Avoid knee-jerk reactions over diesel

Sir, - Those of us who were encouraged to buy diesel cars a few years ago by our Government, the EU, Friends of the Earth and Greenpeace, will be dismayed by the current ditch-the-diesel campaign demonising diesel owners as polluters and the source of unnecessary deaths and illnesses.

Nitrogen dioxide produced by diesel exhausts is allegedly linked to the deaths of 40,000 people each year.

However, life and medical science is never that simple or obvious as the popular press and many of our political representatives make out.

The evidence for the effects of nitrogen dioxide and its implication in so many deaths is actually by correlation and not as an implicitly causative factor. Correlation does not imply causation.

For example, since 1950, cases of obesity and the concentration of carbon dioxide have risen sharply, therefore, it could be said carbon dioxide must cause obesity.

This, of course, is a fallacy but illustrates how careful we must be before exercising expensive knee-jerk reactions to perceived risks which might be out of all proportion.

There are no tests which show nitrogen dioxide as a direct causative factor in any of the 40,000 deaths allegedly linked to the gas.

Other factors such as age, lifestyle, smoking, alcohol intake, working environment, genetic factors and the presence of other diseases must also come into play and distort any meaningful link to diesel emissions as a factor other than one of correlation.

Invoking the precautionary principle at every turn can be very counter productive. Risk aversion can be restrictive and impede progress.

Let’s think this through more objectively before committing to the possibility of unnecessary disruption and expensive regulation.

Iain G Richmond.

Guildy House,

Monikie.

Picture: Press Association. Traffic pollution has been linked to ill-health.