As part of Wallonia’s Environment-Health Plan, ISSeP was commissioned to estimate the environmental impact of introducing communal low-emission zones by combining in situ measurements of pollutant concentrations with air quality modelling on a communal scale. The municipalities of Namur and Eupen served as pilot cities for this study, whose report has now been finalized.
To improve air quality, in January 2019 the Walloon Parliament adopted a decree on the fight against air pollution linked to vehicle traffic (http://environnement.wallonie.be/legis/air/air084.html). This decree provides for a gradual ban on the most polluting vehicles from 2023 throughout Wallonia and the possibility for communes to introduce low-emission zones (ZBE) on their territory from 2020.
Within a communal Low Emission Zone, access to the most polluting vehicles would be progressively banned, depending on engine type (diesel, petrol, etc.) and European emission standard (European Union regulation setting maximum pollutant emission limits for new vehicles).
Based on traffic data and emission factors specific to each vehicle category and driving style, pollutant emissions were assigned to each road section in the municipalities of Namur and Eupen. Counts were also carried out by ISSeP to supplement existing municipal and regional data.
These emissions were used to feed the ATMO-Street atmospheric dispersion model, which simulates the dispersion of pollutants from their main sources of emissions, i.e. industry and the road network. Pollutant concentrations are then calculated at various points in the study area and interpolated (projected by calculation) for the whole zone. The model takes into account the geographical configuration of the site (height of buildings) and atmospheric conditions (wind, temperature, etc.), which can lead to poor dispersion and therefore local accumulation of pollutants through a “canyon effect”.
High-resolution mapping (⁓10 meters) of air quality in Namur and Eupen was carried out with this model. It includes concentrations of nitrogen dioxide (NO2), fine particulates (PM10 and PM2.5) and black carbon (BC), as well as projections of the impact of a BIA on pollution levels. These projections take into account expected emissions reductions in relation to the phasing-out schedule already set out in the decree.
In both Namur and Eupen, ATMO-Street model projections show mixed results. Expected reductions are low for two pollutants for which standards must be met: nitrogen dioxide (up to 26% reduction by 2025) and fine particulates (no more than 10% reduction by 2025). On the other hand, a communal low-emission zone would have a significant impact on concentrations of a pollutant for which there is as yet no standard, black carbon, which is closely linked to road traffic. For black carbon, concentration reductions in Namur could reach 60% by 2025 compared to 2018 levels.
In Eupen, given the size of the conurbation, the introduction of a communal low-emission zone would be irrelevant, as concentrations are only really critical on the outskirts of the city center during the morning and evening rush hours.
In Namur, aware of the results of the study, the city has already implemented measures to improve air quality. These include the launch of a 20 km zone to promote soft mobility in the city center, the continued development of the bus service, the “greening” of the municipal vehicle fleet, the development of pedestrian-cycling infrastructures, plantations, P+R parking facilities, the installation of electric charging stations, new public squares, improved urban logistics and measures targeting residential heating.
In Eupen, to reduce air pollution, a traffic plan adapted to peak hours is favored.
Céline Tellier: “A gradual regional ban on the most polluting vehicles is planned from 2023. The study carried out here provides a nuanced response to the relevance of introducing communal low-emission zones in the meantime. As Brussels has also demonstrated, a communal low-emission zone is only effective above a certain critical size of conurbation. Other measures, such as the introduction by some towns and cities of shared zones where car speeds are reduced to 20 km/h, could prove just as relevant. I hope to be able to measure their effects with a reinforced network of measures”.
The final report of the “2ZBE” study on the relevance of setting up communal low-emission zones, including all the results and conclusions of this research, is available to download: https: //www.issep.be/wp-content/uploads/Rapport_final_2ZBE.pdf