The impact of COVID-19 partial lockdown on the air quality of the city of Rio de Janeiro, Brazil.

The first COVID-19 case in Brazil was confirmed on February 25, 2020. On March 16, the state's governor declared public health emergency in the city of Rio de Janeiro and partial lockdown measures came into force a week later. The main goal of this work is to discuss the impact of the measures on the air quality of the city by comparing the particulate matter, carbon monoxide, nitrogen dioxide and ozone concentrations determined during the partial lockdown with values obtained in the same period of 2019 and also with the weeks prior to the virus outbreak. Concentrations varied with substantial differences among pollutants and also among the three studied monitoring stations. CO levels showed the most significant reductions (30.3-48.5%) since they were related to light-duty vehicular emissions. NO2 also showed reductions while PM10 levels were only reduced in the first lockdown week. In April, an increase in vehicular flux and movement of people was observed mainly as a consequence of the lack of consensus about the importance and need of social distancing and lockdown. Ozone concentrations increased probably due to the decrease in nitrogen oxides level. When comparing with the same period of 2019, NO2 and CO median values were 24.1-32.9 and 37.0-43.6% lower. Meteorological interferences, mainly the transport of pollutants from the industrial areas might have also impacted the results.

Air quality monitoring assessment during the 2016 Olympic Games in Rio de Janeiro, Brazil.

In 2009, the city of Rio de Janeiro was announced as the host city of the 2016 Olympic Games (Rio 2016). For this event, the Brazilian government, in partnership with the International Olympic Committee (IOC), undertook the task of monitoring the air quality in the city. This study discusses the PM10, PM2.5, and O3 profiles at ten sampling sites located near the arenas in 2016, including during the Olympic Games period. At all sampling stations, the annual mean values of PM10 and PM2.5 were below either Brazilian air quality standards or United States Environmental Protection Agency (U.S. EPA) guidelines. In addition, no violations lasting 24 h were observed for particulate matter in 2016. Only two ozone episodes occurred in 2016, both in Campos dos Afonsos (163 and 195 µg m-3) near the extreme sports arena. However, during the pre-Olympic period (2013-2015), in the same area were registered 16, 81, and 18 violations per year, respectively. The results showed an improvement in air quality in Rio de Janeiro in 2016. The reduction in pollutant levels, especially O3 and PM2.5, is probably due to the conclusion of the structural construction of the Olympic arenas and efforts to improve urban mobility.