“New Normal”: The Dynamics of Air Pollutants on the Interruption–Recovery Pattern Related to the COVID-19 Pandemic in Recife, Northeastern Brazil

Abstract

Recife, located in Northeastern Brazil, was one of the first cities in the country to suffer the devastating effects of the COVID-19 Pandemic. The strict measures adopted in the first months of the pandemic seem to have had results and the city had a second wave less intense than other Brazilian capitals. This condition allowed a series of measures to make human activities more flexible until September 2021. In this context, the aim of the study was to evaluate the behavior of Air Pollutants between the months of May 2020 and September 2021, observing the timeline of Interruption–Recovery of economic activities. The concentrations of pollutants (O3, NO2, SO2, PM2.5, PM10 and CO) were obtained by satellite, as well as meteorological variables, used to predict the levels of pollutants in the year 2021 using machine learning. The comparison of monthly averages of pollutants between 2020 and 2021 showed a significant increase in NO2, SO2, PM2.5, PM10 and CO, in addition to a decrease in O3 concentrations. Estimated data for the year 2021 from machine learning showed that the levels of NO2, SO2, PM2.5, PM10 and CO were higher than expected at 15.9%, 14.6%, 25.9%, 15.3% and 2.2%, respectively, while O3 levels were 6.7% lower than expected. The results show the return of pollutant levels (except O3) to higher levels compared to those measured in the months of greater restriction of human mobility, a behavior similar to that found in other parts of the world.