COVID-19 outbreak, lockdown, and air quality: fresh insights from New York City

The outbreak of the COVID-19 pandemic has adversely affected all aspects of life and poses a severe threat to human health and economic development. New York City administration enacted a strict isolation decision at the end of March 2020 to tackle the COVID-19, creating a unique opportunity to assess air quality. Therefore, we investigated the impact of the lockdown on air quality in New York City. We evaluated the air pollutants concentration, i.e., PM_2.5, CO, NO₂, SO₂, and O_3, during the lockdown and compared them with pre-COVID-19. We explored the first phase of lockdown through a spatial approach, then formulated the air quality index (AQI) of each pollutant before and during the lockdown. Our findings revealed that (1) there was a significant decline in the concentration level of PM_2.5 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. Our key findings can provide critical environmental implications for policymakers, researchers, academics, and the US government.