Samenvatting

Since 2009, the Dutch public authorities have been working together to improve air quality through the National Air Quality Cooperation Programme (NSL Nationaal Samenwerkingsprogramma Luchtkwaliteit (Nationaal Samenwerkingsprogramma Luchtkwaliteit)). The NSL (Nationaal Samenwerkingsprogramma Luchtkwaliteit) was a Dutch national program in the framework of the environmental law (“Wet milieubeheer”), with the aim to assess and improve the air quality in the Netherlands. In 2024, the “Wet milieubeheer” was replaced by a new legislative framework, the “Omgevingswet”. In the context of the NSL, and later the “Omgevingswet”, local authorities collect information on traffic situations on the main highways and roads. This information is used in an air quality management and monitoring tool to, among other things, check whether the Netherlands complies with European limit values for air quality. The calculation of nitrogen dioxide (NO2 Stikstofdioxide (Stikstofdioxide)) concentrations is an important part of the NSL monitor. In this study, we compare the modelled NO2 concentrations of the NSL monitor with the urban EMEP Europese model voor de verspreiding van lucht (Europese model voor de verspreiding van lucht ) (uEMEP). The uEMEP model is an air quality downscaling model based on Gaussian modelling principles, which, in this study, is embedded in the EMEP4NL model. Here, we focus on the city of Utrecht and its surroundings, in the Netherlands, where an extensive network of monthly and hourly NO2 concentration measurements is available. First, the modelled NO2 concentrations from uEMEP and EMEP4NL for the year 2019 are compared to measurements from 2019. After a calibration of the background, the modelled NO2 concentrations from uEMEP are compared to those of the NSL monitor at all measurement locations.