There are more and more cities introducing emergency air quality traffic bans, this page looks at them in more detail. 

The schemes include emergency diesel bans, alternating number plate schemes, complete traffic bans, calls for less travel by car.

Which cities have emergency air quality schemes?

Do odd even schemes work to reduce pollution?


Where are the odd and even number plate and emergency air quality schemes in Europe?

There are increasing numbers of Odd and even number plate and emergency air quality schemes in Europe. These are in operation at times of very high pollution, or when very high pollution episodes are predicted:

Stuttgart request to not drive during pollution episodes, and cheaper public transport

Paris odd and even scheme, cheap/free public transport

Grenoble emergency low emission zone, cheap/free public transport

Lyon odd and even scheme

Bergen odd-even numberplate scheme.

Oslo a diesel ban or an odd-even numberplate scheme.

Madrid odd and even numberplate

Milan traffic ban

Rome odd and even number plate scheme

Florence: traffic ban

Pavia:  traffic ban

Perugia & Ponte San Giovanni: emergency LEZ scheme in Umbria

Athens an odd and even car ban from September to June every year.


Do emergency air quality traffic schemes work?

What impact do alternating even schemes have on pollution?

There is evidence that they can have an impact in the case of temporary measures in cases of high pollution. They may reduce traffic, but often not by the half that would be expected.

There is considerable evidence that they do not have significant impact if implemented permanently. This is because people either have two cars anyway, and ensure that they have both an odd and an even numberplate, or they buy a cheaper (and therefore older and more polluting) car with the other numberplate type.

A number of cities that have had the impact of their emergency schemes assessed, and the results are summarised below.

The impact of Paris's emergency odd even traffic scheme in March 2014

Airparif (the Paris air quality monitoring agency) estimates that the emergency measures to reduce pollution in cases of high pollution works. Implementing the measures during the event in March 2014 led to an estimated 2% PM10 in average on the day for the urban background. Close to major traffic routes, the reduction was 6% and during rush hour on the Paris ring road particulate levels fell by 20%. Rush hour levels of nitrogen oxides fell by as much as 30%. 

Impact of Bergen’s emergency odd even traffic scheme in January 2016.

Bergen had odd even traffic restrictions on two days in January 2016, and a report was undertaken. In summary, the report said:

It was as hard to say anything about what effect the date driving has had on air pollution in Bergen. Pollution reduced during the measure and increased after the measure. It can be assumed that the pollution after would have been even higher without the scheme.  Fewer vehicles within the toll road will give fewer emissions within the ring road, but potentially higher pollution outside due to drivers diverting.

A TOI report after a similar measure in the winter 2010, showed the measure only had an impact on the day itself, with a 27% reduction of traffic on the Friday of the measure compared to Fridays later in January.

In the 2016 case as comparison, there was a traffic reduction through the toll booth of approx. 14.5%. It is also worth mentioning that other measures against poor air quality were undertaken before and during the measure, such as dust binding and washing of the roadways, urging not to fire in the oven if you have other heating sources, these measures will have an effect on PM10 and PM2.5-pollution.

Source: Bergen city


 Madrid emergency scheme, 3rd December 2015

"Data from yesterday and the day before yesterday have been extraordinary, with an average of 73 km/h. That means that there is a very important citizen response without practically put fines" as highlighted Mayor Carmena. Who pointed out that in the previous episode of high pollution they were implemented with the intention of raising awareness rather than punishing measures. In that episode, only with the restriction of car parks in the Centre (filled with 20% of car parks) and the limitation of speed, managed to reduce the level of nitrogen dioxide emissions down to normal levels.

Source: Madrid city website


Stuttgart, January 2015

Stuttgart's first smog (Feinstaub) alarm ended on Friday the 22nd January 2016, having started on Sunday 17th January. There are questions about how much impact it had, discussions about 3% traffic reduction.


Beijing 2008 

Results show that during the traffic restriction period, although more than 50% of vehicles were forbidden to travel in Beijing, the traffic volume was only reduced by 20% and 40% while the travel speed had been increased by 10% and 20%. Smoother travel in cities can reduce emissions.

This suggests that such traffic restriction policy may be an effective short-term management measure in dealing with increased transportation demand and congestion during major events, such as the Olympic Games. Results also indicate that vehicle travel demand does not decrease with the same proportion as the total vehicles forbidden, at least for the expressway and main arterials in a city.

Source: Scientific paper


Delhi impact odd even scheme January 2016

Delhi operated an emergency odd-even numberplate traffic ban between January 1-15, 2016. Additional public transport was provided, and schools had an extended holiday.

We measure the impact of the odd-even program on PM2.5 concentrations in New Delhi using a difference-in-differences (DiD) approach. To do this, we compare air pollution levels before and after the program, within and outside Delhi in the National Capital Region, where the program was not implemented.

The estimated reduction in PM2.5 concentrations was about 35-47 μg/m3, or 10-13% on average.

A statistically significant additional 10% reduction in emissions is estimated on average between 8am-8pm; however, air quality levels in the evening after 7pm are relatively unaffected.

Sources: Scientific paper, Also see animated map of differences, and summary on the Forbes website.

Guangzhou China, 2010 

Guangzhou operated temporary traffic control measures during the Asian Games in 2010. The restriction was with different levels (both ‘Green Labels’ or not and odd-even), and different timings.

Emissions were reduced by an estimated 38-52% during the first stage of the scheme and 28- 36% for the second stage. During the Asian Games, NOx and PM10 emissions were reduced by an estimated 26%, and 30%, respectively, compared with those before the Games.

Source: scientific paper    


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