The conclusions of the Quality of Urban Air Review Group were attacked by the motor industry. One in five cars sold in Britain is diesel; five years ago it was one in twenty. They consume less fuel and are cheaper to run; manufacturers have advertised them as more environment-friendly than petrol cars.
But Professor Roy Harrison, chairman of the group, which comprises 11 scientists from universities and government laboratories, said yesterday: 'I would most certainly prefer a petrol car with a catalytic converter.'
The group's main concerns are oxides of nitrogen and particulates - airborne specks of soot one thousandth of a millimetre across, small enough to travel deep into the lungs. Diesel cars produce more of these pollutants than petrol vehicles with catalytic converters - very much more in the case of particulates.
Oxides of nitrogen damage lungs and contribute to acid rain and photochemical smog. Particulates contain several chemicals thought to cause cancer in humans. Recent American research claims a strong connection between particulate levels and deaths from lung cancer and other heart and lung diseases. 'It's new evidence, but it's very worrying and requires prudent action,' said Dr Harrison, Professor of Environmental Health at Birminghan University.
He urged the Government to raise the duty on diesel. The motor industry has been lobbying the Chancellor to lower it for several years. Duty levels are 128p per gallon on diesel, 131p on unleaded petrol and 153p on leaded, with the final pump price of diesel about the same as unleaded.
'Any increase in the proportion of diesel vehicles . . . is to be viewed with considerable concern unless problems are effectively addressed,' concludes the report, commissioned by the Department of the Environment.
Robert Atkins, Minister of State for the Environment, said yesterday the Government would seek quick advice from medical experts on the health effects of particulates and consider whether to tighten standards further for diesel engines. Tougher standards will come into force under European Union law in 1996.
Diesel engines produce less of other air pollutants - carbon monoxide, a broad mixture of chemicals derived from unburnt fuel called hydrocarbons, and carbon dioxide, the most important man-made global warming gas. Manufacturers have claimed that diesel's greater fuel efficiency helps to conserve a non-renewable resource.
The Society of Motor Manufacturers and Traders said the report was alarmist and engines could be developed to reduce emissions.Reuse content