Weekend Effect of Air Pollutants in a Tropical Brazilian Metropolis

This study sought to evaluate the extent of the weekend effect of O-3, NO2, SO2 and PM2.5, 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% & GE; or & LE; 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 SO2 levels were significantly correlated with NO2 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.

Automated summary

This study evaluated the weekend effect of air pollutants in Recife, a tropical Brazilian metropolis, during a 2-year period of monitoring, including the post-COVID-19 restrictions period. The results showed no weekend effect in both annual contexts, suggesting minimal impact. However, seasonal variations were observed in the dynamics of air pollutants, which were likely influenced by factors other than meteorological parameters. The study also found an impact of the end of COVID-19 restrictions on the weekend effect in the first year, and a significant correlation between SO2, NO2, and O-3 levels, indicating a shared source for these pollutants. The findings aim to assist in the development of air pollution control policies.