Comparison of respiratory symptoms between schoolchildren in China and Japan

Abstract

Background: Despite improvements in air pollution, the prevalence and incidence of bronchial asthma, which has attracted a great deal of attention in relation to air pollution, is tending to increase in Japan as well as worldwide. Severe air pollution conditions currently exist in China due to sulfur dioxide and particulate matter, resulting from coal burning and motor vehicle exhaust gases associated with the rapid increase in the number of vehicles.
Methods: Using the same questionnaire in China and Japan, we conducted a comparative study of the prevalence of various respiratory symptoms among schoolchildren in Anshan (n = 4395), Taiyuan (n = 3784 in 1997; n = 3995 in 1999) and Chengdu (n = 7795 in 1991; n = 3000 in 1998) in China and in Yokohama (n = 4161) in Japan. The pollution concentrations in the survey area of China resembled the concentrations observed in heavy industry areas in Japan in the 1970s.
Results: Comparisons between schoolchildren in Japan and China showed that the prevalence of persistent cough and persistent phlegm (persistent congestion and phlegm) was higher among schoolchildren in China (e.g. the prevalence of persistent cough in boys in China was 2.4-8.1%, whereas the rate was only 2.1% for boys in Yokohama), whereas the prevalence of wheezing and asthma-like symptoms was higher among schoolchildren in Japan (e.g. the prevalence of asthma-like symptoms was 0.2-1.8% for boys in China, whereas this rate was 9.6% in Yokohama, Japan).
Conclusions: If China follows the same path as Japan, that is, proceeds with conversion from coal to oil as its primary energy source, the popularization of motor vehicles and chemical contamination of food, housing and clothing, there is a risk that the prevalence of bronchial asthma in Chinese children will increase in the same way as it has in Japan. It is hoped that research will be conducted to determine the cause of the increases in bronchial asthma in Japan and that preventive measures will be established so that Chinese children do not repeat the experience of Japanese schoolchildren.