Lisbon, Sept. 8, 2026 (Lusa) - Air quality in the Portuguese capital improved in 2025, with the European limit value for nitrogen dioxide (NO₂) being met – something that had not happened since the Covid-19 pandemic – the Lisbon city council has revealed.
«This result is particularly significant on Avenida da Liberdade, traditionally the location with the highest levels of nitrogen dioxide associated with road traffic,» stated Lisbon city council (CML) in a press release issued on Monday to mark International Clean Air Day.
According to the CML, in 2025, the air quality monitoring station on Avenida da Liberdade, the main thoroughfare in central Lisbon, «recorded an annual average concentration of 40 µg/m³ [micrograms per cubic metre]" of nitrogen dioxide, complying with the annual limit value currently in force in the European Union and in Portugal, which is precisely 40 µg/m³.
«The data for 2025 confirm a positive trend in air quality in Lisbon, with compliance with the annual limit value currently in force for nitrogen dioxide (NO₂) at all stations in the Air Quality Monitoring Network,» stated the municipality, chaired by Carlos Moedas (PSD).
Since the Covid-19 pandemic, which occurred between 2020 and 2022, the year 2025 «is the first year in which Lisbon has complied with the limit value for NO₂ at all monitoring stations, including on Avenida da Liberdade», emphasised the CML, noting that, during the pandemic crisis, the reduction in economic activity and car traffic led to an exceptional decrease in emissions and concentrations of atmospheric pollutants.
In the city council's view, the 2025 data highlight «a downward trend in nitrogen dioxide concentrations that has been observed in the Lisbon region over recent years», which reflects, amongst other factors, technological advances in vehicles, the gradual renewal of the vehicle fleet and the efforts made by public authorities, including the municipality, to improve mobility and reduce emissions.
Quoted in a press release, the Mayor of Lisbon, the Social Democrat Carlos Moedas, emphasised that the 2025 figures «confirm that Lisbon is making sustained progress and improving air quality».
«We have made significant progress over the last three years and this trend has provided further encouragement to continue investing in more environmentally friendly transport,» said Moedas, whilst noting, however, that the coming years will present «daunting challenges» in terms of air quality.
Councillor Vasco Anjos (IL), who is responsible for the Environment, said, as quoted in the same press release, that the results achieved show that Lisbon is making «consistent progress in improving air quality», noting that «it is an encouraging sign» which the municipality is highlighting on International Clean Air Day, and which «gives us even greater impetus to continue investing in more sustainable transport and a healthier city for everyone».
Also marking International Clean Air Day, the environmental organisation Zero and the Portuguese Council for Health and the Environment (CPSA) warned that nitrogen dioxide (a pollutant emitted by combustion-engine cars) «remains a critical pollutant in urban areas», noting that traffic is «one of the main sources of pollution» and singling out Avenida da Liberdade in Lisbon as one of the most serious cases of NO₂ concentration.
The two environmental organisations indicated that, in 2025, according to provisional data, «Avenida da Liberdade recorded 40.3 μg/m³, meeting the limit only due to rounding», a result they attribute «most likely to more favourable weather conditions, the dispersion of pollutants and the renewal of the vehicle fleet, rather than to public policy measures specifically aimed at improving air quality».
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