Evaluating traffic policies on NO₂ pollution in Brussels: impact of the Low Emission Zone and the Good Move Plan, 2022-2035

Even though air quality has improved over the past two decades in European cities, it remains a significant concern as a primary environmental factor contributing to mortality and morbidity. In Brussels, NO₂ pollution, mainly emitted from thermal vehicles—poses a major threat. Although the current annual EU threshold for NO₂ concentration is set at 40 µg/m³ and is being adhered to in Brussels, the EU plans to lower its threshold to 20 µg/m³ by 2030, a target not yet met as of 2022. In this context, Brussels has implemented several policy measures, including a Low Emission Zone (LEZ) that progressively bans the most polluting vehicles. Additionally, the Good Move plan covers many objectives that could have an impact on NO₂ concentration in Brussels. However, this master’s thesis focuses specifically on its goal to reduce the kilometers traveled by passenger cars and reroute traffic from local roads to the main arteries. This master’s thesis evaluates the impact of the LEZ and the additional effects of Good Move on annual NO₂ concentrations in Brussels from 2022 to 2035. It also assesses how these policies will help adhere to the forthcoming EU threshold. The study uses SIRANE, a pollutant dispersion model, to assess spatialized NO₂ concentrations, with traffic NOx emissions projections as input, which has been refined to more accurately map road emissions to corresponding road hierarchies. Then, the model has been calibrated for 2022 to fit the measured concentrations. With these two enhancements, the SIRANE model for 2022 is estimated robust and validated through statistical indicators. On average, from 2022 to 2035, the LEZ is projected to reduce NO₂ concentrations by 1.18 µg/m³ (24% excluding background concentrations), with the most significant impact on high-traffic roads and a peak reduction in 2025 following the ban of Euro 5 diesel light vehicles. Good Move’s additional impact is eight times smaller than LEZ’s impact, contributing a further average reduction of 0.15 µg/m³ (2.9%), primarily affecting urban roads and mostly in 2028. Without any policy measures, the annual EU threshold in 2030 would be exceeded, but it would likely be respected with the LEZ and Good Move. Further research on the health and socio-economic impacts of LEZ and Good Move using the obtained NO₂ concentration maps is advised.