AUTHOR=Ibarra-Espinosa Sergio , Rehbein Amanda , Dias de Freitas Edmilson , Martins Leila , Andrade Maria de Fatima , Landulfo Eduardo 

TITLE=Changes in a Bottom-Up Vehicular Emissions Inventory and Its Impact on Air Pollution During COVID-19 Lockdown in São Paulo, Brazil

JOURNAL=Frontiers in Sustainable Cities

VOLUME=Volume 4 - 2022

YEAR=2022

URL=https://www.frontiersin.org/journals/sustainable-cities/articles/10.3389/frsc.2022.883112

DOI=10.3389/frsc.2022.883112

ISSN=2624-9634

ABSTRACT=During the lockdown associated with the severe COVID-19 crisis all 
cities across the world experienced changes in air pollution. 
The changes were registered using surface monitoring stations or 
satellite observations. However, modeling those changes has remained a 
challenge because of our limitations in the emissions estimation and also, 
for the numerical modeling itself. In this study, the vehicular emissions 
were estimated for March 2020 in the megacity of São Paulo using the model 
VEIN. Then, a set of WRF-Chem simulations were performed with different 
chemical mechanisms and initial conditions. The emissions estimation 
showed an increment of VOC/NO2 in downtown, due to the decrease of 
circulation of urban transportation and light vehicles. The chemical 
mechanisms covered were RADM2, CB05, CBMZ, and SAPRC99. The modeled 
diurnal cycles represents the variations observed in March 2020 for the 
periods pre-lockdown, transition and lockdown, with lower magnitude although. 
Our results show that the chemical mechanism CBMZ could reproduce the air 
pollutant concentrations. However, it is imperative to include other sources 
than vehicular to have a local and comprehensive emissions inventory.