Scientists warned British ministers 22 years ago their planned “dash for diesel” could cause a public health disaster, but were ignored because the then government believed climate change was more important, documents released under freedom of information rules have revealed.
About 50,000 people die annually because of air pollution, yet many deaths might have been prevented had ministers heeded a 1993 report handed to the then environment secretary, John Gummer — now Lord Deben — warning that any increase in diesel could have just such a consequence.
It said that although diesel produced less of the key greenhouse gases (carbon dioxide, methane and nitrous oxide), it produced more of the toxic nitrogen dioxide and particulates that damage health.
It added: “The impact of diesel vehicles on urban air quality is a serious one. Any increase in the proportion of diesel vehicles on urban streets is to be viewed with concern unless problems of particulate matter and nitrogen oxides emissions are addressed.”
But the warning came at a time when climate change was seen as a more pressing issue than air quality. Margaret Thatcher had championed climate issues, telling the UN in 1989: “The most pressing task which faces us at the international level is to negotiate a framework convention on climate change.”
She also told ministers to prioritise the problem, a policy that continued when John Major replaced her as prime minister in 1990, overseeing budgets that favoured diesel. In 1992 this included a sharp cut in the tax on diesel company cars.
The documents show concerns about air quality were sidelined by civil servants in favour of climate change: “Research so far suggests that diesel emissions present a very low level of health risk.”
This was untrue; by then many scientists had warned of the risk if the government continued to promote diesel.
Among them was Martin Williams, head of the former Department of the Environment’s air quality research unit for 20 years from 1993, who said ministers were clear climate change and fuel efficiency had priority.
“Climate change took precedence. At that time there were discussions in Europe to cut the average CO2 emissions of new cars by 25%. Diesel was seen as the way to achieve this because it was considered more efficient,” he said.
In 1994 Gummer showed some awareness of scientists’ concerns over diesel. Asked whether unleaded petrol or diesel-powered cars were “better for the environment”, he said: “When diesel cars are used largely for longer journeys, there is a real environmental advantage. If they are used for stopping and starting in towns, the balance goes the other way.”
Last week Gummer, who is now chairman of the government committee on climate change, said he could not remember discussions from so long ago, but he added: “In attempting to solve one problem, we inadvertently land ourselves with another.”
Up to 9,400 people died prematurely in 2010 because they spent years breathing in pollutants commonly found in fumes from diesel trucks, buses and cars, according to a study by King’s College London academics.
That is more than twice the number calculated in previous studies and it shows Londoners are more likely to be killed by the air they breathe than a car accident, said the British Lung Foundation.