Low emission zones (LEZ) manage traffic entering cities by granting access only to vehicles that meet certain emission standards. This study evaluated if implementation of LEZs in Antwerp (2017) and Brussels (2018) improved air pollution within the boundaries of the defined zones, if spatial spillover effects occurred, if socioeconomic inequality in air pollution exposure changed over time, and if health was affected. The study population comprised 420,007 individuals living within the LEZs, within seventeen control cities or within adjacent areas of these cities. Annual residential air pollution (PM, PM, NO, BC) was calculated for 2016-2022. Individual-level health outcomes (diabetes, cardiovascular disease, obstructive airway diseases, antidepressants, antithrombotic agents) were available for 2014-2023. Random effect models were constructed to assess the impact of LEZs on air pollution and socioeconomic disparities, and a comparative interrupted time series analysis was conducted to evaluate the health impact. Findings suggest that with the introduction of the LEZ, all pollutant concentrations declined significantly more rapidly in both Antwerp and Brussels and adjacent areas compared to other Belgian cities and adjacent areas. Socioeconomic disparities in BC and NO concentrations decreased over time. Findings for the evolution of diabetes suggested a positive impact of the LEZ for this particular outcome. This study suggests that LEZ implementation holds strong advantages that may extend beyond the boundaries of the defined zones. As air pollution concentrations in European cities are still high, policies such as LEZs are required to attain the World Health Organisation Global Air Quality Guidelines.