Insights into the dynamics and sources of atmospheric lead and particulate matter in São Paulo, Brazil, from high temporal resolution sampling

We present the first results of a study investigating the processes that control concentrations and sources of Pb and particulate matter in the atmosphere of São Paulo City, Brazil. Aerosols were collected with high temporal resolution (3 hours) during a four-day period in July 2005. The highest Pb concentrations measured coincided with large fireworks during celebration events and associated to high traffic occurrence. Our high-resolution data highlights the impact that a singular transient event can have on air quality even in a megacity. Under meteorological conditions non-conducive to pollutant dispersion, Pb and particulate matter concentrations accumulated during the night, leading to the highest concentrations in aerosols collected early in the morning of the following day. The stable isotopes of Pb suggest that emissions from traffic remain an important source of Pb in São Paulo City due to the large traffic fleet, despite low Pb concentrations in fuels.