London Fog

In December 1952, thick fog rolled across many parts of the British Isles. In the Thames Valley, the fog mixed with smoke, soot and sulfur dioxide from coal-burning homes and factories, turning the air over London into a dense yellow mass. Due to a temperature inversion, the fog stayed put for several days, during which the city s hospitals filled to over-flowing. According to the Parliamentary Office of Science and Technology, more than 

000 people died that month because of the polluted air. Similar, less-severe episodes occurred in 1956, 1957, and 1962. The 1956 event killed more than 

London s deadly smog was caused by usual-practice pollution. Due to the widespread use of cheap, high-sulfur coal, the air in London had been bad for decades, but post-war growth made it worse than ever. In response to the incidents, Parliament passed Clean Air Acts in 1956 and 1962, prohibiting the use of high-sulfur fuels in critical areas. 

---

Ministry of Health, Mortality and Morbidity during the London Fog of December 1952, Rep. of Public Health and Related Subject No, 95. H.M. Stationery Office, London, 1954. 

Other examples of trends come from Great Britain, where the emission of industrial smoke was reduced from 1.4 million tonnes per year in 1953 to 0.1 million tonnes per year in 1972 domestic smoke emission was reduced from 1.35 million tonnes per year in 1953 to 0.58 million tonnes per year in 1972 and the number of London fogs (smogs) capable of reducing visibility at 9 AM to less than 1 km was reduced from 59 per year in 1946 to 5 per year in 1976. 

In 1948 in the steel-mill town ofDonora, Pennsylvania, intense load smog killed nineteen people. In 1952 in London over 3000people died in one of the most notorious smog events known as London Fogs in 1962 another 700 Londoners died. 

Ministry of Public Health (1954) Mortality and morbidity during the London fog of December 1952. London, Her Majesty s Stationary Office (Reports on Public Health and Medical Subjects No. 95). 

The incidence of adverse health impacts decreased rapidly as the smog disappeared. It appears from the time course of the toxicity that it was a threshold phenomenon that is, effects were related to the maximum pollution dose and abated quickly when the dose decreased. Other air pollution episodes for instance, the 1952 London fog, followed a different response pattern in that the effects were influenced mainly by the total pollution dose (concentration averaged over time). 

However, the great London fog of 1952 that resulted in 4000 deaths refocused attention on the public health consequences of air pollution and the lessons from Donora. The tremendous death toll in London made it clear that air pollution was more than just a nuisance and led to the enactment of legislation on both the state and federal level to control this type of environmental insult. The Commonwealth of Pennsylvania passed a state Clean Air Act in 1955, the first such law to control air pollution. This was followed in 1970 by the passage of the Federal Clean Air Act hearings on this bill were marked by references to the events that happened in Donora in 1948. 

A. Novakov and T. Novakov, Eyewitness The Chromatic Effects of Late Nineteenth-century London Fog, Literary London, vol. 4, http //www.literary-I0nd0n.0rg/l0nd0n-j0urnal/september2006/n0vak0v.html (2006). 

Logan WPD. Mortality in the London fog incidenL 1952. Lancet 1953 Feb 14th 336-339. 

Thus, several lines of evidence suggest that persons in the population at risk Irom inhaled particles are those with severe heart and lung diseases. The newer findings mirror the historical record from times of much higher exposures. In the London fog of 1952, the proportion of deaths attributed to heart and lung diseases increased during the dates of the fog (21). Additionally, because heart disease is the leading cause of death in the United States, any effect of particulate air pollution on total mortality would be expected to reflect at least an adverse effect on persons with heart disease. 

Figure 1 Daily mean pollution concentrations and daily number of deaths during the London fog episode of 1952.

---