Remote Sensing-Based Evaluation of Social Distancing Effects During the COVID-19 Pandemic on NO2 Levels in the Urban Areas of Brasília, Anápolis and Goiânia

Abstract

Due to the COVID-19 pandemic, reductions of nitrogen dioxide (NO2) concentrations in the atmosphere were observed in several countries, since the gas is related to the burning of fossil fuels from means of transport. This study aims to identify the changes in the NO2 emission pattern associated with measures to restrict circulation with confinement during the COVID-19 pandemic, in the urban areas of Brasília (DF), Anápolis and Goiânia (GO). Tropospheric NO2 data were collected through the TROPOMI sensor, from the Sentinel-5P satellite, and precipitation data by satellite monitoring from the Global Precipitation Measurement (GPM) network. The average values ​​of NO2 and precipitation (mm/h) were calculated for each of the images between the years 2019 and 2021, as well as the weekly moving averages for each urban area. Thus, six two-month periods were defined, and the ratio of the moving average between the years 2020/2019 and 2021/2019 was calculated. In the aforementioned period, a decrease in the density of the NO2 column was observed in 2020, with a later increase, in 2021, in the same period and in the three regions. In Brasília the drop was more expressive, being, on average, -9.35%, followed by Goiânia with -2.61% and Anápolis with -1.34%. The biggest increase was observed in Goiânia, with +30.3%, followed by Anápolis, +19.30%, and +16.08% in Brasília. Despite the drop in emissions in 2020, in the following year there was an increase on the NO2 emission levels.