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

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 PM _2.5 , NO ₂ , CO, and O ₃ 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 NO ₂ and CO and a slight decline in PM _2.5 . We further compared a month-long lockdown period with the same period in the preceding two years, revealing NO ₂ and CO declined up to 40% during the lockdown. On the other hand, PM _2.5 concentrations either decreased or increased depending on the comparison year. In contrast, O ₃ concentrations consistently increased during the lockdown, likely driven by the decrease in NO _x , which is in correlation with the decrease in transportation and fuel consumption. This study finds that COVID-19 restrictions yielded cleaner air for NO ₂ , CO, and PM _2.5 while their characteristic diurnal patterns remain unchanged. By contrast, the O ₃ levels climbed as an unanticipated consequence of lower NO _x 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 NO _x concentrations by 14.56% in the area, a significant reduction similar in magnitude to the lockdown impact. Although PM _2.5 concentrations may not dramatically decrease with the adoption of electric vehicles, ozone increases could be curtailed by careful and simultaneous reduction of hydrocarbon emissions.