Characteristics and effects of low emission zones in Europe. A systematic literature review

Low Emission Zones (LEZs) have become one of the most widely used urban policies to try to reduce the levels of air pollution that, according to the World Health Organisation, cause more than four million premature deaths per year worldwide. In this research, an overview of the existing LEZs in Europe is carried out using official sources of information at local and national levels, considering their basic characteristics and the restrictions implemented on vehicle entry. In addition, all recent research (91 research studies published between 2002 and 2024) on the effects of LEZs on public health, pollution levels, mobility, and the socio-economic fabric of the affected areas, as well as the public acceptability and perception of LEZs, has been reviewed. This review has been carried out using a systematic methodology of literature analysis to answer two research questions: What kind of effects can LEZs generate? What have been the estimated ex-ante and ex-post effects in different case studies? The results show that there are currently 363 LEZs in Europe with very heterogeneous sizes and restrictions (permanent/seasonal and in terms of vehicles affected). Most of the research has detected a significant decrease in pollutant emissions such as NO2 and PM10 within LEZs. However, the improvements in public health measured so far have been generally modest and heterogeneous. This is partly due to the large number of different indicators used to measure health effects in different studies. LEZs can also have relevant effects on modal shifts, favouring public transport and active modes. Future research should focus more on measuring the effect of LEZs on freight transport, the distributional effects among different socio-economic groups, and how different LEZ designs can affect the effects obtained.