January 1, 2025 was a date marked on the calendar of residents of the Barcelona metropolitan area. After months of half-heartedness, six low-emission zones (LEZ) began to operate at full capacity and, therefore, with fines. This is the case of Sant Boi de Llobregat, Cerdanyola, Sant Joan Despí, Gavà and Viladecans. In these cities, residents with polluting cars can circulate in the affected neighborhoods for a maximum of 24 days a year if they are registered, but if they exceed this threshold and do not prove any special circumstances, such as low income levels or transport needs for health reasons, they are fined. There is only one exception: Cerdanyola has decided to exempt all registered residents from fines for the next three years. Now, other municipalities will follow the same path.

It is difficult to understand the ultimate meaning of Catalonia's High Court's ruling annulling Barcelona's low emission zone (LEZ), in a city with very high pollution rates and which has been in the European spotlight over this issue for some years now. In fact, the Catalan capital is one of the European cities with the highest vehicle traffic density. The High Court should not ignore that the European courts have opened a sanctioning procedure against Spain for the fact that both Barcelona (and several cities in its metropolitan area) and Madrid exceed in a "systematic and continuous" way the limits on nitrogen dioxide emissions (NO2). The LEZ that is now endangered –although not suspended, since there is room for judicial appeals– was a response to this justified and logical European pressure. Moreover, the European Environment Agency has warned that the LEZ is not enough. All this should be known by the judges of the Catalonia's High Court, whose ruling contradicts this environmental and judicial reality at European level.