Improving academic performance through low emission zones?

An original study led by Manuel Valdés, Mar C. Espadafor (UNED*) and Risto Conte Keivabu (MPIDR**) showcases the positive impact of a low emission zone (LEZ) in Madrid’s city center on academic performance. Students schooled in Madrid’s LEZ and neighbouring area achieved higher university admittance examination scores.

Pexels / George Pak

By Mijail Figueroa González

Low emission zones (LEZ) are a popular measure to reduce air pollution and align with international air quality guidelines in European cities. In late 2018, Madrid introduced a Low Emission Zone (LEZ) in the city center to combat air pollution. Valdés and colleagues analyse whether Madrid’s LEZ improved the air quality and how this influenced students’ academic performance schooled in the area.

By leveraging pollution data from 24 monitoring stations in Madrid, encompassing daily Nitrogen Dioxide (NO2) measures, and intertwining it with the high-stakes university admittance (EvAU) scores from 261 schools over an 8-year period—encompassing four years before (2015-2018) and four years after (2019-2022) Madrid’s LEZ implementation – researchers established a causal link between the implementation of Madrid’s LEZ and student’s EvAU scores.

The study revealed a significant drop in the Nitrogen Dioxide levels following the Madrid’s LEZ implementation (figure 1), confirming previous research. The authors concluded thus, that “Madrid’s LEZ was effective in reducing traffic-related emissions and substantially improved air quality in the designated area during the following four years.”

Figure 1. Dynamic difference-in-differences (DiD) model for the effect of Madrid’s LEZ on NO2 levels.
Figure 2. Results from the dynamic DiD for EvAU scores.

The authors found that the improvement in air quality led to higher EvAU scores in schools within the LEZ area and neighboring schools (Figure 2), within 0.5 km. These higher EvAU scores represent a crucial advantage for gaining entry into the most competitive university programs. Furthermore, the positive effects of Madrid’s LEZ consistently increased over time, suggesting cumulative benefits from longer exposure to improved air quality.

* National Distance Education University

** Max Planck Institute for Demographic Research

Download the study:


Valdés, M. T., C. Espadafor, M., & Conte Keivabu, R. (2023). Can a low emission zone improve academic performance? Evidence from a natural experiment in the city of Madrid (WP-2023-048; 0 ed., p. WP-2023-048). Max Planck Institute for Demographic Research.

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