NO2 Correlation Using Sentinel-5P Images and on-site Measurements during the Evolution of COVID-19 and its Influence in the Metropolitan District of Quito, Ecuador

Since the first outbreak of coronavirus disease (COVID-19) reported in Wuhan (China) on December 31, 2019, countries all over the world have decreed different security measures such as lockdowns and confinement, resulting in reduced levels of air pollution. The present study explores the correlation of the levels of nitrogen dioxide (NO2) measured using two different source data as Sentinel - 5P images and the on-site database of three monitoring stations belonging to the Environmental Monitoring Network in the Metropolitan District of Quito, within three periods of time during the progression of COVID-19. The result of this analysis shows an overall correlation of ninety-three percent of the levels of NO2 for both measurements in the period January to June 2020. During the lockdown and confinement measures from March to April 2020 a reduction of forty-nine percent was found, but when confinement measures were reduced within the period May to June 2020, an increase in NO2 concentration was again observed and the reduction was only thirteen percent; thus, the reduction in NO2 concentrations may be attributed partly due to the significant reduction in vehicle exhaust gas emissions. From the correlation of the results obtained, it can be concluded that this methodology, using Sentinel-5P image analysis may be used to measure the NO2 concentrations in the atmosphere in cities where there is no on-site air quality monitoring network