Below we highlight the findings of some of these studies.
In the second half of the 1980s, a study performed in
Barcelona (Spain) evaluated the relationship between daily
emergency-room admissions for COPD for the period 1985-1989 (70% were over age 65) and ambient sulphur dioxide (SO2). It was found that an increment of 25 µg/m3
in 24-hour average SO2 concentration produced an increase of 6% and 9% in admissions during winter and summer, respectively. For black smoke (BS), a similar change was
found during winter, whereas the change was smaller in summer (15).