In a statement, Zero defended an update of the Reduced Emissions Zone in Lisbon “or, desirably, the creation of a Zero Emissions Zone, both in Lisbon and in Porto, covering the city centres”.

In these areas, only “public transport, resident vehicles and vehicles with limited emissions” could circulate, clarified the association, defending a firm commitment to soft mobility, which creates conditions for pedestrian circulation and good integration with cycle paths and public transport.

After compliance with the air quality indicators in 2020 and 2021, due to the “strong reduction in travel” in the Lisbon Metropolitan Area (AML), in 2022 frequent exceedances were again recorded.

In the first three months of 2023 (January 1 to April 6), “data still subject to final validation”, from the monitoring station on Avenida da Liberdade, “point to an average value of nitrogen dioxide of 48 micrograms per cubic meter ( μg/m3), 03 μg/m3 above the average registered in 2022”.

On the other hand, measurement stations in traffic areas with usually higher values in Porto (Praça Sá Carneiro) and Braga “point to average values of approximately 36 and 35 μg/m3, respectively”.

The association highlighted that these values of nitrogen dioxide (NO2), a pollutant attributed mainly to the combustion of diesel engines, exceeded the annual limit values stipulated in European legislation of 40 micrograms per cubic meter (μg/m3) and the recommendations of 10 μg/m3 of the World Health Organization (WHO).

“These values are substantially higher than the limits proposed for the new Air Framework Directive that approach the values suggested by the WHO (20 μg/m3). In this scenario, the number of non-compliant air quality measurement stations could increase dramatically, leading to the need to act as soon as possible”, underlined the association.

Environmentalists consider that "the role of the State is fundamental to avoid the inaction of the municipalities", which must create Air Quality Improvement Plans and the corresponding Execution Programs.

Zero also mentioned that, so far, no Implementation Program has yet been published for the Air Quality Improvement Plan for the Lisbon and Tagus Valley Region, approved in 2019.