The COVID-19 outbreak led to a 21-day nationwide lockdown, beginning 22 March, that restricted the day-to-day movements of the mass population, greatly reducing daily traffic. Consequently, Delhi saw a fall in average concentrations of fine particulates (PM2.5) by almost 80 percent within the first week. The city's air quality status improved to "satisfactory" (AQI 50-100) or "good" (AQI 0-50) category. This is a dramatic change when compared to the PM2.5 concentrations of March in the last last two years.