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ABSTRACT: Our aim was to study the association of smoking habits and environmental tobacco smoke exposure (ETS) with bronchial hyperresponsiveness (BHR).A random sample of 292 adults was examined with a structured interview, spirometry, skin prick tests, FeNO (fractional exhaled nitric oxide) and bronchial histamine challenge.A large majority of subjects with BHR were smokers or ex-smokers. Starting to smoke before 20 years of age was significantly associated with BHR, as did current smoking, the quantity of smoking, and ETS. The severity of BHR increased significantly with increasing pack years (p<0.001). Current smokers with decreased lung function were at a particularly high risk for BHR. Impaired FEV1 and MEF50 were independent determinants for more severe BHR regardless of age. In multivariate analysis, smoking remained as an independent determinant for BHR after adjustment for impaired lung function and other co-variates: 15 or more pack years yielded an OR 3.00 (95%CI 1.33-6.76) for BHR. The association between BHR and FeNO was dependent on smoking habits.The results indicate that smoking is a significant risk factor for BHR with a dose-dependent pattern and that the severity of BHR increases with pack years. The findings strongly suggest assessment of smoking habits in subjects with BHR.
European Respiratory Journal 05/2013; · 5.89 Impact Factor
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Jonas Eriksson,,
Linda Ekerljung,,
Britt-Marie Sundblad,,
Jan Lötvall,,
Kjell Torén,,
Eva Rönmark,,
Kjell Larsson,, Bo Lundbäck
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ABSTRACT: Background
The harmful effects of tobacco smoke on human health, including respiratory health, are extensive and well documented. Previous data on the effect of smoking on rhinitis and allergic sensitization are inconsistent. We sought to investigate how smoking correlates with prevalence of allergic and chronic rhinitis among adults in Sweden.
Methods
The study population comprised 27 879 subjects derived from three large randomly selected cross-sectional population surveys conducted in Sweden between 2006 and 2008. The same postal questionnaire on respiratory health was used in the three surveys, containing questions about obstructive respiratory diseases, rhinitis, respiratory symptoms and possible determinants of disease, including smoking habits. A random sample from one of the cohorts underwent a clinical examination including skin prick testing.
Results
Smoking was associated with a high prevalence of chronic rhinitis in both men and women and a low prevalence of allergic rhinitis in men. These associations were dose dependent and remained when adjusted for a number of possible confounders in multiple logistic regression analysis. Prevalence of chronic rhinitis was lowest in nonsmokers and highest in very heavy smokers (18.5% vs 34.5%, P < 0.001). Prevalence of sensitization to common airborne allergens was lower in current smokers (25.9%, P = 0.008) and ex-smokers (28.2%, P = 0.022) than in nonsmokers (38.5%).
Conclusion
We found that smoking was associated with a high prevalence of chronic rhinitis in both sexes and a low prevalence of allergic rhinitis in men. The associations were dose dependent and remained when adjusting for several possible confounders.
Allergy 01/2013; · 6.27 Impact Factor
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ABSTRACT: In contrast to asthma and rhinitis, few studies among adults investigating the prevalence and risk factors of eczema have been published.
To investigate the prevalence and risk factors of eczema among adults in West Sweden. A further aim was to study the associations between asthma, rhinitis and eczema.
A questionnaire on respiratory health was mailed in 2008 to 30,000 randomly selected subjects in West Sweden aged 16-75 years; 62% responded. The questionnaire included questions about eczema, respiratory symptoms and diseases and their possible determinants. A subgroup of 669 subjects underwent skin prick testing against common airborne allergens.
'Eczema ever' was reported by 40·7% and 'current eczema' by 11·5%. Both conditions were significantly more common among women. The prevalence decreased with increasing age. The coexistence of both asthma and rhinitis with eczema was common. The main risk factors were family history of allergy and asthma. The dominant environmental risk factor was occupational exposure to gas, dust or fumes. Smoking increased the risk. Eczema was associated with urbanization, while growing up on a farm was associated with a decreased risk. Added one by one to the multivariate model, asthma, allergic rhinitis and any positive skin prick test were associated with eczema.
Eczema among adults is a common disease with more women than men having and having had eczema. Eczema is associated with other atopic diseases and with airway symptoms. Hereditary factors and exposure to gas, dust and fumes are associated with eczema.
British Journal of Dermatology 02/2012; 166(6):1301-8. · 3.67 Impact Factor
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P S Bakke,
E Rönmark,
T Eagan,
F Pistelli,
I Annesi-Maesano,
M Maly,
M Meren,
P Vermeire Dagger,
J Vestbo,
G Viegi,
J Zielinski, B Lundbäck
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ABSTRACT: The prevalence of chronic obstructive pulmonary disease (COPD) has been extensively studied, especially in Western Europe and North America. Few of these data are directly comparable because of differences between the surveys regarding composition of study populations, diagnostic criteria of the disease and definitions of the risk factors. Few community studies have examined phenotypes of COPD and included other ways of characterising the disease beyond that of spirometry. The objective of the present Task Force report is to present recommendations for the performance of general population studies in COPD in order to facilitate comparable and valid estimates on COPD prevalence by various risk factors. Diagnostic criteria in epidemiological settings, and standardised methods to examine the disease and its potential risk factors are discussed. The paper also offers practical advice for planning and performing an epidemiological study on COPD. The main message of the paper is that thorough planning is worth half the study. It is crucial to stick to standardised methods and good quality control during sampling. We recommend collecting biological markers, depending on the specific objectives of the study. Finally, studies of COPD in the population at large should assess various phenotypes of the disease.
European Respiratory Journal 12/2011; 38(6):1261-77. · 5.89 Impact Factor
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D Hastan,
W J Fokkens,
C Bachert,
R B Newson,
J Bislimovska,
A Bockelbrink,
P J Bousquet,
G Brozek,
A Bruno,
S E Dahlén, [......], B Lundbäck,
E Salagean,
A Todo-Bom,
P Tomassen,
E Toskala,
C M van Drunen,
J Bousquet,
T Zuberbier,
D Jarvis,
P Burney
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ABSTRACT: Chronic rhinosinusitis (CRS) is a common health problem, with significant medical costs and impact on general health. Even so, prevalence figures for Europe are unavailable. In this study, conducted by the GA²LEN network of excellence, the European Position Paper on Rhinosinusitis and nasal Polyps (EP³OS) diagnostic criteria are applied to estimate variation in the prevalence of Chronic rhinosinusitis (CRS) for Europe.
A postal questionnaire was sent to a random sample of adults aged 15-75 years in 19 centres in Europe. Participants reported symptoms of CRS, and doctor diagnosed CRS, allergic rhinitis, age, gender and smoking history. Definition of CRS was based on the EP³OS diagnostic criteria: the presence of more than two of the symptoms: (i) nasal blockage, (ii) nasal discharge, (iii) facial pain/pressure or (iv) reduction in sense of smell, for >12 weeks in the past year--with at least one symptom being nasal blockage or discharge.
Information was obtained from 57,128 responders living in 19 centres in 12 countries. The overall prevalence of CRS by EP³OS criteria was 10.9% (range 6.9-27.1). CRS was more common in smokers than in nonsmokers (OR 1.7: 95% CI 1.6-1.9). The prevalence of self-reported physician-diagnosed CRS within centres was highly correlated with the prevalence of EP³OS-diagnosed CRS.
This is the first European international multicentre prevalence study of CRS. In this multicentre survey of adults in Europe, about one in ten participants had CRS with marked geographical variation. Smoking was associated with having CRS in all parts of Europe.
Allergy 05/2011; 66(9):1216-23. · 6.27 Impact Factor
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ABSTRACT: To examine the incidence of allergic rhinoconjunctivitis and asthma, and to assess allergic rhinoconjunctivitis as a risk factor for incident asthma, we performed a 11-year follow-up postal survey.
The original study population was a random population sample of 8000 inhabitants of Helsinki aged 20-69 years in 1996. Participants in the first postal questionnaire survey, 6062 subjects, were invited to this follow-up study, and provided 4302 (78%) answers out of 5484 traced subjects in 2007.
Cumulative incidence of asthma from 1996 to 2007 was 4.0% corresponding to an annual incidence rate of 3.7/1000/year. After exclusion of those with asthma medication or physician-diagnosed chronic bronchitis or COPD at baseline in 1996, the cumulative incidence decreased to 3.5% (incidence rate 3.2/1000/year), and further to 2.7% (2.5/1000/year) when also those reporting recurrent wheeze or shortness of breath during the last year in 1996 were omitted from the population at risk. Remission of asthma occurred in 43 subjects and was 16.9% over 11 years. Cumulative 11-year incidence of allergic rhinoconjunctivitis was 16.9% corresponding to 16.8/1000/year, and cumulative remission was 18.1%. Incidence of allergic rhinoconjunctivitis was significantly lower among those who had lived in the countryside or on a farm during the first 5 years of life, but this was not true for asthma. In multivariate analysis, farm living during the first 5 years of life was protective for the development of allergic rhinoconjunctivitis, OR 0.75 (95%CI 0.57-0.99). Allergic rhinoconjunctivitis was a significant independent risk factor for incident asthma, OR 2.15 (95%CI 1.54-3.02). In the cohort, the prevalence of rhinoconjunctivitis increased from 38.0% in 1996 to 40.9% in 2007, physician-diagnosed asthma from 6.8% to 9.4%, while current smoking decreased from 31.3% to 23.3%.
Incidence of allergic rhinoconjunctivitis was higher than in earlier studies, while asthma incidence remained on similar level, both being significantly higher in women. Allergic rhinoconjunctivitis doubled the risk for incident asthma.
Respiratory medicine 05/2011; 105(10):1449-56. · 2.33 Impact Factor
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ABSTRACT: Epidemiological questionnaires have failed to identify individuals with severe asthma. The extent of symptoms of asthma can, however, be easily established in epidemiology, by identification of multiple symptoms. We hypothesise that reporting of multiple symptoms of asthma reflects uncontrolled disease and is a sign of more severe asthma. The aims of the current study were, therefore, to determine the prevalence and determinants of multi-symptom asthma. A postal questionnaire was sent to 30,000 randomly selected individuals aged 16-75 yrs. A subgroup underwent clinical examinations. Multi-symptom asthma was defined as reported physician-diagnosed asthma, use of asthma medication, recurrent wheeze, attacks of shortness of breath and at least one additional respiratory symptom. The prevalence of multi-symptom asthma was 2.0%, and it was more common among females (2.4 versus 1.5%; p<0.001) and those with a body mass index >30 kg · m(-2). Multi-symptom asthmatics had lower forced expiratory volume in 1 s, higher exhaled nitric oxide fraction and more pronounced hyperresponsiveness. Family history of both asthma and allergy (OR 7.3), and occupational exposure to gas dust or fumes (OR 2.0) were also significant risk factors. Multi-symptom asthmatics comprise 2% of the general population; multi-symptom asthma is related to signs of more severe disease and could be used as an epidemiological marker of disease severity.
European Respiratory Journal 02/2011; 38(4):825-32. · 5.89 Impact Factor
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European Respiratory Journal 07/2010; 36(1):1-3. · 5.89 Impact Factor
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ABSTRACT: An increase in the prevalence of asthma has previously been reported worldwide. However, the current trend is debatable.
To assess changes in the prevalence of asthma and respiratory symptoms in a defined study area in Stockholm, Sweden, using identical methods.
A questionnaire was sent by mail in 1996 and 2007 to randomly selected subjects aged 20-69 years. On both occasions, 8000 subjects received the questionnaire, with response rates of 72% and 68%, respectively. Questions on asthma, respiratory symptoms, asthma medication and possible determinants were included. Logistic regression analysis was used to assess determinants.
Ever asthma increased from 8.7% in 1996 to 11.0% in 2007 and physician-diagnosed asthma from 7.6% to 9.3%. The proportion of asthma patients reporting one to two symptoms increased by 14% during the study period. There were few significant changes in the prevalence of respiratory symptoms: wheeze in the previous 12 months (15.9-17.3%), wheezing with breathlessness apart from cold (3.2-4.1%) and recurrent wheeze (8.3-6.8%). There was no major difference in the risk factor pattern between the surveys.
An increase in the prevalence of asthma with few symptoms as well as an unchanged prevalence of symptoms was demonstrated, which may indicate a change in diagnostic practices.
The international journal of tuberculosis and lung disease: the official journal of the International Union against Tuberculosis and Lung Disease 06/2010; 14(6):764-71. · 2.73 Impact Factor
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ABSTRACT: Various studies have reported a low prevalence of allergic rhinitis in farmers and farmers' children. We sought to investigate whether the protective effect of childhood farm environment is conserved throughout adulthood and how it corresponds to different degrees of urbanization.
A questionnaire on respiratory health was mailed in 2008 to 30,000 randomly selected subjects aged 16-75 in West Sweden, 29,218 could be traced and 18,087 (62%) responded. The questionnaire included questions on allergic rhinitis, asthma, respiratory symptoms and possible determinants.
When stratified into age groups of 15 years, subjects that lived on a farm during their first 5 years of life had a lower prevalence of allergic rhinitis in all groups, even among the oldest (61-75 years). The negative correlation between childhood farm living and prevalence of allergic rhinitis was similar in 46-75 years of age (OR 0.82; 95% CI 0.70-0.95) as in 16-45 years of age (OR 0.78; 0.64-0.95). There was a significant trend of increasing prevalence of allergic rhinitis with increasing degree of urbanization independent of the effect of childhood farm living.
We found a lifelong protective effect of childhood farm living on the prevalence of allergic rhinitis. In addition, we found an increasing prevalence of allergic rhinitis with increasing degree of urbanization both in those raised on a farm and those not, thus emphasizing the influence of both childhood and adult exposure for the development of allergic disease.
Allergy 05/2010; 65(11):1397-403. · 6.27 Impact Factor
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ABSTRACT: Recent data suggest that the previously rising trend in childhood wheezing symptoms has plateaued in some regions. We sought to investigate sex-specific trends in wheeze, asthma, allergic conditions, allergic sensitization and risk factors for wheeze.
We compared two population-based cohorts of 7 to 8-year olds from the same Swedish towns in 1996 and 2006 using parental expanded ISAAC questionnaires. In 1996, 3430 (97%) and in 2006, 2585 (96%) questionnaires were completed. A subset was skin prick tested: in 1996, 2148 (88%) and in 2006, 1700 (90%) children participated.
No significant change in the prevalence of current wheeze (P = 0.13), allergic rhinitis (P = 0.18) or eczema (P = 0.22) was found despite an increase in allergic sensitization (20.6-29.9%, P < 0.01). In boys, however, the prevalence of current wheeze (12.9-16.4%, P < 0.01), physician-diagnosed asthma (7.1-9.3%, P = 0.03) and asthma medication use increased. In girls the prevalence of current symptoms and conditions tended to decrease. The prevalence of all studied risk factors for wheeze and asthma increased in boys relative to girls from 1996 to 2006, thus increasing the boy-to-girl prevalence ratio in risk factors.
The previously reported increase in current wheezing indices has plateaued in Sweden. Due to increased diagnostic activity, physician diagnoses continue to increase. Time trends in wheezing symptoms differed between boys and girls, and current wheeze increased in boys. This was seemingly explained by the observed increases in the prevalence of risk factors for asthma in boys compared with girls. In contrast to the current symptoms of wheeze, rhinitis or eczema, the prevalence of allergic sensitization increased considerably.
Allergy 10/2009; 65(1):48-55. · 6.27 Impact Factor
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ABSTRACT: Epidemiological population-based studies about lung health in Sweden have mostly been focused on obstructive airway diseases. From the 1960s to the 1980s, the epidemiological studies were cross-sectional, aiming at the study of the prevalence of asthma, chronic bronchitis and respiratory symptoms and their associations with mainly demographic data. With the exception of highly stratified samples, for instance the men born on 1913 in Gothenburg and cohorts of occupational groups or work places, general population-based cohorts for studies of lung health in adults are still not very common. Two large-scale studies of lung health have been in progress in Sweden for more than 20 years; the Obstructive Lung Disease in Northern Sweden (OLIN) Studies, which started in 1985, and the Swedish part of European Community Respiratory Health Survey (ECRHS) since 1989 with the follow-up survey labelled Respiratory Health in Northern Europe (RHINE). During the 1990s the comparative studies between Finland, Estonia and Sweden (The FinEsS Studies) started. These and other studies will be reviewed in the following exemplifying change of aims and study designs over time as well as change of focus of risk factors under study.
The Clinical Respiratory Journal 10/2008; 2 Suppl 1:2-9. · 1.06 Impact Factor
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ABSTRACT: Prospective studies of asthma and allergic conditions based on the general population are scarce.
To summarize the methods and main results from a prospective study among school children.
In 1996, a cohort of 3525 children aged 7/8 years in Northern Sweden were invited to a questionnaire survey using an expanded ISAAC protocol, and 97% participated. The cohort has been followed up yearly with high participation rate. Skin prick tests were conducted 1996, 2000 and 2006/2007. Allergens in dust from homes and schools have been analyzed. Sub samples have participated in interviews, lung function tests, bronchial hyper reactivity test, and analyses of IgE and IgG antibodies in serum.
The prevalence of asthma was 6% at age 7-8 years and increased by age. The incidence of physician-diagnosed asthma after the age of 7-8 years was around 1/100/year. The prevalence of positive skin prick test increased from 21% at age 7-8 to 30% at age 11-12 years. Remission of allergic sensitization was rare, while asthma remission was 5% yearly. The main risk factor for asthma and allergic sensitization increased in importance with increasing age. Allergic and non-allergic asthma had different risk factor pattern. Environmental risk factors decreased in impact after the age of 7. Avoidance of pets at home did not protect from asthma or allergic sensitization.
The study includes important sources of data for further longitudinal analyses that will contribute to the understanding of the development and the nature of asthma and allergic sensitization.
The Clinical Respiratory Journal 10/2008; 2 Suppl 1:26-33. · 1.06 Impact Factor
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ABSTRACT: Most epidemiological data on chronic obstructive pulmonary disease (COPD) are cross-sectional, and the longitudinal course of disease on population bases is incompletely described.
To describe an epidemiological study designed to follow the longitudinal course of disease in chronic obstructive lung disease, COPD, including co-morbidity and mortality and further, to evaluate the impact of COPD on quality of life and health economics.
From the Obstructive Lung Disease in Northern Sweden studies database cohorts I-IV, all subjects with COPD according to the Global Initiative for Chronic Obstructive Lung Disease spirometric criteria, FEV(1)/FVC < 0.70 (n = 993), were identified together with a similar size age- and gender-matched control group. The study population was invited to a yearly examination starting in year 2005. The examinations included structured interview, spirometry with reversibility testing, oxygen saturation and health-related quality of life questionnaires.
On the first year, 83% of the population was examined, and the subjects unable to attend the examination were interviewed by telephone. Altogether, 91% of the original study population participated (95% of all subjects were alive at the end of the first year). Mortality was significantly higher among subjects with COPD, 5.1%, compared with controls, 3.0% (P = 0.018).
The study design including cases of COPD representative of COPD by disease severity in the general population and a similar sized control group, together with a high participation rate in the first study year, creates excellent conditions for evaluating the impact of COPD on population bases, and to follow the longitudinal course of disease in COPD.
The Clinical Respiratory Journal 10/2008; 2 Suppl 1:64-71. · 1.06 Impact Factor
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ABSTRACT: Two major studies on asthma and respiratory symptoms are presently in progress in Stockholm. The FinEsS-studies has been ongoing since 1996, with a follow-up study preformed in 2006 and a new cohort selected in 2007. The FinEsS studies focus on prevalence and incidence of asthma and respiratory symptoms in a general population. Clinical follow-up surveys will also target COPD. Further aims include remission and relapse of disease and symptoms and their determinants. The Stockholm adult Asthma Study (SaAS) began in the spring of 2007 and data is being collected presently. The SaAS study focus on the medical care and medication given to asthmatics in Stockholm, and the study population consists of asthmatics found in the two Swedish cohort studies.
The Clinical Respiratory Journal 10/2008; 2 Suppl 1:127-8. · 1.06 Impact Factor
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H Bisgaard,
S Pedersen,
J Anhøj,
L Agertoft,
G Hedlin,
A Gulsvik,
L Bjermer,
K H Carlsen,
L Nordvall, B Lundbäck,
G Wennergren,
S Werner,
K Bønnelykke,
S T Weiss
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ABSTRACT: Asthma patients exhibit an increased rate of loss of lung function. Determinants to such decline are largely unknown and the modifying effect of steroid therapy is disputed. This cross-sectional study aimed to elucidate factors contributing to such decline and the possible modifying effect of steroid treatment.
We analyzed determinants of lung function and airway hyperresponsiveness (AHR) in a Scandinavian study of 2390 subjects from 550 families. Families were selected for the presence of two or more asthmatic children as part of a genetic study, Scandinavian Asthma Genetic Study (SAGA).
The primary analysis studied the association between the lung function and delay of inhaled corticosteroids (ICS) after asthma diagnosis among asthmatic children and young adults with a history of regular ICS treatment (N=919). FEV(1) percent predicted (FEV(1)% pred) was 0.25% lower per year of delay from diagnosis until treatment (p=0.039). This association was significantly greater in allergy skin prick test negative children. There was no significant influence of gender, age at asthma onset, or smoking. In the secondary analysis of the whole population of 2390 asthmatics and non-asthmatics, FEV(1)% pred was inversely related to having asthmatic siblings (-7.9%; p<0.0001), asthma diagnosis (-2.7%; p=0.0007), smoking (-3.5%; p=0.0027), and positive allergy skin prick test (-0.47% per test; p=0.012), while positively related to being of female gender (1.8%; p=0.0029). Risk of AHR was higher by having asthmatic siblings (OR 2.7; p<0.0001), being of female gender (OR 2.0; p<0.0001), and having asthma (OR 2.0; p<0.0001).
These data suggest that lung function is lower in asthmatics with delayed introduction of ICS therapy, smoking, and positive allergy skin prick test. Lung function is lower and AHR higher in female asthmatics and subjects with asthmatic siblings or established asthma.
Respiratory Medicine 07/2007; 101(7):1477-82. · 2.47 Impact Factor
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ABSTRACT: Methacholine tests were used in an epidemiologic study of the prevalence of asthma and chronic bronchitis in northern Sweden. Of 6610 subjects in three age groups from eight representative geographic areas in the northernmost province of Sweden, 5698 (86%) completed a postal questionnaire on respiratory symptoms, and 1506 underwent a structured interview and a lung function test. A total of 292 (5%) were diagnosed as having asthma. A subsample of 284 subjects (of 320 invited) classified at the interview as having asthma (n= 98) or as having respiratory symptoms that might be due to asthma but not fulfilling the interview criteria for the diagnosis of asthma (n= 186) underwent a methacholine test. Subjects who, before the interview study, already had a well-defined asthma diagnosis were not invited to the methacholine testing. Of those 98 subjects classified as having asthma, 61 % reacted to methacholine doses ≤ 4 mg/ml and 79% to doses ≤ 8 mg/ml, while the corresponding figures in the symptomatic but nonasthma group were 20% and 34%, respectively. The results show that a carefully performed structured interview accurately diagnoses asthma in epidemiologic studies. The methacholine tests provide important diagnostic information primarily in subjects in whom the medical history is equivocal.
Allergy 04/2007; 48(2):117 - 124. · 6.27 Impact Factor
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ABSTRACT: To assess the persistence of respiratory symptoms in ex-miners after cessation of mining exposure.
Population-based cross-sectional study using a postal questionnaire comparing prevalence of symptoms between ex-miners who had stopped mining at least 1 year before the study and referents not occupationally exposed to irritants or dust. Age, smoking and a family history of asthma were considered as possible confounders in the analysis.
A total of 206 ex-miners and 4,560 referents participated. Ex-miners had on average been working as miners for 13 years and had stopped mining 16 years before the study. Chronic productive cough and physician-diagnosed chronic bronchitis were significantly more common among ex-miners (P < 0.05 and <0.01, respectively). Furthermore, there was a trend that other respiratory symptoms were more common in ex-miners.
Ex-miners had an increased risk of chronic productive cough and physician-diagnosed chronic bronchitis many years after they had stopped working as a miner.
Occupational Medicine 09/2006; 56(6):380-5. · 1.14 Impact Factor
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ABSTRACT: The objective of this case-control study was to evaluate whether traffic-related air pollution exposure at home increases the risk of asthma in adults and to compare two commonly used exposure variables and differences between urban and rural living. Incident cases of asthma and matched controls of subjects aged 20-60 yrs were recruited in Luleå, Sweden. In total 203 cases and 203 controls were enrolled in the study. Exposure was estimated by traffic flow and measured levels of outdoor nitrogen dioxide (NO2) in the surrounding environment of each home, respectively. The relationship between measured levels of NO2 and traffic flow was studied using linear regression. The results indicated a nonsignificant tendency between living in a home close to a high traffic flow and an increased risk of asthma. The association between asthma and measured NO2 was weak and not significant, but the skin-prick test result acted as an effect modifier with a borderline significant association among positives. The correlation between traffic flow and outdoor NO2 was low. The results suggest that living close to high traffic flows might increase the asthma incidence in adults, while the tendency for nitrogen dioxide was only seen among atopics. Traffic flow and nitrogen dioxide had a lower than expected correlation.
European Respiratory Journal 08/2006; 28(1):75-81. · 5.89 Impact Factor
