Effects of Low Emission Zones on Air Quality, New Vehicle Registrations, and Birthweights: Evidence from Japan

During the early 2000s, five prefectures in Japan introduced a Low Emission Zone (LEZ) policy that banned highly polluting diesel trucks and buses from entering. This paper analyzes effects of this policy intervention on air quality, new vehicle registrations, and birthweights. To do so we use a matching approach to construct a control group that is comparable to the designated areas in terms of pollution levels and road traffic volumes of regulated vehicles and apply a difference-in-differences (DD) design. We find that the LEZs led to a reduction in hourly suspended particulate matter concentrations and to reduced incidence of low birthweights in the treated prefectures relative to the control group, holding the gestational period and other controls constant. Evidence also suggests that the LEZs led to an increase in new registrations of trucks and buses, but not of passenger cars, which were exempt from the regulations. Our paper is the first to study such a large-scale LEZ intervention and to provide evidence linking LEZs to reduced incidence of low birthweights.