新冠肺炎與跨境空氣污染──冠狀病毒改善了台灣的空氣品質嗎？

COVID-19 and Transboundary Air Pollution: Did Coronavirus Improve Air Quality in Taiwan?

我們研究2020年1月新冠肺炎爆發後的台灣空氣品質。我們發現在新冠肺炎爆發後，台灣各地PM2.5的平均濃度減少了14.6%。藉由比較2019年10月至2020年4月期間新冠肺炎爆發前後PM2.5平均濃度的改變，以及2016/2017、2017/2018、2018/2019同期間前後PM2.5平均濃度的改變，本文得以同時控制了年份及時間因素，也使得我們的發現不致於受到政策或季節因素影響。在14.6%的平均濃度減少中，我們發現約12.9個百分點的減少可能與中國大陸、日本、以及韓國的空氣品質改善，以及跨境空氣污染的減少有關。

"We study Taiwan’s air quality after the outbreak of coronavirus disease 2019 (COVID-19) pandemic in January 2020. Wefind 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, wefind 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."