Diesel cars can improve air quality, claims motor industry group?

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Car manufacturers in the UK have hit back at the recent spate of negative comments, reports and scientific data about diesel vehicles, saying that the latest iterations of the diesel engine as “the cleanest in history” and “light years away from their older counterparts”.

That may be so but just because the new diesel engines are cleaner than their older counterparts does not make a diesel engine clean.

It’s like saying, ‘I have taken out half of the poison from the class of water, so go ahead and drink up’. It just doesn’t make sense?

The Society of Motor Manufacturers and Traders (SMMT) in the UK has made claims that the latest diesel vehicles are the ‘cleanest ever’ and vital in the fight against climate change?

They are suggesting that diesel cars could play an important role in helping improve air quality in towns and cities and in tackling climate change.

The latest engines may well be the ‘cleanest ever’ but vital in the fight against climate change is certainly a stretch.

What is diesel exhaust?

Diesel exhaust is produced when an engine burns diesel fuel. It is a complex mixture of thousands of gases and fine particles or soot that contains more than 40 toxic air contaminants.

These include many known or suspected cancer-causing substances, such as benzene, arsenic and formaldehyde. It also contains other harmful pollutants, including nitrogen oxides.

The Dangers of Diesel Fuel Emissions

Diesel cars emit up to six times more nitrogen oxides (NOx) on the road than they do in emissions tests.

Nitrogen oxides are poisonous gases that contribute to such things as acid rain and suffocating smog.

These gases are found in the fumes of diesel cars like the ones Volkswagen has admitted to fitting with emissions-cheating software with the express purpose of hiding the dangerous elements of the fuel emissions.

Exposure to diesel exhaust can have immediate health effects such as irritating the eyes, nose, throat and lungs. It can also cause coughs, headaches, lightheadedness and nausea.

How a motoring organisation can say diesel cars can improve air quality is quite frankly preposterous.

Here is a direct quote from the HSE in the UK “Control of diesel engine exhaust emissions in the workplace

Health effects:
    • 11 It is not precisely known which components of combustion are responsible for ill health effects, but exposure to DEEEs is associated with irritation of the eyes and the respiratory tract. This is particularly noticeable when there are high levels of white smoke in the workplace such as in bus garages when the bus engines are started from cold in the morning with no controls. Irritation of the upper respiratory tract is the primary health effect following exposure to DEEEs.
    • 12 Prolonged exposure to DEEEs, in particular to any blue or black smoke, could lead to coughing, increased sputum production and breathlessness.
    • 13 Diesel engine exhaust emissions contain many known carcinogenic substances, for example, Polycyclic Aromatic Hydrocarbons known as PAHs which are adsorbed onto the soot particulates. These particulates are easily inhaled into the respiratory tract and there is epidemiological evidence, which indicates that sustained occupational exposure to DEEEs may result in an increase in the risk of lung cancer.  

A report from the International Council on Clean Transportation (ICCT), a research group, who also played a key role in exposing Volkswagen’s cheating, compared the emissions from trucks and buses in realistic driving conditions and found some startling results.

They also showed that diesel cars being sold in the UK emit an average of six times more nitrogen oxide in real-world driving than the legal limit used in official tests.

Last week, the Mayor of London Sadiq Khan, announced a new charge on diesel cars driving into the city. Under these new proposals, drivers of diesel cars that are more than four years old in 2019 and petrol cars that are more than 13 years old will pay £12.50 a day on top of the congestion charge in an attempt to cut air pollution.

Environmental Protection Agency Report Ireland

A recent Environmental Protection Agency Report seems to have slipped under the news radar when it should have been headline news.

Pollution is causing an estimated 1,200 premature deaths in Ireland every year - some 400,000 across Europe

The major cause of all these deaths in Ireland, Europe and indeed the world is transport pollution and most transport pollution is, by definition, caused by diesel.


Extract from Irish EPA report: Air Quality and Health Air pollution and health impact: a very significant issue in Europe:

Under WHO and EU estimates, more than 400,000

premature deaths are attributable to poor air quality in

Europe annually, which elevates air quality to being a

policy priority. In Ireland the premature deaths attributable

to air pollution are estimated at 1,200 people. The most

common causes of premature death attributable to poor

air quality are strokes and heart disease. The economic

impact is also significant, with the increased costs of

healthcare and lost working days. A recent report by the

OECD concluded that the economic cost of air pollution

(in terms of global economic output) will, by 2060, equate

to US$330 per person per annum, or US$176 billion; and

the annual number of work days lost is estimated to rise

to 3.7 billion (OECD, 2016). What all of this means at

a human level is that, across Europe, tens of thousands

of people are losing 3–4 years of their lives because of

air pollution, years they could have been spending with

their families and communities in good health had they

not been exposed to dangerous levels of air pollution

throughout their lives. It should also not be forgotten that

air pollution has significant impacts on ecosystems and

buildings (EEA, 2014).

Diesel is just not that clean

The SMMT do outline a number of facts which taken by themselves can be valid but the overall big picture remains the same. Diesel is just not that clean and certainly not as clean as they are saying.

They list of “10 facts you need to know about diesel”. They maintain that some of the recent reports had failed to differentiate between older diesel cars and those on sale today which comply with Euro 6 emissions standards, adding: “This is unfair and dismissive of progress made.”

They also say that modern diesel engines have special filters and technology that convert most of the nitrogen oxide (NOx) from the engine into harmless nitrogen and water before it reaches the exhaust.
“Contrary to recent reports, diesel cars are not the main source of urban NOx. In London, gas heating of homes and offices is the biggest contributor, responsible for 16%. While road transport as a whole is responsible for around half of London’s NOx, diesel cars produce just 11%, although concentrations will vary at different times depending on congestion.”

The SMMT’s chief executive, Mike Hawes said:
“Euro 6 diesel cars on sale today are the cleanest in history. Not only have they drastically reduced or banished particulates, sulphur and carbon monoxide but they also emit vastly lower NOx than their older counterparts – a fact recognised by London in their exemption from the Ultra Low Emission Zone that will come into force in 2019.”

He added: “In addition to their important contribution to improving air quality, diesel cars are also a key part of action to tackle climate change while allowing millions of people, particularly those who regularly travel long distances, to do so as affordably as possible.”


Justin Kavanagh
Justin Kavanagh is a recognised leader in automotive intelligence and vehicle data supply to the entire motor industry. He has almost 20 years experience in building systems from the ground up. As the Managing Director of Vehicle Management System, he understands the need and importance of trustworthy and reliable vehicle history and advice to both the trade and the public.
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