Increment Of O3 During Lockdown Related To Spatial-Temporal Variability Of VOC/NO2 Emissions-Ratio In São Paulo, Brazil

Abstract:

The COVID-19 pandemic has yielded to efforts to stop the transmission of SARS COV2. A key measure widely adopted evolve several types of quarantines, which have resulted in the improvement of air quality indicators. This is critical because early literature is showing that small increments of air pollution trigger a severe response on cases and deaths related to COVID-19 (Zhu et al., 2020). However, in the city of São Paulo, a significant increment of O₃ was observed with values up to 50% (Freitas et al., 2020). To our knowledge, none other city has experienced such a severe increment of air pollution. Since the vehicular emissions are the most important source of pollution in São Paulo, we developed a detailed vehicular emissions basis at street level for each hour of the months of March, April and June of 2020, by using the VEIN model along with travel demand models and hourly traffic counts for March and April 2020 (Ibarra-Espinosa et al., 2020). Our results show that the increment of O₃ is due to the spatial and temporal variability of the VOC/NO₂ ratio (Seguel et al., 2020). These results covered only March 2020 and we will include hourly emissions at street level for April and June 2020. This ratio remained relatively constant with some positive increment at down-town. However, it decreased substantially outside the city center. The decrease of the ratio VOC/NO₂ is due to the higher demand of house goods, which triggered the circulation of heavy trucks. Air quality simulations will be done using the model CityChem (Karl et al., 2019).

Zhu, Y., Xie, J., Huang, F., & Cao, L. (2020). Association between short-term exposure to air pollution and COVID-19 infection: Evidence from China. STOTEN, 727, 138704.

Ibarra-Espinosa, et al. 2018. VEIN v0.2.2: an R package for bottom-up vehicular emissions inventories. GMD. 11, 2209–2229.

Freitas, ED., et al (2020). Mobility restrictions and air quality under COVID-19 pandemic in São Paulo, Brazil. Preprints.

Seguel, R., et al. Primary and secondary air pollutant response during the first COVID-19 lockdown in South American Megacities: learning about present and future air quality. under review STOTEN.

Karl, M., et al The Eulerian urban dispersion model EPISODE – Part 2: Extensions to the source dispersion and photochemistry for EPISODE–CityChem v1.2 and its application to the city of Hamburg, GMD.

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