Following hurricanes Katrina and Rita in August 2005, the Federal Emergency Management Agency (FEMA) purchased more than 145,000 travel trailers, park model trailers, manufactured homes, and non-mobile pre-fabricated housing units to provide temporary housing for families who were displaced by the storms and had no other options for housing. This report contains the findings for this investigation, "Evaluation of Mitigation Strategies for Reducing Formaldehyde Concentrations in Unoccupied Federal Emergency Management Agency-Owned Travel Trailers." This research was conducted jointly by the National Center for Environmental Health (NCEH) of the Centers for Disease Control and Prevention (CDC) and the National Aeronautics and Space Administration (NASA) at NASA's John C. Stennis Space Center in Mississippi.