Preliminary studies of the effect of aerosols on nitrogen dioxide photolysis rates in the city of São Paulo, Brazil

To characterize the influence of different particles in the photolysis rates, results were correlated to aerosol composition. Particles that are mostly composed of black carbon had a high impact, decreasing photolysis rates when their concentrations were high. Aerosol optical properties analyzed as single-scattering albedos were found to participate significantly in the reduction of photolysis rates. It was observed that urban aerosols in São Paulo reduce both photolysis rates (round 15%) and ozone concentrations. Comparing July and August, photolysis rates were lower in July due to solar position.