[en] A regional-scale air quality model incorporating transport dispersion, chemical transformation, dry deposition, and precipitation scavenging was used to test the sensitivity of such models to different treatments of wet removal. Average ground-level air concentration and deposition patterns of SO₂ and sulfate particulate over a 29-day period were produced for the emission estimates of 30 power plant sources in the northeast United States. More than twice the wet removal of SO₂ was observed for the time-averaged precipitation than for the real-time precipitation. The SO₂ not removed in the real-time precipitation case was available for transformation into sulfate particulate and resulted in higher ground-level air concentrations of sulfate particulate by about a factor of two, as well as more deposited sulfate and significantly more sulfate escaping the computational area