Search

Background: In most epidemiological surveys the estimated prevalence of asthma is based on questionnaire responses, which may depend on the individual's perception as well as medical consulting habits in a given population. Therefore, measurement of bronchial hyper-responsiveness as a key feature of asthma has been suggested as an objective parameter for asthma., Objective: The aim of the present study was to validate questionnaire responses on asthma and wheeze against bronchial response to hypertonic saline (HS) (4.5%) in populations previously shown to have a lower prevalence of asthma and allergies: farmers' children and children from anthroposophic families., Methods: Children whose parents had completed a written questionnaire in the cross-sectional PARSIFAL-study were drawn from the following four subgroups: 'farm children' (n=183), 'farm reference children' (n=173), 'Steiner schoolchildren' (n=243) and 'Steiner reference children' (n=179). Overall, 319 children with wheeze in the last 12 months and 459 children without wheeze in the last 12 months performed an HS challenge., Results: Odds ratios, sensitivity, specificity, likelihood ratios and measures of association did not differ significantly between the four subgroups. The correlation between the bronchial response to HS and wheeze and asthma questions was moderate and similar for farm children, farm reference children, Steiner schoolchildren and Steiner reference children (kappa for 'wheeze': 0.25, 0.33, 0.31, 0.35, respectively, P=0.754, kappa for 'doctor's diagnosis of asthma': 0.33, 0.19, 0.33, 032, respectively, P=0.499)., Conclusion: The findings from this study suggest that the reliabilitiy of questionnaire responses on asthma and wheeze is comparable between farmers' children, children raised in families with anthroposophic lifestyle and their respective peers.

Background: Growing up on a farm and an anthroposophic lifestyle are associated with a lower prevalence of allergic diseases in childhood. It has been suggested that the enhanced exposure to endotoxin is an important protective factor of farm environments. Little is known about exposure to other microbial components on farms and exposure in anthroposophic families., Objective: To assess the levels and determinants of bacterial endotoxin, mould beta(1,3)-glucans and fungal extracellular polysaccharides (EPS) in house dust of farm children, Steiner school children and reference children., Methods: Mattress and living room dust was collected in the homes of 229 farm children, 122 Steiner children and 60 and 67 of their respective reference children in five European countries. Stable dust was collected as well. All samples were analysed in one central laboratory. Determinants were assessed by questionnaire., Results: Levels of endotoxin, EPS and glucans per gram of house dust in farm homes were 1.2- to 3.2-fold higher than levels in reference homes. For Steiner children, 1.1- to 1.6-fold higher levels were observed compared with their reference children. These differences were consistently found across countries, although mean levels varied considerably. Differences between groups and between countries were also significant after adjustment for home and family characteristics., Conclusion: Farm children are not only consistently exposed to higher levels of endotoxin, but also to higher levels of mould components. Steiner school children may also be exposed to higher levels of microbial agents, but differences with reference children are much less pronounced than for farm children. Further analyses are, however, required to assess the association between exposure to these various microbial agents and allergic and airway diseases in the PARSIFAL population.

Questions Under Study: During June to August 2003, high temperatures were reported across Europe including Switzerland. In many European countries, particularly in France the heat wave was associated with an increase in mortality. This is the first analysis investigating whether the high temperatures during summer 2003 in Switzerland had a measurable impact on mortality., Methods: Daily data on all-cause mortality for the period January 1990 to December 2003, and meteorological data from 20 different stations for the same period were analysed. Excess mortality for different age groups, gender and geographic regions was calculated. Daily mortality and temperature in 2003 was correlated with lags of temperature up to 7 days., Results: An estimated 7% increase in all cause mortality occurred during June to August 2003. Excess mortality was limited to the region north of the Alps, to inhabitants of cities and suburban areas and was more pronounced among the elderly and the inhabitants of Basel, Geneva and Lausanne. North of the Alps, deviations in daily mortality were significantly correlated with deviations in maximum daily temperatures and night temperatures. The combination of day temperature above 35 degrees C and night temperatures above 20 degrees C predominantly occurred in Basel and Geneva and might in part explain the regional differences in excess mortality., Conclusions: As the number of elderly people in Switzerland continues to rise and the occurrence of heat waves is predicted to increase as a consequence of global warming, preventive programmes targeting susceptible populations during heat waves are warranted.

Asthma is the most common chronic disease in childhood, imposing a huge burden on the patient, their family and society. It is a worldwide disease with variable expression between countries and between different populations in a country. There is evidence that its prevalence has increased considerably over the last two decades and is still increasing, despite there being some indications that the increase in prevalence may have plateaued in some countries in the last few years. Better understanding of the natural course of asthma and improved asthma control can lead to a decreased burden on the patient, their family and society. The burden of asthma consists mainly of a decreased quality of life for the patient and their family, as well as high costs for society; the healthcare expenditures for asthma in developed countries are 1-2% of the total healthcare costs.

Background: An increasing number of studies report pet exposure to be associated with lower risk of asthma and allergies. This 'protective pet effect' has been suggested to result from a modified T-helper (Th)2-cell response, or because of increased microbial load in homes where pets are kept. We examined the associations between pet contact and the occurrence of asthma and allergies in children of the rural Allergy and Endotoxin (ALEX) population, taking farm animal contact, endotoxin and cat allergen levels in mattress dust into account., Methods: Information about contact with pets and farm animals, asthma and allergy were collected for 812 children by a standardized parents' questionnaire and an interview. Mattress dust endotoxin and cat allergen levels as well as specific IgE and IgG4 antibodies to Fel d1 were determined., Results: Current contact with dogs was inversely associated with diagnosed hay fever (OR 0.26, 95% CI 0.11-0.57), diagnosed asthma (OR 0.29, 95% CI 0.12-0.71), sensitization to cat allergen (OR 0.48, 95% CI 0.23-0.99) and to grass pollen (OR 0.55, 95% CI 0.33-0.94), but not with increased IgG4 levels. Early and current contact with cats were associated with reduced risk of wheezing (OR 0.48, 95% CI 0.23-1.00, and OR 0.49, 95% CI 0.26-0.92, respectively) and grass pollen sensitization. Adjustment for farm animal contact but not for endotoxin and cat allergen exposure attenuated these associations and the effect of pet was stronger among farmers' children., Conclusion: Although pet exposure was very frequent in this rural population, the inverse relation between current dog contact, asthma and allergy was mostly explained by simultaneously occurring exposure to stable animals or was restricted to farm children. In addition, a subtle form of pet avoidance may contribute to the protective effect of pet.

This study describes time trends for very low birth weight multiple births in relation to very low birth weight singletons. Two cohorts of very low birth weight (less than 1250 gm) children recruited between 1983-85 (cohort 1, n = 115) and 1992-94 (cohort 2, n = 144) were compared. The Bayley Scales of Infant Development and a standardized neurologic examination were administered at 2 years corrected age. Neurodevelopmental outcome did not change between cohort 1 and 2 for singletons. For multiple births, mean Mental Developmental Index increased after adjustment for neonatal risk factors [adjusted mean (standard deviation) 81.8 (11.7) to 96.5 (18.6), analysis of covariance P = 0.007]. The prevalence of cerebral palsy decreased, however not significantly [adjusted odds ratio (95% confidence interval) 0.3 (0.1-1.5), P = 0.14]. The proportion of disease-free survival (no cerebral palsy and no developmental delay) increased for multiple births (7-37%, P = 0.002), but not for singletons. In cohort 2, neurodevelopmental outcome of multiple births was similar to that of singletons. The cognitive outcome of very low birth weight multiple births improved, possibly because of changes in perinatal practice. However, neurodevelopmental outcome was similar to that of very low birth weight singletons who were unaffected by changes in neonatal care with high proportions of motor delay and cerebral palsy.

Background: A multidisciplinary approach and a multi-modal methodology are needed to assess idiopathic environmental illnesses., Sample: 61 patients took part in all diagnostic steps., Method: In the Basel pilot research project on environmental illness, a threefold diagnostic approach was established: patients had a medical and allergological examination, a psychiatric and psychological exploration and an environmental analysis of their homes., Results: There is a clear psychological impact on environmental illness: 46 % of the symptoms could be traced back to psychological factors, and 18 % seemed to be influenced by them. Nevertheless, in 28 % more than one of the three dimensions was seen as important. Values within the self reporting questionnaires show high correspondence. Whereas patients and experts agree in many instances that there are psychological factors, they disagree in attributing clinical relevance to them. This discrepancy is helpful for explaining the difficulties therapists may encounter as to the patients' compliance., Consequences: Environmental illness should be diagnosed and treated on an interdisciplinary basis including psychosomatic medicine.

Environmental illnesses raise diagnostic and therapeutic conflicts in scientific discussions and clinical practice. When a patient's health-belief model, based on environmental origins, does not match that of the expert, the therapeutic relationship can be endangered. Our study investigates this discrepancy, which has not been empirically evaluated so far. Patient (n=61) and expert disease concepts were systematically investigated. Our results indicate that in cases in which both concepts are favourable, the patient suffered minor psychiatric disorders with stable psychic structures and the symptoms were associated with medical or environmental causes. If both concepts were unfavourable, a higher proportion of psychiatric disorders with unstable psychic structures were present. In the case of incongruent concepts, the expert evaluations allow a more accurate assessment of the psychiatric diagnoses, psychic states and the psychic attribution of somatic and psychic burden.

Background and Aim: In Switzerland, the prevalence of health problems attributed to environmental exposures is unknown, and views differ regarding its magnitude. In the present study we investigated the frequency of environmentally related health problems amongst the patients of Swiss sentinel physicians and assessed symptoms and suspected environmental exposures., Methods: During 2002, nearly 250 "Swiss Sentinel Surveillance Network" physicians were asked to record the number of patients presenting with environmental health problems and to complete a questionnaire inquiring about suspected environmental exposures and health problems. Physicians offering "alternative" medical therapies also participated in the study. The results were compared with the experience of a Basel University pilot project which evaluated patients with environment-related health problems simultaneously from the medical, psychiatric and environmental viewpoint., Results: 354 environment-related consultations were reported by 72 physicians, corresponding to 0.03% of all sentinel-physician consultations. There were considerable differences both within the group of Sentinella physicians, and between physicians offering "alternative" medical therapies and the Sentinella physicians, in the frequency of environmentally-related consultations, the character of the reported symptoms and the suspected environmental exposures., Conclusion: Overall, environmental medicine consultations in general practice were rare. However, experience of the environmental medicine pilot project showed that concerned persons seek help from various health care providers and from environmental agencies. Effective treatment should include counselling by medical, psychiatric and environmental professionals.

Problem: To assess symptoms attributed to the environment from an interdisciplinary perspective and to evaluate the plausibility of the participants' individual theory of a causal relationship between exposure and health impairment., Method: We assessed the medical, psychiatric and environmental background in every participant in an environmental medicine project and discussed the explanatory value of our findings for each reported symptom., Results: Every second participant had at least one symptom that could be plausibly explained by simultaneously occurring medical, psychological or environmental findings. In 40% of the participants the research team rated the association between an environmental exposure and the health complaints to be 'plausible'. Psychiatric disorders were frequent, but did not exclude environmentally caused symptoms., Conclusion: Only an interdisciplinary structure including medical, psychiatric and environmental expertise is likely to adequately diagnose and advise persons with environmentally related symptoms.

Background: Endotoxin exposure has been shown to be associated with a decreased prevalence of atopic sensitization and symptoms. Yet endotoxin represents only a part of the indoor microbial exposure. Muramic acid, a constituent of peptidoglycan, is present in gram-negative and gram-positive bacteria in the environment and may therefore serve as an additional marker of microbial exposure., Objective: To study the factors determining the level of indoor exposure to muramic acid/peptidoglycan, as well as its potential association with respiratory health., Methods: In 553 farm and nonfarm school children from Austria, Switzerland, and Germany, mattress dust muramic acid concentrations were determined, and health was assessed by using IgE measurements and questionnaire information., Results: The muramic acid concentration was found to be significantly higher in dust from farm children's mattresses than in dust from nonfarm children's mattresses (157 vs 131 ng/mg). Children with higher mattress dust muramic acid concentrations had a significantly lower prevalence of wheezing (odds ratio of highest vs lowest tertile of muramic acid concentration, 0.3; 95% CI, 0.1-0.9), regardless of farming status and endotoxin exposure. The association for asthma was similar, and no association was found with atopic sensitization., Conclusion: Next to endotoxin, muramic acid provides us with an independent marker of microbial exposure. Unlike endotoxin, muramic acid was inversely associated with wheezing rather than with atopic sensitization.

Prevalence rates of childhood asthma and allergy have been on the increase for several decades. The present study investigated whether this trend continued during the 1990s in adolescents living in Switzerland. Between 1992 and 2000, the change in prevalence of specific immunoglobulin E to aeroallergens, asthma symptoms and hay fever symptoms assessed by parents' and students' answers to the International Study of Asthma and Allergies in Childhood questions was investigated using three cross-sectional surveys. In total 1,324 (74.9%), 1,668 (80.6%) and 1,250 (73.9%) adolescents participated. Prevalence rates of asthma and current asthmatic symptoms remained constant, irrespective of whether the assessment was based on parental questionnaires or the student's self-completed written or video questionnaires (students' report of current wheeze 8.8, 7.3, and 8.3%). Similarly, no further increase was observed for reported hay fever rates and allergic sensitisation rates (positive multiscreen allergy test, SX1-test: 34.6, 38.9, and 35.6%, respectively). Although time trends in the occurrence of a series of known risk factors were recorded, none of these factors had a significant impact on asthma and allergy prevalence over time. No further increase in asthma and allergy rates occurred during the 1990s in adolescents living in Switzerland. However, to adequately assess the trend a longer period of observation is needed.

In carrying out two projects involving environmental health indicators--a national environmental health programme evaluation and an international environmental health indicator system--in parallel, it became apparent that an international indicator set has limitations regarding the evaluation of a national programme such as the Swiss National Environment and Health Action Plan (NEHAP). The international indicator set proposed by WHO serves the structured description of the underlying cause-effect chains, allows an integrated monitoring of the general environment and health situation and provides valuable international comparisons. However, the relevance of an international indicator set varies in the national context. Moreover, it does not allow the evaluation of a national implementation process, which is highly important in assessing success or failure of an environmental health promotion programme. For a comprehensive evaluation of such a programme, a specific evaluation concept derived from the formulated goals and targets needs to be developed with emphasis on evaluation of the implementation process.

Background: The finding that the prevalence of asthma and allergies is less frequent in children raised on animal farms has led to the conjecture that exposure to microbial products modifies immune responses. The toll-like receptors (TLRs) represent an evolutionarily conserved family of innate immunity receptors with microbial molecules as ligands., Objectives: We reasoned that polymorphisms in genes encoding TLRs might modulate the protective effects observed in farming populations., Methods: Farmers' and nonfarmers' children living in rural areas in Austria and Germany and who were enrolled in the cross-sectional ALEX study were genotyped for single nucleotide polymorphisms in the TLR2 and TLR4 genes. The frequencies of asthma, allergic rhinitis, and atopic sensitization were compared between the genotypes in relation to exposure to farming and endotoxin., Results: Among farmers' children, those carrying a T allele in TLR2/-16934 compared with children with genotype AA were significantly less likely to have a diagnosis of asthma (3% vs 13%, P = .012), current asthma symptoms (3% vs 16%, P = .004), atopic sensitization (14% vs 27%, P = .023), and current hay fever symptoms (3% vs 14%, P = .01). The association between TLR2/-16934 and asthma among children of farmers was independent of atopy. No such association was found among children from the same rural communities but not living on farms., Conclusion: Our results suggest that genetic variation in TLR2 is a major determinant of the susceptibility to asthma and allergies in children of farmers.

Background: Lower frequencies of asthma and hayfever have been observed in children with contact to livestock. At school age, the amount of endotoxin measured in the dust of children's mattresses is inversely related to the occurrence of atopic asthma, hayfever and atopic sensitization both in children from farming and non-farming households., Objective: The aim of the present study was to investigate which home and lifestyle characteristics of farm and non-farm families contribute to endotoxin levels measured in different indoor home environments., Methods: In the framework of the Allergy and Endotoxin (ALEX) Study, endotoxin was measured in dust samples from the living room floor and the child's mattress of 319 farmers' families and 493 non-farming families, and in settled dust from stables. Endotoxin content of all dust samples was determined by a kinetic Limulus assay (Limulus-Amebocyte-Lysate test). Information about the child's activities on farms, home characteristics and cleaning behaviours was obtained from parental questionnaires., Results: Endotoxin levels in stables did not predict the amount of endotoxin measured in floors or mattresses. However, a dose-dependent association between the child's activity on the farm and indoor home endotoxin levels was observed, both in farm and non-farm children. In non-farm children pet keeping and the frequency of floor cleaning were additionally associated with endotoxin levels, whereas in farm children parental farm activities, study area, time since last cleaning, the mattress type as well as younger age of the children contributed to increased microbial exposure., Conclusion: These results demonstrate that regular contact to farm animals increases indoor home endotoxin concentrations, both in farm and non-farm children, and might thus explain the protective effect of contact to livestock on atopic outcomes. To assess children's individual exposure to a microbial environment, measures of mattress dust exposure are needed as stable endotoxin concentrations were not associated with indoor home levels.

From June 2001, health questionnaires were distributed to people who complained about symptoms of ill health which they ascribed to exposure to electromagnetic fields (EMF). The objective of the survey was to gain a better knowledge of the anxieties of complainants, to obtain hints of possible problems and of actions that should be taken to solve the problems. The survey was not designed to establish a causal association between exposure to EMF and symptoms of ill health. Within one year, 429 questionnaires were returned of which 394 persons reported symptoms. The average age of the complainants was 51.0 years and 57 percent were female. The complainants were older, had a higher educational level and were more likely to be married compared to the general Swiss population. A mean of 2.7 different symptoms were reported. Sleep disorders (58%), headaches (41%), nervousness or distress (19%), fatigue (18%), and concentration difficulties (16%) were most common complaints. Complainants related their symptoms most frequently to exposure to mobile phone base stations (74%), followed by mobile phones (36%), cordless phones (29%) and power lines (27%). No distinct symptoms related to a specific field source could be identified. Eighty-five percent of the people who consulted a public authority because of their symptoms were unsatisfied with the response, whereas consultation of self-help groups or building ecologists usually fulfilled expectations. Two thirds of complainants had taken some action to reduce their symptoms. The most common measure was to avoid exposure if possible. Removing or disconnecting indoor sources was judged to be the most effective action.

Background: Diagnostics and therapy of environmentally related disorders are hampered by one-sided assumptions and by discrepancies between therapists' and patients' assessments of the disease cause., Objectives: Discrepancies between patient and expert opinions are examined as to (1) whether the sample can be classified in subgroups according to the convergence or divergence between self and expert rating, (2) which features and (3) which disorder-related behaviour and concepts characterize these groups., Methods: Medical, psychopathological and environmental symptoms were assessed and their relative influence evaluated. Four subgroups were defined by differentiating between high and low psychological stress according to self and expert judgment, and then compared using statistical and qualitative methods., Results: 61 patients were assessed and assigned to four different subgroups according to the number of psychiatric diagnoses, psychological conflicts, personality structure, environmental exposure and psychosocial integration., Conclusions: Diagnostics of environmentally related disorders must be based on interdisciplinary tools. Treatment should incorporate the individual patient's conception of his or her disorder.

Human Th2 cytokines (interleukins 4 and 13) induce co-expression of IgE and IgG4 through sequential switching. The regulation of IgG4 responses and the role of these responses in the pathogenesis of allergy have not been characterized. We are addressing these issues by comparing and contrasting the expression of allergen-specific IgE and IgG4 in a population of European children thoroughly defined for lifestyle, environmental exposures and allergic phenotypes. The current analysis focused exclusively on children from non-farming families (n=493) in order to avoid potential effects of exposure to microbial products abundant in farming environments. We found that allergens induce Th2-mediated IgG4 and/or IgE responses in the majority of the population. Approximately two-thirds of the children had allergen-specific IgG4 but not IgE, only a minority had both IgG4 and IgE, only a few were negative for both, and virtually none had only IgE. The prevalence of asthma and hay fever was dramatically higher in children with high IgG4 and IgE compared to children who only mounted IgG4 or low IgG4 and IgE responses. These results appear to recapitulate different stages of in vivo Th2-dependent sequential switching from IgG4 to IgE. These patterns of Th2-induced antibody responses may warrant a redefinition of the notion of allergen sensitization.

This paper gives an overview of present scientific knowledge in health research on the effects from radio and microwave frequency radiation, at levels to which the general population is typically exposed. The review is based on human experimental and epidemiological studies investigating the effects of radiation in the frequency range between 100 kHz and 10 GHz. The relevant studies were identified via systematic searches of the databases Medline and ISI Web of Science. The review concludes that the existing scientific knowledge base is too limited to draw final conclusions on the health risk from exposure in the low-dose range. Only few studies have investigated the effect of long-term exposure on the general population in the normal environment. Accordingly, little can be predicted regarding long-term health risks. Various studies observed an increased risk for tumours in the hematopoietic and lymphatic tissue of people living in the proximity of TV and radio broadcast transmitters. However, methodological limitations to these studies have been identified and their findings are controversial. In studies of a possible association between brain tumours and mobile phone use, the average period mobile phones use was short compared to the known latency period of brain tumours. Although these studies did not establish an overall increased risk of brain tumours associated with mobile phone use, there were some indications of an association. Immediate effects associated with mobile phone use have been observed in human experimental studies that cannot be explained by conventional thermal mechanisms. The observed effects are within the normal physiological range and are therefore hard to interpret with respect to an increased risk to health. However, it can be concluded that mechanisms other than the established thermal mechanisms exist. Because of the present fragmentary scientific database, a precautionary approach when dealing with radio and microwave frequency radiation is recommended for the individual and the general population.

It is well known that UV radiation contributes to the development of skin cancer. Exposure to solar radiation is predominantly responsible for the high incidence rate of skin cancer, but there are also indications that sunbeds are involved. The aim of the present investigation was to determine the UV emission spectra of sunbeds. It included the most common sunbed models, which cover more than 50% of the Swiss market. The UV emission spectra of sunbeds have special characteristics and are different from the sun spectrum, which can be seen in high-resolution spectral measurements. Sunbed emission spectra are similar to the sun spectrum in the UVB (280-320 nm) range but reach values 10 to 15 times higher in the UVA (320-400 nm) range. An average erythema-effective irradiance of 0.33 W/m2 was determined for sunbeds. This corresponds to a UV index of 13, which is significantly higher than the UV index of 8.5 of the high summer sun at noon at intermediate latitudes. The measurements were spread over the whole effective area of the sunbeds, and an inhomogeneous distribution of the irradiances with variations of up to 30% from the average value was found.

Children of farmers are at decreased risk of developing allergies. Results of epidemiological studies suggest increased exposure to microbial compounds might be responsible for this reduced risk. Alterations in adaptive immune response are thought to be the underlying mechanism. We measured expression of receptors for microbial compounds known to trigger the innate immune response. We showed that blood cells from farmers' children express significantly higher amounts of CD14 (0.96 vs 0.43, p=0.0013), and Toll-like receptor 2 (0.11 vs 0.04, p<0.0001) than those from non-farmers' children. We propose that the innate immune system responds to the microbial burden in the environment and modulates the development of allergic disease.

The National Environment and Health Action Plans (NEHAPs) are a novel attempt to integrate environmental protection and health promotion in political programmes. Throughout Europe, about 40 NEHAPs have been developed so far. The Swiss NEHAP was among the first to be developed in an industrialised country. We discuss strength and weaknesses of the Swiss NEHAP and draw first conclusions on the development and implementation process of such programmes, illustrated by examples of other European NEHAPs. The strengths of the Swiss NEHAP lie in the formulation of specific targets in selected areas, its approach as a environmental health promotion programme, and its comprehensive evaluation. Weaknesses in most NEHAPs are the lack of involvement of the general public and of the economic sector, and the absence of an implementation strategy along with adequate financing.

Objectives: A constant rise in the number of skin cancer cases has been observed during the last few years. An important reason for this trend is that exposure of the population to UV radiation is higher. Although natural UV radiation is the major source, exposure due to use of sunbeds must be considered from the point of view of prevention., Methods: 151 sunbed users in Bern and Basel were questioned on their reasons for visiting a solarium, their behaviour when using a sunbed and their awareness of risks resulting from UV radiation., Results: It was shown that young women are the most frequent sunbed users. Also, sunbeds are often used regularly, not only for cosmetic reasons but also from a desire for relaxing and well-being in the warmth and light. Although most of the persons questioned were aware of certain health risks resulting from UV radiation, this knowledge hardly influenced their behaviour. Thus, more than half the people questioned use sunbeds longer and more often than advised by international recommendations., Conclusions: In view of a continuing increase in the number of skin cancer cases the improvement of preventive strategies for sunbed users is of major importance. Another urgent requirement is informing the public and increasing the general awareness of possible adverse health effects caused by UV radiation.

Study Objective: To examine whether changes in environmental housing quality influence the wellbeing of movers taking into account other dimensions of housing quality and sociodemographic factors., Design: Cross sectional telephone survey. Associations between changes in satisfaction with 40 housing quality indicators (including environmental quality) and an improvement in self rated health (based on a standardised question) were analysed by multiple logistic regression adjusting for sociodemographic variables. Objective measures of wellbeing or environmental quality were not available., Setting: North western region of Switzerland including the city of Basel., Participants: Random sample of 3870 subjects aged 18-70 who had moved in 1997, participation rate 55.7%., Results: A gain in self rated health was most strongly predicted by an improved satisfaction with indicators related to the environmental housing quality measured as "location of building" (adjusted odds ratio (OR) =1.58, 95% confidence intervals (CI) =1.28, 1.96) and "perceived air quality" (OR=1.58, 95% CI=1.24, 2.01) and to the apartment itself, namely "suitability" (OR=1.77, 95% CI=1.41, 2.23), "relationship with neighbours" (OR=1.46, 95% CI=1.19, 1.80) and "noise from neighbours" (OR=1.32, 95% CI=1.07, 1.64). The destination of moving and the main reason to move modified some of the associations with environmental indicators., Conclusion: An improvement in perceived environmental housing quality was conducive to an increase in wellbeing of movers when other dimensions of housing quality and potential confounders were taken into account.

Background: Little is known about the seroprevalence of anti-varicella-zoster virus (VZV) serum antibodies in adolescents in Switzerland as in most other European countries., Methods: Serum specimens from 13- to 15-year-old students from eight urban and rural areas in Switzerland, obtained as part of an allergy risk assessment study project (SCARPOL), were available for analysis of IgG antibodies against VZV by enzyme-linked immunosorbent assay (ELISA) and confirmation by fluorescent antibody staining of membrane antigen in a subcohort. Serum specimens and comprehensive sociodemographic data had been collected during two study periods between 1992 and 1995., Results: Data and serum specimens were available from 1709 and 1788 subjects, respectively. Seroprevalence of anti-VZV antibodies as measured by ELISA was 95.5% (95% confidence interval, 94.5 to 96.4). When serum specimens that were indeterminate by ELISA were tested by FAMA, seroprevalence was 96.5% (95% confidence interval, 95.7 to 97.4). After logistic regression analysis, the number of siblings was the only factor that significantly influenced the presence of VZV antibodies (90.1% in those with no siblings, >96% with 1 or more siblings), whereas residence (urban vs. rural), parental education, nationality and gender did not., Conclusions: Seroprevalence of anti-VZV serum antibodies is comparatively high among Swiss adolescents. Individuals who grow up without siblings have a significant risk of evading natural VZV infection in childhood, and they therefore form a potential target group for varicella immunization in Switzerland.

Background: Several recent studies have shown that growing up on a farm confers significant protection against the development of atopy. These findings point particularly towards the importance of exposure to stable dust and farm animals. It has furthermore been reported that endotoxin, an intrinsic part of the outer membrane of gram negative bacteria, is abundant in environments where livestock and poultry is kept. The aim of this study was therefore to measure the level of environmental endotoxin exposure in homes of farmers' children, children with regular contact to livestock and control children with no contact to farm animals., Methods: Eighty-four farming and nonfarming families were identified in rural areas in Southern Germany and Switzerland. Samples of settled and airborne dust were collected in stables, and of settled dust indoors from kitchen floors and the children's mattresses. Endotoxin concentrations were determined by a kinetic Limulus assay., Results: Endotoxin concentrations were highest in stables of farming families, but were also significantly higher indoors in dust from kitchen floors (143 EU/mg vs 39 EU/mg, P < 0.001) and children's mattresses (49479 EU/m2 vs 9383 EU/m2, P < 0.001) as compared to control children from nonfarming families. In addition, endotoxin levels were also significantly higher in mattresses and dust from kitchen floors in households where children had regular contact to farm animals (38.6 EU/mg and 23340 EU/m2, respectively) as compared to control subjects., Conclusion: We propose that the level of environmental exposure to endotoxin and other bacterial wall components is an important protective determinant for the development of atopic diseases in childhood.

To evaluate the validity of fixed-site fine particle levels as exposure surrogates in air pollution epidemiology, we considered four indicator groups: (1) PM2.5 total mass concentrations, (2) sulfur and potassium for regional air pollution, (3) lead and bromine for traffic-related particles, and (4) calcium for crustal particles. Using data from the European EXPOLIS (Air Pollution Exposure Distribution within Adult Urban Populations in Europe) study, we assessed the associations between 48-hr personal exposures and home outdoor levels of the indicators. Furthermore, within-city variability of fine particle levels was evaluated. Personal exposures to PM2.5 mass were not correlated to corresponding home outdoor levels (n = 44, rSpearman (Sp) = 0.07). In the group reporting neither relevant indoor sources nor relevant activities, personal exposures and home outdoor levels of sulfur were highly correlated (n = 40, rSp = 0.85). In contrast, the associations were weaker for traffic (Pb: n = 44, rSp = 0.53; Br: n = 44, rSp = 0.21) and crustal (Ca: n = 44, rSp = 0.12) indicators. This contrast is consistent with spatially homogeneous regional pollution and higher spatial variability of traffic and crustal indicators observed in Basel, Switzerland. We conclude that for regional air pollution, fixed-site fine particle levels are valid exposure surrogates. For source-specific exposures, however, fixed-site data are probably not the optimal measure. Still, in air pollution epidemiology, ambient PM2.5 levels may be more appropriate exposure estimates than total personal PM2.5 exposure, since the latter reflects a mixture of indoor and outdoor sources.

The spatial variability of different fractions of particulate matter (PM) was investigated in the city of Basel, Switzerland, based on measurements performed throughout 1997 with a mobile monitoring station at six sites and permanently recorded measurements from a fixed site. Additionally, PM10 measurements from the following year, which were concurrently recorded at two urban and two rural sites, were compared. Generally, the spatial variability of PM4, PM10, and total suspended particulates (TSP) within this Swiss urban environment (area = 36 km2) was rather limited. With the exception of one site in a street canyon next to a traffic light, traffic density had only a weak tendency to increase the levels of PM. Mean PM10 concentration at six sites with different traffic densities was in the range of less than +/- 10% of the mean urban PM10 level. However, comparing the mean PM levels on workdays to that on weekends indicated that the impact of human activities, including traffic, on ambient PM levels may be considerable. Differences in the daily PM10 concentrations between urban and more elevated rural sites were strongly influenced by the stability of the atmosphere. In summer, when no persistent surface inversions exist, differences between urban and rural sites were rather small. It can therefore be concluded that spatial variability of annual mean PM concentration between urban and rural sites in the Basel area may more likely be caused by varying altitude than by distance to the city center.

Several studies have reported lower rates of allergic sensitization and allergies in children living in rural as compared to urban communities. This has been attributed to the lower levels of air pollution in rural areas. The question arises whether other factors in the rural environment could explain the lower prevalence rates of allergic sensitization and hay fever. A first report from rural South Bavaria in Germany demonstrated that children living in a home where coal and wood were used for heating had a significantly lower risk of suffering from hay fever (odds ratio 0.57 (0.34-0.98)), of being sensitized to common allergens (OR 0.67 (0.49-0.93)) and of having bronchial hyperresponsiveness (OR 0.55 (0.34-0.90)) than their peers living in homes with other heating systems. Subsequently, the Swiss Study on Childhood Allergy and Respiratory Symptoms with Respect to Air Pollution (SCARPOL) tested the hypothesis that farming as parental occupation was associated with a lower risk of hay fever and atopy. A total of 1620 (86.0%) 6-15-year-old schoolchildren living in three rural communities of Switzerland were examined using a standardized questionnaire completed by the parents and IgE antibodies against six common aeroallergens in serum samples of 404 (69.3.0%) of the 13-15-year-olds. Farming as parental occupation was significantly associated with lower rates of reported hay fever symptoms and allergic sensitization. Comparing children from farming with those from non-farming environments, the adjusted OR was 0.34 (95% CI: 0.12-0.89) for sneezing attacks during the pollen season, and 0.31 (95% CI: 0.13-0.73) for a sensitization to allergens. These results have recently been confirmed in a new and much larger survey in rural South Bavaria. Several alternative explanations have to be considered when interpreting these findings, namely, selection bias, the development of tolerance, increased microbial stimulation and a more traditional lifestyle (diet and housing conditions). Based on present knowledge, the underlying environmental factor explaining the protective effect of the farming environment has not yet been identified.

In 1987, the Swiss Federal Health Office (BAG) and the Swiss cantons launched the MMR-vaccination campaign. Within the frame of the SCARPOL Study, the vaccination status of 649, 8th class students was registered and serum samples were collected. The measles, mumps and rubella specific antibody levels were determined. The vaccination rate was 84% for measles, 74% for mumps, and 62% for rubella, 55% of these children had been vaccinated with the combined vaccine MMR. The vaccination rate for the different study areas varied from 70% to 95% for measles, 42% to 94% for mumps and 18% to 89% for rubella, 92% of the children tested seropositive for measles specific antibodies, 87% for mumps and 84% for rubella. The seroprevalence for measles, mumps and rubella was significantly higher for vaccinated than for unvaccinated children. Non-Swiss children had, without exception, a higher seroprevalence rate than Swiss children. Undergoing the disease did not influence the seroprevalence for measles, but it did so for mumps and rubella, for vaccinated and unvaccinated children alike. By analysis according to study site, we observed that sites with higher vaccination rates (e.g. Grabs in Rheintal) sometimes showed a lower seroprevalence than sites with lower vaccination rates (e.g. Langnau). This was the case for all three vaccines. This, together with other observations, shows that a booster is necessary for an adequate immunisation--as a wild virus infection or as a second vaccination.

Aims: This study determines the prevalence of exposure to environmental tobacco smoke and its relation to respiratory and allergic symptoms among schoolchildren in Switzerland., Methods: We studied 4470 children aged 6-14 years as part of a multicentre study (SCARPOL study--Swiss Study on Childhood Allergy and Respiratory Symptoms with Respect to Air Pollution, Climate and Pollen) conducted in Switzerland between 1992 and 1993. Environmental tobacco smoke exposure, maternal smoking during pregnancy and respiratory symptoms were assessed by means of a self-administered parental questionnaire., Results: Forty-seven percent of all children were exposed to environmental tobacco smoke. Sixteen percent of the mothers smoked during pregnancy. Children exposed to environmental tobacco smoke at home had an increased risk of respiratory infections (odds ratio (OR) 1.19, 95% confidence intervals (CI) 1.03, 1.37). The risk increased if they were exposed to maternal smoking (OR 1.25, CI 1.06, 1.48) and if the mother also smoked during pregnancy (OR 1.42, CI 1.14, 1.76). Wheezing (OR 1.36, CI 1.03, 1.80) and repeated coughing (OR 1.36, CI 1.14, 1.61) were only associated with maternal smoking. Children exposed to more than 20 cigarettes per day were at highest risk for respiratory problems., Conclusion: Almost half of all schoolchildren in Switzerland, especially those from lower socioeconomic classes, are exposed to environmental tobacco smoke. Children with environmental tobacco smoke exposure suffer significantly more often from respiratory symptoms. Maternal smoking during pregnancy additional to current smoking further increases the risk of respiratory morbidity. These findings underline the importance of prevention strategies to reduce the prevalence of smoking and its impact on children's health.

Introduction: Lower prevalence rates of allergic diseases in rural as compared with urban populations have been interpreted as indicating an effect of air pollution. However, little is known about other factors of the rural environment which may determine the development of atopic sensitization and related diseases., Objective: The authors tested the hypothesis that children growing up on a farm were less likely to be sensitized to common aerollergens and to suffer from allergic diseases than children living in the same villages but in nonfarming families., Materials and Methods: Three age groups of schoolchildren (6-7 years, 9-11 years, 13-15 years) living in three rural communities were included in the analyses. An exhaustive questionnaire was filled in by 1620 (86.0%) parents. A blood sample was provided by 404 (69.3%) of the 13-15 year olds to determine specific IgE antibodies against six common aeroallergens., Results: Farming as parental occupation was reported for 307 children (19.0%). After adjustment for potential covariates such as family history of asthma and allergies, parental education, number of siblings, maternal smoking, pet ownership, indoor humidity and heating fuels, farming as parental occupation was significantly associated with lower rates of sneezing attacks during pollen season (adjusted OR 0.34, 95% CI 0.12-0.89) and atopic sensitization (adjusted OR 0.31, 95% CI 0.13-0.73) whereas the association with wheeze (adjusted OR 0.77 95% CI 0.38-1.58) and itchy skin rash (adjusted OR 0.86, 95% CI 0.49-1.50) was not statistically significant. The risk of atopic sensitization was lower in children from full-time farmers (adjusted OR 0.24, 95% CI 0.09-0.66) than from part-time farmers (adjusted OR 0.54, 95% CI 0.15-1.96)., Conclusion: Factors directly or indirectly related to farming as parental occupation decrease the risk of children becoming atopic and developing symptoms of allergic rhinitis.

The primary objective of the study was to determine the impact of the identity of the respondent (parents versus adolescents) on prevalence estimates of asthma symptoms in Swiss adolescents. In addition, factors influencing agreement between parents' and adolescents' responses to the same questions were analysed. One thousand three hundred and seventy-four (78.4%) adolescents, aged 14 years, self-completed a questionnaire at school based on the International Study of Asthma and Allergy in Childhood (ISAAC) core questions on wheezing and asthma. The same questions were incorporated into a questionnaire to be completed by the parents at home. The adolescents' self-reported prevalence rates of current asthma symptoms and "asthma ever" were significantly higher than those obtained from the parental questionnaires. 856 (62.6%) parental questionnaires were filled in by parents without the help of the adolescents, 460 (37.4%) were completed by parents and adolescents and 51 (3.7%) were completed by the adolescents without the parents. Prevalence rates were higher when parents and adolescents completed the questionnaire jointly than when questionnaires were completed by parents alone. The level of agreement between parental and self-completed questionnaires was moderate to low (kappa coefficients 0.22-0.68). Agreement between parental and adolescents reports of asthma symptoms was best when questionnaires were completed jointly by parents and adolescents, when the adolescent was a girl, when a family history of asthma was recorded, when the adolescent was a non-smoker, and when the parental education was high. We conclude that the higher reporting of prevalence rates of current asthma symptoms by adolescents compared to reporting by their parents demonstrates the need to take the respondent to a questionnaire into account when comparisons are made between prevalence studies. The results also suggest that factors related to the family milieu influence symptom reporting.

The evidence for the adverse health effects of today's "normal" air pollution relies heavily on epidemiologic studies. Given the major impact of these effects on environmental, economic and social policy, the causality of epidemiologic findings becomes a central issue. The scientific process of establishing causality based on the air pollution epidemiology literature is reviewed. It consists of two steps: first, the quality and validity of each epidemiologic study must be rigorously assessed (design, selection, confounding); second, the overall evidence across all valid studies must be appraised. Of major importance are the consistency of results between replicate studies and the coherence of effects across a variety of different pathophysiologically or logically interrelated epidemiologic health outcomes, such as respiratory symptoms, exacerbations of respiratory diseases, use of health care, sick absenteeism, or, among the most sensitive subjects, mortality. Demonstration of a dose-response association is crucial and has been shown in many studies. Valid studies may use varied indicators of the air pollution mixtures, such as particulate matter, NO2, SO2, or others. However, epidemiology is incapable of investigating the biologic pathophysiologic mechanisms, which require experimental studies. Such studies may increase the biologic plausibility of epidemiologic findings. Given the common sources of many of the air pollution indicators used in epidemiology, a knowledge of pathophysiologic mechanisms is not a prerequisite for public health action aimed at improving air quality in cities.

Unlabelled: The primary aim of the study was to assess the validity of the ISAAC core questions on rhinitis in a population of Swiss school children by comparing them to skin prick test results. Second, the positive predictive value in detecting atopy among children with rhinitis symptoms was determined. Third, agreement between parental reports of hay fever and rhinitis symptoms was evaluated, since earlier Swiss prevalence surveys had exclusively relied on reported hay fever., Material and Methods: Two thousand nine hundred and fifty-four (81.2%) parents of 7, 10 and 14-year old children filled in an exhaustive questionnaire which included the ISAAC core questions on rhinitis. Two thousand one hundred and twenty children also underwent skin prick testing against six common aeroallergens (grass mixture, birch, mugwort, D. pteronyssinus, cat and dog dander). The analysis is restricted to children with both questionnaire data and skin prick test results., Results: Sensitization to any allergen was most strongly associated with reported hay fever (OR = 5.7, 95% CI 4.4-7.4), nose problems accompanied by itchy-watery eyes (OR = 4.4, 95% CI: 3.3-5.7), symptoms occurring only during pollen season (March through September) (OR = 4.9, 95% CI: 3.6-6.5) and a combination of these latter two symptoms (OR = 5.8, 95% CI: 4.1-8.1). The association was stronger for a sensitization to outdoor allergens than for indoor allergens. The specificity of the various questions was high, ranging from 77.5% to 97.6%, but the sensitivity was low (2.6% to 42.7%). The positive predictive value for atopy among children with symptoms was 63% for sneezing accompanied by itchy-watery eyes, 67% for symptoms occurring only during the pollen season and 70% for reported hay fever. However, agreement between reported rhinitis symptoms and hay fever was only moderate. About one third of the children with symptoms indicative of seasonal rhinitis did not report the label "hay fever"., Conclusions: We conclude from our analyses that the ISAAC core questions on rhinitis are highly specific and therefore useful in excluding atopy. In addition they have a high positive predictive value in detecting atopy among children with symptoms, but they are not helpful for detecting atopy in a general population of children (low sensitivity). To monitor time trends in the prevalence of allergic rhinitis in Switzerland, questions on rhinitis symptoms as well as on the diagnostic label "hay fever" have to be included in a questionnaire because they contain complementary information since under-diagnosis of allergic rhinitis is common.

The impact of long-term exposure to air pollution on respiratory and allergic symptoms and illnesses was assessed in a cross-sectional study of schoolchildren (ages 6 to 15 yr, n = 4,470) living in 10 different communities in Switzerland. Air pollution measurements (particulate matter less than 10 microns in diameter [PM10], nitrogen dioxide [NO2], sulfur dioxide [SO2], and ozone) and meteorologic data were collected in each community. Reported symptom rates of chronic cough, nocturnal dry cough, and bronchitis, adjusted for individual risk factors, were positively associated with PM10, NO2, and SO2. The strongest relationship was observed for PM10 (adjusted odds ratios for chronic cough, nocturnal dry cough, and bronchitis between the most and the least polluted community for PM10 were 3.07 [95% CI: 1.62 to 5.81], 2.88 [95% CI: 1.69 to 4.89], and 2.17 [95% CI: 1.21 to 4.89], respectively). The high correlation between the average concentrations of the pollutants makes the assessment of the relative importance of each pollutant difficult. No association between long-term exposure to air pollution and classic asthmatic and allergic symptoms and illnesses was found. There was some indication that frequency of fog is a risk factor of chronic cough and bronchitis, independent of air pollution. In conclusion, this study provides further evidence that rates of respiratory illnesses and symptoms among children augment with increasing levels of air pollution even in countries like Switzerland with moderate average air pollution concentrations.

Unlabelled: This report focuses on the occurrence of middle ear effusion in children with acute otitis media (n = 62), upper respiratory tract infection (n = 81) as well as in healthy control children (n = 152). Data are reported in age categories 0-4 and 5-13 years. Middle ear effusion was found in 86% of children with acute otitis media, 49% of children with upper respiratory infection and 13% of healthy children. The younger the child, the more likely the presence of middle ear effusion in all groups. Acute otitis media and upper respiratory tract infection were clinically indistinguishable in infants., Conclusion: Middle ear effusion is not generally a particularly significant clinical problem in children.

This study was conducted in Switzerland between May and October 1989 to assess possible decrements in lung function occurring as a result of 10 minute exposure to ambient air containing different ozone concentrations. Once a month, 128 children in two different areas of Southern Switzerland (Chiasso and Aurigeno) had a pulmonary function test before and after a standardized 10 minute exercise (pulse rate, 170/min) on a cycle ergometer, outdoors. Ozone concentrations were similar in both areas, ranging from 40 to 157 micrograms/m3 (1/2h means) during the exercise tests. The two communities differed with respect to long-term average pollution levels. The mean NO2 concentration over the six months study period was 70 micrograms/m3 in Chiasso and 18 micrograms/m3 in rural Aurigeno. Of the eligible children 85% participated and attended 4-6 tests. Parents completed a standardized questionnaire on family background, home characteristics and the child's early and present illness history. A total of 500 acceptable pairs of spirograms and corresponding ozone concentrations (average 3.8 per child) were available for analysis. Regressions of each individual's pre-post differences of FVC, FEV1 and peak flow on ozone concentrations measured during the outdoor exercise indicated that elevated ozone levels significantly reduced peak flow values. Adjustments for temperature and relative humidity increased the magnitude of the peak flow slopes. The average adjusted regression coefficient for delta-peak flow on ozone was -2.28 mL/s/micrograms/m3 (95% CI, -0.57 -3.99). It is noteworthy that the observed relationships occurred at ozone concentrations below 160 micrograms/m3 and after an exercise duration of only 10 minutes.

The objective of this study was to assess to what extent the subjective annoyance is influenced by the actually measured or calculated street traffic noise and by sociodemographic factors. In the study on air pollution and health in Basle a representative sample of 1033 families with children up to five years were asked how they perceived street traffic noise. The extent of annoyance was assessed with a scale from 0 (no annoyance) to 10 (unbearably annoyed). The actual noise levels were taken from the official noise-register. Nearly 30% of the families were exposed to > 65 dB(A) in daytime. Immigrant families as well as participants with low education more frequently lived in streets with higher noise levels than Swiss families or participants with higher education. 16.4% considered themselves heavily annoyed by traffic noise (scale 8-10). The proportion of heavily annoyed participants was positively correlated with the actual noise levels, the slope was steepest at a noise level between 60-65 dB(A). By means of a multiple regression it could be shown that, adjusting for education level and city district, the actual noise level was the best predictor of subjective annoyance.

A diary study on a random sample of 625 Swiss children aged 0 to 5 yr was conducted in two cities in Switzerland to investigate the association between air pollution and respiratory symptoms. Total suspended particulates (TSP), SO2 and NO2 were measured by city monitor. In addition, passive samplers inside and outside the home measured NO2 concentration during the 6 wk each child was on the diary. Diaries were filled out by parents, and 20% were validated with the attending pediatrician's case notes. Incidence and duration of symptom episodes were examined separately. The study included any episode, episodes of coughing without runny nose, upper respiratory episodes, and episodes of breathing difficulty. In regressions using 6-wk average pollution that controlled for medical history, NO2 measured outdoors but not indoors was associated with the duration of any symptom. Total suspended particulates were a more significant predictor of duration of any symptom than NO2. The 6-wk average TSP was significantly associated with incidence of coughing episodes and marginally significant as a predictor of upper respiratory episodes. Previous day's TSP was a significant predictor of incidence of upper respiratory symptoms. Annual average of NO2 was associated with the duration of any episode and of upper respiratory episodes. We conclude that the incidence and duration of respiratory symptom episodes are likely associated with particulate concentrations and duration may be associated with NO2.

The purpose of the present statistical analysis was the assessment of the relation between time series of environmental factors and of frequencies of diseases of the respiratory system in pre-school children. During about one year, daily measurements of air pollutants and climatic variables were taken. During the same period of time two series of medical data were collected: (i) The daily relative number of pre-school children, exhibiting diseases of the respiratory tracts who either came to the outpatients' clinic of the children's hospital or were reported by paediatricians in Basle (ENTRIES). (ii) The daily relative frequency of symptoms of the respiratory tracts observed in a group of randomly selected pre-school children (SYMPTOMS).By means of transfer function models the relation between the two target variables and the 'explaining' variables was analysed. Several practical problems did arise: Choice of the appropriate transformation of the different series, interpretation of the crosscorrelation function using different methods of 'prewhitening', time splitting and nonstationarity of the crosscorrelation structure. In particular, it was found that after prewhitening the crosscorrelation function between the explanatory series SO2 and the response series SYMPTOMS changes with time. While during the 'winter period' an instantaneous relation between these two series (and to a lesser extent between NO2 and SYMPTOMS) was identified, no such relation was found for the other seasons.

The department of social and preventive medicine of the University of Basle is conducting an epidemiologic study on the health effect of air pollution on preschool children. Nitrogen dioxide in childrens' immediate surrounding measured with personal samplers is used as reference substance for air pollution. Meteorologic and Data on air pollution of all permanent air quality control stations are included in the analysis. Health data are collected by means of a diary in which parents record daily respiratory symptoms of their child. Physicians in pediatric services record daily attendance of children with respiratory diseases.

A one year study on a random sample of 1225 Swiss children aged 0-5 years was conducted in four different areas (two urban, one suburban and one rural) of Switzerland to investigate the relationship between air pollution and respiratory symptoms. For each child daily symptoms over a six week period were recorded by their parents in the form of a standard diary and air pollution was assessed by personal NO2-samplers. 20% of the diaries were validated by comparison with the attending pediatrician's case-notes and showed good agreement (87%). The frequency of respiratory symptoms per child per day was found to increase with increasing levels of NO2 measured outdoors, but not with NO2 concentration indoors (when other indoor sources for NO2 where present). Possible other factors were accounted for by multiple regression analysis and the variables "season" and "child's susceptibility to colds" also showed a significant association with respiratory symptoms. But the relationship between NO2 outdoors and respiratory symptoms per child per day remained statistically significant. The multiple regression model explains 7% of the total variability. The result indicates that air pollution is a contributory factor in the development of respiratory symptoms in children.

Children are particularly susceptible for respiratory diseases, this is why studies on health effects of air pollution are often investigating children. Children have some other advantages: they do not smoke and they are not exposed to potentially noxious environment at work, also they spend their time fairly constantly in their usual environment. Studies from England and the United States show higher incidence of acute and a higher prevalence of chronic respiratory disease in children living in areas with higher concentration of air pollutants than in groups living in areas with lower concentration of pollutants. Some studies show these effects in concentration similar to those observed in swiss townships. Nevertheless specific studies in Switzerland are indicated in order to investigate the effect of the particular composition of pollutants in Switzerland and to assess effects of future possible improvements of the air quality.