Effect of lockdown amid COVID-19 pandemic on air quality of most polluted cities of Punjab (India)

In the last month of 2019, the outbreak of a viral disease named COVID-19 started in Wuhan, China. The disease has spread in most of the countries of the world and it was declared as a global pandemic in March 2020 by the World Health Organization (WHO). Many countries implemented countrywide lockdown. COVID-19 has forced many countries to observe complete lockdown. This complete lockdown has improved the air quality significantly due to less human activities. In India, a complete lockdown of 21 days was implemented in phase I (March 25, 2020 to April 14, 2020) to avoid the spread of corona virus disease. Further, this lockdown was extended to phase II (April 15, 2020–May 3, 2020), phase III (May 4–17, 2020) and phase IV (May 18–31, 2020) with some relaxations in restrictions. In the present work, we have analyzed the data of major air pollutants PM(2.5), PM(10), SO(2), NO(2), CO and O(3) from the three most polluted cities of Punjab for March 03–24, 2020 (before lockdown) vs. March 25, 2020 to May 31, 2020 (during lockdown divided into four phases). Further, an extensive comparison of the mean concentration of major air pollutants has been made for the different phases of lockdown including before lockdown period with the same periods in 2019. It is observed that the concentration of PM(2.5), PM(10), NO(2) and SO(2) has reduced significantly ~50% after first phase of lockdown. As observed in this study, there is an urgent need for interventions across northern India to knockdown air pollutant levels by more than 40% or so by adopting cleaner fuel technology and avoiding poor combustion activities.