Low emission zones cut PM2.5 by 4 percent, spillovers confirmed
A Banco de España working paper finds that low emission zones reduce fine particulate matter exposure by approximately 4 percent within designated areas across 33 European countries. Crucially, pollution also declines in adjacent zones, with network effects and fleet renewal dominating traffic displacement.
Density doubles pollution, zones push back
Using a high-resolution geospatial panel of 1km grid cells across 33 European countries from 2007 to 2022, authors Nicolás Forteza and José M. Labeaga estimate that LEZ adoption reduces population-weighted PM2.5 exposure by approximately 4 percent within designated zones.
The study also quantifies the pollution-density elasticity for European cities: a 1 percent increase in population density raises PM2.5 exposure by 6 percent — roughly half the 0.14 elasticity documented for US cities using comparable methods.
The lower European figure points to differences in urban form, transport infrastructure and industrial structure.
As of 2025, over 320 LEZs had been implemented across European cities, yet continental-scale empirical evidence on their effectiveness remained scarce before this study.
The European Environment Agency estimated that in 2021 alone, at least 253,000 deaths in the EU were attributable to PM2.5 concentrations exceeding WHO thresholds.
Size and density determine who benefits
Average effects mask substantial heterogeneity.
Pollution reductions concentrate in larger, denser cities and in cities where the LEZ covers a medium share of total urban area.
The smallest cities and smallest zones show no detectable effect.
Moderate-stringency LEZs, as typically implemented across Europe, deliver aggregate city-wide pollution reductions of approximately 1.8 percent, with modal shift and fleet renewal mechanisms dominating traffic displacement.
The authors use a staggered difference-in-differences design accounting for spatial spillovers and an instrumental variables strategy exploiting historical settlement patterns — including historical population density, soil quality and aquifer presence — to address endogeneity in the density estimates.
Good news with an asterisk
The finding that spillovers are positive rather than displacing pollution to adjacent streets is the paper's most policy-relevant result, directly challenging the common critique that LEZs merely redistribute harm.
The 4 percent within-zone reduction is modest compared to Madrid Central's 19 percent, but that gap reflects design and enforcement intensity, not policy failure.
Policymakers targeting the European Green Deal's 55 percent reduction in pollution-related premature deaths by 2030 should note that zone size relative to urban area matters as much as the decision to implement one at all.