The continuous decline in the period death rate from respiratory tuberculosis in the second half of the 19th century contrasts with an increase in the death rate from other respiratory diseases (mainly bronchitis and pneumonia) from the 1840s to the 1870s. The respiratory disease death rate then leveled off in the 1870s and 1880s until the influenza pandemic of 1889–91, which affected all age groups (figs. 10.1 and 10.2). Apart from this epidemic, the general trend over the period 1875–1915 reflects changes in the bronchitis death rate, which declined from the 1890s, while the long-term decline for pneumonia began around 1905 (figs. 10.3 and 10.4). Trends for subcategories are likely to have been affected to some extent by changes in classification of the primary cause of death. The trend in the respiratory disease death rate at ages 45–64 was relatively unaffected by transfer of recording from the “old age” and “ill-defined” categories, although there may have been some transfer of diagnosis from respiratory tuberculosis in the second half of the 19th century. Although the death rate among adults declined, the downturn in the death rate at all ages from the 1890s reflects a decline among young children (0–4 years) in particular (fig. 10.2). After the 1890s, the total respiratory disease death rates declined for males and females, apart from World War I years and in the major influenza pandemic of 1918 (fig. 10.1). After World War II, the death rate for females leveled off while that for males increased, most likely due to higher prevalence of cigarette smoking.

A review of trends in death rates from respiratory disease in the 20th century focused on three categories because of changes in classification: asthma, pneumonia, and chronic obstructive pulmonary disease or COPD (chronic bronchitis, emphysema, bronchiectasis, bronchial catarrh, and other obstructive airway diseases). The COPD death rate at ages 15–74 declined steadily with a more rapid decline after the 1960s, which probably reflects the decline in cigarette smoking among older men. The risk of chronic respiratory disease is affected by smoking and other irritants, as well as recent severe acute respiratory infections; however, it is also partly determined by experiences earlier in life. The study found that the long-term trend in period mortality was superimposed on a declining trend over successive cohorts born in the second half of the 19th century.