Weekend Effect of Air Pollutants in a Tropical Brazilian Metropolis

This study sought to evaluate the extent of the weekend effect of O 3 , NO 2 , SO 2 and PM 2.5 , in Recife, a tropical Brazilian metropolis, taking into account a 2-year period of monitoring air pollutants, including a portion comprising the end of restrictions related to COVID-19. Our results show that Recife did not experience a weekend effect of air pollutants in both annual contexts, presenting magnitudes that can be considered practically null (− 2% ≥ or ≤ 2%) in the two annual scenarios evaluated. This finding is interesting because the behavior of air pollutants observed in this metropolis was fundamentally different from what previously found in other similar urban environments. However, seasonally this does not happen, existing seasonal discrepancies in the dynamics of all air pollutants. In addition, these seasonal changes in the weekend effect were not primarily associated with meteorological parameters and probably other factors are influencing this effect, especially the behavior and life habits of the population of this tropical city. In view of the two scenarios evaluated, there was an existence of an impact of the final moment of the COVID-19 restrictions and the beginning of the resumption of “normal” activities on the weekend effect in year 1. Furthermore, weekly SO 2 levels were significantly correlated with NO 2 and O 3 levels, this implies that the majority of these pollutants were probably generated by the same source. We hope that the information provided in our findings will assist in defining and guiding policies aimed at dealing with air pollution control.