The Air Quality and Well-Being Effects of Low Emission Zones

To avoid the violation of SUTVA, we determine the spatial scope of spillovers empirically with regression discontinuity (RD) designs and use this information to restrict the control group of the CS-DD model accordingly.4 Our results confirm previous studies on the effectiveness of LEZs at decreasing the concentrations of PM10 and NO2 (Wolff, 2014; Pestel and Wozny, 2021; Gehrsitz, 2017). [...] To the best of our knowledge, the increase in O3 is the first evidence of LEZs’ unintended impacts on secondary pollutants arising from the interaction between air pollutants in the lower atmosphere.5 Reassuringly, even with the rise in the concentration of O3, our results imply overall air quality improvements as captured by the zones’ effect on the AQI. [...] The vertical axis contains the average of each criteria pollutant and the horizontal axis the time to treatment, i.e., number of years to the introduction of a LEZ. [...] Regardless of the season, LEZs consistently reduce the value of the AQI, suggesting that they are indeed effective at improving air quality within the zones’ borders despite the unintended increases in the concentration of O3. [...] Health effects We complement our results by analyzing the impact of LEZs on objective health mea- sures and utilization of the health care system as proxied by the number of doctor visits.42 Since 2009, the SOEP bi-annually surveys several illness categories and the number of doctor visits within the last twelve months prior to the interview.