This study evaluated the pollutant levels (NO2, SO2, CO, and O3), air quality index (AQI) and the influence of meteorological variables and coronavirus disease (COVID-19) pandemic on the air quality in Rio de Janeiro. The data set used comprises periods before (March-April, 2019) and during pandemic (March-April, 2020). According to the AQI results, on most days, the air quality was ranked as “good”. Brazilian air quality standards for SO2, O3, and NO2 were not exceeded in any of the monitoring stations during partial lockdown, while CO exceeded in all periods in one site due to industrial emission. Comparing both periods, descriptive statistics for the meteorological parameters presented no differences, which suggests similar conditions. However, when evaluated week by week in 2020, weather conditions presented some differences that probably affected pollutant concentrations. The correlations between O3 and NO2 and some meteorological parameters indicate that variations in both favored ozone formation, since it is a photochemical process favored by temperature and solar radiation and that, in Rio de Janeiro, low NO2 concentrations lead to increased O3. The improvements on air quality during the partial lockdown may be attributed mainly to a reduction on emission sources rather than weather conditions.

Cities urbanization and modernization increase emission sources, contributing to particulate matter (PM) composition heterogeneity and enhance the risk to human health and environment. This paper intends to survey the studies on particulate matter carried out in the state of Rio de Janeiro. The sampling of PM is generally made using Hi-Vol samplers to collect particles in fiberglass filter during 24 h every 6 days. Spectrometric techniques are used for elemental determination and ion chromatography for water-soluble species. The Environmental State Institute (INEA) is responsible for air quality monitoring in RJ. After 30 years, air quality standards have become more stringent and have included new pollutants. The highest PM concentrations were found in urban and industrial sites and the lowest in places away from urban activities or near the coast. Over the years, PM concentrations near steel complexes reduced even below the limits and varied at other places, remaining above the limits. Nitrate and sulfate were the main ionic compounds, and Fe, Al and Zn were the major elements in PM samples. It was also found Ni, V, Cd, Pb and Cu. Although air quality monitoring is efficient, it still needs to be improved to help reduce the environmental impact.

Coarse particulate matter (PM10) concentrations and chemical composition were monitored from 2014 to 2017 at three sampling sites in the Metropolitan Region of Rio de Janeiro, namely Botafogo, Gávea, and Gericinó. All sites are located close to the 2016 Olympic Game arenas. The average annual PM10 concentrations were above the limits recommended by the World Health Organization (WHO) at all sampling sites. Of all the analyzed water-soluble ions, the highest concentrations were obtained for NO3-, SO42-, Cl- and Na+. Sulfate displayed a higher anthropic contribution (ca. 70%). Iron and copper were present in all samples, originated from soil resuspension and traffic (fuels and brakes, among others). Overall, civil works to restructure the city and the construction of the Olympic Game arenas increased PM10 and some of its constituent levels prior to 2016. After the Olympic Games, PM10 concentrations have decreased, due to governmental policies regarding traffic planning and civil work finalization.