Epidemiology of Chronic Airways Diseases in Japan: Prevalence of Respiratory Symptoms
Since the 1960s, when air pollution became one of the most serious health problems in Japan, numerous surveys using the British MRC questionnaire on respiratory symptoms have been taken throughout the country to discover the direct health hazard of high concentrations of SO,. Fortunately, air pollution by SO, was lowered rapidly by technical improvement; however, cigarette smoking, air pollution by N02, NO,, etc, and indoor pollution are still important health hazards even now More detailed surveys on Respiratory symptoms using ATS-DLD questionnaires are necessary and should be carried out repeatedly to make clear the long-term effects of these factors.
Recently, the Environmental Agency of the government has carried out extensive surveys on respiratory symptoms among schoolchildren and their parents, with special reference to the effects of air pollution. It is useful to investigate the prevalence of respiratory symptoms and related factors among children, because many adult patients with CAD have a history of childhood respiratory troubles, as has been shown by Burrows.
The modified ATS-DLD questionnaire was used from 1980 to 1984 among 123,526 schoolchildren aged 6-11 who live in various parts of Japan where the trends of air pollution by NO*, NO, NO,, S04, and SP were measured for more than 3 years, Of the total surveyed, the questionnaires for 98,695 children who had been residing in the survey area for more than 3 years were analysed. Prevalences of respiratory symptoms are shown in Table 2. Of the total, 88.7% of children had no respiratory symptom(s), and the prevalences of persistent cough) sputum production, asthma-like symptoms, arid wheezing were 1.6%* 1.1%, 3.7%, and 5.6%, respectively. As seen in Table 3, the higher the concentration df NO,, the higher the prevalence of symptoms. The correlation between the Concentration of NO and/or NO* and the prevalence of symptoms was almost the same as for NO,. It was shown that the prevalence of respiratory symptoms among children correlates Significantly with the Various air pollutants, as shown in Table 4.
Table 2—Prevalence of Respiratory Symptoms Among Schoolchildren, 1980-84 (the Environmental Agency)
|Total, No. (%)||Boys, No. (%)||Girls, No. (%)|
|Total no. surveyed||123,526||62,977||60,549|
|Total no. analyzed*||96,695(100.0)||50,351 (100.0)||48,344 (100.0)|
|Persistent cough||1,538 (1.6)||916 (1.8)||622(1.3)|
|Barsistent rattling and/or phlegm||1,042(1.1)||616(1.2)||426(0.9)|
|Asthma-like symptoms||3,600(3.7)||2,300(4.6)||1,390 (2.9)|
|Wheezingf||5,565 (5.6)||3,147(6.3)||2,418 (5.3)|
|No respiratory symptoms||87,549(88.7)||43,783 (87.0)||43,766(90.5)|
Table 3—Prevalence of Respiratory Symptoms by AfO, Concentration (the Environmental Agency)
|NO,Concentration||No.Observed||Persistent Cough, %||Persistent Phlegm, %||Asthpia-like Symptoms, %||Wheezing, %|
Table 4—Correlation Coefficients Between Prevalence of Respiratory Symptoms and Air Pollution Level (the Environmental Agency)