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.

While criteria pollutants have established emission limits for motorcycles in Brazil, aldehydes limits have not been established and conclusive studies have not been found in the existing literature, despite the growing number of motorcycles using flex fuel in Brazil. This work presents results for the emissions of criteria pollutants, such as carbon monoxide, hydrocarbons and nitrogen oxides, acetaldehyde and formaldehyde. The motorcycle was tested with 22, 61, and 100% of ethanol in gasoline blends. Fourier transform infrared (FTIR) and high performance liquid chromatography (HPLC) were used to determine the pre- and post-catalytic converter emissions. Aldehyde emissions directly increased with the ethanol content in the fuel blend. The tailpipe aldehyde emissions for 22, 61, and 100% of ethanol in gasoline were 3.9, 8.5, and 38.8 mg km-1, respectively. These results demonstrated that aldehyde emissions in motorcycles are not negligible, and higher emissions are observed during the cold phase of the engine.

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.