Chronic obstructive pulmonary disease in two cities of contrasting air quality.

Spirometric tests of 3280 Ottawa residents in 1969-71 and 2208 Sudbury residents in 1972-73 showed that the mean ratio of forced vital capacity to forced expiratory volume in 1 second was lower in Sudbury, where sulfur dioxide concentrations in the air tend to be appreciably higher than in Ottawa. This difference was significant for both males and females considered separately, and held true when age and smoking habits were taken into account. The prevalence of symptomatic chronic bronchitis was significantly higher in Sudbury males than in Ottawa males, but no such difference could be detected in females.