How mobility restrictions policy and atmospheric conditions impacted air quality in the State of São Paulo during the COVID-19 outbreak

Abstract

Mobility restrictions are among actions to prevent the spread of the COVID-19 pandemic and have been pointed as reasons for improving air quality, especially in large cities. However, it is crucial to assess the impact of atmospheric conditions on air quality and air pollutant dispersion in the face of the potential variability of all sources. In this study, the impact of mobility restrictions on the air quality was analyzed for the most populous Brazilian State, São Paulo, severely impacted by COVID-19. Ground-based air quality data (PM 10 , PM 2.5 , CO, SO 2 , NO x , NO 2 , NO, and O 3 ) were used from 50 automatic air quality monitoring stations to evaluate the changes in concentrations before (January 01 - March 25) and during the partial quarantine (March 16 - June 30). Rainfall, fires, and daily cell phone mobility data were also used as supplementary information to the analyses. The Mann-Whitney U test was used to assess the heterogeneity of the air quality data during and before mobility restrictions. In general, the results demonstrated no substantial improvements in air quality for most of the pollutants when comparing before and during restrictions periods. Besides, when the analyzed period of 2020 is compared with the year 2019, there is no significant air quality improvement in the São Paulo State. However, special attention should be given to the Metropolitan Area of São Paulo (MASP), due to the vast population residing in this area and exposed to air pollution. The region reached an average decrease of 29% in CO, 28% in NO x , 40% in NO, 19% in SO 2 , 15% in PM 2.5 , and 8% in PM 10 concentrations during the mobility restrictions period compared to the same period in 2019. The only pollutant that showed an increase in concentration was ozone, with a 20% increase compared to 2019 during the mobility restrictions period. Before the mobility restrictions period, the region reached an average decrease of 30% in CO, 39% in NO x , 63% in NO, 12% in SO 2 , 23% in PM 2.5 , 18% in PM 10 , and 16% in O 3 concentrations when compared to the same period in 2019. On the other hand, Cubatão, a highly industrialized area, showed statistically significant increases above 20% for most monitored pollutants in both periods of 2020 compared to 2019. This study reinforces that the main driving force of pollutant concentration variability is the dynamics of the atmosphere at its various time scales. An abnormal rainy season, with above average rainfall before the restrictions and below average after it, generated a scenario in which the probable significant reductions in emissions did not substantially affect the concentration of pollutants.

Empirical evidence shows that air quality changes during COVID-19 pandemic lockdown in Jakarta, Indonesia are due to seasonal variation, not restricted movements

“…The air quality in Jakarta as measured by PM10 and PM2.5 did not change significantly during the lockdown period. The same was observed in the State of São Paulo, Brazil ( Rudke et al, 2021 ).…”

“…Nevertheless, the climate also varies annually and is affected by global circulation, such as El-Nino. Studies such as Kolluru et al (2021) and Rudke et al (2021) compared air quality values during lockdown with the corresponding period in 2019. As shown in the example, comparing 1–2 previous years could also present some uncertainty.…”

Assessment of air quality changes during COVID-19 partial lockdown in a Brazilian metropolis: from lockdown to economic opening of Rio de Janeiro, Brazil

“…Thus, even with decrease in PM 10 emission in 2020, the average concentration remained similar with that of the previous years. The same behavior of rainfall was also observed by Rudke et al (2021) in a study conducted in the metropolitan area of São Paulo.…”

“…Currently, to economic opening which contributed to increase in mobility, and consequently in pollutant emission, fires recorded at Amazon and Pantanal may transport pollutants to southeast Brazil, contributing to pollutant increasing. Rudke et al (2021) also considered that fires contributed to air pollution in São Paulo in the months that followed stricter isolation measures.…”

WITHDRAWN: Assessment of COVID-19 pandemic effects on ship pollutant emissions in major international seaports

“…So far, most of the existing literatures related to the environmental impact of COVID-19 focused on quantifying the concentration change of atmospheric pollutants in the global context ( Bai et al, 2020 ; Deb et al, 2020 ; Le et al, 2020 ; Dang and Trinh, 2021 ; Keola and Hayakawa, 2021 ; Liu et al, 2021c ; Nguyen et al, 2021 ; Smith et al, 2021 ; Venter et al, 2020 ), countries ( Bao and Zhang, 2020 ; Berman and Ebisu, 2020 ; He et al, 2020 ; Petetin et al, 2020 ; Sharma et al, 2020 ; Shi and Brasseur, 2020 ; Wang et al, 2020 ; Isphording and Pestel, 2021 ), regions ( Li et al, 2020 ; Jiang et al, 2021 ; Ma et al, 2021 ; Sulaymon et al, 2021 ; Xian et al, 2021 ), urban ( Adams, 2020 ; Cameletti, 2020 ; Kanniah et al, 2020 ; Kerimray et al, 2020 ; Kumar, 2020 ; Otmani et al, 2020 ; Zangari et al, 2020 ; Zheng et al, 2020 ; Hong et al, 2021 ; Zhao et al, 2021 ), suburban ( Cui et al, 2020 ; Menut et al, 2020 ; Wang et al, 2020 ; Du et al, 2021 ; Hayakawa and Keola, 2021 ; Páez-Osuna et al, 2021 ), and remote areas ( Mandal and Pal, 2020 ). In the transportation sector, many studies concentrated on road traffic ( Ding et al, 2020 ; Dutheil et al, 2020 ; Li et al, 2020 ; Mahato et al, 2020 ; Shehzad et al, 2020 ; Tobías et al, 2020 ; Wang and Su, 2020 ; Xu et al, 2020 ; Chen et al, 2021 ; Hu et al, 2021 ; Rudke et al, 2021 ). The findings generally highlighted a drastic reduction in the transportation activities which greatly reduces the amount of fuel consumption and consequent emissions during the cities’ lockdown period ( Ba...…”