Heat recovery ventilators prevent respiratory disorders in Inuit children

ArticleinIndoor Air 19(6):489-99 · August 2009with 509 Reads
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Abstract
Unlabelled: Inuit infants have high rates of reported hospitalization for respiratory infection, associated with overcrowding and reduced ventilation. We performed a randomized, double-blind, placebo controlled trial to determine whether home heat recovery ventilators (HRV) would improve ventilation and reduce the risk of respiratory illnesses in young Inuit children. Inuit children under 6 years of age living in several communities in Nunavut, Canada were randomized to receive an active or placebo HRV. We monitored respiratory symptoms, health center encounters, and indoor air quality for 6 months. HRVs were placed in 68 homes, and 51 houses could be analyzed. Subjects had a mean age of 26.8 months. Active HRVs brought indoor carbon dioxide concentrations to within recommended concentrations. Relative humidity was also reduced. Use of HRV, compared with placebo, was associated with a progressive fall in the odds ratio for reported wheeze of 12.3% per week (95%CI 1.9-21.6%, P = 0.022). Rates of reported rhinitis were significantly lower in the HRV group than the placebo group in month 1 (odds ratio 0.20, 95%CI 0.058-0.69, P = 0.011) and in month 4 (odds ratio 0.24, 95%CI 0.054-0.90, P = 0.035). There were no significant reductions in the number of health center encounters, and there were no hospitalizations. Use of HRVs was associated with in improvement in air quality and reductions in reported respiratory symptoms in Inuit children. Practical implications: Reduced ventilation is common in the houses of Inuit children in arctic Canada, and is associated with an increased risk of respiratory infection. Installation of HRV brings indoor carbon dioxide concentration, as a marker of adequate ventilation, to within recommended concentrations, although relative humidity is also reduced. Installation of HRV is associated with improvements in indoor air quality, and a reduced risk of wheezing and rhinitis not associated with cold air exposure in young Inuit children. Further research is required to explore traditional Inuit cultural attitudes about air movement in dwellings.

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    Since 1978 R-values of the building envelope of local houses have been continuously increased. Whole home mechanical ventilation systems are becoming more and more popular for New Zealand house owners. Positive pressure roof cavity ventilation systems are the most common type of ventilation systems used in thousands of local houses. To investigate winter indoor thermal conditions of mechanically ventilated Auckland houses with different R-value of insulation and glazing in their envelopes, two local houses built in 2000 and 2012 with positive pressure roof cavity ventilation systems are selected for field studies of winter indoor microclimatic conditions. The study not only identifies improvement of winter indoor thermal conditions of two local houses with increased R-value in their envelopes, associated with the updated New Zealand building standards or codes since 2000, but also the major problems of local housing thermal design according to the current building standards or codes in a climate with a mild and wet winter. Also, investigated are the impacts of a positive input ventilation system on winter indoor thermal comfort conditions of a house. The study compares and evaluates winter indoor thermal conditions of a house with or without a positive pressure ventilation system.
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    L’asthme est un grave problème de santé pour les enfants inuits et des Premières nations. Chez les enfants de moins d’un an, il faut distinguer l’asthme de la bronchiolite virale, anormalement fréquente chez les enfants autochtones du Canada. Chez les enfants de moins de six ans, le diagnostic dépend de la présence de symptômes classiques, de l’absence de caractéristiques atypiques et de la consignation de la réponse au traitement, notamment la réponse rapide et transitoire aux bronchodilatateurs. Chez les enfants plus âgés, il faut, dans la mesure du possible, déterminer la présence d’une obstruction réversible des voies aériennes par spirométrie afin de confirmer le diagnostic, ainsi qu’évaluer et corriger les déclencheurs environnementaux. L’utilisation régulière de corticoïdes en aérosol est la principale mesure à prendre pour maintenir un bon contrôle de l’asthme chez les enfants asthmatiques. Les clients et leur famille devraient recevoir une formation sur l’asthme. Il faut réévaluer régulièrement le contrôle aux visites de suivi dans des centres de santé et rajuster le traitement à la dose la plus basse possible pour le maintien de ce contrôle.
  • Article
    Inuit children in Nunavut, Canada, have high rates of lower respiratory tract infection (LRTI) early in life. Whether this commonly results in chronic respiratory symptoms later in life is unknown. A cross-sectional survey of 3- to 5-years-old Inuit children was conducted in all three regions of Nunavut, as part of the "Qanuippitali, what about us, how are we?" survey. Reported chronic cough and wheezing were common in preschool Inuit children, although reported asthma diagnosed by a healthcare professional was uncommon. The presence of smokers in the home tended to be associated with severe LRTI in the first 2 years of life. Reported wheezing as well as reported bronchitis or pneumonia in the previous 12 months was significantly associated with severe LRTI in the first 2 years of life. Reported wheezing was also strongly associated with reported bronchitis or pneumonia in the past 12 months. The prevalence of chronic moist cough could not be clearly assessed, due to limitations in the questionnaire. Severe LRTI in the first 2 years of life was associated with ongoing respiratory morbidity in preschool Inuit children, although symptoms appeared to lessen in severity over time.
  • Article
    The study of the prevalence and determinants of asthma and allergy in different populations may provide clues to their etiology. We describe airway function and its determinants among Inuit schoolchildren living in far Northern Quebec. We assessed the presence of airways hyperresponsiveness (AHR), defined as a 15% drop in FEV1 with exercise, airflow obstruction, as judged by a reduced FEV1/FVC, and atopy, as evidenced by skin test positivity to inhaled aeroallergens, among 509 Inuit aged mostly from 6 to 13 yr. Smoking by the children (31.9%) and their parents was common, including maternal smoking during pregnancy (79.5%). Atopy was found in only 5.3% of children. Apart from age, there were no significant associations between AHR and any of the determinants examined. Airflow obstruction was present among 7.7% of children and occurred most commonly among children with higher levels of salivary cotinine and in those with four or more lower respiratory illnesses in the first 2 yr of life. Asthma and atopy were uncommon in this population whereas evidence of chronic airflow obstruction was frequently found. Measures to reduce the spread of respiratory infection and prevention of smoking are likely to be of most benefit in improving respiratory health in these isolated communities.
  • Venmar Constructo 1.5. Available at
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    Care Med., 177, A615. YES Environment Technologies Inc. (2003) YES-206LH Series, Indoor Air Quality Monitor – Logger, Operation Manual. REV C. 12-3-2003. Delta, BC, Canada.
  • Venmar Constructo 1.5 Available at: http://www.expair.ca/en/ products-details/hrv_heat_recovery_ ventilation
    • Expair
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  • Exposure Guidelines for Residential Indoor Air Quality: A Report of the Federal-Provincial Advisory Committee on Environmental and Occupational Health
    Health Canada, (1989) Exposure Guidelines for Residential Indoor Air Quality: A Report of the Federal-Provincial Advisory Committee on Environmental and Occupational Health, Ottawa, Canada, Health Canada Publications/Communications.
  • Selfreported prevalence of asthma symptoms in children in Australia
    • N Pearce
    • S Weiland
    • U Keil
    • P Langridge
    • H R Anderson
    • D Strachan
    • A Bauman
    • L Young
    • P Gluyas
    • D Ruffin
    • J Crane
    • R Beasley
    Pearce, N., Weiland, S., Keil, U., Langridge, P., Anderson, H.R., Strachan, D., Bauman, A., Young, L., Gluyas, P., Ruffin, D., Crane, J. and Beasley, R. (1993) Selfreported prevalence of asthma symptoms in children in Australia, England, Germany and New Zealand: an international comparison using the ISAAC protocol, Eur. Respir. J., 6, 1455–1461.
  • Effect of improved ventilation in the homes of adults with house dust mite-sensitive asthma
    • G R Wright
    • R Chaudhuri
    • S Howleson
    • C Mcsharry
    • A D Mcmahon
    • J Thompson
    • I Fraser
    • E M King
    • M D Chapman
    • L Mcalpine
    • S Wood
    • N C Thomson
    Wright, G.R., Chaudhuri, R., Howleson, S., McSharry, C., McMahon, A.D., Thompson, J., Fraser, I., King, E.M., Chapman, M.D., McAlpine, L., Wood, S. and Thomson, N.C. (2008) Effect of improved ventilation in the homes of adults with house dust mite-sensitive asthma [abstract], Am. J. Respir. Crit.
  • Improvement in air quality parameters in intervention study homes of asthmatic children [abstract], Am
    • P F Rosenbaum
    • J L Abraham
    • G Siwinski
    • A Fernandez
    Rosenbaum, P.F., Abraham, J.L., Siwinski, G. and Fernandez, A. (2008) Improvement in air quality parameters in intervention study homes of asthmatic children [abstract], Am. J. Respir. Crit.
  • Article
    The aim of this study was to obtain quantitative information from published data on the association between environmental tobacco smoke (ETS) exposure and the prevalence of serious lower respiratory tract infections (LRTI) in infancy and early childhood. We identified 21 relevant publications on the relation between ETS and the prevalence of serious LRTI by reviewing reference lists in relevant reports and by conducting manual and computer searches (Medline database; Dissertation abstracts index of Xerox University Microfilms) of published reports between 1966 and 1995. Thirteen studies were included in a quantitative overview using random effects modeling to derive pooled odds ratios.Sensitivity analyses were conducted to test the decision rules used in extracting odds ratio data. The results of community and hospital studies are broadly consistent and show that the child of a parent who smokes is at approximately twice the risk of having a serious respiratory tract infection in early life that requires hospitalization. This association was pronounced in children younger than age two and diminished after the age of two. The combined odds ratio for hospitalization for lower respiratory tract infections in infancy or early childhood is 1.93 (95% CI 1.66–2.25); the combined odds ratio of prevalence of serious LRTI at age less than 2 years, between 0 and 6 years, and between 3 and 6 years were 1.71 (95% CI 1.33–2.20); 1.57 (1.28–1.91), and 1.25 (0.88–1.78), respectively. There was no evidence of heterogeneity across the studies in these combined odds ratios. We conclude that this meta-analysis provides strong evidence that exposure to ETS causes adverse respiratory health outcomes such as either a serious LRTI or hospitalization for LRTI. New public health campaigns are urgently needed to discourage smoking in the presence of young children. Pediatr Pulmonol. 1999; 27:5–13. © 1999 Wiley-Liss, Inc.
  • Article
    Although bronchiectasis has become a rare condition in U.S. children, it is still commonly diagnosed in Alaska Native children in the Yukon Kuskokwim Delta. The prevalence of bronchiectasis has not decreased in persons born during the 1980s as compared with those born in the 1940s. We reviewed case histories of 46 children with bronchiectasis.We observed that recurrent pneumonia was the major preceding medical condition in 85% of patients. There was an association between the lobes affected by pneumonia and the lobes affected by bronchiectasis. Eight (17%) patients had surgical resection of involved lobes.We conclude that the continued high prevalence of bronchiectasis appears to be related to extremely high rates of infant and childhood pneumonia. Pediatr Pulmonol. 2000;29:182–187. Published 2000 Wiley-Liss, Inc.
  • Article
    Full-text available
    Health care workers have long observed increased rates of hospital admissions for respiratory illness in infants from the northern regions of Canada. Particularly high rates have been reported in the Inuit population. The purpose of the present study was to compare rates of hospital admission in Inuit versus non-Inuit infants from the perspective of a single northern health region. A retrospective review of all hospital admissions for lower respiratory tract infections (LRTIs) in infants from the Northwest Territories and the Kitikmeot region of Nunavut between 2000 and 2004 was completed and admission rates were compared by health region. Hospital admission rates for LRTIs in infants were above the Canadian rate for all regions. The rate of hospital admission for LRTIs in infants from the Kitikmeot region of Nunavut was dramatically high at 590 hospital admissions/1000 live births in the first 12 months of life. The majority of hospitalized infants were previously healthy, non-breastfed term infants with no underlying disease. The rate of hospital admission in the Kitikmeot region of Nunavut is the highest reported in the current literature. The reason for such significant morbidity is difficult to explain and raises the question of an underlying predisposition to severe disease in this infant population. The question warrants further study to gain a better understanding of risk factors as well as the role of prevention.
  • Article
    An outbreak of adenovirus type 3 infection occurred in a hospital in 19 North American Indian infants and young children who were being treated for unrelated problems. Pneumonia occurred in 14 and was usually severe, with persistent signs of airway obstruction. Eleven of the 14 were followed periodically and complete medical reviews were conducted 8 to 10 years later. Ten had abnormal chest radiographs, and bronchography revealed bronchiectasis and minor airways changes in seven. In three cases there was clear evidence that these changes were directly related to the adenovirus type 3 infection. Pulmonary function studies showed a combination of restrictive and obstructive changes with minimal hypoxemia in most. Despite the presence of a persistent productive cough all were able to carry on a relatively normal life.
  • Article
    Many young children wheeze during viral respiratory infections, but the pathogenesis of these episodes and their relation to the development of asthma later in life are not well understood. In a prospective study, we investigated the factors affecting wheezing before the age of three years and their relation to wheezing at six years of age. Of 1246 newborns in the Tucson, Arizona, area enrolled between May 1980 and October 1984, follow-up data at both three and six years of age was available for 826. For these children, assessments in infancy included measurement of cord-serum IgE levels (measured in 750 children), pulmonary-function testing before any lower respiratory illness had occurred (125), measurement of serum IgE levels at nine months of age (672), and questionnaires completed by the children's parents when the children were one year old (800). Assessments at six years of age included measurement of serum IgE levels (in 460), pulmonary-function testing (526), and skin allergy testing (629). At the age of six years, 425 children (51.5 percent) had never wheezed, 164 (19.9 percent) had had at least one lower respiratory illness with wheezing during the first three years of life but had no wheezing at six years of age, 124 (15.0 percent) had no wheezing before the age of three years but had wheezing at the age of six years, and 113 (13.7 percent) had wheezing both before three years of age and at six years of age. The children who had wheezing before three years of age but not at the age of six had diminished airway function (length-adjusted maximal expiratory flow at functional residual capacity [Vmax FRC]) both before the age of one year and at the age of six years, were more likely than the other children to have mothers who smoked but not mothers with asthma, and did not have elevated serum IgE levels or skin-test reactivity. Children who started wheezing in early life and continued to wheeze at the age of six were more likely than the children who never wheezed to have mothers with a history of asthma (P < 0.001), to have elevated serum IgE levels (P < 0.01), to have normal lung function in the first year of life, and to have elevated serum IgE levels (P < 0.001) and diminished values for VmaxFRC (P < 0.01) at six years of age. The majority of infants with wheezing have transient conditions associated with diminished airway function at birth and do not have increased risks of asthma or allergies later in life. In a substantial minority of infants, however, wheezing episodes are probably related to a predisposition to asthma.
  • Article
    The first widely used questionnaire in respiratory epidemiology was the questionnaire from the Medical Research Council (MRC) of Great Britain. In the first version, from 1960, there were only a few questions about wheezing, but in later editions, more questions about asthma and asthma-like symptoms were added. The MRC questionnaire initiated the development of other questionnaires such as the European Community for Coal and Steel (ECSC) questionnaire of respiratory symptoms and the questionnaire from the American Thoracic Society and the Division of Lung Diseases (ATS-DLD-78). In Tucson, Ariz, a questionnaire was developed in the 1970s that was focused on the subject's own report of asthma. In Great Britain, a questionnaire was developed in the 1980s with the intention of finding the most valid symptom-based items for identifying asthma, "the IUATLD (1984) questionnaire." When judging the validity of a questionnaire, it is essential to understand sensitivity and specificity. Sensitivity is the fraction of the truly diseased subjects found to be diseased using the questionnaire. Specificity is the fraction of the truly healthy subjects found to be healthy using the questionnaire. Regarding questionnaires dealing with asthma, the situation is confusing because of the absence of any gold standard for asthma. The most usual mode of validation has been to test the questionnaire against the results of a clinical physiologic investigation, often a nonspecific bronchial challenge test. Another approach has been to compare the answers from the questionnaire with the clinical diagnoses of asthma. When validated in relation to bronchial challenge tests, the questions about self-reported asthma have a mean sensitivity of 36 percent (range, 7 to 80 percent) and a mean specificity of 94 percent (range, 74 to 100 percent). The questions about "physician-diagnosed asthma" have even higher specificity, 99 percent. When validated in relation to a clinical diagnosis of asthma, the mean sensitivity for the question about self-reported asthma was 68 percent in the reviewed studies (range, 48 to 100 percent). The specificity was 94 percent (range, 78 to 100 percent). One problem in using the presence of bronchial hyperreactivity (BHR) as a gold standard for asthma is that many people with BHR report no respiratory complaints. In other words, the presence of BHR is a measure with high sensitivity but low specificity for asthma. The effect of using a methacholine challenge test as a standard for the disease will thus be an underestimation of the sensitivity of the questionnaire.(ABSTRACT TRUNCATED AT 400 WORDS)
  • Article
    Abstract Abstract Inuit infants have extremely high rates of lower respiratory tract infection (LRTI), but the causes for this are unclear. The aims of this study were to assess, in young Inuit children in Baffin Region, Nunavut, the feasibility of an epidemiologic study of the association between indoor air quality (IAQ) and respiratory health; to obtain data on IAQ in their housing; and to identify and classify risk factors for LRTI. Twenty houses in Cape Dorset, Nunavut with children below 2 years of age, were evaluated using a structured housing inspection and measurement of IAQ parameters, and a respiratory health questionnaire was administered. Twenty-five percent of the children had, at some time, been hospitalized for chest illness. Houses were very small, and had a median of six occupants per house. Forty-one percent of the houses had a calculated natural air change rate <0.35 air changes per hour. NO2 concentrations were within the acceptable range. Smokers were present in at least 90% of the households, and nicotine concentrations exceeded 1.5 μg/m3 in 25% of the dwellings. Particulates were found to be correlated closely with nicotine but not with NO2 concentrations, suggesting that their main source was cigarette smoking rather than leakage from furnaces. Mattress fungal levels were markedly increased, although building fungal concentrations were low. Dust-mites were virtually non-existent. Potential risk factors related to IAQ for viral LRTI in Inuit infants were observed in this study, including reduced air exchange and environmental tobacco smoke exposure.
  • Article
    Full-text available
    Inuit infants have the highest reported rate of hospital admissions because of lower respiratory tract infections in the world. We evaluated the prevalence of reduced ventilation in houses in Nunavut, Canada, and whether this was associated with an increased risk of these infections among young Inuit children. We measured ventilation in 49 homes of Inuit children less than 5 years of age in Qikiqtaaluk (Baffin) Region, Nunavut. We identified the occurrence of lower respiratory tract infections using a standardized questionnaire. Associations between ventilation measures and lower respiratory tract infection were evaluated using multiple logistic regression models. The mean number of occupants per house was 6.1 people. The mean ventilation rate per person was 5.6 L/s (standard deviation [SD] 3.7); 80% (37/46) of the houses had ventilation rates below the recommended rate of 7.5 L/s per person. The mean indoor carbon dioxide (CO2) concentration of 1358 (SD 531) ppm was higher than the recommended target level of 1000 ppm. Smokers were present in 46 homes (94%). Of the 49 children, 27 (55%) had a reported history of lower respiratory tract infection. Reported respiratory infection was significantly associated with mean CO2 levels (odds ratio [OR] 2.85 per 500-ppm increase in mean indoor CO2, 95% confidence interval [CI] 1.23-6.59) and occupancy (OR 1.81 for each additional occupant, 95% CI 1.14-2.86). Reduced ventilation and crowding may contribute to the observed excess of lower respiratory tract infection among young Inuit children. The benefits of measures to reduce indoor smoking and occupancy rates and to increase ventilation should be studied.
  • Article
    There is a need for a standardized approach to international and regional comparisons of the prevalence and severity of asthma, and for the monitoring of asthma morbidity over time. In 1991, standardized written and video questionnaires were developed and administered in surveys of schoolchildren, aged 12-15 yrs, in five regions in four countries: Adelaide, Australia (n = 1,428); Sydney, Australia (n = 1519); West Sussex, England (n = 2,097); Bochum, Germany (n = 1928); and Wellington, New Zealand (n = 1863). The self-reported prevalence of wheezing during the previous 12 months was similar in West Sussex (29% using the written questionnaire and 30% using the video questionnaire), Wellington (28 and 36%), Adelaide (29 and 37%), and Sydney (30 and 40%), but was lower in Bochum (20 and 27%). The one year prevalence of severe wheezing limiting speech was greater in Wellington (11%), Adelaide (10%) and Sydney (13%), than in West Sussex (7%) and Bochum (6%). The self-reported one year prevalences of frequent attacks, frequent nocturnal wheezing, and doctor diagnosed asthma, were also higher in the Australasian centres than in the European centres. We conclude, that an international comparison of asthma symptom prevalence in childhood, using simple standardized instruments, is feasible. Possible explanations for the differences in reported asthma severity between the Australasian and European centres include differences in exposure to risk factors and differences in the management of asthma.
  • Article
    We assessed the effect of exposure to environmental tobacco smoke on the risk of developing bronchial obstruction in a 2-year cohort study of 3,754 children born in Oslo, Norway, during a period of 15 months in 1992-1993. We collected questionnaire information on the child's health and environmental exposures at birth and when the child was age 6 months (follow up rate = 95%), 12 months (92%), 18 months (92%), and 24 months (81%). The outcome of interest was defined as two or more episodes of bronchial obstruction or one obstruction lasting more than 1 month, and it was verified by a specialist group evaluating data from questionnaires, clinical examinations, and health records. The risk of bronchial obstruction was increased in children exposed to environmental tobacco smoke (cumulative incidence = 0.109) compared with unexposed children (0.071), with an adjusted odds ratio of 1.6 [95% confidence interval (CI) = 1.3-2.1]. The effect was seen for maternal smoking alone (odds ratio = 1.6; 95% CI = 1.0-2.6), paternal smoking alone (odds ratio = 1.5; 95% CI = 1.1-2.2), and both parents smoking (odds ratio = 1.5; 95% CI = 1.0-2.2). There was no clear exposure-response pattern. The findings indicate that exposure to environmental tobacco smoke such as is experienced in Norwegian housing increases the risk of developing bronchial obstruction during the first 2 years of life.
  • Acute infections and environmental exposure to orga-nochlorines in Inuit infants from Nuna-vik, Environ. Health Perspect
    • F Dallaire
    • E Dewailly
    • G Muckle
    • C Vez-Ina
    • S W Jacobson
    • J L Jacobson
    • P Ayotte
    Dallaire, F., Dewailly, E., Muckle, G., Vez-ina, C., Jacobson, S.W., Jacobson, J.L. and Ayotte, P. (2004) Acute infections and environmental exposure to orga-nochlorines in Inuit infants from Nuna-vik, Environ. Health Perspect., 112, 1359– 1365.
  • Article
    The aim of this study was to obtain quantitative information from published data on the association between environmental tobacco smoke (ETS) exposure and the prevalence of serious lower respiratory tract infections (LRTI) in infancy and early childhood. We identified 21 relevant publications on the relation between ETS and the prevalence of serious LRTI by reviewing reference lists in relevant reports and by conducting manual and computer searches (Medline database; Dissertation abstracts index of Xerox University Microfilms) of published reports between 1966 and 1995. Thirteen studies were included in a quantitative overview using random effects modeling to derive pooled odds ratios. Sensitivity analyses were conducted to test the decision rules used in extracting odds ratio data. The results of community and hospital studies are broadly consistent and show that the child of a parent who smokes is at approximately twice the risk of having a serious respiratory tract infection in early life that requires hospitalization. This association was pronounced in children younger than age two and diminished after the age of two. The combined odds ratio for hospitalization for lower respiratory tract infections in infancy or early childhood is 1.93 (95% CI 1.66-2.25); the combined odds ratio of prevalence of serious LRTI at age less than 2 years, between 0 and 6 years, and between 3 and 6 years were 1.71 (95% CI 1.33-2.20); 1.57 (1.28-1.91), and 1.25 (0.88-1.78), respectively. There was no evidence of heterogeneity across the studies in these combined odds ratios. We conclude that this meta-analysis provides strong evidence that exposure to ETS causes adverse respiratory health outcomes such as either a serious LRTI or hospitalization for LRTI. New public health campaigns are urgently needed to discourage smoking in the presence of young children.
  • Article
    Hospitalization rates for respiratory syncytial virus (RSV) infection range from 1 to 20/1000 infants. To determine the rate and severity of RSV infections requiring hospitalization for infants in the Yukon-Kuskokwim (YK) Delta of Alaska, a 3-year prospective surveillance study was conducted. The annual rate of RSV hospitalization for YK Delta infants <1 year of age was 53–249/1000. RSV infection was the most frequent cause of infant hospitalization. RSV disease severity did not differ among non—high-risk infants in the YK Delta and at Johns Hopkins Hospital (JHH). On average, 1/125 infants born in the YK Delta required mechanical ventilation for RSV infection. During the peak season, ∼$1034/child <3 years of age was spent on RSV hospitalization in the YK Delta. In YK Delta infants ⩽6 months old, RSV micro-neutralizing antibody titers <1200 were associated with severe disease (odds, ratio = 6.2 P = .03). In the YK Delta and at JHH, newborns may be at greater risk for severe RSV illness than previously thought.
  • Article
    The relationship between exposure to house dust mite (HDM) allergens and prevalence of sensitization to these allergens in patients with asthma has been confirmed in many studies. Mite population growth is regulated by humidity. Reducing humidity and removing allergen by efficient vacuuming should control mite allergen and reduce symptoms. We sought to investigate the effect of mechanical ventilation and high-efficiency vacuuming on HDM numbers and Der p 1 concentrations in the homes of mite-sensitive asthmatic subjects and to evaluate the effect of any reductions on symptoms. The homes of 40 HDM-sensitive asthmatic subjects were randomized to receive (1) mechanical ventilation and a high-efficiency vacuum cleaner (HEVC); (2) mechanical ventilation alone; (3) an HEVC alone; and (4) no intervention. Homes and patients were monitored for 12 months. Change in absolute humidity, mite numbers, Der p 1 concentrations, lung function, bronchial hyperresponsiveness, and symptom scores were analyzed. Homes with mechanical ventilation achieved significantly lower humidity levels than those without (P <.001), with an associated reduction of mite numbers (P <.05) and Der p 1 concentrations (P <.001 ¿in nanograms per gram, P =.006 ¿in milligrams per square meter) in bedroom carpets and some other mite sources in the ventilated areas of the homes. The addition of a vacuum cleaner enhanced this effect. There was a trend for an improvement in histamine PC(20) (P =.085) in the patients whose homes were ventilated. The use of a mechanical ventilation system in suitable homes resulted in some reduction in numbers of HDM and Der p 1 concentrations. The addition of an HEVC slightly enhanced the effect but not sufficiently to see an improvement in symptoms.
  • Article
    Although bronchiectasis has become a rare condition in U.S. children, it is still commonly diagnosed in Alaska Native children in the Yukon Kuskokwim Delta. The prevalence of bronchiectasis has not decreased in persons born during the 1980s as compared with those born in the 1940s. We reviewed case histories of 46 children with bronchiectasis. We observed that recurrent pneumonia was the major preceding medical condition in 85% of patients. There was an association between the lobes affected by pneumonia and the lobes affected by bronchiectasis. Eight (17%) patients had surgical resection of involved lobes. We conclude that the continued high prevalence of bronchiectasis appears to be related to extremely high rates of infant and childhood pneumonia. Pediatr Pulmonol. 2000;29:182-187. Published 2000 Wiley-Liss, Inc.
  • Article
    Full-text available
    Over the last decade there has been an apparent increase in childhood wheeze. We speculated that much of the reported increase may be attributed to the term wheeze being adopted by parents to describe a variety of other forms of noisy breathing. To investigate terminology used by parents to describe their children's breath sounds. An interview was carried out with the parents of 92 infants with noisy breathing, beginning with an open question and then directed towards a more detailed description. Finally, the parents were asked to choose from a wheeze, ruttle, and stridor on imitation by the investigator and video clips of children. Wheeze was the most commonly chosen word on initial questioning (59%). Only 36% were still using this term at the end of the interview, representing a decrease of one third, whereas the use of the word ruttles doubled. Our results reflect the degree of inaccuracy involved in the use of the term wheeze in clinical practice, which may be leading to over diagnosis. Imprecise use of this term has potentially important implications for therapy and clinical trials.
  • Article
    Full-text available
    It has long been suspected that Canadian Inuit children suffer from frequent severe lower respiratory tract infections (LRTIs), but the causes and risk factors have not been documented. This study assessed the infectious causes and other epidemiologic factors that may contribute to the severity of LRTI in young Inuit children on Baffin Island. A prospective case study was carried out at the Baffin Regional Hospital in Iqaluit, Nunavut, of infants less than 6 months of age, who were admitted to hospital between October 1997 and June 1998 with a diagnosis of LRTI. Immunofluorescent antibody testing was used to identify respiratory viruses, and enzyme immunoassay (EIA) and polymerase chain reaction (PCR) were used to test for Chlamydia trachomatis. Demographic and risk factor data were obtained through a questionnaire. The annualized incidence rate of admission to hospital for bronchiolitis at Baffin Regional Hospital was 484 per 1000 infants who were less than 6 months of age; 12% of the infants were intubated. Probable pathogens were identified for 18 of the 27 cases considered in our study. A single agent was identified for 14 infants: 8 had respiratory syncytial virus, 2 adenovirus, 1 rhinovirus, 1 influenza A, 1 parainfluenza 3 and 1 had cytomegalovirus. For 4 infants, 2 infectious agents were identified: these were enterovirus and Bordetella pertussis, adenovirus and enterovirus, cytomegalovirus and respiratory syncytial virus, and respiratory syncytial virus and adenovirus. C. trachomatis was not identified by either EIA or PCR. All infants were exposed to maternal smoking in utero, second-hand smoke at home and generally lived in crowded conditions. Inuit infants in the Baffin Region suffer from an extremely high rate of hospital admissions for LRTI. The high frequency and severity of these infections calls for serious public health attention.
  • Article
    Influenza poses special hazards inside healthcare facilities and can cause explosive outbreaks of illness. Healthcare workers are at risk of acquiring influenza and thus serve as an important reservoir for patients under their care. Annual influenza immunisation of high-risk persons and their contacts, including healthcare workers, is the primary means of preventing nosocomial influenza. Despite influenza vaccine effectiveness, it is substantially underused by healthcare providers. Influenza can be diagnosed by culturing the virus from respiratory secretions and by rapid antigen detection kits; recognition of a nosocomial outbreak is important in order to employ infection-control efforts. Optimal control of influenza in the acute-care setting should focus upon reducing potential influenza reservoirs in the hospital, including: isolating patients with suspected or documented influenza, sending home healthcare providers or staff who exhibit typical symptoms of influenza, and discouraging persons with febrile respiratory illness from visiting the hospital during a known influenza outbreak in the community. (Note: influenza and other respiratory viruses can cause non-febrile illness but are still transmissible.) The antiviral M2 protein inhibitors (amantadine, rimantadine) and neuraminidase inhibitors (zanamivir, oseltamivir) have proven efficacy in treating and preventing influenza illness; however, their role in the prevention and control of influenza in the acute hospital setting remains to be more fully studied.
  • Article
    Full-text available
    Acute respiratory infections (ARI) are frequent in Inuit children, in terms of incidence and severity. A cohort of 294 children <2 years of age was formed in Sisimiut, a community on the west coast of Greenland, and followed from 1996 to 1998. Data on ARI were collected during weekly visits at home and child-care centers; visits to the community health center were also recorded. The cohort had respiratory symptoms on 41.6% and fever on 4.9% of surveyed days. The incidence of upper and lower respiratory tract infections was 1.6 episodes and 0.9 episodes per 100 days at risk, respectively. Up to 65% of the episodes of ARI caused activity restriction; 40% led to contact with the health center. Compared with studies from other parts of the world, the incidence of ARI appears to be high in Inuit children.
  • Article
    To systematically review the evidence of randomized trials evaluating the effects of residential air filtration systems on patients with asthma. We searched for published and unpublished studies using MEDLINE, the Cumulative Index to Nursing and Allied Health Literature, and the Cochrane Collaboration. We reviewed all reference lists for additional articles of relevance, and contacted experts in the field and air filter manufacturers. We identified 10 relevant randomized controlled trials that examined the influence of a residential air filtration system on patients with asthma. In duplicate and independently, we abstracted data on the methodologic quality, population, intervention, and outcomes. Five of 10 studies enrolled adults only. One study included children only. The sample size ranged from 9 to 45 participants in each study, for a total of 216 patients across all studies. Two studies reported a statistically significant decrease in airway responsiveness associated with air filter utilization. Air filters were associated with significantly lower total symptom scores (weighted mean difference of 0.47; 95% confidence interval [CI], 0.69 to 0.25) on a 10-point scale, and lower sleep disturbance score (weighted mean difference of 0.93; 95% CI, 1.44 to 0.42); however, heterogeneity of results weakens the inferences from these trials. Air filtration systems were not associated with any differences in medication use or morning peak expiratory flow values. None of these trials employed validated scales to measure clinical symptoms or quality of life. Among patients with allergies and asthma, use of air filters is associated with fewer symptoms. Rigorous sufficiently powered randomized clinical trials are needed to more precisely define the influence of air filtration on health-related quality of life and symptom control for asthmatic patients.
  • Article
    Alaska Native children experience extremely high rates of hospitalization for respiratory syncytial virus (RSV) infection. We evaluated the effect of palivizumab prophylaxis on the incidence of RSV hospitalizations in high risk Alaska Native children. We analyzed two retrospective cohorts. The first analysis, of southwest Alaska Native children hospitalized with acute respiratory infections during 1993 to 1996 and 1998 to 2001, compared RSV hospitalization rates among premature and nonpremature infants born before (1993 to 1996) and after (1998 to 2001) palivizumab use. The second analysis, of Alaska Native infants with a history of prematurity or lung disease during 1998 through 2001, compared RSV hospitalization among children receiving palivizumab during protected periods (within 32 days after a dose of palivizumab) and unprotected periods. First RSV hospitalizations in premature infants from southwest Alaska meeting criteria for palivizumab prophylaxis decreased from 439 per 1000 births before to 150 per 1000 births after palivizumab (relative rate, 0.34; 95% confidence interval, 0.17 to 0.68), whereas the rate in nonpremature infants remained stable (148 per 1000 births compared with 142 per 1000). Among high risk Alaska Native children during 1998 through 2001, the rate of first RSV hospitalization was 0.55 per 1000 protected days and 1.07 per 1000 unprotected days (relative rate, 0.52; 95% confidence interval, 0.28 to 0.93). Palivizumab reduced RSV hospitalizations in high risk infants in a region with high rates of RSV hospitalization.
  • Article
    Full-text available
    Acute respiratory infections cause considerable morbidity among Inuit children, but there is very little information on the risk factors for these infections in this population. To identify such factors, the authors performed a prospective community-based study of acute respiratory infections in an open cohort of 288 children aged 0-2 years in the town of Sisimiut, Greenland. Between July 1996 and August 1998, children were monitored weekly, and episodes of upper and lower respiratory tract infections were registered. Risk factor analyses were carried out using a multivariate Poisson regression model adjusted for age. Risk factors for upper respiratory tract infections included attending a child-care center (relative risk = 1.7 compared with home care) and sharing a bedroom with adults (relative risk = 2.5 for one adult and 3.1 for two adults). Risk factors for lower respiratory tract infections included being a boy (relative risk = 1.5), attending a child-care center (relative risk = 3.3), exposure to passive smoking (relative risk = 2.1), and sharing a bedroom with children aged 0-5 years (relative risk = 2.0 for two other children). Breastfeeding tended to be protective for lower respiratory tract infections. The population-attributable risk of lower respiratory tract infections associated with passive smoking and child-care centers was 47% and 48%, respectively. The incidence of acute respiratory infections among Inuit children may be reduced substantially through public health measures.
  • Article
    Abstract Abstract The Wells–Riley equation, which is used to model the risk of indoor airborne transmission of infectious diseases such as tuberculosis, is sometimes problematic because it assumes steady-state conditions and requires measurement of outdoor air supply rates, which are frequently difficult to measure and often vary with time. We derive an alternative equation that avoids these problems by determining the fraction of inhaled air that has been exhaled previously by someone in the building (rebreathed fraction) using CO2 concentration as a marker for exhaled-breath exposure. We also derive a non-steady-state version of the Wells–Riley equation which is especially useful in poorly ventilated environments when outdoor air supply rates can be assumed constant. Finally, we derive the relationship between the average number of secondary cases infected by each primary case in a building and exposure to exhaled breath and demonstrate that there is likely to be an achievable critical rebreathed fraction of indoor air below which airborne propagation of common respiratory infections and influenza will not occur.
  • Article
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    The Inuit population of Nunavik (Canada) is exposed to immunotoxic organochlorines (OCs) mainly through the consumption of fish and marine mammal fat. We investigated the effect of perinatal exposure to polychlorinated biphenyls (PCBs) and dichlorodiphenyldichloroethylene (DDE) on the incidence of acute infections in Inuit infants. We reviewed the medical charts of a cohort of 199 Inuit infants during the first 12 months of life and evaluated the incidence rates of upper and lower respiratory tract infections (URTI and LRTIs, respectively), otitis media, and gastrointestinal (GI) infections. Maternal plasma during delivery and infant plasma at 7 months of age were sampled and assayed for PCBs and DDE. Compared to rates for infants in the first quartile of exposure to PCBs (least exposed), adjusted rate ratios for infants in higher quartiles ranged between 1.09 and 1.32 for URTIs, 0.99 and 1.39 for otitis, 1.52 and 1.89 for GI infections, and 1.16 and 1.68 for LRTIs during the first 6 months of follow-up. For all infections combined, the rate ratios ranged from 1.17 to 1.27. The effect size was similar for DDE exposure but was lower for the full 12-month follow-up. Globally, most rate ratios were > 1.0, but few were statistically significant (p < 0.05). No association was found when postnatal exposure was considered. These results show a possible association between prenatal exposure to OCs and acute infections early in life in this Inuit population.
  • Article
    Unlabelled: Indoor air pollutants are a potential cause of building related symptoms and can be reduced by increasing ventilation rates. Indoor carbon dioxide (CO(2)) concentration is an approximate surrogate for concentrations of occupant-generated pollutants and for ventilation rate per occupant. Using the US EPA 100 office-building BASE Study dataset, we conducted multivariate logistic regression analyses to quantify the relationship between indoor CO(2) concentrations (dCO(2)) and mucous membrane (MM) and lower respiratory system (LResp) building related symptoms, adjusting for age, sex, smoking status, presence of carpet in workspace, thermal exposure, relative humidity, and a marker for entrained automobile exhaust. In addition, we tested the hypothesis that certain environmentally mediated health conditions (e.g., allergies and asthma) confer increased susceptibility to building related symptoms. Adjusted odds ratios (ORs) for statistically significant, dose-dependent associations (P < 0.05) for combined mucous membrane, dry eyes, sore throat, nose/sinus congestion, sneeze, and wheeze symptoms with 100 p.p.m. increases in dCO(2) ranged from 1.1 to 1.2. Building occupants with certain environmentally mediated health conditions were more likely to report that they experience building related symptoms than those without these conditions (statistically significant ORs ranged from 1.5 to 11.1, P < 0.05). Practical implications: These results suggest that provision of sufficient per-person outdoor ventilation air, could significantly decrease prevalence of selected building related symptoms. The observed relationship between indoor minus outdoor CO(2) concentrations and mucous membrane and lower respiratory symptoms suggests that air contaminants are implicated in the etiology of building related symptoms. Levels of indoor air pollutants that are suspected to cause building related symptoms could be reduced by increasing ventilation rates, improving ventilation effectiveness, or reducing sources of indoor air pollutants, if known.
  • Article
    Environmental tobacco smoke (ETS) can be a major constituent of air pollution in indoor environments, including the home. Regulation on smoking in the workplace and public places has made the home the dominant unregulated source of ETS, with important potential impacts on children. Between 40% and 60% of children in the United Kingdom are exposed to ETS in the home. Many experimental and human and studies have investigated the adverse health effects of ETS. Substantial evidence shows that in adults ETS is associated with increased risk of chronic respiratory illness, including lung cancer, nasal cancer, and cardiovascular disease. In children, ETS increases the risk of sudden infant death syndrome, middle ear disease, lower respiratory tract illness, prevalence of wheeze and cough, and exacerbates asthma. Although banning smoking in the home would be the optimal reduction strategy, several barrier and ventilation methods can be effective. Nevertheless, such methods are not always practical or acceptable, particularly when social pressures contribute to a lack of support for ETS control in the home. Smoking cessation interventions have had limited success. Research is needed to explore the barriers to adopting ETS risk-reducing behaviors.
  • Article
    Full-text available
    Rhinoviruses are major causes of morbidity in patients with respiratory diseases; however, their modes of transmission are controversial. We investigated detection of airborne rhinovirus in office environments by polymerase chain reaction technology and related detection to outdoor air supply rates. We sampled air from 9 A.M. to 5 P.M. each workday, with each sample run for 1 work week. We directly extracted RNA from the filters for nested reverse transcriptase-polymerase chain reaction analysis of rhinovirus. Nasal lavage samples from building occupants with upper respiratory infections were also collected. Indoor carbon dioxide (CO2 concentrations were recorded every 10 minutes as a surrogate for outdoor air supply. To increase the range of CO2 concentrations, we adjusted the outdoor air supply rates every 3 months. Generalized additive models demonstrated an association between the probability of detecting airborne rhinovirus and a weekly average CO2 concentration greater than approximately 100 ppm, after controlling for covariates. In addition, one rhinovirus from a nasal lavage contained an identical nucleic acid sequence similar to that in the building air collected during the same week. These results suggest that occupants in buildings with low outdoor air supply may have an increased risk of exposure to infectious droplet nuclei emanating from a fellow building occupant.
  • Article
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    To study the prevalence and risk factors for asthma in a cohort of 494 children born in 1993 and followed up to the age of six years in Pelotas, state of Rio Grande do Sul, Brazil. A standardized and validated asthma questionnaire, based on the International Study of Asthma and Allergies in Childhood (ISAAC), was applied. Other information was also collected about socioeconomic background, genetic, nutritional, gestational and allergic factors, and previous infectious episodes. The prevalence of asthma found in this study was 12.8% (95%CI: 10-15.9%). In the multivariate analysis, risk factors such as non-white skin color (RR = 1.9 95% CI: 1.1-3.3%), family history of asthma (RR = 2.8 95% CI: 1.5-5.1), allergic rhinitis in children (RR = 2.6 95% CI: 1.5-4.4) and maternal smoking during pregnancy (RR = 1.7 95%CI: 1-2.9) were associated with asthma. Childhood asthma is highly prevalent in Pelotas, and it is a serious public health problem. Therefore, specific programs should be developed for its control.
  • Article
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    Previous epidemiological studies have shown acute effects of ambient air pollutants in children with respiratory disorders. The chronic effects of air pollution in Bangkok children were investigated. Children aged 10-15 years were examined for lung functions using spirometry tests and for respiratory symptoms by the American Thoracic Society's Division of Lung Diseases (ATS-DLD-78-C) questionnaire during May-August 2004. Effects of residential area were estimated by multiple logistic regression analysis. Of the 878 children, 722 (82%) had completed lung function test and ATS-DLD questionnaire. In children, who live in roadside (R) and general (G) areas with high (H) pollution, the prevalence of respiratory symptoms increased significantly [odds ratios (95% confidence interval) in HR and HG are 2.44 (1.21-4.93) and 2.60 (1.38-4.91), respectively]. Children with normal lung function were less observed in H- and M-polluted roadside and general area [HR, OR = 1.41 (95% CI 0.89-2.22); HG, 1.08 (0.71-1.64); and MR, 0.99 (0.63-1.57)]. Residential locations and family members were associated with the prevalence of respiratory symptoms, whereas factors such as the responder of ATS-DLD, gender, age, residential years, home size, parental smoking habits, use of air conditioners, and domestic pets were not associated. Age was associated with the impaired lung function, whereas others factors were not associated. The prevalence of respiratory symptoms and impaired lung function were higher among children living in areas with high pollution than those in areas with low pollution.
  • Article
    During 1993 to 1996, Alaska Native infants <1 year of age from the Yukon Kuskokwim (YK) Delta in Alaska experienced a respiratory syncytial virus (RSV) hospitalization rate 5 times the U.S. general infant population rate. We describe trends in lower respiratory tract infection (LRTI) and RSV hospitalizations in YK children from 1994 to 2004. We abstracted hospital dates, RSV test results and clinical information from the hospital records for YK children <3 years of age hospitalized between July 1994 and June 2004. : The RSV hospitalization rate in YK Delta children <1 year of age decreased from 178 per 1000 infants per year (1994-1997) to 104 per 1000 infants per year (2001-2004) (P < 0.001), and the RSV hospitalization rate for premature infants decreased from 317 to 123 per 1000 infants per year (P < 0.001). The risk reduction for RSV hospitalization was greater in premature (relative risk, 0.39) than in term infants (relative risk, 0.60; P = 0.04). The rate of non-RSV LRTI hospitalizations increased from 153 to 215 per 1000 infants per year (P < 0.001). The median RSV season length was 30.5 weeks. Pneumonia was diagnosed in more than half of RSV admissions. In YK infants, the RSV hospitalization rate decreased by one-third between 1994 and 2004; however, the overall LRTI hospitalization rate did not change. The median RSV season was twice as long as for the U.S. population. Palivizumab prophylaxis may be responsible for the larger decrease in the RSV hospitalization rate among premature infants; however, the 2001-2004 RSV hospitalization rate among YK infants remained 3 times higher than the U.S. infant rate.
  • Article
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    There have been few recent studies demonstrating a definitive association between the transmission of airborne infections and the ventilation of buildings. The severe acute respiratory syndrome (SARS) epidemic in 2003 and current concerns about the risk of an avian influenza (H5N1) pandemic, have made a review of this area timely. We searched the major literature databases between 1960 and 2005, and then screened titles and abstracts, and finally selected 40 original studies based on a set of criteria. We established a review panel comprising medical and engineering experts in the fields of microbiology, medicine, epidemiology, indoor air quality, building ventilation, etc. Most panel members had experience with research into the 2003 SARS epidemic. The panel systematically assessed 40 original studies through both individual assessment and a 2-day face-to-face consensus meeting. Ten of 40 studies reviewed were considered to be conclusive with regard to the association between building ventilation and the transmission of airborne infection. There is strong and sufficient evidence to demonstrate the association between ventilation, air movements in buildings and the transmission/spread of infectious diseases such as measles, tuberculosis, chickenpox, influenza, smallpox and SARS. There is insufficient data to specify and quantify the minimum ventilation requirements in hospitals, schools, offices, homes and isolation rooms in relation to spread of infectious diseases via the airborne route. © 2007 The Authors Journal compilation 2007 Blackwell Munksgaard.
  • Article
    To analyse the importance of mothers' smoking during pregnancy and/or environmental tobacco smoke (ETS) exposure in early childhood for children's health and well-being at the age of 3 years. Four groups from a population based cohort (n=8850) were compared: children with nonsmoking mother during pregnancy and nonsmoking parents at the age of 3 years (n=7091); children with only foetal exposure (n=149); children exposed only postnatally (n=895) and children exposed both pre- and postnatally (n=595). Odds ratios and 95% confidence intervals were calculated. Children exposed both pre- and postnatally had more wheezing (1.14; 1.07-1.21) and rhinitis (1.16; 1.06-1.26), used more cough-mixture (1.07; 1.01-1.14) and broncodilatating drugs (1.08; 1.02-1.15) and suffered more from excessive crying (1.31; 1.13-1.51) and irritability (1.27; 1.09-1.48) compared to children with nonsmoking parents. Children exposed only postnatally had more rhinitis (1.24; 1.12-1.37), used more cough-mixture (1.14; 1.05-1.29) and suffered more from poor sleep (1.26; 1.07-1.47) than children of nonsmoking parents. Children with prenatal exposure only used more broncodilatating drugs (1.45; 1.03-2.04) and suffered more from poor sleep (2.06; 1.09-3.87). Health differences, small but significant, indicate that prenatal and/or postnatal ETS exposure alone, or in combination, seems to interfere with child health, supporting the importance of zero tolerance. However, as most smoking parents in Sweden try to protect their children from ETS exposure, the results also might indicate that protective measures are worthwhile.
  • Article
    Full-text available
    Few studies have investigated the prevalence and risk factors of asthma in Canadian Aboriginal children. To determine the prevalence of asthma and asthma-like symptoms, as well as the risk factors for asthma-like symptoms, in Aboriginal and non-Aboriginal children living in the northern territories of Canada. Data on 2404 children, aged between 0 and 11 years, who participated in the North component of the National Longitudinal Survey of Children and Youth were used in the present study. A child was considered to have an asthma-like symptom if there was a report of ever having had asthma, asthma attacks or wheeze in the past 12 months. After excluding 59 children with missing information about race, 1399 children (59.7%) were of Aboriginal ancestry. The prevalence of asthma was significantly lower (P<0.05) in Aboriginal children (5.7%) than non-Aboriginal children (10.0%), while the prevalence of wheeze was similar between Aboriginal (15.0%) and non-Aboriginal (14.5%) children. In Aboriginal children, infants and toddlers had a significantly greater prevalence of asthma-like symptoms (30.0%) than preschool-aged children (21.5%) and school-aged children (11.5%). Childhood allergy and a mother's daily smoking habit were significant risk factors for asthma-like symptoms in both Aboriginal and non-Aboriginal children. In addition, infants and toddlers were at increased risk of asthma-like symptoms in Aboriginal children. In analyses restricted to specific outcomes, a mother's daily smoking habit was a significant risk factor for current wheeze in Aboriginal children and for ever having had asthma in non-Aboriginal children. Asthma prevalence appears to be lower in Aboriginal children than in non-Aboriginal children. The association between daily maternal smoking and asthma-like symptoms, which has been mainly reported for children living in urban areas, was observed in Aboriginal and non-Aboriginal children living in northern and remote communities in Canada.