Monday, 3 July 2017


Daily Telegraph 17/04/17

Michael Fitzpatrick GP

As somebody who groped his way to school through winter smogs in
Sheffield in the Fifties and Sixties, I have always been sceptical
about the claims of environmental campaigners that air pollution in
British cities is now reaching critical levels of toxicity. I recall
playing football on pitches where neither goal was visible from the
halfway line. No doubt any therapeutic benefits were outweighed by the
damage to our youthful lungs.

Yet recent headlines proclaim that our children are being exposed to
illegal levels of toxic air, and London mayor Sadiq Khan has declared
a public health emergency. He quotes epidemiological studies claiming
9,000 Londoners are dying prematurely each year due to poor air
quality. Estimates of national fatalities have increased from 40,000
to 60,000 per year.

It is worth recalling that the Great Smog of December 1952, widely
regarded as an environmental catastrophe, killed only 4,000 people in
London. Can it really be true that air pollution is now killing more
than twice that number every year in the capital, and 10 to 15 times
as many nationwide?

Well, no. On closer inspection, it turns out that these are not actual
deaths, but estimates, produced by mathematical modelling, of the
number of premature deaths that can be attributed to air pollution.
The figures are derived from calculations of the "years of life" lost
across the whole population resulting from the increased risks
associated with particular pollutants. According to Cambridge risk
statistician Prof David Spiegelhalter, another way of presenting the
same data would be to state that the average loss of life expectancy
over the whole adult population is... three days.

It is true that the character of air pollution has changed. Whereas we
inhaled soot and sulphur oxides as the by-products of burning coal,
our children are now inhaling particulates and nitrogen oxides, partly
because of the last Labour government's "green" incentives to persuade
us all to switch to diesel-fuelled cars.

However, levels of particulates and nitrogen oxides have been falling
steadily for decades - they are now about a quarter of what they were
in 1970. It is also worth noting that air pollution in London is about
one eighth of that in Delhi, a quarter of that in Beijing, and lower
than that in Paris.

In the words of Brighton respiratory physician Prof Anthony Frew, who
served on the original Royal College of Physicians' working party on
air pollution, the claim of 9,000 deaths in London is a "zombie
statistic - however much you try to kill it, it comes back and it's
simply not true".

Further reference H/T Paul Withrington.

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