Dieselgate casts doubt over low emission zones

The local government announced on November 11 that the low emission zone was having a positive effect on air quality: on certain roads, 20 percent reduction of soot emissions was measured.

All over Europe cities have put in place, or are considering, low emission zones to improve air quality.

Such zones usually ban dirty trucks or vans, but increasingly, older passenger cars are also targeted.

London's city government, for example, is considering in 2017 to introduce an additional daily £10 (€11.65) charge for cars entering the city during office hours, if these cars were registered before 2005.

The goal is simple enough: to make the air more breathable. But how do cities decide which cars are clean enough?

This is where the story gets technical.

The main tool to decide which cars are clean enough to enter, and which ones will be banned, are the European emissions standards, or Euro standards: limits that become stricter with every new generation, from Euro 1 to Euro 6.

The higher the Euro number, the cleaner the car, in theory.

Following the Volkswagen scandal, we learned through on-road tests of diesel cars that a whole variety of brands are performing much worse than their Euro generation suggests.

In particular, the European standards on nitrogen oxides (NOx), which can cause respiratory problems and other health issues, are not being reached in the real world.

A recent report by the Dutch car approvals authority, RDW, showed that a majority of tested diesel cars in the official laboratory test passed as Euro 5 cars, were on the road sometimes performing worse than the Euro 3 standard.

That raises the question whether the Euro standards are still a good way to determine which cars to ban.

In part, cities already knew that the Euro standards were not being achieved on the road.

“We have known since 2010 that there is a gap between laboratory results on the type approval test and real-world emissions, so we have developed a method to calculate the effects of low emission zones based on actual measurements,” emissions expert, Richard Smokers, from the Netherlands Organisation for Applied Scientific Research (TNO) told EUobserver.

“Most cities use calculations based on real-world emission data to assess the impact of low emission zones,” he said.

The idea is; even if cars emit more on the road than in the official test, the total emissions go down as newer generations of cars come on the market.

“In terms of nitrogen dioxide, some Euro 5 diesel cars that are allowed in low emission zones may, in reality, be dirtier than some of the Euro 3 cars that are banned,” said Smokers.

“But taken as a whole, the Euro 4 and 5 fleet of diesel cars that may replace the banned older fleet is still on average cleaner than the Euro 3 fleet,” he noted.

However, that average improvement stops with the Euro 4 generation, at least for NOx.

If the only goal is to reduce NOx, then banning Euro 4 diesel cars and hoping they will be replaced by Euro 5 diesel cars "would not make sense", said TNO's Smokers.

“For NOx emissions in urban driving our data show that a Euro 5 diesel car is on average dirtier than a Euro 4 diesel car,” he added.

Paris

That may thwart plans by the Parisian government.

As of 1 July 2016, between 8AM and 8PM, Paris only allows Euro 3 and newer cars.

But the French capital has already prepared further subdivisions, for potentially tighter controls in future.

Car owners can get a sticker to show how clean their car is.

Euro 5 and Euro 6 diesel cars receive a “number 2” sticker, while Euro 4 diesel cars receive a “number 3” sticker, a distinction which for NOx does not match reality. The Paris administration was not available to comment.

Still relevant for other pollutants

So are low emission zones useless once all Euro 3 diesel cars and older are replaced?

Not quite, said Smokers.

“For particulate matter, Euro 5 is significantly cleaner due to the application of closed diesel particulate filters,” Smokers noted.

Officials from city governments also point out that NOx is not the only pollutant causing trouble.

Like Rotterdam, the Dutch city Utrecht has a low emission zone that bans diesel cars older than 2001 – allowing only diesel cars in the category Euro 4, 5, or 6.

A report by TNO published earlier this year showed the effect of the low emissions zone on NOx levels in Utrecht was rather limited.

“The effect [on NOx levels] has indeed been disappointing,” said Thijs Weistra, member of the city council of Utrecht in the Netherlands. But, he noted that newer cars were a lot cleaner in terms of particulate matter and soot.

The city of Ghent in Belgium is preparing to introduce a low emission zone in 2020, but its main goal is to reduce the levels of pollutants soot and black carbon, said Christophe Rogolle, a member of the cabinet of the city's alderwoman for environment Tine Heyse.

“We do not expect a significant drop in concentrations of NOx emissions as an effect of the low emission zone,” Rogolle told EUobserver.

The Belgian city Antwerp has similar expectations, said Matthias Janssens, advisor to that city's alderwoman for environment. Antwerp's low emission zone will be introduced in February 2017.

Janssens pointed to other effects of the zone. “It is not correct to assume that every old diesel car will be replaced by a newer diesel car,” he said, noting that those who get rid of their old dirty diesel will in many cases opt to buy a petrol car, or to use other means of transport more often.

Volkswagen relatively clean

But if you do want to stick to diesel: which car do you choose?

Jane Thomas from Emissions Analytics gave some consumer advice in Berlin recently.

Since 2011, Emissions Analytics has tested cars on the road and compiled a database of real-world emissions performances per car model, and a ranking.

Perhaps somewhat counter-intuitively, nine of the twelve best-performing Euro 6 diesel cars were produced by Volkswagen Group.

“Their reputation is so damaged by the scandal, but … they are producing [some of] the cleanest cars on the market,” said Thomas.

Nevertheless, the company's cheating has caused it to lose a lot of goodwill.

In Switzerland, all VW cars in the Euro 5 category have been banned from registration, even though, according to Emissions Analytics' data, there are many car types that perform just as poorly.

And while a new real driving emissions (RDE) test coming into force next year will improve the situation, carmakers will be granted breathing room: they will pass the test if the car emits up to 168 milligrammes of NOx per kilometre – 2.1 times the EU limit.

Cities feel effect of EU policy

It is decisions like this that bother local officials like Utrecht's council member Weistra, who is a member of the left-wing Green party.

“We are fighting in Utrecht for healthy air for our inhabitants, while car manufacturers are receiving flexibility in Brussels,” he said.

International Council on Clean Transportation researcher Peter Mock said cities should not only rely on RDE. Mock was one of the researchers whose report in 2014 triggered the US investigation into VW.

When asked by EUobserver how cities should determine which cars should or shouldn't enter the city, he said it's “a very difficult question”, saying instead that he would recommend EU regulators to “improve RDE”.

But what can cities do?

“A relatively easy answer would be to ban diesel cars, but that would be politically very difficult,” he said, adding that it would also be “stupid” to treat all diesel cars with equal distrust.

Mock says, “There is no real easy answer.”