Between 2024 and 2025, there was no real improvement in air quality at 24 measuring stations across the Brussels conurbation. Annual nitrogen dioxide concentrations even rose slightly, measurements taken by the BRAL urban movement with the support of the Brussels Environment Agency show. According to the BRAL, which fights for a sustainable, inclusive and livable Brussels, the figures are a direct consequence of the postponement of the tightening of the Brussels low-emission zone.
Brussels air quality stagnates: Postponement of low-emission zone gets the blame
Colin Clapson
Published:
BRAL monitored the amount of nitrogen dioxide (NO2) in the air in Brussels for two years as part of the Expair project. This gas is a good indicator of local air pollution, especially from car traffic.
Of the 24 measuring points, the Guldenvlieslaan on the inner-city orbital ‘Kleine Ring’, the Piersstraat in Oud-Molenbeek and the Flemish Gate (Vlaamsepoort) score worst. These are either particularly busy traffic arteries, with a lot of braking and starting movements, or, in the case of the Piersstraat, a narrow residential street with quite a lot of car traffic. At these three points, Brussels exceeds the legal European limit of 40µg/m³.
But it is the general trend that is of particular concern to the BRAL. After a period of steady improvement, the figures have stagnated. Between June 2024 and June 2025, the NO2 average was 33.2 µg/m³, which is even slightly higher than the previous average (32.4µ/m²).
The urban movement calls the results ‘worrying’. The European standard, which Brussels must achieve by 2030, is 20 µg/m². No measuring point has yet achieved this target.
A lost year for air quality
The stagnating figures are no coincidence, but the result of postponing the tightening of the low emission zone, says the BRAL. ‘The figures show that postponing the LEZ phase planned for 2025 means a lost year for improving air quality in Brussels. The effectiveness of the LEZ depends on a clear roadmap and timetable, which gives citizens the necessary insight and time to adapt their behaviour,‘ says Lauren de Crombrugghe in a response to Brussels media outlet BRUZZ. ’The recent political uncertainty doesn’t allow this and only creates more confusion.’
Figures from the CurieuzenAir project did show a positive trend in the period before the postponement.
One in six suffer from respiratory disease
Stagnating air quality poses a health risk, the BRAL emphasises, a warning that paediatrician Daan Van Brusselen also recently made. 'Air pollution causes respiratory and cardiovascular problems and also has consequences for mental well-being and attention disorders. One in six Brussels residents suffers from a respiratory disease. That is why policy must continue to focus on health.'