Prevalence of Asthma and Asthmatic Symptoms in Children in Relation to Environmental Factors —Epidemiological Studies in School Children in Taiyuan, China

Abstract

There has been a rapid increase in prevalence of asthma in Chinese children. However, the current level is still lower when compared to the prevalence in Western countries. Environmental factors might be associated with the increasing prevalence of children’s asthma and asthmatic symptoms in China. In this study, a cross-sectional survey was performed in 10 randomly selected schools involving 1993 children (mean age 13 years old) in urban areas in Taiyuan, China. Data on children’s asthma and asthmatic symptoms were collected by a questionnaire taken from the International Study on Asthma and Allergies in Childhood (ISAAC). Data on environmental exposure, including indoor and outdoor chemical air pollutants and indoor biological contamination in the settled dust, were quantitatively evaluated in the school environment. The results showed that the indoor school environment in urban areas in Taiyuan was contaminated with chemical air pollutants of outdoor origin (SO2, NO2, O3 and formaldehyde), and that the air pollutants were positively associated with children’s wheezing and daytime attacks of breathlessness. Different microbial components in the settled dust showed different effects regarding the prevalence of children’s respiratory symptoms, for example, muramic acid, a marker of gram positive bacteria, was negatively associated with children’s respiratory health, while ergosterol, a marker of fungi, showed positive associations. There was a low level of allergen contamination in the settled dust in the school environment and the detected airborne cat and dog allergens were not associated with any health parameters included in this study. In addition, environmental tobacco smoking (ETS) and emissions from new furniture in the home environment were risk factors for children’s respiratory symptoms. In conclusion, chemical air pollutants in schools may adversely affect children’s asthmatic symptoms while biological components resulted in more complex effects. This further research on different environmental factors and their potential interactions needs to be explored.