Foi usado um modelo de trajetórias simples e o modelo químico SAPRC, com inclusão da química do etanol e do metil-terc-butil-eter (MTBE), para simular as concentrações de ozônio na Avenida Brasil, uma rua muito movimentada na cidade de Rio de Janeiro (Brasil), onde pode considerar-se que a principal fonte de poluição são os veículos. O máximo calculado para ozônio, 22,4 ppb às 14:57 h, está em bom acordo com os dados experimentais. Foram calculadas as isopletas de ozônio, usando dados meteorológicos e de emissões apropriados para esse local, mostrando que esses níveis de ozônio na cidade de Rio de Janeiro são uma conseqüência das altas concentrações de NOx.

A simple trajectory model and the chemical mechanism, including the chemistry of ethanol and methyl-tert-butyl ether (MTBE), were used to simulate ozone concentrations at Avenida Brasil, a busy expressway in the city of Rio de Janeiro where emissions from mobile sources are considered to be the major source of air pollution. The calculated ozone maximum of 22.4 ppb at 14:57 h is in good agreement with experimental measurements. Ozone isopleth diagrams were calculated based on the meteorological and emission scenario of that expressway, showing that ozone concentrations in Rio de Janeiro are a consequence of the high levels of NOx .

The plasma etching of semiconductor surfaces with fluorine-containing compounds has technological interest. Presently, considerable effort is being devoted to understand the chemistry involved. In this work, a numerical modeling analysis of the gas-phase decomposition of CF4/O2 mixtures, in the presence of silicon, was performed. The relative importance of individual processes was determined as well as the effect of the parameters' uncertainties. The results were compared with experimental data. The main etching agent in the system is the fluorine atom. The concentration of the main species, SiF4, CO, CO2 and COF2 depend on the composition of the mixture.

In this work, a numerical modeling analysis of the gas-phase decomposition of SF6 / O2 mixtures, in the presence of silicon, was performed. The relative importance of individual processes and the effect of the parameters' uncertainties were determined. The model was compared with experimental data for the plasma etching of silicon and with the calculated results for the CF4 / O2 system. In both systems the main etching agent is the fluorine atom and the concentration of the major species depends on the composition of the mixture. The etching rate is greater for SF6 / O2.

Numerical modeling studies of urban atmospheres were performed with a photochemical box submodel which incorporates primary emission rates, temperature and solar irradiance rate coefficients. Actinic flux calculations were made for an appropriate latitude for Rio de Janeiro and initial concentrations and emission rates were taken from experimental data. The relative importance of individual reactions is discussed as well as the effect of enhanced aldehyde emissions from vehicles using ethanol and ethanol-containing fuel.