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

During the COVID-19 pandemic, restrictive measures are taken by several cities around the world, as well as Rio de Janeiro, reducing routine activities in large urban centers and primary pollutant emissions. This study aims to assess air quality during this partial lockdown through O 3 , CO, and PM 10 concentrations and meteorological data collected in five air quality monitoring stations spread over the whole city, considering the substantial changes in city routine. The period evaluated starts in March 2020, when the partial lockdown was decreed, and ends in September 2020, when economic opening ended. Compared with 2019 data, CO concentration reduced significantly, as expected since the main source of these pollutants is vehicular traffic. O 3 concentration increased, most probably as a consequence of the reduction in primary pollutants. On the other hand, PM 10 concentration did not vary significantly. From June to September, pollutant concentrations increased responding to the economic opening. Thereby, the partial lockdown contributed to improving air quality in Rio de Janeiro City, which means that changes in work format may be an alternative to reduce atmospheric pollution in big cities, since home office contributes to mobility reductions, and consequently to vehicular emissions. Highlights • Lockdown contributed to CO reduction and O 3 increase. • Differences on rain profile explain low variation on PM 10 concentrations. • Lockdown has been like a very long weekend concerning atmospheric pollution. • Home office and distance learning improve air quality.