Environmental Exposure and Genetic Predisposition as Risk Factors for Asthma in China

Asthma is the most common chronic pulmonary disease worldwide and places a considerable economic burden on society. China is the world's largest developing country and has the largest population. China has undergone dramatic changes in the past few decades. The traditional lifestyle and living environment have changed in ways that directly affect the prevalence of asthma. The prevalence of asthma is lower in Chinese children and adults than in developed countries, but the prevalence has been on the rise during the past 30 years. The prevalence significantly varies among different parts of China. Polymorphisms of multiple genes, outdoor air pollution caused by PM2.5, PM10, SO2, NO2, environmental tobacco smoke, and coal, indoor pollution, and inhaled allergens, such as house dust mites, pollen, and cockroach particles, are risk factors for asthma.

Changing Prevalence of Allergic Diseases in the Asia-Pacific Region

Asia-Pacific is one of the most densely populated regions of the world and is experiencing rapid economic changes and urbanization. Environmental pollution is a significant problem associated with the rapid modernization of many cities in South Asia. It is not surprising that the prevalences of asthma and allergies are increasing rapidly, although the underlying reasons remain largely unknown. Many studies from this region have documented the changing prevalence of allergic diseases in various parts of the world. However, the methodologies used were neither standardized nor validated, making the results difficult to evaluate. The International Study of Asthma and Allergies in Childhood (ISAAC) has provided a global epidemiology map of asthma and allergic diseases, as well as the trend of changes in the prevalence of these diseases. Allergic sensitization is extremely common in many Asian communities. However, the prevalence of allergic diseases remains relatively rare. The rapid urbanization in the region, which increases environmental pollution and can affect the rural environment, will likely increase the prevalence of asthma and allergies in Asia.

Disparity of asthma prevalence in Chinese schoolchildren is due to differences in lifestyle factors / 中华儿科杂志

<p><b>OBJECTIVE</b>To investigate the environmental lifestyle risk factors which may explain the disparity of asthma prevalence in the Chinese population.</p><p><b>METHODS</b>In a cross-sectional study, 10 902 schoolchildren were recruited from Hong Kong (n = 3110), Beijing (n = 4277), and Guangzhou (n = 3565) using the ISAAC Phase II protocol. The average age of the children among three cities was 10.1-10.4 years and 50%-53% were male. Each subject was given an ISAAC Phase II questionnaire to be completed by the parents or guardians. Random subgroups of at least 1000 children from each city, added up to 3479 children underwent skin-prick testing. The sensitivity to eight common aeroallergens was assessed. Logistic regression analysis was used to determine the environmental and lifestyle risk factors for asthma and atopy.</p><p><b>RESULTS</b>The prevalence of wheezing in the past 12 months (Hong Kong, 5.8%; Beijing, 3.8%; Guangzhou, 3.4%) was significantly higher in schoolchildren from Hong Kong than that from the Mainland of China (OR 1.64, 95% CI 1.35-1.99). Multivariate logistic regression analyses revealed that the use of gas cooking (OR 2.08, 95% CI 1.32-3.26), foam pillow (OR 1.94, 95% CI 1.19-3.16), and house dampness (OR 1.84, 95% CI 1.25-2.71) were significant risk factors for "current wheezing". The use of cotton quilt (OR 0.70, 95% CI 0.56-0.87), breast-feeding (OR 0.79, 95% CI 0.66-0.96), and attendance of daycare (OR 0.73, 95% CI 0.59-0.88) were protective factors against "current wheezing". When a summary measure of these variables was introduced into a regression model, the Mainland residency was no longer associated with "current asthma" or "current wheezing" suggesting that either these factors or other unmeasured factors associated with above factors are responsible for the lower prevalence of asthma in the Mainland of China.</p><p><b>CONCLUSION</b>Several environmental and lifestyle factors represented characteristic of life in Mainland of China, including breast feeding, attendance of daycare, use of cotton quilt, use of pillow other than foam pillow, use of cooking fuel other than gas, and the absence of damp spots on the walls or ceiling, were the significant risk factors contributed to the disparity of asthma prevalence in children from Hong Kong and the Mainland of China.</p>