Air Quality Assessment During the Initial Implementation Phase of a Traffic-Restricted Zone in an Urban Area: A Case Study Based on NO2 Levels in Seville, Spain

Abstract

Traffic-related air pollution significantly affects air quality. Many cities have introduced low emission zones (LEZs) to restrict urban transport. Nitrogen dioxide (NO2) is a dangerous pollutant associated with adverse health effects, such as respiratory diseases, cancer, and death. This research aimed to evaluate the impact of implementing an LEZ during an informative period in which no fines were imposed on vehicles. The methodology consisted of several phases. Firstly, the legal levels to guarantee compliance with air quality standards of the Directive 2008/50/EC were studied. Secondly, this study analyzed the temperature and wind speed patterns of the city under investigation. Finally, an in-depth statistical study evaluated the impact of the LEZ at each air quality monitoring station throughout the municipality. The case study focused on Seville, Spain, using data from 2022, 2023, and the first quarter of 2024, the latter corresponding to the reporting period without fines. The results reveal a wide dispersion and periodicity in NO2 concentrations at the monitoring stations. Seville complied with NO2 air quality regulations before the implementation of the LEZ, with similar seasonal patterns observed. A low overall impact was observed in the first three months after implementation. This methodology can be used universally.