Short-term chronic and acute aquatic bioassays are valuable tools in screening a variety of environmental samples. However, only a limited number of studies have used these methods for testing the toxicity of atmospheric particulate matter samples. Previous studies have shown that compounds known to have adverse biological effects, such as polycyclic aromatic hydrocarbons, are deposited in significant quantities into Lake Michigan (USA); however, these compounds comprise a small portion of the total particulate matter deposition. In the present study, a method is described for using Ceriodaphnia dubia, Selenastrum capricornutum (green algae), and MitoScan bioassays to compare the toxicities of reconstituted hard freshwater and methylene chloride extracts of atmospheric particulate matter collected at three locations around the southern shore of Lake Michigan in August 2000. The locations include an urban/industrial site in Milwaukee (WI, USA), an urban-impacted/industrial site in Porter (IN, USA), and a rural site in Bridgman (MI, USA). The bulk chemistry, including organic and elemental carbon, sulfate, nitrate, ammonium, and chloride, shows regional similarities over the sampling event, but the toxicities vary spatially by site, by extraction solvent, and by bioassay. Thus, the bioassays are sufficiently sensitive to show differences in toxicity among the atmospheric particulate matter extracts and have significantly different responses to the samples to enable an initial comparison of toxicity from the different sites.