Diesel, once hailed as a relatively clean, environmentally friendly alternative to petrol, is increasingly being recognised as a threat to public health. After decades of support and the promotion of the widespread belief that diesel releases less CO2 when burnt than petrol, sales of diesel vehicle in the UK have increased steadily.

However, the truth is that some old diesel cars emit other pollutants by up to 20 times as much as their petrol equivalents, especially on congested city streets. To fix this, four capital cities – Paris, Athens, Madrid, and Mexico City – have agreed to remove diesel vehicles from their centres by 2025. Now, there are calls to ban them from London too.

The white skies in Paris over the winter break did not signal snow. Rather, drivers faced two days of mayhem after concern over an unsettlingly low and dense layer of smog caused the authorities to restrict traffic in the city by banning vehicles with odd license-plates one day, and even ones the next. In return, public transport in Paris was free for those two days. Comparatively, when the pollution in London reaches terribly unhealthy levels, Plume Labs (who monitor air quality in London) advise Londoners to “avoid all physical activities outside”. There is something ironic about being advised to shun life-prolonging activities in order to prolong your life.

A recent study by the King’s College, London, Environmental Research Group for Transport for London and the Greater London Authority investigated the health impacts of poor air quality in the capital. They estimated that, in 2010, approximately 140,743 years were shaved off people’s lives as a result of air pollution in the city – the equivalent of 9,416 (normal length) lives lost. Diesel exhaust, which contains harmful gases (such as nitrogen dioxide), fine particulates, and soot, is a major cause of reduction in air quality. 

Doctors Against Diesel are taking a stand to change this. Last December, hundreds of medical professionals and environmental campaigners amassed along Euston Road, reportedly one of London’s most polluted thoroughfares. The group gathered to call on the city’s mayor, Sadiq Khan, to impose a ban on diesel in the city centre and to gradually curb its use in the suburbs. Professor Jonathan Grigg, who is both a consultant paediatrician at the Royal London Hospital and a researcher into the effects of pollution on children at Queen Mary University of London, told the Guardian that “if you’re going to design something that would effectively deliver a toxic substance into the lungs, you couldn’t do better than the diesel soot particle”.

This is a popular sentiment. The progressive UK think-tank, the Institute for Public Policy Research, has stated that “it is likely that diesel cars will have to be completely phased out on London’s roads over the next decade in order to reach compliance with safe and legal levels of air pollution”.

Diesel has been in the headlines since last September, when the US Environmental Protection Agency (EPA) and the California Air Resources Board (CARB) accused Volkswagen of having knowingly installed ‘defeat devices’ in 482,000 Volkswagen and Audi diesel engines in the US alone since 2008, to devastating effect. The software allowed the cars to pass the required emissions testing in laboratories, but in the real world they released harmful nitrogen oxides (NOx) at “40 times more pollution than emissions standards allow”.

In London, Sadiq Khan responded to ‘Dieselgate’ by demanding that Volkswagen replace the £2.5m that the city would have accrued in Congestion Charge returns. Now he’s gone two steps further – imposing an extra £10 toxicity charge for the most polluting vehicles in the city centre, and recommending the development of a “detailed proposal for a national diesel scrappage scheme for government to implement”, as well as declaring that, from 2018, London will obtain no new pure diesel buses. Khan also unveiled his contribution to the anti-diesel effort, which takes the form of the first hydrogen fuel-cell-powered double-decker bus, and promised that future single-decker buses will be zero emission.

While these measures are promising, London still has a long way to go before its air is fit to breathe. Some 90% of NO2 emissions from road transport in central London are the result of diesel engines and, warned Helena Molin Valdés, head of the United Nations’ climate and clean air coalition, “soot from diesel vehicles is among the big contributors to ill health and global warming”.

However, Transport for London recently sought public consultation on what they should do to improve air quality. Its website notes that people are twice as likely to die from lung diseases if they live in “deprived vs. affluent areas of London”, both signs that this problem is too complex to be solved by a blanket ban on diesel cars.

Its current plan is to formulate more detailed proposals from the opinions collected during the consultation, particularly regarding the creation of an Ultra Low Emission Zone and whether it should come into force in 2019 or 2020. Ultimately, the mayor will make this decision, but his choices must be based on the responses received during the three consultation stages that TfL plans to complete this year.

Less than a week into 2017, a monitor on Brixton Road had noted that NO2 concentration levels had surpassed 200 micrograms per cubic metre, which European Law dictates must not occur more than 18 times per year. Last year, ClientEarth, a non-profit activist organisation that specialises in environmental law, won a High Court ruling against the government over its failure to adequately handle the issue of the UK’s air pollution by citing an EU directive that allowed them to push the government to prosecute people who drive old diesel vehicles in urban zones. Mr. Justice Garnham stated that ministers were aware that pollution modelling was being based on the deceptive results of faulty lab tests instead of recorded road emissions. Although the government denied that it would appeal the decision, at Prime Minister’s Questions Theresa May claimed, “We have taken action, there is more to do and we will do it”.

Alan Andrews, one of ClientEarth’s lawyers, spoke to a Commons Select Committee, and conceded that a blanket ban on diesel cars would ignore the nuance of the situation. Instead, he supported Khan’s proposal for a government-backed “range of measures to disincentivise diesel, including a scrappage scheme and changes to vehicle exise duty”. Khan has also called for new legislation that updates the Clean Air Act to reflect the dangers posed by diesel in the 21st century. The last Clean Air Act, passed in 1956, came about as a result of the Pea Souper – otherwise known as the Great Smog of London. As viewers of Netflix’s popular series, The Crown, will tell you, though, there was nothing great about the air pollution plague.

There are fears that leaving the EU will allow the UK to repeal the emissions laws that hold the government accountable for increases in air pollution – particularly due to diesel exhausts. However, with the recent court cases and public scrutiny due to the dangerously low air quality in London, it seems probable that the government will support almost any means necessary to make cities less hazy. Although this does not mean the immediate implementation of a diesel ban, it is likely alternative fuel sources will be phased in alongside actions such as the rollout of an Ultra Low Emissions Zone.

While this in itself will not eradicate the issue of air pollution in the capital as diesel vehicles are not the only sources of pollutants, the effects of such legislation will not be insignificant and, combined with other green policies, are a step in the right direction towards a cleaner future.

Anjuli R. K. Shere is a 2016-17 Wellcome Scholar and science intern at our parent title the New Statesman, where this article was originally published.

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