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Keywords: Air quality in Taiwan, COVID-19, PM2.5, Transboundary air pollution
JEL classification: I12, Q53, Q56
ABSTRACT
We study Taiwan's air quality after the outbreak of coronavirus disease 2019 (COVID19) pandemic in January 2020. We find a significant reduction, about 14.6%, in the daily PM2.5 concentration after the COVID-19 outbreak. Our paper controls for both year effects and time-of-year effects by comparing the average change over time in the PM2.5 levels before and after the outbreak of COVID-19 in the period from October 2019 to April 2020, to the average change over time from October to April in 2016/17, 2017/18, and 2018/19, and is robust to the policies and seasonal patterns in each year. Among the 14.6% decrease in PM2.5 concentration, we find that about 12.9 percentage points are related to the air quality improvement in China, Japan, and Korea and the reduction of transboundary air pollution.
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1.INTRODUCTION
It had been found by both satellite observations and ground-based monitoring stations that, after all the lockdowns, traffic reductions, and economic downturns due to the coronavirus disease 2019 (COVID-19) pandemic, there were improvements in the air quality in China (Almond et al., 2020; Burke, 2020; He et al., 2020; NASA, 2020; Wang and Su, 2020), Europe (Baldasano, 2020; Donzelli et al., 2020; Briz-Redon et al., 2021), North America (Adams, 2020; Chen et al., 2020; Parker et al., 2020; Tanzer-Gruener et al., 2020; Zangari et al., 2020), and Taiwan (Griffith et al., 2020). Although some researches did show that there were still several severe haze episodes with high levels of fine airborne particulate matters with diameters < 2.5 ^m (PM2.5) over northern China (Chang et al., 2020; Le et al., 2020; Li et al., 2020; Sun et al., 2020; Wang et al., 2020; Huang et al., 2021), recently, Hammer et al. (2021) compared the PM2.5 levels from January through April in 2020 to 2018 and 2019, and found a minor, about 11-15 ^g/m3 reduction in PM2.5 in China.
In this paper, we study Taiwan's air quality after the outbreak of COVID-19 pandemic. Our main finding is twofold. First, we find a significant reduction, about 14.6%, in the daily PM2.5 concentration after the COVID-19 outbreak in January 2020. Second, among the 14.6% decrease in...