Epidemiological study of chronic bronchitis with special reference to effect of air pollution

Summary

From 1962 to 1969 an investigation on chronic bronchitis was conducted to clarify the chronic influence of air pollution to human health in 9 areas selected from Osaka and Hyogo prefectures showing different degrees of air pollution.

Self-administered questionnaire based upon the standard of the British Medical Research Council's Committee was distributed to every residents over 40 years of age in surveyed areas. The questionnaires numbered 36374 with response rate of 85.9%.

Cases of chronic bronchitis were diagnosed from the responded following the Fletcher's criteria of chronic bronchitis. Those cases were asked to take further examinations consisting of doctor's direct interview by the standardized questionnaire by the British Medical Research Council's Committee, chest X-ray test, pulmonary function test by McKenson's Vitalor and other optional medical examinations. At the same time, some apparently normal subjects and some other who had less severe symptoms of sputum, cough and/or short breath were likewise medically checked up as the controls.

From this investigation, it became clear that the prevalence of chronic bronchitis is influenced by age, smoking and air pollution (sulfur dioxide). The relation among age, smoking and air pollution with the prevalence of chronic bronchitis is mathematically analysed as follows: Y=1.94α+10⁻⁴ · 3 · N(x −20)²−3.18 where Y: prevalence of chronic bronchitis, N: smoking quantity per day, α: sulfur dioxide, x: age.