> Our findings revealed that (1) there was a significant decline in the concentration level of PM2.5 from 10.3 to 4.0 μg/m3 during phase one of lockdown. (2) NO2 concentrations have been decreased by up to 52% in 1st phase of lockdown. (3) O3 concentration has been increased by 44.4%. (4) Brooklyn, Manhattan, Queens, and Staten Island County encountered 18.75%, 55.62%, 47.14%, and 47% diminution in AQI due to lockdown as compared to 2018, respectively