Influence of the COVID-19 pandemic on air quality in Taipei, Taiwan: Insights about a transition to electric vehicles

Abstract As in many areas worldwide, COVID-19 lockdowns also had a major impact on air quality in Taiwan; however, studies about traffic management and other issues in large urban areas like Taipei are still reflecting on those lockdown periods to optimize the lessons learned. In this study, we compared PM2.5, NO₂, CO, and O₃ concentrations during a week-long lockdown period with pre-lockdown concentrations from the week before. The results indicate that the lockdown policy contributed to a more than 25% decrease in NO₂ and CO and a slight decline in PM2.5. We further compared a month-long lockdown period with the same period in the preceding two years, revealing NO₂ and CO declined up to 40% during the lockdown. On the other hand, PM2.5 concentrations either decreased or increased depending on the comparison year. In contrast, O₃ concentrations consistently increased during the lockdown, likely driven by the decrease in NOx, which is in correlation with the decrease in transportation and fuel consumption. This study finds that COVID-19 restrictions yielded cleaner air for NO₂, CO, and PM2.5 while their characteristic diurnal patterns remain unchanged. By contrast, the O₃ levels climbed as an unanticipated consequence of lower NOx emissions. According to Taiwan's new regulation, electric vehicles should reach 35% of new vehicle sales by 2030. According to our findings, this may reduce NOx concentrations by 14.56% in the area, a significant reduction similar in magnitude to the lockdown impact. Although PM2.5 concentrations may not dramatically decrease with the adoption of electric vehicles, ozone increases could be curtailed by careful and simultaneous reduction of hydrocarbon emissions.