high but the alternative could be millions of angry customers not an attractive option for germany's carmi. either. of these city of dusseldorf has some of germany's most polluted air it was one of the cities sued by environmental action germany for repeatedly violating pollution limits of nitrogen oxide well the mayor of dusseldorf is thomas guys well he joins me tonight from dusseldorf good evening to you mr mayor so what does today's ruling mean for you will you now ban diesel vehicles from your city well good evening well first of all it does not necessarily mean that we have to bend these will cars i mean what the court has decided is that a ban on diesel cars is legally possible but it has to be implemented by maintaining what they call the proportionality principle that means only if a ban on diesel cars is the only efficient means to reach the threshold values for what is that nitrogen oxides as it is in english and nitrogen oxide only then it needs to be implemented what other means there are other shoals what are what are they what what are they i mean you got there the dirtiest