The Supreme Court has ruled that the UK government must take action to
cut pollution.
This has prompted a swathe of
articles predicting the
demise of diesel cars.
I would suggest that we all look at the evidence, rather than rhetoric, before making sweeping recommendations. Although action is required promptly, it is important that the right action is taken so we can be confident that we will all be breathing clean air within a few years.
Cast your mind back to 2001, when the focus was on carbon dioxide emissions. The government changed vehicle excise duty so that cars which emitted a higher level of carbon dioxide (petrol vehicles) faced a higher level of vehicle excise duty.
This caused a big increase in diesel cars, which now number more than 11 million and represent about a third of vehicles. At that time, diesel vehicles emitted 10 times the amount of fine particles and up to twice the amount of nitrogen dioxide that more modern vehicles do. So, in short, these emissions have contributed to the pollution we are experiencing now.
Most people agree that taxes and incentives should be based on whether vehicles meet the latest emissions standards. Yet, because they regard diesel as dirty, they believe that diesel vehicles should be taxed more than others.
The vast majority of Londoners think emissions from diesel vehicles have risen over the last 15 years, when they have in fact fallen - and they are unaware that new diesel cars have to meet strict new Euro 6 standards.
Over the last decade, the car industry has invested millions, if not billions, in reducing emissions, regardless of fuel. We need the politicians, public and media to be aware that today’s diesel engines are significantly cleaner than those built just a decade ago, thanks to improvements in engine design and efficient exhaust after-treatments.
The
data tells us that over the last 15 years, oxides of nitrogen emissions from diesel cars have decreased by 64%, while particulate matter emissions decreased by 90%. It also tells us that diesel vehicles emit up to 20% less carbon dioxide than their petrol counterparts.
It is important that we challenge outdated, negative perceptions of diesel and increase understanding of new diesel technology, positioning the benefits of advanced diesel technologies so that diesel’s contribution to improving air quality is acknowledged.
There have been suggestions that diesel cars should be scrapped or banned from cities. This is not a helpful suggestion in terms of business or to reduce pollution.
A more realistic approach would be to incentivise people to trade in old vehicles, and upgrade to a vehicle with lower emissions sooner. Educating the public on the facts and figures of vehicle emissions will help them make a sensible buying choice.
The car industry should be encouraged to continue with a mix of technologies, especially electric and hybrid, but the targets must be clearly laid out.
I would encourage the “green” options, which I suspect will need to comply with the court ruling. Congestion charging is likely to increase, and walking and bicycle routes should be expanded. Some European cities are banning cars when pollution is high, and offering free public transport. These measures may be necessary here.
Reducing vehicle emissions is not the whole problem, as they only represent 27% of the total oxides of nitrogen emissions. Compare that with electricity generation, which causes 30%.
While vehicle emissions are often concentrated in built up areas, and are therefore potentially more damaging, pollution does not respect city boundaries and can have far-reaching effects. So I would advocate a wider perspective in terms of geography and industry sector.
Whilst I am wholly in favour of less pollution and safe air, I think blaming diesel cars is a convenient and simplistic response. Let’s make sure we look at the latest technology and all the data in order to make informed recommendations.
I believe the automotive industry has a great track record in developing technology that ensures that they comply with emissions targets. So let’s acknowledge that new diesel engines can have a positive impact on improved air quality, and end the demonisation of diesel.
Philippa Oldham CEng MIMechE is the Institution's Head of Transport and Manufacturing. She works with members to raise the profile of engineers and provides thought leadership within the transport and manufacturing realm.
Follow or contact Philippa on Twitter @Philippa_IMechE