key: cord-259325-2yl7kl7b
authors: Nakada, Liane Yuri Kondo; Urban, Rodrigo Custodio
title: COVID-19 pandemic: Impacts on the air quality during the partial lockdown in São Paulo state, Brazil
date: 2020-04-29
journal: Sci Total Environ
DOI: 10.1016/j.scitotenv.2020.139087
sha: 
doc_id: 259325
cord_uid: 2yl7kl7b

Abstract In early March 2020, the World Health Organization declared the COVID-19 as a pandemic, and in late March 2020 partial lockdown was ordered by the São Paulo State government. The aim of this study was to assess impacts on air quality in São Paulo – Brazil, during the partial lockdown implemented to provide social distancing required due to the COVID-19 pandemic. We have analyzed data from four air quality stations in São Paulo, Brazil to assess air pollutant concentration variations during the partial lockdown. Data were compared to the five-year monthly mean and to the four-week before the partial lockdown. Overall, drastic reductions on NO (up to −77.3%), NO2 (up to −54.3%), and CO (up to −64.8%) concentrations were observed in the urban area during partial lockdown compared to the five-year monthly mean. By contrast, an increase of approximately 30% in ozone concentrations was observed in urban areas highly influenced by vehicle traffic, probably related to nitrogen monoxide decreases. Although the partial lockdown has contributed to a positive impact on air quality, it is important to take into account the negative impacts on social aspects, considering the deaths caused by COVID-19 and also the dramatic economic effects.

J o u r n a l P r e -p r o o f

On March 11, 2020, the World Health Organization (WHO) declared that the COVID-19disease caused by the new Coronavirus SARS-CoV-2 -had been characterized as a pandemic (WHO, 2020) . In Brazil, the first case was confirmed on February 26, 2020, in São Paulo -SP. To date (April 26, 2020) , there are 61,888 confirmed cases in all regions of Brazil, most of the cases (20,715) confirmed in São Paulo State (Brazil, 2020) , being São Paulo -SP, the city with most confirmed cases (13,513) (SEADE, 2020).

On March 24, 2020, partial lockdown was ordered by São Paulo State government (São Paulo, 2020a) , closing shopping malls, restaurants, fitness centers, elementary, middle and high schools, and universities. Supermarkets and drugstores started working with restrictions concerning person-to-person distance, and public transportation started working with reduced hours. Since partial lockdown was first ordered, social isolation varied from 54% (March 24), achieving a minimum of 47% (April 09) and a maximum of 59% (several dates), with an average of 54% (São Paulo, 2020b). The aim of this study was to assess impacts on air quality in São Paulo, Brazil, during the partial lockdown implemented to provide social distancing required due to the COVID-19 pandemic. and 2019 were used to calculate the mean levels of each pollutant for each month, and therefore estimate a five-year monthly trend. Similarly, data from February 25, 2020 to March 23, 2020 (four-week before partial lockdown) and from March 24, 2020 to April 20, 2020 (fourweek during partial lockdown) were used to calculate the mean levels of each pollutant both before and during the partial lockdown. Furthermore, the variations in mean concentrations Journal Pre-proof J o u r n a l P r e -p r o o f 5 (μg•m ─3 , ppb or ppm) were calculated to assess relative change (%) comparing the partial lockdown period to the five-year monthly trend or to the four-week before partial lockdown.

Nitrogen dioxide (NO 2 ) data obtained by remote sensing and provided by the Copernicus Sentinel-5 Precursor Tropospheric Monitoring Instrument (S5p/TROPOMI), developed by the European Space Agency (ESA) was used to assess NO 2 levels (Tobías et al. 2020).

Brazil is currently in the autumn season, and thus under good conditions to pollutant dispersion. During winter season São Paulo commonly faces the temperature inversion phenomena, when the air pollutants reach their peaks. Meteorological monitoring data bulletin made available by the São Paulo State Environmental Agency (CETESB, 2020) show that favorable conditions to pollutant dispersion were found both before partial lockdown (February 25 -March 23) and during partial lockdown (March 24 -April 20), therefore indicating that observed pollutant reductions were not highly determined by changes in dispersion conditions. Before partial lockdown, in a few days (March 11 -17) adverse conditions to ozone dispersion were observed, and in the same period ozone peaks were detected.

In the industrial area we observed low levels of variation when compared to the five-year monthly mean (2015-2019), and also concentration increases of all analyzed pollutants when compared to the period before the partial lockdown (Table 1) . It is important to mention that the industry was not ordered to lockdown, albeit some industrial sectors have been affected by decreasing demand.

In the urban area we observed significant air quality improvements considering decreases in air pollutants monitored in areas highly influenced by vehicle traffic (Urban Road I, Urban Road Journal Pre-proof J o u r n a l P r e -p r o o f 6 II and City center) (Table 1 and Figure 1 ). High reductions of air pollutants concentration were found during partial lockdown compared to the five-year monthly mean (variation A), while significant reductions were found in comparison to the period before partial lockdown (variation B). Drastic reductions on NO (−48.6%, −77.3% and −72.7% in Urban Road I, Urban

Road II and City center, respectively), NO 2 (−30.1%, −54.3% and −46.5% in Urban Road I, Urban

Road II and City center, respectively) and CO (−36.1%, −53.1% and −64.8% in Urban Road I, Urban Road II and City center, respectively) concentrations were observed in the urban area during partial lockdown compared to the five-year monthly mean. In São Paulo -SP, road traffic accounts for approximately 68% of NOx and 98% of CO emissions (Andrade et al. 2017) .

One recent research has demonstrated that traffic emissions from heavy-duty diesel trucks are major sources of NO (He et al. 2020) . During the partial lockdown, vehicle traffic considerably decreased in all analyzed areas, positively affecting the air quality. Decreases in pollutant concentrations in Urban Road I were lower than in the other analyzed areas, probably because this urban road is the connecting route for several highways and also is the main route in São Paulo.

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