Air Pollution and COVID-19 Nexus: Insights from Wavelet Approach for Selected Groups of Countries

The COVID-19 pandemic has induced shutdowns, closures of schools and manufacturing industries, and social distancing protocols worldwide. As a result, the world has witnessed a massive reduction in air pollution. This study intends to analyze the causal relationship between air pollution and COVID-19 using the top ten heavily polluted countries and the top ten least polluted countries. By applying the wavelet coherence approach, this study finds that air quality index (AQI) negatively influences COVID-19 in Estonia, Finland, Portugal, Spain, and Norway. In the case of Canada, Denmark, Germany, New Zealand, Sweden, Afghanistan, Bangladesh, India, Mongolia, and Uzbekistan, COVID-19 negatively influences AQI. For China and Indonesia, COVID-19 increases air pollution. The findings of wavelet-based Granger causality confirm that the causal connection is strong and significant in the most polluted countries during the short and medium run period, whereas, during the long run period, the causal connection is significant for both samples, which are the least and most polluted countries. The study suggests important policy implications for these countries regarding air pollution.