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Air Pollution Calculations

Questions to the Mayor of London – answered on 17th October 2019.

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Photo of Keith Prince Keith Prince Conservative

What is the formal record of cause of death to which the Mayor is referring, from which he has calculated that 9.500 London residents are dying each year due to air pollution in the city?

Photo of Sadiq Khan Sadiq Khan Mayor of London

Cause of death as recorded on a death certificate is not always the same as an attributable factor in death. For example, were a heavy smoker to die from lung cancer the cause of death would be lung cancer. The best scientific evidence, around which there is a strong consensus, is that this death would be attributable to smoking. The cause of death, however, would be recorded as lung cancer. Similarly, there is a strong scientific consensus that in London thousands of premature deaths a year are attributable to air pollution. The causes of death attributable to air pollution exposure include cancer, stroke and heart disease.

The number of premature deaths in London attributable to air pollution was independently calculated by King’s College London in 2015 and the report explaining how they came to this figure is available on the website ( This report was based on the best scientific evidence at the time on mortality attributable to air pollution, more recent updates suggest that the true impact may be higher (please see Mayor's Question 2019/19768).