Byens ånde. Luftforurening og dødsårsager i København, ca. 1800-1920
The Breath of the City: Air Pollution and Mortality in Copenhagen, c. 1800-1920
This article investigates the effect of air pollution on mortality in the city of Copenhagen during its industrialization c. 1800–1920, subdivided into two periods. Overall, the investigation shows it to be highly probable that air pollution had a negative effect on mortality from lung afflictions among the city’s inhabitants. However, pulmonary tuberculosis caused as many deaths, and the negative effects of air pollution were counteracted by a range of other factors and developments during the period.
From the mid-1830s until the mid-1880s, the crude death rate per 1000 inhabitants (CDR) in Copenhagen was higher than in the rest of Denmark, and fairly stable. The most common causes of death in the city were related to the lungs and not to the digestive system, despite the city’s well-known lack of clean water, sewers and refuse disposal. It turned out that in this period, the single most important cause of death related to the lungs was pulmonary tuberculosis. However, other lung-related causes of death became more pronounced and, as early as 1847, already constituted an almost equal share of the city’s CDR. In the following period, c. 1885–1920, the order of importance was reversed and other lung afflictions, collectively, became the most important cause of death. At the same time, mortality from both pulmonary tuberculosis and other lung afflictions was decreasing steadily, arguably due in part to two pollution-lowering conditions. First, the growing volume of air pollution was dispersed over much larger geographical areas as factories and residences relocated, especially after the city’s fortifications were demolished in 1856. Second, (indoor) air pollution from wood-burning inside residences, which had been quite severe long before the relocation began, became less pronounced as households turned to less-polluting fuels for heating, cooking and lighting, especially after 1885. These reductions in emissions, however, were to some extent counteracted by an increase in tobacco smoking during the period.
Mortality from both pulmonary tuberculosis and other lung afflictions continued to decrease during the second period c. 1885–1920, even as ambient air pollution from coal-fired factories increased. Certainly, the annexation of new territory to Copenhagen in 1901 and 1902 meant a reduction in the number of inhabitants per square kilometre and thus a dispersion of the air pollution, but this dispersion does not seem to have had any noticeable effect on the steady decrease in mortality from pulmonary tuberculosis and other lung afflictions. Instead, the most likely explanation of the decrease in mortality during this period is the private and public initiatives to prevent pulmonary tuberculosis that gained momentum in the mid-1880s. Further, the same initiatives (disinfection of homes, better hygiene and sanatoria) also reduced the propensity of other deadly lung afflictions, especially pneumonia.