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.
troposphere; aldehyde pollution; numerical modeling
