On November 19, 2018, 30 years after establishment, the updated Brazilian National Air Quality Standards (NAQS) were published. These NAQS were formulated as a fundamental part and instrument of the National Program for the Control of Air Quality and considering, as a reference, the World Health Organization Air Quality Guidelines, published in 2005. An important contribution is the inclusion of PM2.5 (particulate matter with an aerodynamic diameter less than 2.5 µm) as a criteria pollutant and a more restrictive target limit for PM10 (particles that have aerodynamic diameters less than or equal to 10 µm). In this work, the NAQS were discussed using, as a case study, data collected during the 2016 Olympic and Paralympic Games. The lack of PM2.5 data for Brazilian cities results in the calculation of a lower air quality index (AQI), leading to ostensibly good air quality. The results presented in this study clearly support the requirement of improvement of the new resolution since, in the present form, it does not meet the main goal of protecting public health.

Atmospheric processes in an urban scenario are very complex and depend on meteorological parameters, emission, transport and deposition processes and the chemical mechanism. Simple air quality models can be used to understand the main aspects of ozone formation and provide information to adopt pollution control strategies. In this work the detailed simulation of ozone concentrations using the air quality model OZIPR (Ozone Isopleth Package for Research) coupled with the SAPRC (Statewide Air Pollution Research Center) chemical model is presented. First, the methods to determine volatile organic compounds (VOCs) are described as well as the statistical treatment of experimental data: Meteorological parameters (temperature, humidity, pressure, wind speed and direction), concentrations of nitrogen oxides (NOx = NO2 + NO), carbon monoxide (CO) and ozone (O3), which are needed to characterize the problem. Then, the construction and adjust of the model (base case) is detailed using, as an example, data for a typical urban area in the city of Rio de Janeiro. Finally, the limitations and the potential of the model are discussed. Clearly the quality of experimental data, mainly NOx and COVs concentrations and the COVs speciation, are a key information to obtain a correct estimation of O3 levels.

The air quality during the Summer 2016 Olympic Games in two Olympic zones, Maracanã (Tijuca) and Deodoro, was studied. Volatile organic compounds (VOCs) were collected and analyzed following method TO-15 (United States Environmental Protection Agency), during and in the days after the Games. The total VOC (C4-C12) concentrations were 39.2-160.9 and 36.6-191.4 µg m-3 for Tijuca and Deodoro, respectively. These concentrations were lower than values previously obtained in Tijuca and other areas of the city. VOC speciation and benzene/toluene ratios were also different as a consequence of the restrictions imposed on vehicular transit during the Olympic Games. Concentrations were discussed considering the reactivity and ozone forming potential of individual compounds. Criteria pollutants, determined by the Tijuca Automatic Monitoring Station, were also analyzed. The preventive policies were successful in decreasing the concentrations of CO and PM10, leading to a decrease in mean ozone levels. However, air quality indexes were not dramatically reduced, because of the increase in NOx emissions and isolated events of higher ozone levels.

In this work, the air quality indexes (AQIs) determined in Rio de Janeiro from July to September 2016, before and during the Summer Olympic and Paralympic Games, in the monitoring stations operated by the Municipal Secretariat of the Environment, were compiled and analyzed. Only four automatic monitoring stations determined all the Brazilian criteria pollutants (smog, total particulate matter, PM10 (particulate matter < 10 mm), NO2, ozone and SO2). NO2 and PM10 levels were generally lower during the Olympic period because of restrictions on vehicular flux. However, ozone concentrations remained high, due to unfavorable meteorological conditions. The worst conditions were observed in Bangu and Irajá Districts, where ozone concentrations frequently exceeded 160 mg m-3. According to the World Health Organization (WHO), as ozone concentrations increase above this value, health effects became increasingly numerous and more severe. Brazilian air quality allowable standards are clearly higher than WHO guidelines, which, in addition to the combined results of the adopted air quality indexes and the use of a restricted number of criteria pollutants to report the air quality, led to AQIs in the intervals good and moderate, despite concentrations frequently being high in terms of WHO guidelines.

A new sampling method using polypropylene syringes and chemical analysis by gas chromatography was proposed and applied to determine CO2, CH4 and N2O. The samples' stability was evaluated and compared with the stability of the samples in stainless steel canisters and Tedlar® bags. This methodology was applied to a case study in the urban area of the city of Rio de Janeiro, Brazil. In 2012, annual averages of 507.6 ± 13.2 µmol mol-1 for CO2, 1.95 ± 0.06 µmol mol-1 for CH4 and 325.3 ± 3.4 nmol mol-1 for N2O were obtained. The results for CO2 and CH4 showed peak values in the warmer months and lower values in winter. This CO2 behavior is the opposite of that observed in studies performed in many other cities around the world and may be climate-related. CH4 and N2O inputs are probably due to the evaporation of liquid and solid waste both from landfill sites located within the city boundaries and from polluted rivers and canals. Additionally, other anthropogenic sources may be considered, such as the release of CH4 by the gas fuel network of the urban area and the emissions due to the use of compressed natural gas by light vehicles.