Air pollutants have decreased less than initially estimated due to the Corona pandemic. Favourable weather conditions also played a role. This year, therefore, an increase is very likely and could spur driving bans again.
We all have images of empty streets and deserted city centres from last year in mind. So researchers had also assumed that the decline in traffic and the downturn in the economy had brought about a significant improvement in air quality in many European countries and around the world. Researchers at the University of Birmingham have now published results showing that the weather also contributed to the improvement in air quality.
In eleven cities worldwide, including London, Berlin, Milan, Rome, Paris and Madrid, the British researchers recalculated the values taking into account the weather conditions. Weather data from 2016 to 2019 and seasonal differences such as a decrease in heating and an increase in pollen in spring were included in the readings.
The result is that nitrogen oxides in particular have decreased less than expected due to the Corona pandemic. In Berlin, a decrease of 28.1% in nitrogen oxides was initially assumed. Taking the weather into account, the decrease was only 25.4% and according to the calculations, in which seasonal changes were included, even only 11.3%. In the case of ozone, a significantly increased ozone value was initially assumed, but according to the new calculations it was only increased by 2.6% instead of 57.8% in Berlin, for example. Since nitrogen oxides in the air contribute to the depletion of ozone, a low nitrogen oxide value can also be explained by an increased ozone value.
The results of the particulate matter measurements are ambiguous, according to the British researchers. In Paris and London, particulate matter levels actually increased during the lockdown.
If the Corona situation allows for an early increase in traffic and a kick-start of the economy, and if the weather is less favourable this year, this does not bode well for low emission zones in Europe. In fact, it shows that even if traffic is reduced, for example through new diesel driving bans or stricter rules in the low emission zones, an immediate improvement in air quality cannot necessarily be expected. For opponents of diesel driving bans in Stuttgart and Hamburg, for example, this also means that the abolition of driving bans cannot simply be justified by a year in which the limit values were complied with.
Environmental zones and diesel driving bans will therefore probably be with us for many years to come.