I in the course of Spread of the new type of corona virus, road traffic has decreased sharply almost everywhere. Take the Stuttgart Neckartor, for example: If there are usually more than 60,000 cars on the road on a normal weekday, at the end of March there were never more than 40,000 according to the 'Stuttgarter Zeitung'. As satellite data show, the air quality is improving in many places as a result. 'The corona crisis is reducing environmental pollution', states the Federal Environment Agency.
High NOx values despite less traffic
The nitrogen oxide values in metropolitan areas, which are largely diesel However, despite the low traffic, they do not decrease to the same extent. Again the example of Stuttgart, Neckartor measuring station. Here the NO2 values between April 14th and 18th were again and again in the range between 60 and 80 micrograms per cubic meter (µg /m³). The measuring station in Munich on Landshuter Allee even repeatedly reached values above 100 µg /m³ in the same period. On April 16, there was even a one-hour value of 171 µg /m³. To classify: The valid NO2-EU limit value for the outside air is 40 µg /m³ on an annual average. The limit value of 200 µg /m³ for the one-hour average may only be exceeded 18 times a year.
The high nitrogen oxide values at these measuring points are causing some politicians to reduce the diesel emissions that have been passed to reduce NOx pollution. Driving bans ( everything worth knowing here ) to question.'In my opinion, the topic of diesel driving bans is finally off the table,' says CDU politician Steffen Bilger in 'Focus'. Why the nitrogen oxide values do not fall despite the rapid decline in traffic raises questions that the responsible environmental authorities have to clarify, says the Parliamentary State Secretary in the Federal Ministry of Transport. Judith Skudelny, the environmental policy spokeswoman for the FDP, thinks it is 'interesting' that 'less traffic is no guarantee of clean air.'
As an annual mean, Stuttgart has so far complied with the limit values
The Federal Environment Agency (UBA), however, warns against jumping to conclusions from the most recent NOx readings. It is not yet possible to say how the measures taken in the course of the Corona crisis will actually affect air quality. The UBA explains the high values with meteorological effects. 'If weather conditions are poor in exchange, the pollutants accumulate in the air - the result is increased concentrations.' On the other hand, strong winds help to distribute the pollutants quickly and reduce the concentrations. 'These effects lead to typical, short-term fluctuations in the measured concentration values.'
Nevertheless, according to the UBA, there were positive effects of the lower volume of traffic in some places. 'Studies from Hessen showed a reduction in NO2 concentrations of around 40 percent, which is attributed to the reduced volume of traffic.' If you use the mean value of the first quarter of 2020, even Stuttgart complies with the EU limit value - albeit only just barely. The regional and local effects can be very different.
'No reason to lift driving bans'
For the Federal Environment Agency there are enough NOx emitters on the even in times of the Corona lockdown Streets. 'Public transport buses and private cars are still on the road in the cities. In fact, an increased volume must be assumed for delivery traffic,' one saidAssessment. In addition, it can be assumed that road traffic will increase to the usual level or even more in a few weeks. In relation to the year as a whole, therefore, no significant improvements are to be expected. 'Since the NO2 limit value for the protection of human health relates to the calendar year, there is no reason to lift driving bans or entry restrictions,' says the UBA.