgers more often, or lived in homes where more unsaturated fat was used in cooking, had a higher prevalence of asthmatic symptoms.
Allergens from furry animals, including from cats, dogs, and horses, were found in all schools and often at high levels. Children had asthmatic symptoms, such as ‘wheeze’ more often in those schools with higher levels of dog and horse allergen. The correlation between allergens in schools and asthmatic symptoms was stronger among children who seldom drank milk and where butter was not used at home. The conclusion is that animal allergens in school can be a risk factor for asthmatic symptoms in pupils, and that there can be an interaction between dietary factors and exposure to allergen.
Another part of the project involved investigating the relationship between asthmatic symptoms and mould, bacteria, MVOC, formaldehyde, and certain plasticizers (texanol, TXIB, 2-ethyl-1-hexanol) in classrooms. The prevalence of asthma diagnosis was higher in pupils in classes with higher levels of MVOC. There was also a relationship between the levels of Texanol and TXIB in the classroom, and asthmatic symptoms. The highest levels of MVOC, Texanol and TXIB were detected in two new schools. There was no relationship between levels of MVOC and levels of moulds or bacteria in the air. There was, however, a correlation between levels of MVOC and plasticizers. The conclusion is that MVOC and plasticizers in class rooms can be risk factors for asthmatic symptoms in pupils, but it is unclear if MVOC is an indicator for exposure to microbes.
Of the personnel, 16.1 % reported being diagnosed with asthma, 18.1 % currently used asthma medicine, 13.1 % were allergic to cats, 9,7% to dogs, and 26 % were allergic to pollen. These levels are over the average level for school personnel in Uppsala County. The correlation between the symptoms in the school personnel and diet, and the schools indoor environment has yet to be analysed.
Publications:
Kim JL, Elfman L, Mi Y, Johansson M, Smedje G, Norbäck D. Current asthma and respiratory symptoms among pupils in relation to dietary factors and allergens in the school environment. Indoor Air 2005; 15: 170-182.
Kim JL, Elfman L; Wieslander G, Smedje G, Norbäck D. Indoor moulds, bacteria, microbial volatile organic compounds (MVOC) and plasticizers in school: Associations with asthma and respiratory symptoms in pupils. (in press 2006).
Validation of Stockholm’s Indoor Environment Questionnaire (SIEQ)
Contac: Karin Engvall
The purpose of the project was to document and validate the questionnaire that Stockholm city has used since the beginning of the 1990’s to evaluate how indoor climate and health is experienced in newly built multi-family residential buildings. The questionnaire is currently recommended in the city’s program for environmentally sound building. There will be a follow-up study concerning how indoor climate and health is experienced in these buildings, as included in the contract with those responsible for building on city-owned land.
The questionnaire is standardised and based on sociological principles for validation. It contains questions regarding how indoor environment is experienced in terms of air quality, temperature, sound and light. There are also questions on the prevalence of asthma, and seven building-related symptoms that are usually included in the so called ‘Sick Building Symptoms’ or SBS. To be reported, problems must occur often or every week for the latest 3 months. There are also questions on the apartment and how it is used, together with questions concerning the occupants and the household. The questionnaire proved to have a high level of concordance on repeated use at various levels – area, building and individual. The response rate has so far been high at over 75%, and the internal refusals have often been low, generally under 6 %. The results are shown in graphical ‘problem profiles’ for indoor environment and health problems respectively. There is a good reference material from a study performed in 1991/93 with answers from 609 multi-home buildings and 9 808 apartments from different building periods in Stockholm. The questionnaire has been used in 2005 within the project on sustainable healthy houses with the purpose of renewing reference values.
The project was performed as part of Karin Engvalls PhD studies, and as a collaboration between the Institution for Medical Science/Occupational and Environmental Medicine and the Institution for Urban and Housing Research, both at Uppsala University, and Stockholm City.
Publications
K Engvall, E Sandstedt, C Norrby.”The Stockholm Indoor Environment Questionnaire: a sociological based tool for assessment of Indoor environment and health in dwellings”. Indoor Air 2003: 13:1-10
Ventilation to reduce allergen exposure in classrooms
Contact: Greta Smedje and Robert Wålinder
The purpose of this study was to investigate how levels of airborne particles, especially those carrying allergens, could be reduced by the ventilation system in the school classroom, and the effect on pupil health. This involved studying the difference between the two principle types of supplying outdoor air, displacement ventilation (DV) and mixing ventilation (MV), and also an investigation of the effect of ventilation airflow and pupil activity on the occurrence of particles and allergens.
The aim of ventilation is to replace contaminated air with clean air. Mixing ventilation involves supplying outdoor air at such a high flow that it mixes with the existing, contaminated air and thereby dilutes out the contaminants. Displacement ventilation involves supplying air at a low flow rate at floor level so that it slowly presses the contaminated indoor air upwards to the ceiling and away from the occupied zone. In both cases the contaminated air is normally extracted through outlets at ceiling level. Up to now it has mostly been the concentration of contaminants in the gas phase that have steered the construction of ventilation systems and there is little understanding of the effectiveness of such systems when it comes to removal of particulate contaminants.
Four classes in the age group 10-11 years old have been studied. Ventilation systems were rebuilt in the classrooms to facilitate switching between DV and MV. The functioning of each ventilation method was determined by measuring levels of particles, cat allergens, carbon dioxide and temperature at different levels in the room. The children completed a short questionnaire on how they experienced the school environment and some physiological parameters were studied. Nasal patency was investigated by acoustic rhinometry and nasal lavage was performed with a saline solution to determine the concentration of various cells that indicate inflammatory and secretory activity.
The project was run in collaboration with the Institution for Built Environment at the University of Gävle.
The analysis of samples and compilation of results is in progress. The results concerning the effect of ventilation method on contaminant levels have been presented at the conference “Healthy Buildings” in Singapore, December 2003. At MV the concentration of particles were lower at higher height and at DV it was higher. The concentrations of particles were, however, the same at the breathing height of approximately 1.1 m over the floor. The concentration of cat allergen was significantly correlated with the level of particles in the size range 1-10 µm.
Publications
Mattsson M, Smedje G, Holmquist L, Vesterberg O, Wålinder R. Mixing and displacement ventilation compared in classrooms; distribution of particles, cat allergen and CO2. Proceedings from Healthy Buildings 2003; (2):458-464.
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