Exposure to Secondhand Tobacco Smoke Enhances Respiratory Symptoms and Responses to Animals in 8,819 Children in Kindergarten: Results from 25 Districts in Northeast China

Abstract

Background: Experimental data suggest that asthma exacerbation by allergens is enhanced by exposure to environmental tobacco smoke (ETS); however, there is little supporting epidemiologic evidence. To our knowledge, few studies have assessed respiratory symptoms and allergies in this context. Objectives: To evaluate whether the association of exposure to animals (indicators of allergen and endotoxin exposure) with asthma-related symptoms is modified by ETS exposure in Chinese children. Methods: A cross-sectional study of 8,819 children in kindergarten was conducted in 25 districts in northern China. Information on respiratory health and exposure to indoor allergens was obtained using a standard questionnaire from the American Thoracic Society. Results: Among the children with ETS exposure in utero, the effects of exposure to animals were significant with respect to persistent cough [adjusted odds ratio (OR) 1.83; 95% confidence interval (CI) 1.12–2.99] and persistent phlegm (adjusted OR 2.40; 95% CI 1.28–4.54). The combined effect of in utero ETS exposure and animal exposure on doctor-diagnosed asthma was approximately as expected on the basis of their independent effects on an additive scale. There was no interaction between animal exposure and ETS exposure in the first 2 years of life or current ETS exposure. Conclusions: This study provides evidence that animal and ETS exposure increases the risk of asthma-related symptoms in children in kindergarten. ETS exposure in utero did modify the effect of animal exposure on persistent phlegm and persistent cough but not on doctor-diagnosed asthma among children.

Decline in Asthma Prevalence and Severity in Israel over a 10-Year Period

“…Active and passive smoking are known to be risk factors for asthma [24]. An important positive environmental change experienced in Israel has been a decrease in the prevalence of cigarette smokers [25].…”

Effects of in utero and Postnatal Exposure to Secondhand Smoke on Lung Function by Gender and Asthma Status: The Seven Northeastern Cities (SNEC) Study

“…Compared to adults, children are more vulnerable to SHS exposure because their respiratory and immune systems are not fully developed. An extensive body of evidence has shown that SHS exposure is associated with respiratory symptoms [2][3][4][5][6] and lung function [7][8][9][10] …”

Second-Hand Tobacco Smoke and Allergens – Double Jeopardy for Childhood Asthma Exacerbations

“…Pregnant mothers need special attention as regards tobacco control strategies. Nevertheless, the underlying message of this study [4] is loud and clear -SHS exposure harms children, the most vulnerable, and they should have the right to be protected from it.…”

“…In this issue of Respiration, Dong et al [4] report findings from a large cohort of 8,819 children (mean age = 4.7 years) sampled randomly from households based in 25 districts of Northeast China. They looked at different forms of respiratory symptoms: from persistent phlegm to current asthma, and from wheeze to doctor-diagnosed asthma both independently and then combined in the presence of childhood allergen and SHS exposure.…”

“…Given the complexities of diagnosing childhood asthma and self-reported asthma and asthmalike symptoms, Dong et al [4] took advantage of a large cohort to report such an association. To the best of our knowledge, no similar studies utilizing such a large cohort of children have yet been reported from any western country.…”