NO₂ pollution decrease in big cities of Latin America during COVID-19 pandemic

Abstract

NO2 is a mainly anthropogenic gas that affects population health and its exposure is associated with several respiratory diseases. Its tropospheric concentration is associated with vehicle emissions. During 2020, COVID-19 lockdowns have impeded populations mobility, hence constructing an almost ideal situation to study their relationship with tropospheric NO2 concentration. We used TROPOMI (TROPOspheric Monitoring Instrument) satellite images, Google mobility reports and vehicule count in order to study these relationships in six big Latin American metropolitan areas: Mexico DF, Sao Paulo, Buenos Aires, Rio de Janeiro, Lima and Bogota. In all of them, tropospheric NO2 concentration decreased during 2020 compared to 2019, particularly during April 2020. Temperature differences alone could not explain the NO2 concentration differences between February and April 2020. The daily vehicle count in Buenos Aires was a significantly important variable in order to explain NO2 concentration variations (p < 0.001) and it could be replaced by the daily Googles residential variation without significant information loss (p~1). This study strengthens previous research findings about NO2 concentration reduction during COVID-19 lockdowns and shows the relationship between human mobility and air pollution in the particular context of Latin America big cities.