Variability of Atmospheric Pollutants and its Association with Meteorological Parameters under Quarantine Period over Sao Paulo City.

São Paulo (SP) has been the most affected state since the first cases of Corononavirus disease - 2019 (COVID-19) were reported in Brazil. Protective actions were taken by governments at national, regional, and local levels to stop the spread of COVID-19. The quarantine period was imposed in SP from later of March and still in July, with some flexibilization in between. During the most restrictive period of quarantine, only essential services still open, which helped to maintain a lower social isolation index. Besides the social and health impacts, the quarantine period provided an opportunity to assess the atmosphere during the decrease in traffic and industries production in the city of SP. We have carried out detailed analysis of multi satellite and surface data from atmospheric parameters at SP city during March 2019 to June 2020. Also, meteorological parameters from satellite and radiosonde was studied, including Global Navigation Satellite Systems (GNSS) data from one station deployed at SP city. Our results show reduction of greenhouse gases and particulate matter concentrations during end of March and early April, where higher social isolation measures throughout the city have been observed. The meteorological conditions (relative humidity, water vapor, integrated water vapor - IWV, surface and air temperature) also contribute to air quality improvement, therefore, the correlation of these parameters with the reduction of pollution was also evaluated, noting that there were changes during the quarantine. This suggests that government restrictions of movement in order to stop the spread of the virus were also effective for improve the air quality, during a shortly period, over the most populated city of the country highly affected by poor air quality and atmospheric pollution.