20 November 1998

Don't Get Stuck Behind A Truck Or A Bus

Science à GoGo bikers and cyclists have long known not to drive too closely behing diesel vehicles; the stench, particles and fumes are clearly much more harmful than those of petrol vehicles, now research supports what you know for a fact, diesel vehicles should clean up their act or get off the road.

New diesel cars are more detrimental to the environment and to health than new petrol-driven cars. Diesel cars have improved considerably over the last ten years, but exhaust emission control technology in petrol-driven cars has developed faster. This is the result of a study commissioned by the Swedish government and performed by the Swedish Environmental Protection Agency.

"Diesel cars emit much greater amounts of nitrogen oxides, particulates and carcinogenic substances than new petrol-driven cars. The current trend in increased sales of diesel cars is actually jeopardising our chances of achieving the environmental goals for cleaner air and reduced acidification and eutrophication", says Reino Abrahamsson at the Swedish EPA.

"For the sake of the environment, it is better if car buyers choose a fuel-efficient environmentally classified petrol-driven car rather than a diesel", he adds.

The rising proportion of diesels among newly sold cars will cause a considerable increase in nitrogen oxide emissions, ascertains the Swedish EPA. The study shows that if diesel car sales rise from 1 to 20 per cent, emissions of nitrogen oxides from new cars will double and particulate emissions will be 2* times higher. Nitrogen oxide emissions contribute to the acidification of our lakes and soil and to the eutrophication of coastal waters.

Diesels use 20 to 25 per cent less fuel. When they are advertised, great stress is put on this fact as being very positive for the environment as it helps to combat global warming. However, since combusting one litre of diesel oil produces about 15 per cent more carbon dioxide than one litre of petrol, emissions of carbon dioxide, which is a greenhouse gas, are only negligibly less from diesel cars. An increase in diesel car sales from 1 to 20 per cent reduces carbon dioxide emissions by a mere 1-2 per cent.

In terms of cancer risk, negative effects on respiratory passages and acute health problems, a modern petrol-driven car has the least negative impact on our health. Emissions from new diesel cars are estimated to be 3-4 times more carcinogenic than emissions from petrol cars. A modern diesel also emits about 10-15 times more particulates than a modern petrol car. New diesels are however much better than older ones. But what about when new diesels become old diesels?

"To help achieve the environmental goals, we should reduce the number of diesel cars. The current trend is going in completely opposite direction. Using diesel cars instead of petrol-driven cars is not an effective way of combating climate change", stresses Reino Abrahamsson.

15 per cent of newly registered private cars in August this year were diesels. At the beginning of the nineties, the proportion of newly registered cars that were diesels was only 1 per cent.