The possible Effects of air pollution on the development of chronic bronchitis

In a study concerned with the possible effects of air pollution on the development of chronic bronchitis, the following data were obtained: A population of 9000 men, aged 45 years, was examined in January 1990. Of these men, 6000 were exposed to high levels of air pollution and 3000 were exposed to low levels of air pollution.

At the physical examination, 90 cases of chronic bronchitis were identified, including 60 cases among the high air pollution exposure group.

All of the men who were initially examined and did not have chronic bronchitis were followed by repeat examination over the next five years. These follow-up exams identified 268 new cases of bronchitis in the total group, including 30 cases among the low exposure group.

6. The prevalence rates of chronic bronchitis in January 1990 were (Show, your work for all groups):

7. Is this a measure of point prevalence or period prevalence? a. Point prevalence b. Period prevalence 8. The incidence proportion of chronic bronchitis over the five years were (Show vour work for all groups):