The document summarizes a regional particulate matter (PM) event that occurred in the Midwestern United States from January 28th to February 7th, 2005. It provides an overview of the various data sources and tools used to analyze the event, including air quality monitors, satellite images, meteorological data and models. Key findings are that the event lasted 10 days, with peak concentrations lower than typical summer events but over a much longer period, and that different regions of the Midwest peaked at different times during the event.