During the summer of 2002 there was a variety of interesting air quality events in the Philadelphia area. Ground measurements were taken using a three wavelength total and back scattering nephelometer and multiple trace gas analyzers (CO, O3, SO2, NO/NO2/NOx). Aloft measurements up to 300m AGL were taken using a tethered atmospheric sounding system, which recorded conventional meteorological variables, ozone concentrations and particle concentrations using laser diode scatterometry. Back trajectories combined with emissions data from the Environmental Protection Agency will be used to identify the possible sources of trace gases. ArcGIS is employed to evaluate source-receptor relationships, dispersion of pollutants along trajectories, and elucidate transport mechanisms. In-depth analysis of events such as the haze event of July 1-3, the Canadian smoke event on July 5-8, the sea breeze event of July 20, and other high ozone episodes will be included.