10 Years Variation of Respiratory Symptoms in a Rapidly Industrialized Region
1978 Volume 13 Issue 1 Pages 1-9
Details
1978 Volume 13 Issue 1 Pages 1-9
Changes in the prevalence of respiratory symptoms in a selected population were analyzed for the period of 10 years to investigate the relationship between the onset of chronic bronchitis and the level of atmospheric pollution.
Kashima, the survey area, was a typical rural district before 1970. Since 1970, when petro-chemical complexes, iron works and power stations started the operation, certain levels of air pollutants (SO2 0.018 ppm, NO2 0.015 ppm, particulate 0.07-0.02mg/m3, annual averages) have always been detected. A series of interview surveys using the BMRC's Questionnaire were performed in 1966, 1969, 1973 and 1976. The subjects, both sexes, 40-59 yrs in age and 800 in number, were selected from the inhabitants living for long in Kashima and Oono (unpolluted area). To hold the comparability of the results, the special attention was paid to follow the standardized procedure for training of interviewers, assigning the subjects to interviewers and setting the situation for interview.
Time-trend of prevalence could not been observed for the 10 year-period, nor the difference between Kashima and Oono. These negative findings in contrast to the definite change in pollutants levels above mentioned may lead to the denial of the relationship between the prevalence of respiratory symptoms and the levels of pollutants. A further long-term observation is desirable to be conclusive of following possibilities implied by the present study.
1. A longer exposure (more than 5 years) may be necessary to develop chronic bronchitis. And a still longer exposure may be necessary, when the subjects had not been exposed to the coal combustion pollutants.
2. Increases in the prevalence of individual symptoms may precede the increase in the prevalence of combined symptoms of “persistent cough and phlegm”.
3. A time-trend estimated by only 4 data points could be consistent.
